Glossary - Cryptology Unlocked - page 491

Diffusion A property of block algorithms which ensures that information about parts
of a plaintext block influence the entire ciphertext block (see also 'confusion'). A
particularly strong diffusion is the avalanche effect (Section 4.1.2).
Digital signature A character string in a digital document that allows a person who knows
the author's public key to verify whether that document really originates from this
author, and that it hasn't been changed (see also 'authentication', 'integrity'). It
cannot be forged without knowing the secret private key of the author.
Digram In the general sense, a pair of consecutive letters in a text. Digrams are
important in classical cryptography (see Section 2.3).
Discrete logarithm See 'primitive root'.
DSA (Digital Signature Algorithm) A very secure method for creating digital signa-
tures developed by the NSA. DSA is an integral part of DSS (Digital Signature
Standard), and uses SHA (Secure Hash Algorithm) as a one-way hash function.
DSS See 'DSA'.
e-cash (electronic cash) Digital money; Section 6.6.7 discusses a protocol for e-cash.
ECB (Electronic Codebook) A ciphering mode used in block algorithms (Section
5.1.1).
Echelon A worldwide surveillance system of the NSA that monitors most international
communications, and parts of national civilian communications (Section 8.2.1).
EES (Escrowed Encryption Standard) US standard for devices in connection with key
escrow (see 'Clipper', 'Capstone', and Section 6.4).
Encoding The deterministic conversion of a text for the purpose of adapting it to special
transmission channels (e.g., Morse code, base64, MIME). This conversion does
not depend on keys. Encoding is often confused with ciphering. The difference is
that encoded text can be easily read if the encoding method is known, whereas
ciphering requires the knowledge of a secret key.
Enigma Famous German ciphering machine that was used to encrypt a considerable
part of German communications (particularly those of German submarines) during
World War II (Sections 2.5.1 through 2.5.3).
Exhaustion method See 'brute force'.