Concepts

Table of Contents

BlockCipher Concept

A BlockCipher is an object intended to compute non-isomorphic permutations over particular sized integers (e.g. rijndael).

Requirements

The type X satisfies BlockCipher if

Given

  • WordType, the type named by X::word_type
  • KeyType, the type named by X::key_type
  • BlockType, the type named by X::block_type
  • RoundConstantsType, the type named by X::round_constants_type
  • StreamProcessor, the type template named by X::stream_processor

The following type members must be valid and have their specified effects

Expression Type Requirements and Notes
X::block_type BlockType BlockType type is a SequenceContainer of type T or std::array<T>
X::word_type WordType WordType type satisfies Integral concept
X::key_type KeyType KeyType type is a SequenceContainer of type T
X::round_constants_type RoundConstantsType RoundConstantsType type satisfies Integral concept

The following static data member definitions must be valid and have their specified effects

Expression Type Requirements and Notes
X::word_bits std::size_t Integral bits amount in WordType
X::key_bits std::size_t Integral bits amount in KeyType
X::block_bits std::size_t Integral bits amount in BlockType
X::block_words std::size_t Integral amount of WordType values in BlockType
X::rounds std::size_t Integral amount of rounds the algorithm does.

The following expressions must be valid and have their specified effects

Expression Requirements Return Type
X(key_type) Constructs stateful BlockCipher object with input key of key_type BlockCipher
X.encrypt(block_type) Encrypts a block of data in decoded format specified for particular algorithm. A block can be of a variable size. Should be a non-mutating function depending only on a BlockCipher object inner state of key_type type. block_type
X.decrypt(block_type) Decrypts a block of data in encoded format specified for particular algorithm. A block can be of a variable size. Should be a non-mutating function depending only on a BlockCipher object inner state of key_type type. block_type