4.1 Study Guide

What has to happen for the encryption to take place?

The computer has to be restarted

ciphertext

The encrypted message generated by a cipher

Substitution cipher

A cipher in which each letter in an alphabet is replaced with a different character or symbol.

What did the Enigma machine do? What was the name of the person that lead the effort to break the code of the Enigma machine?

Germany and Italy used the Enigma during World War II to encrypt their radio communications including their submarine routes. Alan Turing

Why is it important to recognize the default filename of a BitLocker recovery key?

It is important to learn this common filename to be able to find a key or to search for a key.

How does the pigpen cipher work? What type of cipher is it?

Pigpen is another substitution cipher that's been around for hundreds of years. The Pigpen cipher key, shown below, uses shapes to represent each letter of the alphabet. shared with the recipients.

Private key encryption

Private key encryption is an encryption method where the sender and receiver share a single private key (such as a number, word, or phrase) to use in the encryption algorithm. Also called shared key and symmetric key encryption, the same key is used in both the encryption and decryption process.

Symmetric key encryption

Private key encryption is an encryption method where the sender and receiver share a single private key (such as a number, word, or phrase) to use in the encryption algorithm. Also called shared key and symmetric key encryption, the same key is used in both the encryption and decryption process.

How does the Vigenere Cipher work? What type of cipher is it?

Similar to the Caesar cipher, letters in the first row of the table have values that correspond to their position in the alphabet. Each subsequent row in the table shifts the letters by one position.A keyword or pass phrase is repeated over and over until the end of the message

Is a key with Alice and Bob listed the same and Bob and Alice for symmetric keys?

Yes it does not matter the order that it is listed

Cryptocurrency

A digital cash system that uses cryptography to secure the exchange financial transactions.

Container

A file that contains other data and acts like a drive. It can be mounted (connected to) or unmounted (removed from) a drive letter, giving administrators greater control when making the data available to users

partitions

A section of a Volume that's formatted for the operating system to use as storage areas. Data used for different purposes are often stored in separate partitions, for example, operating system software versus user data

What formula is used in the Ceasar Cipher? What kind of cipher is it?

A shift cypher y=x+n X is the original message in the thing

Encryption key

A string of characters used as a parameter that determines the output of an encryption algorithm.

How does symmetric key encryption work?

Alice (A) wants to send an encrypted message {M} to Bob (B). Since they are using symmetric key encryption, Alice and Bob must first create a shared key (K) which can be a password or passphrase. Then, they agree on an encryption algorithm to encrypt a message. The process looks like the following. Alice applies shared key (K) to message {M} using the encryption algorithm (En). This results in the encrypted message. Alice sends the encrypted message to Bob. To decrypt the message, Bob applies the same shared key (K)using the same algorithm but in reverse (Dc), decrypting the message.

Hash

Also called hashing, it is a computational process that converts data of varying size to a fixed-size. In cryptographic hash functions, the data is converted using a one-way function so the process cannot be reversed

Ciphers

An algorithm used for encryption or decryption

RSA Algorithm

An example of public key encryption developed by Rivest, Shamir, and Adelman, the founders of RSA - an American computer and network security company.

What are the advantages of asymmetric encryption?

In asymmetric encryption, if Alice or Bob is compromised, only the communication to Alice from Bob (or vice versa) may be exposed, not all communication with Alice or Bob as in symmetric encryption. Another advantage of asymmetric encryption is its key space. because of its one-way function, asymmetric encryption is more secure than symmetric

What tool can you use to crack container passwords?

John the Ripper tool

What are the disadvantages of symmetric encryption?

Key space Ability to keep the keys secret

Asymmetric encryption

Public key encryption is an encryption method that uses two keys, a public key available to everyone and a private key belonging to one owner. Also called asymmetric key encryption, the keys are combined mathematically to create one key used in the encryption/decryption algorithm

How do recovery files and hash files differ?

Recovery keys are created by the operating system to store the key to the drive, in the event a password is lost.Hash values are created at encryption time and represent passwords that control access to the encrypted data.

What are the advantages of symmetric encryption?

Simplicity Speed

volumes

Sometimes called a logical volume or logical drive, the accessible storage area on a hard disk or disks. A logical volume can span multiple disks but doesn't have to.

What is a scytale and what was it used for?

Spartans used it as a strip of leather to write different messages then they would remove the leather to reveal it

How does the Affine cipher work?

The affine cypher is a more complex shift cipher that uses a linear equation y=[a*x+b]mod26

What is the difference between cryptocurrency and a traditional bank?

The most important difference is that banks have government regulations. For example, they must maintain a certain amount of money, provide public reports, balance their investments, and so on. Currently, cryptocurrency exists without a centralized government or authority. Users of the currency do not know how it's managed, who is managing it, and other details. Its encryption algorithm is sophisticated and secure, making it very difficult to crack or to see inside the cryptocurrency process.

plaintext

The original message that needs to be encrypted

Disks

The physical drives inside of a computer

Cryptography

The science and art of delivering a message securely and confidentially.

How do you know that the disk is encrypted?

There is a lock on it.

What do users need to encrypt a hard drive using TPM full encryption? What is the benefit of this?

They must have a password or key to access the drive. The benefit is that you can guarantee the integrity of the data.

How does asymmetric encryption work?

Unlike symmetric key encryption where the shared key could be a password or passphrase, the paired keys in asymmetric key encryption are very large prime numbers that are not randomly chosen. They are in fact generated using a complex mathematical function and only work when they're paired together as two parts of the encryption/decryption algorithm. The owner of the paired keys shares one of the numbers publicly (known as the public key) and keeps the other number secret (known as the private key). Encryption with public keys will encrypt plaintext into ciphertext. And since the public keys are, well public, anyone can encrypt a message. However, the message can only be decrypted using the recipient's private key. The public key cannot decrypt a message.

If you lost the password to your encrypted drive, what could you do to recover it?

Using bitlocker execute a file name search match- the grep command with wildcard characters( *)in the correct format will help you find the password

How does frequency analysis work?

You analyze a message by how often letter like E and T occur in the message.

What do you have to do to the container before you can use it?

You have to mount it

TPM (Trusted Platform Module)

a mechanism that provides secure encryption for a drive

What are the disadvantages of asymmetric encryption?

because of its one-way function, asymmetric encryption is more secure than symmetric but takes longer

What command is used to use the brute force dictionary method?

john hash_values.txt

What formula can you use to calculate the unique number of keys for a given number of people?

n(n-1)/2

What command is used to show the contents of the file?

type hash_values.txt

What file shows all of the successfully hacked passwords?

type john.pot

How does the Caesar Cipher deal with numbers over 26?

y=x+n(mod26)