Chapter 8 Cryptography

Currently there are 15 published PKCS standards what are they?

1. PKCS #1: RSA Cryptography Standard 2. PKCS #2: Incorporated in PKCS #1 3. PKCS #3: Diffie-Hellman Key Agreement Standard 4. PKCS #4: Incorporated in PKCS #1 5. PKCS #5: Password-Based Cryptography Standard 6. PKCS #6: Extended-Certificate Syntax Standard 7. PKCS #7: Cryptographic Message Syntax Standard 8. PKCS #8: Private-Key Information Syntax Standard 9. PKCS #9: Selected Attribute Types 10. PKCS #10: Certification Request Syntax Standard 11. PKCS #11: Cryptographic Token Interface Standard 12. PKCS #12: Personal Information Exchange Syntax Standard 13. PKCS #13: Elliptic Curve Cryptography Standard 14. PKCS #14: Pseudorandom Number Generators 15. PKCS #15: Cryptographic Token Information Format Standard These standards are coordinated through RSA; however, experts worldwide are welcome to participate in the development process.

SHA is a one-way hash that provides?

A hash value that can be used with an encryption protocol. This algorithm produces a 160-bit hash value.

The second major reason for implementing a cryptographic system involves providing assurance that?

A message wasn't modified during transmission. Modification may render a message unintelligible or even worse, inaccurate. Image the consequences if record alterations weren't discovered in medical records involving drug prescriptions. If a message is tampered with, the encryption system should have a mechanism to indicate that the message has been corrupted or altered.

Know the principals of symmetric algorithm?

A symmetric algorithm requires that receivers of the message use the same private key. Symmetric algorithms can be extremely secure. This method is widely implemented in governmental applications.

What is a extended validation certificate?

As the name suggest, require more validation of the certificate holder; thus, they provide more security.

A substitution cipher is a type of?

Coding or ciphering system that changes one character or symbol to another.

The study of how to break cryptographic algorithms is called?

Cryptanalysis. The two subjects taken together are generally referred to as cryptology. All of these disciplines require a strong mathematics background, particularly in number theory.

Whether you are using asymmetric or symmetric cryptography, it is important to use only proven?

Cryptographic technologies.

In addition to understanding the essentials of cryptography algorithms and techniques, you should understand the implementation of cryptography.

Cryptography is implemented as part of your network infrastructure.

The study of cryptographic algorithms is called?

Cryptography.

Another issue in using cryptographic system is when you should encrypt the?

Data

In cryptography, latency refers to the?

Difference between the time you input plain text and the time get out cipher text. You might think that it would be good simply to keep churning away at input, scrambling it more and more. However, low latency is a goal of any cipher. This is particularly important in lower-power devices. The longer it takes to encrypt data, the more power is consumed.

The Message Digest Algorithm (MD) also creates a?

Hash value and uses a one-way hash. The hash value is used to help maintain integrity. There are several versions of MD; the most common are MD5, MD4, and MD2.

Be able to describe the process of a hashing algorithms?

Hashing algorithms are sued to generate a fixed-length value mathematically from a message. The most common hashing standards for cryptographic applications are SHA and MD algorithms.

Cryptography is a field almost as old as?

Human kind. The first recorded cryptographic efforts occurred 4,000 years ago. These early efforts included translating messages from one language into another or substituting characters. Since that time, cryptography has grown to include a plethora of possibilities. Ultimately, all cryptography seeks to obfuscate the plain text so that it is not readily readable. Classic methods used relatively simple techniques that a human being could usually break in a reasonable amount of time. The obfuscation used in modern cryptography is much more sophisticated and can be unbreakable within a practical period of time.

What does the brute force method involve?

Is simply involves trying everything possible key. It is guaranteed to work, but it is likely to take so long that it is simply not usable. For example, to break a Caesar cipher, there are only 26 possible keys, which you can try in a very short time. But even DES, which has a rather wea key, would take different attempts. That is 72,057,594,037,927,936 possible DES keys. To put that in perspective, if you try 1 million keys per second, it would take you just a bit over 46,190,765 years to try them all.

What is a key recovery agent?

It is an entity that has the ability to recovery a key, key components, or plain text messages as needed. Obviously, a key recovery agent is a sensitive position. This person could potentially access all of the keys for a given key escrow. This is an excellent place to implement separation of duties so that no one person can independently access the key escrow account.

What is EL Gamal?

It was developed by Taher El Gamal in 1984. It is an asymmetric algorithm, and several variations of El Gamal have been created, including Elliptical Curve El Gamal. El Gamal and related algorithms use what is called ephemeral key. An ephemeral key is simply a key that exists only for that session. Essentially, the algorithm creates a key to use for that single communication session, and it is not used again. Not as many asymmetric algorithms have been discussed here as have symmetric encryption algorithms, but it can still be difficult keeping all of them straight.

Microsoft replaced the LANMAN protocol with?

NTLM (NT Lan Manager) with the release of Windows NT.

What are the numerous standards?

Numerous standards are available to establish secure services. Some of the standards that will be presented in the following sections have already been discussed in greater detail in earlier chapters. The movement from proprietary governmental standards toward more unified global standards is a growing trend that has both positive and negative implications. Higher interoperability between disparate systems will also mean that these standards will be widely used. The more that standards are used, the more that attackers will focus on them to try to break them. As a security administrator, you have to weigh the pros and the cons of the various standards and evaluate them against your organization's needs.

Now many government agencies are involved in the creation of standards for secure systems?

Several. They either directly control specific sectors of government or provide validations, approval, and support to government agencies.

A cryptographic system is a?

System. Method, or process that is used to provide encryption and decryption. It may be hardware, software, or manually preformed process. Cryptographic systems exist for the same reasons that security exists: to provide confidentiality, integrity, authentication, nonrepudiation, and access control.

What is PEM?

The PEM extension is used for different types of X.509v3 files that contain ASCII (Base 64) armored data prefixed with a BEGIN line.

The government uses cryptography to help ensure?

The safety and well-being of its citizens. Entire governmental agencies have been created to help ensure secrecy, and millions of dollars have been spent trying to protect national secrets of other countries.

What is P7b?

These are base 64 encoded ASCII files. They actually include several variations: P7B, P7C, etc.

There are two primary approaches to key exchange what are they?

They are in-band key exchange and out-of-band key exchange.

Corporations want—and need to protect what?

They need to protect financial records, trade secrets, customer lists, and employment information.

Symmetric methods use what?

They use either a block or stream cipher.

What are code signing certificates?

They were mentioned earlier. These are X.509 certificates used to digitally sign some type of computer code.

What is PFX?

This is an archive file for PKCS#12 standard certificate information.

What is P12?

This refers to the sue of PKCS#12 standard.

SHA-2 is the most widely?

Used algorithm for when it comes to the secure hash algorithm, but SHA-3 has been released.

Usually, secrete algorithms have not been properly?

Vetted. The cryptology community has not been given the opportunity to examine the algorithm for flaws. This all leads to a basic principle: you should only use proven cryptography technology—that is, avoid new and "secret" methods.

The most famous example of a multi-alphabet substitution from historical times was the?

Vigenere cipher. It used a keyword to look up the cipher text in a table. The user would take the first letter in the text that they wanted to encrypt, go to the Vigenere table, and match that with the letter from the keyword in order to find the cipher text letter. This would be repeated until the entire message was encrypted. Each letter in the keyword generated a different substitution alphabet.

The public key cryptography standards (PKCS) is a set of?

Voluntary standards created by RSA and security leaders. Early members of this group included Apple, Microsoft, DEC (now HP), Lotus, Sun, and MIT.

What is Diffie-Hellman?

Whitfield Diffie and Martin Hellman conceptualized the Diffie-Hellman key exchange. They are considered the founders of the public/private key concept. This algorithm is used primary to generate a shared secret key across public networks. The process isn't used to encrypt or decrypt messages; it's used merely for the creation of a symmetric key between two parties. An interesting twist it's that the method had actually been developed a few years earlier by Malcom J Williamson of the British Intelligence Service, but it was classified.

Many wireless routers also provide the option of using?

Wi-Fi protected setup (WPS) to establish an initial connection. WPS uses a PIN to connect to the wireless access point. This means that for the first connection you only need the PIN in order to connect. This is quite convenient but it does open up a system to a particular attack. The WEPS attack attempts to intercept the PIN in transmission, connect the WAP, and then steal the WPA2 password.

At some point, all symmetric ciphers use an?

XOR operation as part of their algorithm. By itself, XOR would be a very weak encryption algorithm—so weak, in fact that it would probably not be accurate to consider it encryption, at least not by modern standards. However, it is a part of symmetric ciphers and combined with a number of other operations.

Modern cryptography is divided into three major areas what are they?

o Symmetric cryptography o Asymmetric cryptography o And hashing algorithms o All three of these are covered extensively on the Security+ certification exam.

Regardless of which vendor's implementation is being discussed, the steps can be summarized as illustrated. Here is the complete handshake process.

1. The client sends the server the client's SSL version number, cipher settings, session specific data, and other information that the server needs to communicate with the client using SSL. 2. The sever sends the client the server's SSL version number, cipher settings, session specific data, and other information that the client needs to communicate with the server over SSL. The server also sends its own certificate, and if the client is requesting a server resource that requires client authentication, the server requests the client's certificate. 3. The clients uses information sent by the server to authenticate the server—for example, in the case of a web browser connecting to a web server, the browser checks, whether the received certificate's subject name actually matches the name of the server being contacted, whether the issuer of the certificate is a trusted certificate authority, whether the certificate has expired, and ideally, whether the certificate has been revoked. If the server cannot be authenticated, the user is wared of the problem and informed that an encrypted and authenticated connection cannot be established. If the server can be successfully authenticated, the client proceeds to the next step. 4. Using all the data generated I the handshake thus far, the client (with the cooperation of the server, depending on the cipher in use) creates the pre-master secret for the session, encrypts it with the server's public key (obtained from the server's certificate, sent in step 2), and then sends the encrypted pre-master secret to the server. 5. IF the server has requested the client authentication (an optional step in the handshake), the client also signs another piece of data that is unique to this handshake and known by both the client and server. In this case, the client sends both the signed data and the client's own certificate to the server along with the encrypted pre-master secret. 6. If the server has requested client authentication, the server attempts to authenticate the client. If the client cannot be authenticated, the session ends. If the client can be successfully authenticated, the server uses its private key to decrypt, the pre-master secret, and then performs a series of steps (which the client also performs, starting from the same pre-master secret) to generate the master secret. 7. Both the client and server use the master secret to generate the session keys, which are symmetric keys used to encrypt and decrypt information exchanged during the SSL session and to verify its integrity (that is, to detect any changes in the data between the time it was sent and the time it is received over the SSL connection). 8. The client sends a message to the server informing it that future messages from the client will be encrypted with the session key. It then sends a separate (encrypted) message indicating that the client portion of the handshake is finished. 9. The server sends a message to the client informing it that future messages from the server will be encrypted with the session key. It then sends a separate (encrypted) message indicating that the server portion of the handshake is finished. This session will stay open until one end or the other issues a command to close it. The command is typically issued when a browser is closed or another URL is requested. · As a security administrator you will occasionally need to know how to configure? o SSL/TLS settings for a website running on your operating system. You should also know that, in order for SSL/TLS to work properly, the clients must be able to accept the level of encryption that you apply. Modern browsers can work with 128-bit encrypted sessions/certificates. Earlier browsers often needed to use 40 or 56-bit SSL encryption. As an administrator, you should push for the latest browsers on all clients. Verisign used a cleaver advertising strategy that makes this point readily comprehensible: It mailed flyers in a clear bag with the lines "Sending sensitive information over the Web without the strongest encryption is like sending a letter in a clear envelope. Anyone can see it." This effectively illustrates the need for the strongest SSL possible.

There are three primary times when data might be encrypted what are they?

1. The first is when data is simply stored—for example, on a hard drive. This is referred to data at rest. 2. The second is when data is being transmitted from point A to point B. This is called data is transit. 3. Finally, should data be encrypted when it is actually being used? This is referred to as data in use. o As a general rule, if it is possible to encrypt data in any of these three states, without unduly interfering with the ability to legitimate users to use the data, then it should be encrypted. Encrypting data at rest is very common, and there is really no compelling reason to not do so.

The National Institute of Standards and Technology, which was formerly known as the National Bureau of Standards (NBS), has been involved in developing and supporting standards for the U.S. government for over?

100 years. NIST has become involved in cryptography standards, systems, and technology in a variety of areas. It's primary concerned with governmental systems, and it exercises a great deal of influence on them. NIST shares many of its findings with the security community because business needs are similar to government needs. NIST publishes information about known vulnerabilities in operating systems and applications. You'll find NIST helpful in a battle to secure systems.

The request for comments (RFC) originated in?

1969, the mechanism used to purpose a standard. It's a document-creation process with a set of practices. An RFC is categorized as a standard (draft or standard), best practice, informational, experimental, or historic.

The SHA-3 standard was published in?

2012, but it is still not widely used. This is not due to any problem with SHA-3, but rather the fact that SHA-1 is perfectly fine. It should also be noted that in 2016, issues with SHA-1 were discovered and it is recommended that you use SHA-2 instead.

SHA-2 has several sizes what are they?

224, 256, 334, and 512 bit.

What is Triple DES (3DES)

3DES is a technological upgrade of DES. 3DES is still used even though AES is the preferred choice for government applications. 3DES is considerably harder to break than many other systems, and it's more secure than DES. It also increases the key length to 168 bits (using three 56-bit DES keys).

One of the oldest know substitution ciphers is called the?

Caesar cipher. It was purportedly used by Julius Caesar. The systems involves simply shifting all letters a certain number of spaces in the alphabet. Supposedly, Julius Caesar used a shift of three to the right. He was working in Latin, of course, but the same thing can be done with any language, including English. Here is an example: I will pass the Security plus test. If you shift each letter three to the right, you will get the following: L zloo sdvv wkh Vhfxulwb soxv whvw.

Certificate chaining refers to the fact that certificates are handled by a?

Chain of trust. You purchase a digital certificate from a certificate authority (CA), so you trust that CA's certificate is a tificate. In turn, that CA trusts a root certificate. In this example the CA's certificate is an intermediate CA, and the ultimate trusts is the root certificate.

One of the first steps to in getting a certificate is to submit?

A certificate-signing request (CSR). This is a request formatted for the CA. The request will have the public key that you wish to use and your fully distinguished name (often a domain name) The CA will then use this to process your requests for a digital certificate. Cas can be either private or public, with companies like DigiCert, Verisign, and others providing certificates to the general public. Many operating system providers allow their systems to be configured as CA systems. These CA systems can be used to generate internal certificates that are sued within a business or in large external settings. The process of providing certificates to users, although effective in helping to ensure security, requires a server. Over time, the server can become overloaded and need assistance. An additional component, the registration authority, is available to help offload work for the CA.

Draft documents are processed through?

A designated RFC editor, who makes sure that the document meets publication standards. Editors play a key role in the RFC process; they are responsible for making sure that proposals are documented properly, and they manage the discussion. The RFC is then thrown open to the computer-user community for comments and critique. This process ensures that all interested parties have the opportunity to comment on an RFC.

What is PRNG?

A pseudo-random number generator is an algorithm used to generate a number that is sufficiently random for cryptographic purposes.

Secure sockets Layer (SSL) is used to establish?

A secure communication connection between two TCP-based machines. This protocol uses the handshake method of establishing a session. The number of steps in the handshake method depends on whether steps are combined and/or mutual authentication is included. The number of steps is always between four and nine, inclusive, based on who is doing the documentation. One of the early steps will always be to select an appropriate cipher suite to use. A cipher suite is a combination of methods, such as an authentication, encryption, and message authentication code (MAC) algorithms used together. Many cryptographic protocols such as TLS use a cipher suite.

Nonrepudiation prevents one party from denying?

Actions that they carried out. To use an analogy, image coming home to find your home's picture window broken. All three of you kids say they did not do it, and the babysitter says it must have been broken when she arrived. All of the parties who could be guilty are "repudiating" the fact that they did it, and its their word against common sense. Now, imagine that you had a nanny-cam running and were able to review the video and see who actually broke it. The video cancels out their saying that they knew nothing about eh broken window and offers "nonrepudiation" of the facts. o In the electronic world, a similar type of proof can be achieved in a two-key system. The problem is that anyone can claim to be a legitimate sender, and if they have access to this type of system, they can send you a public key. So, although you have received the message, you would have no way of verifying that the sender is really who they say they are, and you need nonrepudiation to verify that the sender is who they say they are.

With a rainbow table, all of the possible hashes are computed in?

Advanced. In other words, you create a series of tables; each has all the possible two-letter, three-letter, four-letter, and so forth combinations and the hash of that combination, using a known hashing algorithm like SHA-2. Now if you search the table, for a given hash, the letter combination in the table that produced the hash must be the password that you are seeking. Popular password cracking tools, such as OphCrack, use rainbow tables.

As the name implies, with a block cipher, the algorithm work on?

Chunks of data, encrypting one and then moving to the next.

Most digital signature implementations also use a hash to verify that the message has not been?

Altered, intentionally or accidently, in transit. In fact, what is normally singed is the hash of the message. The receiver compares the singnature area referred to as a message digest in the message with the calculated value. If the values match, the message hasn't been tampered with and the originator is verified as the person they claim to be. This process provides message integrity, nonrepudiation, and authentication. Since this process provides nonrepudiation, the receiver can be confident the message was sent by the sender, not someone pretending to be the sender. In some cases, digital signatures are also part of authentication. For example, a user logs in and provides their username and password, but the login information is digitally singed.

Cryptography is the science of?

Altering information so that it cannot be decoded without a key. It is the practice of protecting information through encryption and transformation. As data becomes more valuable, it is an area of high interests to governments, businesses, and, increasing individuals. People want privacy when it comes to their personal and other sensitive information. '

Atbash is another?

Ancient substitution cipher. Hebrew scribes copying the book of Jeremiah used this substitution cipher. Applying the Atbash cipher is fairly simple—just reverse the order of the letters of the alphabet. This is, by modern standards, a very primitive and easy-to-break cipher. For example, in English: A becomes Z, B becomes Y, C becomes X, and so forth. Of course, the Hebrews used a different alphabet, with aleph being the first letter and tav the last letter. However, I will use English examples to demonstrate this: Attack at dawn becomes Zggzxp zg wzdm.

What are wildcard certificates?

As the name suggest, they can be used more widely, usually with multiple subdomains of a given domain. So rather than have a different X.509 certificate for each subdomain, you would use a wildcard certificate for all subdomains.

Be able to describe the process of asymmetric algorithms?

Asymmetric algorithms use a two-key method of encryption. The message is encrypted using the public key and decrypted using a second key or private key. The key is derived from the same algorithm.

The need to keep records secure from internal disclosure may be just as great as the need to keep records secure from outside?

Attacks. The effectiveness of a cryptographic system in preventing unauthorized decryption is referred to as its strength. A strong cryptographic system is difficult to crack. Strength is also referred to as the algorithm's work factor: the work factor describes an estimate of the amount of time and effort that would be necessary to break a system. The system may be considered weak if allows weak keys, has defects in its design, or is easily decrypted. Many systems available today are more than adequate for business and personal use, but they are inadequate for sensitive military or governmental applications.

What is Blowfish and Two fish?

Blowfish is an encryption system invented by a team led by Bruce Schneier that performs a 64-bit block cipher at very fast speeds. It is a symmetric block cipher that can use variable-length keys (from 32 bit to 448 bits). Two-fish is quite similar, and works on 128-bit blocks. The distinctive feature of the latter is that it has a complex key schedule.

In a chosen plain text attack the attacker obtains the?

Cipher text corresponding to a set of plain texts of their own choosing. This allows the attacker to attempt to derive the key used and thus decrypt other messages encrypted with that key. This can be difficult, but it is not impossible. Advanced methods such as differential cryptanalysis are types of chosen plain-text attacks.

The Rail Fence Cipher is a?

Classic example of a transposition cipher. With this cipher, you write message letters out diagonally over a number or rows and then read off cipher row by row. For example, you write the message out as: mematrhtgpry etefeteoaat yielding the cipher text: MEMATRHTGPRYETEEETEOAAT.

Digital signatures are also used for?

Code signing. When code is distributed over the Internet, be it some device driver or ActiveX web component, it is essential that the user be able to trust that it was really produced by the claimed sender. An attacker would very much like to produce a fake device driver or web component that purported to be from some major vendor but was really malware. Using code signing mitigates this danger.

The National Security Agency is responsible for creating?

Codes, breaking codes, and coding systems for the U.S. government. The NSA was chartered in 1952. It tries to keep a low profile, for many years, the government didn't publicly acknowledge its existence. The NSA is responsible for obtaining foreign intelligence and supplying it to the various U.S. government agencies that need it. It's said to be the world's largest employer of mathematicians. The NSA's missions are extremely classified but its finger is in everything involving cryptography and cryptographic systems for the U.S. government, government contractors, and the military.

The RFC process allows open?

Communication about the Internet and other proposed standards. Virtually all standards relating to the Internet that are adopted go through this process. Several industrial associations have assumed roles that allow them to address specific environments.

As mentioned at the beginning of the chapter, early cryptography standards were primarily designed to secure?

Communications for the government and military. Many different standards groups exist today, and they often provide standards that are incompatible with the standards of other groups. These standards are intended to address the specific environments in which these groups exist.

Another mode called; Galois Counter Mode (GCM) is a bit more?

Complex than ether ECB or CBC. This mode uses a hash function of a binary Galois field to provide encryption that is authenticated. In normal counter mode, each block is encrypted with a cipher in a sequential manner to produce a stream cipher. The GCM uses a Galois field with a hash to have an authenticated cipher. The details of the Galois fields are beyond the scope of the Security+ exam.

Historical methods of cryptography predate the modern?

Computer age. These methods did not depend on mathematics, as many modern methods do, but rather on some technique for scrambling the text.

One of the major reasons to implement a cryptographic system is to ensure the?

Confidentiality of the information being used. Confidentiality may be intended to prevent the unauthorized disclosure of information in a local network or to prevent the unauthorized disclosure of information across a network. A cryptographic system must do this effectively in order to be of value.

The other concept that is relevant to symmetric ciphers is?

Confusion. This term is not a reference to how you might feel after reading a chapter on cryptography. It is instead the concept that the relationship between the plain text, cipher text, and key are very difficult to see. This can be best understood by examining the opposite. Consider the XOR operation previously described. In that operation, the relationship between plain text cipher text, and the key is very easy to see. There is virtually no confusion at all. Modern symmetric ciphers are structed so that they have a great deal of confusion.

The Wi-Fi Protected Access (WPA) and Wi-Fi protected Access 2 (WPA2) technologies were designed to address the?

Core problems with WEP. WPA couples the RC4 encryption algorithm with TKIP (Temporal Key Integrity Protocol)

Part of implementation is the selection of?

Cryptographic modules and cryptographic providers. It is very unlikely that you will program you own cryptography background. Therefore, you will use some third-party cryptographic modules and providers. One of your goals of your leaning more about cryptography is that you can ask the right questions of such vendors. For example, you should ask about their key generation and key storage models. Other issues include time and power consumption. A cryptographic module that is slow might not be useful for commercial solutions. A cryptographic module that requires significant power won't be useful for low-power devices. This is essentially a comparison of resources versus security. Cleary security is critical, but the cryptographic solution should not be a strain on system resources.

The sender sues a private key to create a?

Digital signature. The message is, in effect, signed with the private key. The sender then sends the message to the receiver. The receiver uses the public key of the sender to validate the digital signature. If the value matches, the receiver knows the message is authentic. The receiver uses a key provided by the sender—the public key—to decrypt the message.

A symmetric key, sometimes referred to as a secret key or private key is a key that is not?

Disclosed to people who are not authorized to use the encryption system. The disclosure of this secret key breaches the security of the encryption system. If a key is lost or stolen, the entire process is breached. These types of systems are common, but the keys require special handling.

Asymmetric algorithms use two keys to?

Encrypt and decrypt data. These asymmetric keys are referred to as the public-key and the private key. The sender uses the public key to encrypt a message, and the receiver uses the private key to decrypt the message; what one key does, the other one undoes. As you may recall, symmetrical systems require the key to be private between the two parties.

With a stream cipher the data is?

Encrypted one bit, or byte at a time.

Some other methods are not truly cryptanalysis, but rather means to get at passwords that someone might have used when they?

Encrypted something. For example, when someone encrypts a hard drive, the user must select a password for later decrypting the password. If the user selected a weak password, then it could be vulnerable to a dictionary attack.

Character substitution can be a relatively easy method of?

Encrypting information.

Human error is one of the major causes of?

Encryption vulnerabilities. If an email is sent using an encryption scheme, someone else may need it in the clear (unencrypted). If a cryptanalyst gets ahold of both messages, the process of decoding future messages will be considerably simplified. A code key might wind up in the wrong hands, giving insights into what the key consists of. Many systems have been broken into as a result of these types of accidents. A classic example involved the transmission of sensitive military-related messages using an encryption system.

An alternative to the freeware PGP is?

GPG (GNU Privacy guard). It is part of the GNU project by the Free Software Foundation., and it is interoperable with PGP. Like its alternative, PGP, it is considered a hybrid program since it uses a combination of symmetric and public key cryptography. This free replacement of PGP can be downloaded from ww.gnupg.org.

MD5 is the newest version of this algorithm. IT produces a 128-bit?

Hash, but the algorithm is more complex than its, processors, and offers greater security. Its biggest weakness is that it does not have strong collision resistance, and thus it is no longer recommended for use. SHA (1 or 2) is the recommended alternatives.

Steganography is the process of?

Hiding a message in a medium such as digital image, audio, file, or other file. In theory, doing this prevents analysts from detecting the real message. You could encode your message in another file, or message and use that file to hide your message. The most common way this is done today called the least significant bit (LSB) method. As you know, everything on a computer is stored in bits that are organized into bytes. For example, a single pixel on a Windows computer screen is stored in 3 bytes/24 bits. If you changed the very last bit (the least significant bit in each byte), then that would not make a noticeable change in the image. In other words, you could not tell that anything had been changed. Using this fact, you can store data by putting it in the least significant bits of an image file. Someone observing the image would see nothing out of the ordinary, It is also possible to hide data in audio files, video files, or literally any digital file type. There are even programs available on the Web for doing steganography. Quick-Stego is a free and easy-to-use program. Invisible Secrets is fairly inexpensive and quite robust.

Hashing is an acceptable integrity check for many situations. However, if an intercepting party wishes to alter a message intentionally and the message is not also encrypted, then the hash is said to be?

Ineffective. The intercepting party can see that there is a 160-bit value, for example, attached to the message. Since SHA-1 produces a 160-bit digest, they can assume that this is a SHA-1 digest. Then the interceptor can simply alter the message as they wish, delete the original SHA-1 hash, and then recalculate a hash from the new, altered message. Note that this terms hash, digest, message digest, and hash value are used interchangeably. A common method of verifying integrity involves adding a message authentication code (MAC) to the message. A MAC is calculated by using a symmetric cipher in cipher block chaining mode (CBC) with only the final block being produced. Essentially, the output of CBC is being used like the output of a hashing algorithm. However, unlike a hashing algorithm, the cipher requires a symmetric key that is exchanged between the two parties in advance. Someone attempting to intercept the message and alter it would not have the key and would not be able to re-create the MAC value.

Integrity can be accomplished by adding?

Information such as redundant data that can be used as checked using a hashing algorithm. Essentially, a hash of the message is generated and appended to the end of the message. The receiving party calculates the hash of the message they received and compares it to the hash they received. IF something changed in transit, the hashes won't match.

Essentially, TKIP mixes a root key with an?

Initialization vector. The key mixing means that there is effectively a new key for each packet.

Another use of PRNGs is to generate?

Initialization vectors (IVs). IVs are numbers that should be used only once and are added to a key to make the algorithm stronger. In fact, the term used in cryptography is nonce (number used only once). As one example, 64-bit WEP uses a 40-bit RC4 key that will be used from some period of time, perhaps moths. However, with each 40-bit key is a 24-bit IV that is only used one time. This means that even if someone should crack the 40-bit RC4 key, they would still not be able to decrypt the message.

The Institute of electrical and electronics engineers (IEEE) is an?

International organization focused on technology and related standards. The IEEE is organized into several working groups and standards committees. IEEE is actively involved in the development of PKC, wireless, and networking protocol standards.

What does key escrow address?

It addresses the possibility that a cryptographic key may be lost. The concern is usually with symmetric keys or with the private key in asymmetric cryptography. If that occurs, then there is no way to get the key back, and the user cannot decrypt messages. Companies that implement encryption throughout their organization often establish key escrows in order to be able to recover lost keys.

What is BitLocker to go?

It allows you to apply the same technology to removeable media. This often means encrypting removable hard drives and USB flash drives, you can also prevent them from being so destructive when intercepted by the wrong hands. There are also several other data encryption technologies beyond BitLocker including the widely used VeraCrypt. Both tools allow you to encrypt either the entire disk or just portions. For example, one might use individual file encryption. A related concept is database encryption. Many relational database systems, such as Microsoft SQL Server, have the option to encrypt the database.

What is a trusted platform module (TPM)?

It can be used to assist with cryptographic key generation. TPM is the name assigned to a chip that can store cryptographic keys, passwords, or certificates. TPM can be used to protect smartphones and devices other than PCs as well. It can also be used to generate values used with whole disk encryption such as BitLocker. BitLocker can be used with or without TPM, it is much more secure when coupled with TPM (and is preferable) but does not require it. The TPM chip may be installed on the motherboard; when it is, in many cases it is set to off in the BIOS by default. More information on TPM can be found at the Trusted Computing Groups website.

What is and in-band key exchange?

It essentially means that they key is exchanged within the same communications channel that is going be encrypted. IPsec, uses in-band key exchange.

WPA2 favors what?

It favors Counter Mode with Cipher Block Chaining Message Authentication Code Protocol (CCMP). CCMP uses 128-bit AES. The most important thing to recall about WPA2 is that it fully implements the 802.11i Wi-Fi security standards.

Data Encryption Standard (DES) what is it?

It has been sued since the mid-1970's. it was the primary standard used in government and industry until it was replaced by AES. It's based on a 56-bit key, and has several modes that offer security and integrity. It is now considered insecure because of the small key size. Note that DES actually generates a 64-bit key, but 8 of those bits are just for error correction and only the 56 bites are the actual key.

What does frequency involve?

It involves looking at blocks of an encrypted message to determine if any common patterns exist. Initially, the analyst doesn't try to break the code but looks at the patterns in the message. In the English language, the letters e and t and words like the, and, that, and is are very common. Single letters that stand alone in a sentence are usually limited to a and I. A determined cryptanalyst looks for these types of patterns and, over time, may be able to deduce the method used to encrypt the data. This process can sometimes be simple, or it may take a lot of effort. This method works only on the historical ciphers that we discussed at the beginning of this chapter. It does not work on modern algorithms.

What is GOST?

It is a DES- like algorithm developed by the Soviets in the 1970s It was classified but released to the public in 1994. It uses a 64-bit block and a key of 256 bits. It is a 32-round Feistel cipher. GOST is an acronym for gosudarstvennyy standard, which translates into English as "state standard". The official designation is GOST 28147-89. It was meant as an alternative to the U.S. DES algorithm and has some similarities to DES.

What is Extensible Authentication Protocol (EAP)?

It is a framework frequently used in wireless networks and point-to-point connections. It was originally defined in RFC 3748, but it has been updated since then. It handles the transport of key's and related parameters. There are several versions of EAP

What is Pretty Good Privacy (PGP)?

It is a freeware email encryption system. As mentioned earlier in the chapter, PGP was introduced in the early 1990's, and it's considered to be a very good system. It's widely used for email security.

What is BitLocker?

It is a full disk encryption feature that can encrypt an entire volume with 128-bit encryption. When the entire volume is encrypted, the data is not accessible to someone who might boot another operating system in an attempt to bypass the computer's security. Full disk encryption is sometimes referred to as hard drive encryption.

What is pinning?

It is a method designed to mitigate the use of fraudulent certificates. Basically, once a public key or certificate has been seen for a specific host, the key or certificate is pinned to the host. Should a different key or certificate be seen for that host, that might indicate an issue with a fraudulent certificate.

What is stapling?

It is a method used with OCSP, which allows a web server to provide information on the validity of its own corticate rather than needing to go to the certificate vendor. This is done by the web server essentially downloading the OVCSP response from the certificate vendor in advance and providing that to browsers. When a key is compromised, a revocation requests should be made to the CA—immediately. It may take a day or longer for the CRL to be disseminated to everyone using the CA. Trust models exist in PKI implementations and come in a number of types.

What is forward secrecy?

It is a property of any key exchange system, which ensures that is one key is compromised, subsequent keys, will not also be compromised.

What is the Transport Layer Security (TLS)?

It is a security protocol that expands on SSL. Though many people still say "SSL", it is highly unlikely you are actually using SSL, as TLS has been around since 1999.

What is a rainbow table?

It is a table of precomputed hashes used to guess passwords by searching for the hash of a password.

In addition to TPM there is HSM (hardware security module) what is this?

It is also a crypto-processor that can be used to enhance security. HSM is commonly used with PKI systems to augment security with Cas. As opposed to being mounted on the motherboard like TPMs, HSMs are traditionally PCI adapters.

What is CAST?

It is an algorithm developed by Carlisle Adams and Stafford Tavares (hence the name). it's used in some products offered by Microsoft and IBM. Cast uses a 40-bit to 128-bit key, and it's very fast and efficient. Two additional versions, CAST-128 and CAST-256, also exist.

What is the Challenge Handshake Authentication Protocol (CHAP)?

It is an authentication protocol that periodically reauthenticates.

What is Ron's cipher (RC)?

It is an encryption family produced by RSA laboratories. RC stands for Ron's cipher or Ron's code. (Ron Rivest is the author of this algorithm). The current levels are RC4, RC5, and RC6. RC5 uses a key size of up to 2,048 bits. It's considered to be a strong system. o RC4 is popular with wireless and WEP/WPA encryption. It is a streaming cipher that works with key sizes between 40 and 2,048 bites, and it is used in SSL and TLS. It is also popular with utilities used for downloading BitTorrent files, since many providers limit the download of these. By using RC4 to obfuscate the header and the stream, it makes it more difficult for the service provider to realize that they are indeed BitTorrent files being moved about.

What is key exchange?

It is an important topic in relation to symmetric cryptography.

What is a certificate authority (CA)?

It is an organization that is responsible for issuing, revoking, and distributing certificates. A certificate is nothing more than a mechanism that associates the public key with an individual. It contains a great deal of information about the user. Each user of a PKI system has a certificate that can be used to verify their authenticity.

What is a symmetric cipher?

It is any cryptographic algorithm that uses the same key to encrypt and decrypt, DES, AES, and Blowfish are examples.

What is salt?

It is bits added to a hash to make it resistant to rainbow table attacks.

The second mode quiet, commonly used, is a cipher-block chaining (CBC) what is this?

It is block ciphers (for example DES, AES, Blow fish, GOST, and others) divide the plain text into blocks (often 64-bit or 128-bit) and encrypt each block, one at a time. What CBC does is that when one block is finished encrypting, before the second block is started, the output of the first block is XOR'd with the plain text on the next block. This causes two interesting improvements in the cipher. The first is that it introduces even more diffusion. The second is that it makes known plain-text attacks totally ineffective. The reason for the second improvement is simply that CBC, even if every single block of plain text were identical, the outputs would be different.

What is an asymmetric cipher?

It is cryptographic algorithms that use two different keys—one key to encrypt and another to decrypt. Also called public key cryptography.

What is the public key infrastructure (PKI)?

It is intended to offer a means of providing security to messages and transactions on a grand scale. The need for universal systems to support e-commerce, secure transactions, and information privacy is one aspect of issues being addressed by PKI.

What is RSA?

It is named after its inventors Ron Riverst, Adi Shamir, and Leonard Adleman. The RSA algorithm is an early public key encryption system that uses large integers as the basis for the process. It's widely implemented, and it has become a de facto standard. RSA works with both encryption and digital signatures. RSA is used in many environments, including Secure Sockets Layer (SSl), and it can be used for key exchange.

What is the Subject Alternative Name (SAN)?

It is not so much a type of certificate as a special field in X.509. It allows you to specify additional items (IP addresses, domain names, and so on) to be protected by this single certificate.

· What is a digital signature?

It is similar in function to a standard signature on a document. It validates the integrity of the message and the sender. The message is encrypted using the encryption system, and a second piece of information, the digital signature, is added to the message.

What is a trust model?

It is simply a model of how different certificate authorities trust each other and consequently how their clients will trust certificates from other certificate authorities. The four main types of trust models that are used with PKI are bridge, hierarchical, hybrid, and mesh.

What is a downgrade attack sometimes used against?

It is sometimes used against secure communications such as TLS in an attempt to get the user to shift to less secure modes. The idea is too trick the user into shifting to a less secure version of the protocol, one that might be easier to break.

What is key registration?

It is the process of providing certificates to users, and a registration authority (RA) typically handles this function when the load must be lifted for a CA. There is also the issue of keys that are no longer to be used. A key may have expired, it may have been canceled due to some breach of security, or it may have been replaced. In any case, there must be some mechanism to find out if a key is still valid. The most widely used method is the certificate revocation list (CRL) This is literally a list of certificates that a specific CA states should no longer be used. CRLs, are now being replaced by a real-time protocol called Online Certificate Status Protocol (OCSP).

What is Bcrypt used for?

It is used with passwords, and it essentially uses a derivation of the Blow fish algorithm converted to a hashing algorithm to hash a password and add Salt to it.

An older method is a replay attack what is this?

It is when a user sends their login information, even if it is encrypted, the attacker captures it and later sends the same information. The user never decrypted the login information; they simply replayed it. Modern authentication methods make this highly unlikely. There are also scenarios in which someone is using a good cryptographic algorithm (like AES) but has it implemented in a weak manner—for example, using weak key generation. A classic example, which we will review later, is Wireless Equivalent Privacy (WEP), which uses RC4, a good algorithm. But it was implemented improperly, making it weak.

What is a collision?

It is when two different inputs into a cryptographic has produce the same output, and is collision resistant.

What is out-of-band key exchange?

It means that some other channel, other than the one that is going be secured, is used to exchange the key.

What is perfect forward secrecy?

It occurs when this process is unbreakable. A common approach uses ephemeral keys.

What is a registration authority (RA)?

It offloads some of the work for a CA. An RA system operates as an intermediary in the process: it can distribute keys, accept registrations for the CA, and validate identities. The RA doesn't issue certificates; that responsibility remains with the CA.

What does the known plain attack relay on?

It relies on the attacker having pairs of known plain text along with the corresponding cipher text. This gives the attacker a place to start attempting to derive the key. With modern ciphers, it would still take many billions of such combinations to have a chance at cracking the cipher. This method was, however, successful at cracking the German Naval Enigma. The code breakers at Bletchley Park in the UK realized that all German Naval messages ended with Heil Hitler. They used this known plain-text attack to crack the key.

What is the Electronic Code Book (ECB)?

It simply means to use the algorithm without any modification at all. Essentially, you implement the algorithm exactly as it is designed.

What is LEAP?

It stands for Lightweight Extensible Authentication protocol which was developed by Cisco and has been used extensively in wireless communications. LEAP is supported by many Microsoft operating systems, including Windows 7. LEAP uses a modified version of MS-CHAP.

What is PBKDF2?

It stands for Password-Based Key Derivation Function 2 which is part of PKCS#5 v2.01. It applies some function (like a hash or HMAC) to the password or passphrase along with Slat to produce a derived key.

What is HMAC?

It stands for hash-based message authentication code which uses a hashing algorithm along with a symmetric key. Thus for example, two parties agree to use an MD5 hash. Once the hash is computed, it is exclusively or'd (XOR) with the digest, and that resultant value is the HMAC. Again, should someone intercept the message and attempt to alter the message and the associated HMAC, that party would not have the key and would not be able to duplicate the HMAC.

In cryptology, one of the key principles is called Kerckhoffs' principle. This principle was first stated by Auguste Kerckhoffs in the nineteenth century. Essentially Kerckhoffs' principles states what?

It states that the security of an algorithm should depend only on the secrecy of the key and not on the secrecy of the algorithm itself. This literally means that the algorithm can be public for all to examine, and the process will still be secure as long as you keep the specific key secret. Allowing the algorithm to be public might seem counterintuitive, Nerveless, all of the major algorithms discussed in this chapter are public, and the entire set of algorithms is published in many books and articles and on numerous websites. This allows researcher to examine the algorithm for flaws.

NTLM uses what?

It uses MD4/MD5 hashing algorithms. Several versions of this protocol exist (NTLMv1, NTLMv2), and it is still in widespread use despite the fact that Microsoft has pointed to Kerberos as being its preferred authentication protocol. Although LANMAN and NTLM both employ hashing, they are used primary for the purpose of authentication.

What is the International Data Encryption Algorithm (IDEA)?

It was developed by a Swiss consortium. It's an algorithm that uses a 128-bit key. This product is similar in speed and capability to DES, but it's more secure. IDEA is used in Pretty Good Privacy (PGP), a public domain encryption system used by many for email. Currently Ascom AG holds the right to market IDEA.

What is data encryption?

It was mentioned earlier in relation to mobile devices, allows data that has bene stolen to remain out of the eyes of intruders who took it as long as they do not have the proper passwords. One of the newest security features that is available only the PRO and Enterprise version of Windows 8.1 (and the Ultimate version of Windows 7) is BitLocker.

Symmetric algorithms require both the sender and receiver of an encrypted message to have the same?

Key and processing algorithms. Symmetric algorithms generate a secret key that must be protected.

Wi-Fi encryption requires a short discussion of its own. In such an environment, the clients and the access point share the same?

Key, using symmetric encryption; RC4 was mentioned for this purpose earlier in this chapter. Since all the clients and the access pint share the same key, this is known a pre-shared key.

Prior to the release of Windows NT, Microsoft's operation systems used the?

LANMAN protocol for authentication. While functioning only as an authentication protocol, LANMAN used LM hash and two DES keys. It was replaced by the NT LAN Manager (NTLM) with the release of Windows NT.

An important issue in symmetric ciphers is the?

Latency.

A counter measure called Salt, refers, to the addition of bits at key?

Locations, either before or after the hash. So, if you type in the password let me in, bits are added by the operating system before it is hashed. Using Salt, should someone apply a rainbow table attack, the has they search for will yield a letter combination other than what you actually typed in.

The RACE Integrity Primitives Evaluation Message Digest (RIPEMD) algorithm was based on?

MD4. There were questions regarding its security, and it has been replaced by RIPEMD-160, which uses 160 bits. There are versions in existence that use 256 and 320 bits (RIPEMD-256 and RIPEMD-320, respectively), but all version of RIPEMD remain.

MD4 was used by NTLM to compute the?

MT hash.

Symmetric ciphers can be executed in several different?

Modes of operation.

The National Security Agency/ Central Security Service (NSA/CSS) is an independently functioning part of the?

NSA. It was created in the early 1970s to help standardize and support Department of Defense (DoD) activities. The NSA/CSS supports all branches of the military. Each branch of the military used to have its own intelligence activities. Frequently these branches did not coordinate their activities well. NSA/CSS was created to help coordinate their efforts.

Password cracking can be done?

Offline. For example, the rainbow tables mentioned earlier in this book can be done online on a live system. Or someone can capture the password hash, and then use offline methods to try to find a match. Offline methods can use more resources and take as long as needed. Offline methods have to be executed quite quickly.

Certificate authorities can be?

Online or offline. Online certificate authorities are the most common. They are always connected and always accessible. Offline is usually for a root certificate authority that has been isolated from network access. It is brought online for specific purposes. The concept is that, since it is isolated, the chances of it being compromised are reduced. That is one reason why this is actually only done with root certificate authorities.

A collision occurs when two different inputs to a hashing algorithm produce the same?

Output. Modern hashing algorithms are designed to make this less likely. However, basic logic should tell you that if a given hash a 160-bit output like (SHA1) and you put in +1 separate inputs, the last one must have a collision with one of the preceding inputs. Now don't be too concerned, is a very large number: 1.4615016373309029182036848327163e+48.

Understand the process used in PKI?

PKI is an encryption system that uses a variety of technologies to provide confidentiality, integrity, authentication, and nonrepudiation. PKI uses certificates issued from a CA to provide this capability as well as encryption. PKI is being widely implemented in organizations worldwide.

The public key may be truly public, or it may be a secret between the two?

Parties. The private key is kept private, and the only owner (reviver knows it). If someone wants to send you an encrypted message, they can use your public key to encrypt the message and then send you the message. You can use your private key to decrypt the message. The private key is always protected. If both keys become available to a third party, the encryption system won't protect the privacy of the message. The real "magic" of these systems is that the public key cannot be used to decrypt a message. If Bob sends Alice a message encrypted with Alice's public key, it does not matter if everyone else on Earth has Alice's public key, which cannot decrypt the message. Only Alice's private key can do that, All asymmetric algorithms are based on a number theory.

A related key attack is like a chosen?

Plain-text attack, except the attacker can obtain cipher texts encrypted under two different keys. This is actually a useful attack if you can obtain the plain text and matching cipher text.

The Internet Engineering Task Force (IETF) is an internal community of computer?

Professionals that include network engineers, vendors, administrators, and researchers. The IETF is mainly interested in improving the Internet; it's also very interested in computer security issues. The IETF uses working groups to develop and propose standards. IETF membership is open to anyone. Members communicate primarily through mailing lists and public conferences.

This also brings us to implementation issues. Yes, selecting a strong algorithm (such as AES 256 bit) is a good idea for cryptography. However, the algorithm must also be implemented?

Properly. This includes aspects such as how the key is generated (using a good PRNG), not reusing keys, and key exchange. It is just as important to be concerned about proper implementation as it is the choice of algorithm.

Third-party organizations called certificate authorities (CAs) manage?

Public keys and issue certificates verifying the validity of a sender's message. The verifying aspect servers as nonrepudiation, as a respected third party vouches for the individual. However, the implementation is a little more difficult than the concept.

The core of the Enigma machine was the?

Rotors. These were disk arranged in a cycle with 26 letters on them. The rotors were lined up. Essentially each rotor represented a different single substitution cipher. You can think of the Enigma as a sort of mechanical ply alphabet cipher.

The cipher used with symmetric algorithms should be a?

Random number. However, this poses a problem. Orderly algorithms don't produce truly random numbers. So instead, cryptographers use pseudo-random number generators. These are algorithms that produce numbers that are random enough. There are many applications for PRNGs. We already mentioned using them to generate keys for symmetric ciphers.

Most messages have a preamble that informs the?

Receiver who the message is for, who sent it, how many characters are in the messages, the date and time it was sent, and other pertinent information. In this case, the preamble was sent in clear text, and this information was also encrypted and put into the message. As a result, the cryptanalysis gained a key insight into the message contents. They were given approximately 50 characters that repeated in the message in code. This error caused a relatively secure system to be compromised. o Another error is to use weak or deprecated algorithms. Overtime, some algorithms are no longer considered appropriate. This may be due to some flaw found in the algorithm. It can also be due to increasing computer power. For example, in 1976 DES was considered very strong. But advances in computer power have made its key length too short. Although the algorithm is sound, the key size makes DES a poor choice for modern cryptography and that algorithm has been deprecated.

Although SHA-3 is now a standard, their simply are no know issues with?

SHA-2, so it is still the most widely used and recommended hashing algorithm. The algorithm was originally named Keccak and designed by Guido Bertoni, Joan Daemen, Michael Peters, and Gilles Van Assche.

A cipher is a method used to?

Scramble or obfuscate characters to hide their value.

WEP (wired Equivalent Privacy) encryption was an early attempt to add?

Security, but it fell short because of weakness in the way the encryption algorithms are employed.

GOST is a symmetric cipher developed in the old?

Soviet Union that has been modified to work as a hash function. GOST processes a variable-length message into a fixed-length output of 256-bits.

The need for security in specific industries, such as the banking industry, has driven the development of?

Standards. Standards frequently begin as voluntary or proprietary efforts.

With the advent of computers, older methods of cryptography are no longer viable. A computer can quickly and easily crack?

Substitution and transposition ciphers. Even Vigenre and the Enigma machine are not able to withstand modern cryptographic attacks.

The two primary types of nonmathematical cryptography, or ciphering methods are?

Substitution and transposition.

PGP uses both?

Symmetrical and asymmetrical systems as part of its process; it is this serial combination of processes that makes it so competent. During the encryption process, the document is encrypted with the public key and also a session key, which is a one-use random number, to create the cipher text. The session key is encrypted into the public key and sent with the cipher text. On the receiving end, the private key is used to decrypt the cipher text back into the original document.

Diffusion means?

That a change in a single bit of input changes more than one bit of the output. With classic ciphers (Caesar Vigenre, and others) that we examined earlier, this is not the case. However, modern symmetric ciphers are structured so that if one changes a single bit of input, multiple output bits are changed.

What is DER?

The DER extension is sued for binary DER-encoded certificates. These files may also bear the CER or CRT extension.

What is X.509?

The X.509 standard is the most widely used standard for digital certificates.

Another issue is high resiliency why is it an issue?

The concern is various rather advanced attacks that can "leak" a portion of the secret key, such as with side-channel attacks. The nature of these attacks is beyond the scope of the text. Nonetheless, the concept of high resiliency is that algorithms that are resilient are less prone to leaking bits of data. The Security+ exam will, at most, mention this in passing. It is a complex topic that requires some background in cryptography.

When setting up Wi-Fi encryption, there are two modes you can use what are they?

The first is a pre-shared key (PSK) mode and enterprise mode. In enterprise mode, a server handles distribution of cryptographic keys and/or digital certificates. In PSK mode, the client and the wireless access point must negotiate and share a key prior to initiating communications. A third mode, sometimes called open, is simply unsecure. This is sometimes used for public Wi-Fi that has no access to any sensitive data, but it is simply a portal to access the Internet. It is also common to launch a web page when users first connect. The web page may list acceptable use policies or require some authentication. This page must be navigated before full access to network resources is grated. The term for this web page is a captive portal.

The Secure Hash Algorithm (SHA) was designed to ensure?

The integrity of a message.

Know the primary objectives for using cryptographic systems?

The main objectives for these systems are confidentiality, integrity, authentication, and nonrepudiation. Digital signatures can be used to verify the integrity and provide nonrepudiation of a message.

What are Machine/computer certificates?

They are X.509 certificates assigned to a specific machine. These are often used in authentication schemes. For example, in order for the machine to sign into the network, it must authenticate using its machine certificate.

What is a domain validation certificate?

They are among the most common certificates. These are sued to secure communication with a specific domain. This is a low-cost certificate that website administrators use to provide TLS for a given domain.

Before we examine specific symmetric algorithms, there are some general principles of symmetric cryptography of which we should take note of. Two terms, in particular, are of interest what are the two terms?

They are diffusion and confusion. These terms come from information theory.

What are user certificates?

They are used for individual users. Like machine/computer certificates, these are often used for authentication. Users must present their certificate to authenticate prior to accessing the resource.

What are root certificate?

They are used for root authorities. These are usually self-signed by that authority.

What is an email certificate?

They are used for securing email. Secure Multipurpose Internet Mail Extensions (S/MIME) uses X.509 certificates to secure email communications.

Summary for this chapter know this.

This chapter focused the basic elements of cryptography and the PKI implementation. · There are three primary methods of encryption: o Symmetric o Asymmetric o Hashing · Symmetric systems require that each end of the connection have the same key. Asymmetric systems use a two-key system. In public key cryptography, the receiver has a private key known only to them; a public key corresponds to it, which it makes known to others. The public key can be sent to all other parties; the private key is never divulged. Hashing refers to performing a calculation on a message and producing a fixed length hash value. · The five main considerations in implementing a cryptography system are as follows: o Confidentially means that the message retains its privacy. o Integrity means that the message can't be altered without detection. o Authentication is used to verify that the person who sent the message is actually who they said they are. o Nonrepudiation prevents the sender from denying it was sent. o Access controls are the methods, processes, and mechanisms of preventing unauthorized access systems. · In this chapter, you also learned about the standards, agencies and associations that are interested in cryptography. Several government agencies have been specially charged with overseeing security and encryption standards. NIST is primarily concerned with nonmilitary standards; NSA/CSS is concerned with military applications.

What is CER?

This is an alternate form of .crt (Microsoft Convention). You can use Microsoft crypto API to convert .crt to .cer (both DER-encoded .cer or base 64 [PEM]-encoded .cer). The .cer file extension is also recognized by IE as a command to run MS crypto API command (specifically rundll32.exe cryptext.dll, CryptExtOpenCer).

It is also possible to generate a self-signed certificate. In fact, this is an easy task to perform using Microsoft Internet Information Services (IIS) The certificate will be an X.509, but it will be digital signed for you what does this mean?

This means although it can be used to transmit your public key, it won't be trusted by browsers. It will instead generate a certificate error message.

Keeping a cryptographic method secret not only makes it impossible for it to be tested by the cryptographic community it is something that security experts use the term security through obscurity what does this mean?

This means that something is not particularly secure, just the details are hidden and you hope that no attacker finds them. This is a very bad approach to security.

What is the protected extensible authentication protocol?

This protocol encrypts the authentication process with an authenticated TLS tunnel. PEAP was developed by a consortium including Cisco, Microsoft, and RSA security. It was first included in Windows XP.

What is EAP-TTLS (Tunneled Transport Layer Security)?

This protocol extends TLS. It was first supported natively in Windows 8. There are currently two version of EAP TTLS EAP-TTLS v0 and EAP-TTLSv1. EAP and its variations are widely used in a number of other protocols. For example, the remote access protocols RADIUS (Remote Authentication Dial-In user service) and Diameter both support EAP for authentication. EAP is also used with 802.1 x. 802.1 x is the IEEE standard for port-based network access control. It can be used on LAN or a WLAN. 802.1 x allows you to secure a port so that only authenticated users can connect to it. Radius Federation is a federation that is using RADIUS to authenticate between the various entities within the federation. Radius is remote authentication dial in user service. It was developed in 19991 and is still used today. It operates at layer 7 in the OSI model.

What is Extensive Authentication Protocol—Transport Layer Security?

This protocol utilizes TLS in order to secure the authentication process. Most implications of EAP-TLS utilize X.509 digital certificates to authenticate the users.

What is EAP -FAST or flexible authentication via secure tunneling?

This protocol was proposed by Cisco as a replacement for the original EAP. EAP-FAST establishes a TLS tunnel for authentication, but it does so using a Protected Access Credential (PAC).

A transposition cipher involves?

Transposing or scrambling the letters in a certain manner. Typically, a message is broken into blocks of equal size, and each block is then scrambled. In the simple example shown in Figure 8.1, the characters are transposed by changing the order of the group. In this case, the letters are rotated three places in the message. You could change the way Block one is transposed from Block 2 and make it a little more difficult but it would still be relatively easy to decrypt.

No discussion of the history of cryptography would be complete without discussing the Enigma machine. The Enigma machine was essentially a?

Typewriter that implemented a multi-alphabet substitution cipher. When each key was hit, a different substitution alphabet was used. The Enigma machine used 26 different substitution alphabets. Prior to computers, this was extremely hard to break. Contrary to popular misconceptions, the Enigma is not a single machine, but rather a family of machines. The first version was invented by German engineer Arthur Scherbius toward the end of World War 1. It was also used by the military of several different countries, not just Nazi Germany.

One of the problems with substitution ciphers is that they did not change the?

Underlying letter and word frequency of the text. One way to combat this was to have multiple substitutions. For example, you might shift the first letter by three to the right, the second letter by two to the right, and the third letter by one to the left; then repeat this formula with the next three letters.

Key stretching refers to processes used to take a key that might be a bit?

Weak and make it stronger, usually by making it longer. The key (or password/passphrase) is input into an algorithm that will strengthen the key and make it longer and thus less susceptible to brute-force attacks. There are many methods for doing this—here's two:

Authentication is the process of verifying that the sender is?

Who they say are. This is critical in many applications. A valid message for an invalid source isn't authentic. One of the common methods of verifying authenticity is the addition of digital signature. This is the most common method used today. In fact, most device drivers are digitally signed by the vendor.

In addition to software-based encryption, hardware-based encryption can be applied where can it be found?

Within the advanced configuration settings on some BIOS configuration menus, for example, you can choose to enable or disable TPM.

A dictionary attack involves attempting common?

Words (such as words in a dictionary) that might be used as a password, hoping one will work.

The Public Key Infrastructure X.509 (PKIX) is the?

Working group formed by the IETF to develop standards and models for the PKI environment. The PKIX working group is responsible for the X.509 standard.

The X.509 standard defines the?

o Certificate formats and fields for public keys. It also defines the procedures that should be used to distribute public keys. The current version of X.509 certificates is version 3, and it comes in two basic types which are: § End-Entity Certificate The most common is the end-entity certificate, which is issued by a CA to an end entity. An end entity is a system that doesn't issue certificates but merely uses them. § CA Certificate The CA certificate is issued by one CA to another CA. The second CA, in turn, can then issue certificates to an end entity.

Before we begin with modern symmetric ciphers, we should discuss the exclusive OR (XOR) operation what is it?

o It is a very simple mathematical operation that is part of all symmetric ciphers. XOR (as it is usually termed) is a simple but powerful binary math operation. Consider two binary numbers, 1011 and 1001. To XOR these numbers, you start at the least significant bit (LSB) and ask a simple question: is there 1 in the top or bottom number, but not both (that is, not and/or)? If so, then the resultant is a 1; if not the resultant is a 0. 1011 1001/0010 o Now that may not look particular interesting until you realize that the XOR operation is reversible. If I take the resultant (0010) and the XOR it with either of the other two numbers, I get back the other. So, for example: 0010 1001/1011

What is Counter Mode (CTM or CTR) used for?

o It is used to convert a block cipher into a stream cipher. It basically works by generating a keystream block by encrypting sequential values of some counter. This counter can be any function that produces a sequence that has a long period with no repetition.

What is the Elliptic Curve Cryptography?

o It provides similar functionality to RSA but uses smaller key sizes to obtain the same level of security. ECC encryption systems are based on the idea of using points on a curve combined with a point at infinity and the difficulty of solving discreate logarithm problems. Many vendors have implemented, or are implementing, the ECC system for security. The National Security Agency has also recommended several implementations of ECC. You can expect that ECC will be commonly implemented in mobile devices sometimes in the near feature think of ECC memory in chrome books to help you remember what ECC means. o There are many variations of the Elliptic Curve including: Elliptic Curve Diffie-Hellman (ECC-DH) Elliptic Curve Digital Signature Algorithm (ECC-DSA)

All X.509 certificates have the following:

o Signature of the issuer. o Version. o Serial number. o Signature algorithm ID. o Issuer name. o Validity period. o Subject name. o Subject public key information. o Issuer unique identifier (relevant for versions 2 and 3 only). o Subject unique identifier (relevant for version 2 and 3 only) o Extensions (in version 3 only) o Object identifiers, or OIDs, are used in X.509 corticate extensions (and thus are optional). These are values that help identify objects. They are dot separated numbers usually. For example, OID 2.5.4.6 might correspond to the country-name value.

What are One-Time Pads?

o They are the only truly completely secure cryptographic implementations. They are so secure for two reasons. First, they use a key that is as long as a plain-text message. This means that there is no pattern I the key application for an attacker to use. Also, one-time pad keys are used only once and then discarded. So even if you could break a one-time pad cipher, the same key would never be used again, so knowledge of the key would be useless. o The Vernam cipher is a type of one-time pad. The concept behind a one-time pad is that the plain text is somehow altered by a random string of data so that the resulting cipher text is truly random. Gilbert Vernam proposed a stream cipher that would be used with teleprinters. It would combine a prepared key, character by character, which was stored on paper tape, with the characters of the plain text to produce the cipher text. The recipient would again apply the key to get back the plain text. o In 1919 Vernam patented his idea (U.S. patent 1,310,719). Vernam's method used the binary XOR (Exclusive OR) operation applied to the bits of the message.

What is a Birthday Attack?

o This is an attack on cryptographic hashes, based on something called the birthday theorem. The basic is this: How many people would you need to have in a room to have a strong likelihood that two would have the same birthday (month and day, but not year)? Obviously if you put 367 people in a room, at least 2 of them must have the same birthday, since there are only 365 days in a year, plus one more in a leap year. The paradox is not asking how many people you need to guarantee a match—just how many you need to have a strong probability. o Even with 23 people in a room, you have a 50 percent chance that 2 will have the same birthday. The probability that the first person does not share a birthday with any previous person is 100 percent, because there are no previous people in the set. That can be written as 365/365. The second person has only one preceding person, and the odds that the second person has a birthday different for the first are 364/365. The third person might share a birthday with two preceding people, so the odds of having a birthday from either of the two preceding people are 363/365 Because each of these is independent, we can compute the probability as follows: 365/365 * 364/365 * 363/365 * 362/365 ... * 342/365. o (342 is the probability of the 23rd person shares a birthday with a preceding person) when we convert these to decimal values, it yields (truncating at the third decimal point): 1 * 0.997 * 0.994 * 0.991 * 0.989 * 0.986 ... 0.936 = 0.49 or 49 percent. The 49 percent is the probability that 23 people will not have any birthdays in common; thus, there is a 51 percent (better than the odds) chance that 2 of 23 will have a birthday in common. o The math works out to about 1.7/ n to get a Collison. Remember, a collision is when two inputs produce the same output. So, for an MD5 hash, you might think that you need +1 different inputs to get a collision—and for a guaranteed collision you do. That is an exceedingly large number: 3.4028236692093846346337460743177e+38. But the Birthday paradox tells us that to just have a 51 percent chance of there being a collision with a hash you only need 1.7/ n (n being ) inputs. The number is still very large: 31,359,464,925,306,237,747.2. But it is much smaller than the brute-force approach of trying every possible input.

The hashes used to store data, such as hash tables, are very different from cryptographic hashes. In cryptography, a hash function must have three characteristics what are they?

§ It must be one-way. This means that it is not reversible. Once you hash something, you cannon un-hash it. § Variable-length input produces fixed-length output. This means that whether you hash two characters or two million, the hash size is the same. § The algorithm must have few or no collisions. This means that hashing two different inputs does not give the same output.