Exam 8: Cryptography

S-HTTP is an extended version of Hypertext Transfer Protocol that provides for the encryption of protected e-mail transmitted via the Internet between a client and server. _________________________

PKI systems are based on public-key cryptosystems and include digital certificates and certificate authorities.

A method of encryption that requires the same secret key to encipher and decipher the message is known as __________ encryption.

More advanced substitution ciphers use two or more alphabets, and are referred to as __________ substitutions.

In addition to being credited with inventing a substitution cipher, Julius Caesar was associated with an early version of the transposition cipher.

Digital signatures should be created using processes and products that are based on the __________.

A(n) ____________________ or cryptosystem is an encryption method or process encompassing the algorithm, key(s) or cryptovariable(s), and procedures used to perform encryption and decryption.

The permutation cipher simply rearranges the values within a block to create the ciphertext.

Encryption is the process of converting the ciphertext message back into plaintext so that it can be readily understood. _________________________

The AES algorithm was the first public-key encryption algorithm to use a 256-bit key length.

Usually, as the length of a cryptovariable increases, the number of random guesses that have to be made in order to break the code is reduced.

A message ____________________ is a fingerprint of the author's message that is compared with the recipient's locally calculated hash of the same message.

Originally released as freeware, ____________________ is a hybrid cryptosystem that combines some of the best available cryptographic algorithms as an open-source de facto standard for encryption and authentication of e-mail and file storage.

Netscape developed the ____________________ Layer protocol to use public-key encryption to secure a channel over the Internet, thus enabling secure communications.

Hash algorithms are public functions that create a message digest by converting variable-length messages into a single fixed-length value. _________________________

Using a database of precomputed hashes from sequentially calculated passwords called a(n) __________, an attacker can simply look up a hashed password and read out the text version.

Diffie-Hellman key exchange uses asymmetric encryption to exchange session keys. _________________________

Common implementations of a registration authority (RA) include functions to issue digital certificates to users and servers.

Nonrepudiation means that customers or partners can be held accountable for transactions, such as online purchases, which they cannot later deny.

The science of encryption is known as ____________________.