Cryptography Reference
In-Depth Information
Capstone chip
A chip produced by Mykotronx for encrypted data communications
with key escrow (Section 6.4.1).
CBC
(Cipher Block Chaining) A ciphering mode used in block algorithms (Section
5.1.1).
CFB
(Cipher Feedback) A ciphering mode used in block algorithms (Section 5.1.1).
Character coincidence
Two characters coincide in the same positions when com-
paring two texts, which is important for computing the index of coincidence
(see 'kappa').
Cipher
A gibberish text (aka 'ciphertext') produced by ciphering (encrypting) a plain-
text.
Ciphering error
An error made in the encryption, impairing the security of the cipher.
These errors often depend on the encryption method used. A typical example is
selecting bad passwords (Section 3.1 and Figure 3.1).
Ciphering mode
An operating mode that specifies how single plaintext and ciphertext
blocks are computed in block algorithms (Section 5.1.1). The four commonly used
modes are ECB, CBC, CFB, and OFB.
Ciphertext
(aka 'cipher') The result of an encryption.
Ciphertext attack
A cryptanalytic method that exploits only the ciphertext.
Clipper chip
A variant of the Capstone chip for encrypted telephone communications.
Codebreaker
A person who breaks encryption codes (as opposed to a cryptanalyst
who develops the underlying theory).
Complexity theory
A subsection of mathematics that tries to estimate the cost involved
in solving a problem. It is very important for cryptology, because it is thought
that only complexity theory can make reliable statements about the security of
current encryption algorithms.
Compromise
A successful cryptological attack against an encryption method or a
cryptographic protocol.
Confusion
The act of blurring the relationship between a plaintext and the correspond-
ing ciphertext in the same text positions, as opposed to diffusion (Section 4.1.2).