Security Ch. 9

What is meant by key distribution?

A trusted repository of all public keys.

Organizations currently use several symmetric algorithms, including ________, which is a substitution-permutation algorithm similar to DES. Unlike DES, its authors made its design criteria public. This 64-bit symmetric block cipher can use keys from 40 to 256 bits. Although it is patented (U.S. patent 5,511,123), its inventors, C.M. Adams and S.E. Tavares, made it available for free use.

CAST

(T/F) Unencrypted information is ciphertext.

False

Chosen-ciphertext attacks have particular uses in attacking encrypted e-mail. True False

False

What name is given to random characters that you can combine with an actual input key to create the encryption key? hash checksum salt value private key

Salt Value

_______________ is another symmetric algorithm that organizations currently use. It is a 64-bit block cipher that has a variable key length from 32 to 448 bits. It is much faster than DES or IDEA and is a strong algorithm that has been included in more than 150 products, as well as v2.5.47 of the Linux kernel. Its author, Bruce Schneier, placed it in the public domain

blow fish

A ________ is one of the simplest substitution ciphers. It shifts each letter in the English alphabet a fixed number of positions, with Z wrapping back to A.

ceaser

________is a one-way calculation of information that yields a result usually much smaller than the original message.

check sum

(T/F) Product cipher is an encryption algorithm that has no corresponding decryption algorithm.

false

(T/F) Unlike symmetric key algorithms, asymmetric algorithms can be fast and are well suited to encrypting lots of data.

false

Which of the following is the definition of Vigenèrecipher?

An encryption cipher that replaces bits, characters, or blocks of information with other bits, characters, or blocks.

The most scrutinized cipher in history is the ________.

Data Encryption Standard (DES)

(T/F) Product cipher is an encryption algorithm that has no corresponding decryption algorithm.

False (one way algorithm)

(T/F) In a known-plaintext attack, the cryptanalyst has access only to a segment of encrypted data, and has no choice as to what that data might be.

False (that is cipher text only attack)

(T/F) A transposition cipher replaces bits, characters, or blocks of information with other bits, characters, or blocks.

False (that is subsitution cipher)

A process that creates the first secure communications session between a client and a server is the definition of ________. nonrepudiation certificate authority (CA) SSL handshake salt value

SSL handshake

What is meant by checksum?

The output of a one-way algorithm; a mathematically derived numerical representation of some input.

The term differential cryptanalysis refers to the act of unscrambling ciphertext into plaintext. True False

True

(T/F) A salt value is a set of random characters that you can combine with an actual input key to create the encryption key.

true

(T/F) An algorithm to encrypt or decrypt information is the definition of cipher.

true

(T/F) Decryption is the act of unscrambling ciphertext into plaintext.

true

What name is given to random characters that you can combine with an actual input key to create the encryption key?

salt value

In a ________, the cryptanalyst can encrypt any information and observe the output. This is best for the cryptanalyst. Known-plaintext attack (KPA) Chosen-ciphertext attack Chosen-plaintext attack Ciphertext-only attack (COA)

Chosen plaintext attack

A ________ is an encryption key used to encrypt other keys before transmitting them.

key encrypting key

the set of all possible keys is a ______.

key space

What name is given to an encryption cipher that uniquely maps any letter to any other letter?

simple subsitution cyphier

(T/F) Digital signatures require asymmetric key cryptography.

true