Chapter 8

steganography

a data hiding method that involves embedding information within other files, such as digital pictures or other images

exclusive or operation (XOR)

a function within boolean algebra used as an encryption function in which two bits are compared. if the two bits are identical, the result is a binary 0; otherwise, the result is binary 1

Diffie hellman key exchange

a hybrid that facilitates exchanging private keys using public key encryption

Message authentication code (MAC)

a key dependent, one way hash function that allows only specific recipients (symmetric key holders) to access the message digest

secret key

a key that can be used in symmetric encryption both to encipher and decipher the message

secure electronic transactions (SET)

a protocol developed by credit card companies to protect against electronic payment fraud

secure socket layers (SSL)

a security protocol developed by netscape to use public key encryption to secure a channel over the internet

secure multipurpose internet mail extension (SIMIME)

a security protocol that builds on the encoding format of the multipurpose internet mail extensions (MIME) protocol and uses digital signatures based on public key cryptosystems to secure e-mail

secure hash standard

a standard issued by the national institute of standards and technology (NIST) that specifies secure algorithms, such as SHA-1, for computing a condensed representation of a message or data file

privacy enhanced mail (PEM)

a standard proposed by the internet engineering task force (IETF) that uses 3DES symmetric key encryption and RSA for key exchanges and digital signatures

polyalphabetic substitution

a substitution cipher that incorporates two or more alphabets in the encryption process

monoalphabetic substitution

a substitution cipher that only incorporates a single alphabet in the encryption process

message digest

a value representing the application of a hash algorithm on a message that is transmitted with the message so it can be compared with the recipient's locally calculated hash of the same message. if both hashes are identical after transmission, the message has arrived without modification. also known as hash value

transposition cipher

also known as a permutation cipher, an encryption method that involves simply rearranging that values within a block based on an established pattern to create the ciphertext

transport mode

an IPSec mode in which only the IP data is encrypted, not the IP headers

tunnel mode

an IPSec mode in which the entire IP packet is encrypted and then placed into the content portion of another IP packet

vigenere cipher

an advance type of substitution cipher that uses a simple polyalphabetic code

substitution cipher

an encryption method in which one value is substituted for another

asymmetric encryption

an encryption method that incorporates mathematical operations involving both a public key and a private key to encipher or decipher a message. either key can be used to encrypt a message, but then the other key is required to decrypt it.

private key encryption or symmetric encryption

an encryption method that incorporates mathematical operations involving the same secret key both to encipher and decipher the message

vernam cipher

an encryption process that generates a random substitution matrix between letters and numbers that is used only one time. also called a one time pad

secure HTTP (S-HTTP)

an extended version of hypertext transfer protocol that provides for the encryption of protected web pages transmitted via the internet between a client and server

public key infrastructure (PKI)

an integrated system of software, encryption methodologies, protocols, legal agreements, and third party services that enables users to communicate securely through the use of digital certificates

internet protocol security (IPSec)

an open source protocol framework for security development within the TCP/IP family of protocol standards

digital signatures

encrypted message components that can be mathematically proven as authentic

encapsulating security payload (ESP) protocol

in IPSec, a protocol that provides secrecy for the contents of network communications as well as system to system authentication and data integrity verification

application header (AH) protocol

in IPSec, a protocol that provides system to system authentication an data integrity verification, but does not provide secrecy for the content for a network communication

certificate revocation list (CRL)

in PKI, a published list of revoked or terminate digital

certificate authority (CA)

in PKI, a third party that manages users digital certificates

registration authority (RA)

in PKI, a third party that operates under the trusted collaboration of the certificate authority and handles day to day certifications functions

session keys

limited use symmetric keys for temporary communications during an online session

hash function

mathematical algorithms that generate a message summary or digest (sometimes called a fingerprint) to confirm message identity and integrity

hash algorithms

public functions that create a hash value, also known as a message digest, by converting variable length message into a single fixed length value

digital certificates

public key container files that allow PKI system components and end users to validate a public key and identify its owner

digital signature standard (DSS)

the NIST standard for digital signature algorithm usage by federal information systems. This is based on a variant of the Elgamal signature scheme

advanced encryption standard (AES)

the current federal standard for the encryption of data, as specified by NIST. This is based on the Rijndael algorithm, which was developed by Vincent Rijmen and Joan Daemen

Cryptography

the process of making and using codes to secure the transmission of information

Cryptanalysis

the process of obtaining the plaintext message from a ciphertext message without knowing the keys used to perform the encryption

nonrepudiation

the process of reversing public key encryption to verify that a message was sent by the sender and thus cannot be refuted

cryptology

the science of encryption, which encompasses cryptography and cryptanalysis