Cryptography Reference
In-Depth Information
IDEA A product algorithm mainly used in PGP; works with 128-bit keys and 64-bit
blocks, and is considered to be very secure.
Identification The act of identifying the author of a message. The receiver identifies
the sender, whereas the sender authenticates himself (proves his identity).
Initialization vector ('IV' for short) A random block required in many ciphering modes
as the first block. The IV causes the encryption of identical or almost identical
plaintexts to produce totally different ciphertexts. Furthermore, it prevents various
cryptanalytic attacks (e.g., pattern recognition).
Integrity A state proving that a (digital) document has not been tampered with, which
is often guaranteed by digital signatures.
IV Short for 'initialization vector'.
Kappa (Character coincidence) A statistical quantity produced from two ciphertexts,
which
can
be
used
to
determine
the
period
length
in
a
Vigenere
cipher
(Section 3.6.1).
KEA A public-key algorithm used by the NSA in Clipper chips (Section 6.1.1).
Kerberos A protocol for authentication and encryption in local area networks (LANs),
which relies on one or two trustworthy computers rather than using an asymmetric
method. Nevertheless, it has several flaws. Kerberos is not discussed in this topic.
Key escrow An attempt toward governmental regulation of cryptography: people can
continue encrypting their stuff, but the government must be given the keys some-
how upon request (see Sections 6.4 and 8.2.2).
Key stream See 'stream cipher'.
Left rotation See 'rotation'.
Linear expression In algebra, an expression in the form of a 1 x 1 +ยทยทยท+ a n x n , where
x i are variables and a i are constants. In cryptology, for example, 64-bit numbers
take the place of real numbers, an addition corresponds to bitwise XOR, and a
multiplication corresponds to bitwise AND. This turns a linear expression into
a XOR sum of bits selected from integer data types (e.g., machine words; see
Section 4.4.4).
MAC (Message Authentication Code) A one-way hash function the hash sum of which
can be calculated only provided one knows the secret key. The simplest example
is the encryption of a hash sum by means of a symmetric method. A secure and
Search WWH ::




Custom Search