CH11

AES

Advanced Encryption Standard: A symmetric cipher that has been approved as a replacement for DES

Algorithm

Procedures based on mathematical formula; used to encrypt data.

Asymmetric Cryptographic Algorithm

Encryption that uses two mathematically related keys.

Bitlocker

A Microsoft Windows Vista hardware enabled data encryption feature.

Block Cipher

A cipher that manipulates an entire block of plaintext at the same time.

Cleartext

Unencrypted data

Blowfish

A block cipher that operates on 64-bit blocks and can have a key length from 32 to 448 bits.

Ciphertext

Data that has been encrypted.

Collision

In cryptography, two different sets of data that produce the same hash.

Cryptography

The science of transforming information into an unintelligible form while it is being transmitted or stored so that unauthorized users can't access it.

DES

Data Encryption Standard: A symmetric block cipher that encrypts data in 64-bit blocks, using 56 bit encryption.

Decryption

The process of changing ciphertext into plaintext.

Diffie-Hellman

A cryptographic algorithm that allows two users to share a secret key securely over a public network.

Digest

The unique signature created by a hashing algorithm.

Digital Signature

An electronic verification of a sender.

Elliptic Curve Cryptography

An algorithm that uses elliptic curves instead of prime numbers to compute keys.

EFS

Encrypting File System: An encryption scheme for Windows operating systems.

Encryption

The process of changing plaintext into ciphertext.

File System

A method used by operating systems to store, retrieve, and organize files.

GPG

GNU Privacy Guard: Free, open-source software that is commonly used to encrypt and decrypt e-mail messages.

Hash

The unique signature created by a hashing algorithm.

Hashing

The process for creating a unique signature for a set of data.

Homoalphabetic Substitution Cipher

A cipher that maps a single plaintext character to multiple ciphertext characters.

IDEA

International Data Encryption Algorithm: A symmetric algorithm that dates back to the early 1990s and is used mainly in Europe.

Key

A mathematical value entered into the algorithm to produce a cipher.

MD

Message Digest: A common hash algorithm of several different versions.

MD2

Message Digest 2: A hash algorithm that takes plaintext of any length and creates a hash that is 128 bits in length after the message is divided into 128 bit sections.

MD4

Message Digest 4: A hash that was created in 1990 for computers that process 32 bits at a time. This is considered compromised.

MD5

Message Digest 5: A revision of MD4 that is designed to address its weaknesses.

Metadata

Data that is used to describe the content or structure of the actual data.

Monoalphabetic Substitution Cipher

A cipher that simply substitutes one letter or character for another.

Nonrepudiation

The process of proving that a user performed an action.

OTP

On-Time Pad: Combining a truly random key with plaintext.

One-way Hash

The process of creating a unique signature of a set of data.

Pad

In cryptography, a truly random key.

Padding

Additional data that is added to a hash to make it the correct number of bytes.

Plaintext

Data input into an encryption algorithm.

PGP

Pretty Good Privacy: A commercial product that is commonly used to encrypt e-mail messages.

Private Key

An asymmetric encryption key that does have to be protected.

Private Key Cryptography

Cryptographic algorithms that use a single key to encrypt and decrypt a message.

Public Key

An asymmetric encryption key that does not have to be protected.

Public Key Cryptography

Encryption that uses two mathematically related keys.

RC2

A block cipher that processes blocks of 64 bits.

RC4

A stream cipher that will accept keys up to 128 bits in length.

RC5

A block cipher that can accept different length keys and blocks.

RC6

A cipher that has three key sizes (128,192, and 256 bit) and performs 20 rounds on each block.

RC

Rivest Cipher: A family of cipher algorithms designed by Ron Rivest.

RSA

An asymmetric algorithm published in 1977 and patented by MIT in 1983.

SHA

Secure Hash Algorithm: A Secure Hash Algorithm that creates hash values of longer lengths.

SHA-1

The first version of Secure Hash Algorithm.

SHA-2

A family of Secure Hash Algorithms that has variations, known as SHA-224, SHA-256, SHA-384, and SHA-512.

Steganography

Hiding the existence of data within a text, audio, image, or video file.

Stream Cipher

An algorithm that takes one character and replaces it with for another.

Substitution Cipher

A cipher that simply substitutes one letter or character for another.

Symmetric Cryptographic Algorithm

Encryption that uses a single key to encrypt and decrypt a message.

Transposition Cipher

A cipher that rearranges letters without changing them.

3DES

Triple Data Encryption Standard: A symmetric cipher that was designed to replace DES.

TPM

Trusted Platform Module: a chip on the motherboard of the computer that provides cryptographic services.

Twofish

A later derivation of the Blowfish algorithm that is considered to be strong.

Whirlpool

A new cryptographic hash function that has received international recognition and adoption by standards organizations.

Whole Disk Encryption

Cryptography that can be applied to entire disks.