ISO/IEC 18033-4:2011 情報技術—セキュリティ技術—暗号化アルゴリズム—パート4：ストリーム暗号 | ページ 6

3.1

big-endian

method of storage of multi-byte numbers with the most significant bytes at the lowest memory addresses

[SOURCE:ISO/IEC 10118-1:2000]

3.2

ciphertext

data which has been transformed to hide its information content

[SOURCE:ISO/IEC 10116:2006]

3.3

confidentiality

property that information is not made available or disclosed to unauthorized individuals, entities, or processes

3.4

data integrity

property that data has not been altered or destroyed in an unauthorized manner

[SOURCE:ISO/IEC 9797-1:2011]

3.5

decryption

reversal of a corresponding encryption

[SOURCE:ISO/IEC 10116:2006]

3.6

encryption

reversible transformation of data by a cryptographic algorithm to produce ciphertext, i.e., to hide the information content of the data

[SOURCE:ISO/IEC 9797-1:2011]

3.7

initialization value

value used in defining the starting point of an encryption process

3.8

key

sequence of symbols that controls the operation of a cryptographic transformation (e.g., encryption, decryption, cryptographic check function computation, signature generation, or signature verification)

[SOURCE:ISO/IEC 11770-1:2010]

3.9

keystream function

function that takes as input, the current state of the keystream generator and (optionally) part of the previously generated ciphertext, and gives as output the next part of the keystream

3.10

keystream generator

state-based process (i.e., a finite state machine) that takes as input, a key, an initialization vector, and if necessary the ciphertext, and gives as output a keystream (i.e., a sequence of bits or blocks of bits) of arbitrary length

3.11

n -bit block cipher

block cipher with the property that plaintext blocks and ciphertext blocks are n bits in length

[SOURCE:ISO/IEC 10116:2006]

3.12

next-state function

function that takes as input, the current state of the keystream generator and (optionally) part of the previously generated ciphertext, and gives as output a new state for the keystream generator

3.13

output function

function that combines the keystream and the plaintext to produce the ciphertext

Note 1 to entry: This function is often bitwise XOR.

3.14

padding

appending extra bits to a data string

[SOURCE:ISO/IEC 10118-1:2000]

3.15

plaintext

unencrypted information

[SOURCE:ISO/IEC 9797-1:2011]

3.16

secret key

key used with symmetric cryptographic techniques by a specified set of entities

[SOURCE:ISO/IEC 11770-3:2008]

3.17

state

current internal state of a keystream generator