CH-13 Encryption and Hashing Concepts

Asymmetric key algorithms------------->

------------------------>

What is non-repudiation?

...

What are the usages of AES?

1. AES is fast algorithm, uses minimal resources, and can be used on variety of platforms. 2. It is encryption algorithm of choice if you have Wireless network running WPA2 protocol. 3. Can encrypt data in motion and as data passes through RAM. 4. AES is good choice for transferring encrypted data quickly to USB flash drive. 5. Uses as Windows Encrypting File System (EFS) 6. Used in Whole Disk Encryption (WDE) techniques

Name few symmetric algorithms?

1. DES ( Data Encryption Standard) 2. 3DES 3. AES (Advanced Encryption Standard)

Name few asymmetric algorithms?

1. RSA (Rivest, Shamir, Aldman) 2. Diffie-Hellman 3. Elliptic curve

If you want to setup an authentication scheme in which employees will use smart cards to log in to the company network. What kind of key should be used to accomplish this?

A private key should be used by users when logging in to the network with their smart card. The key should certainly not be public.

What is digital signature?

A signature that authenticates a document, letting the recipient know that the document was created and sent by the actual sender and not someone else.

Which of the following might a public key be used to accomplish? A. To decrypt the hash of a digital signature B. To encrypt web browser traffic C. To digitally sign a message D. To decrypt wireless message

A. Public keys can be used to decrypt the hash of a digital signature. Session keys are used to encrypt web browser traffic. Private keys are used to digitally sign a message and decrypt wireless messages.

What is cipher?

An algorithm that can perform encryption or decryption.

What are two types of symmetric key algorithms?

Answer: A stream cipher is a type of algorithm that encrypts each binary digit in the data stream, one bit at a time. A block cipher is a type of algorithm that encrypts a group of bits collectively as individual units knowns as blocks. E.g. the Advanced Encryption Standard (AES) algorithm can use 128-bit or 256-bit block ciphers.

Which encryption algorithms use symmetric key?

Answer: DES, 3DES, RC, and AES. What if a user who encrypted a file left company and their user account along with key used to encrypt got deleted, how would you recover data? Answer: Using a software known as recovery agent.

You are tasked with selecting an asymmetric encryption method that allows for the same level of encryption strength, but with a lesser key length than is typically necessary. Which encryption method fulfills your requirements? A. RSA B. ECC C. DHE D. Twofish

B. The ECC (elliptic curve cryptography) method allows for lesser key lengths but at the same level of strength as other asymmetric methods. This reduces the computational power needed. RSA and Diffie-Hellman require more computational power due to the increased key length. DHE especially uses more CPU power because of the ephemeral aspect. Twofish is symmetric algorithm.

You are asked with ensuring that messages being sent and received between two systems are both encrypted and authenticated. Which of the following protocols accomplish this? A. Diffie-Hellman B. BitLocker C. RSA D. SHA-1

C. RSA can both encrypt and authenticate messages. Diffie-Hellman encrypts only. BitLocker is a type of Whole Disk Encryption (WDE), which deals with encrypting entire hard drives, but it not used to send/receive messages. SHA-1 is a cryptographic hash function used to preserve the integrity of files.

What is cryptography?

Cryptography is the practice and study of hiding information, or more accurately, hiding the meaning of the information.

WEP improperly uses an encryption protocol and because of this is considered to be insecure. What encryption protocol does it use? A. AES B. RSA C. RC6 D. RC4

D. RC4 has several vulnerabilities when used incorrectly by protocols such as WEP. WEP doe not use AES, RSA, or RC6, all of which are secure protocls if used correctly.

Analogy for asymmetric keys

Imagine that you are the night shift security guard for a warehouse that stores CPUs. When your shift is over you are required to lock up. But the warehouse uses a special lock. Your key can only lock the warehouse door; it cannot unlock it. Conversely, the morning watchman has a key that can only unlock the door, but not lock it. This is analogous to asymmetric keys used in encryption. One key is used to encrypt data; the other, dissimilar key is used to decrypt the data.

If you want to use a cryptographic algorithm that cannot be decoded by being reversed then you will use One-Way function

In cryptography, the one-way function is one option of an algorithm that cannot be reversed, or is difficult to reverse, in an attempt to decode data. An example of this would be hash such as SHA-2, which creates only small hashing number from a portion of the file or message. There are ways to crack asymmetric and symmetric encryption, which enable complete decryption (decoding) of the file.

What is key?

Key: The key is the essential piece of information that determines the output of a cipher. The length of the key determines its strength. Keys can be private or public. Private Key is only known to a specific user or users who keep the key, a secret. Public key is known to all parties involved in encrypted transactions within a group.

Does public key cryptography need secure exchange of secret keys?

No, it does not need the secure exchange of secret keys.

What is asymmetric key management scheme?

Public Key Infrastructure is the asymmetric key management scheme.

What are public key cryptography algorithms?

Public key cryptography uses asymmetric keys alone or in addition to symmetric keys. It does not need the secure exchange of secret keys, instead the asymmetric key algorithms creates a secret key and a published public key. The public key is well known, and anyone can use it to encrypt messages. However, only the owner(s) of the paired or corresponding private key can decrypt the message. The security of the system is based on the secrecy of the private key.

Which algorithms are examples of asymmetric encryption?

RSA (Rivest, Shamir, & Adleman), Diffie-Hellman system and elliptic curve.

An SHA algorithm will have how many bits?

SHA-2 algorithm blocks have 512 bits and SHA-1 is 160-bit.

Advantage symmetric algorithms over asymmetric algorithms

Symmetric encryption is the preferred option when encrypting and sending large amounts of data because it takes far less time to encrypt and decrypt data than asymmetric encryption does.

Important Point about symmetric key algorithms

Symmetric key algorithms also require secure initial exchange of one or more secret keys to both the sender and receiver. It is also possible to encrypt the initial exchange of the secret keys

Which encryption scheme is used by PGP to encrypt the session key before it is sent?

Symmetric scheme

What is another term for secret key encryption?

Symmetrical key encryption uses a secret key. The term symmetric key is also referred to as the private key, single key, and shared key and sometimes as session key.

Asymmetric keys are not identical, but how they are related to each other?

The two asymmetric keys are related mathematically.

What is public key cryptography?

Uses asymmetric keys alone or in addition to symmetric keys. The asymmetric key algorithm creates a secret private key and a published public key.

What is AES key strength and encryption algorithm type?

Uses three different versions of block ciphers: AES-128, AES-192, and AES-256. Actually, each of these has the same 128-bit cipher block size, but the key sizes for each are 128-bit, 192-bit and 256-bit respectively.

What is encryption?

When data is encrypted, it is modified in such a way that it cannot be understood by anyone who does not have the correct key. Encryption is done by using an algorithm (or cipher). The reverse is decryption, which is done by using the proper key to unlock the data, and second by cracking the original encryption key.

Symmetric keys also referred to as

secret key, private key, single key, and shared key.