AES in LYaPAS.pdf The objective of the paper is to present the description of the AES encryption and key expansion algorithms [1, 2] in the revised Russian programming language vLYaPAS [3]. The presented programs show the compactness, transparency and effectiveness of cryptographic algorithm representations in the language which was originally aimed at the representation of logical synthesis algorithms. It is assumed that the number of the cipher rounds is 10, and the lengths of the cipher block and key equal 128 bits. A ciphertext block is considered as a 2-measured array of 4 x 4 bytes. It is called a state and is represented by a logical complex of cardinality 4 whose elements are the rows of the state. Further, the texts of the head programs and their subprograms are given. The external parameters in them are the following: L1—the state (with the initial value equaled a plaintext block); L2 — the array of eleven 128-bit round keys (the complex of cardinality 44); L3 — ciphertext block; L4 — substitution table (S-box) for the operation of byte substitution; L5 — private key. Encryption of a block Encrypt(L1,L2,L4/L3) *AddRoundKey(L1,L2,0/L3) Oi §1 Ai®10^2 *SubBytes(L3,L4/L3) *ShiftRows(L3/L3) *MixColumns(L3/L3) *AddRoundKey(L3,L2,i/L3) ^ 1 §2 *SubBytes(L3,L4/L3) *ShiftRows(L3/L3) *AddRoundKey(L3,L2,10/L3) ** Addition modulo 2 of a text block and a round key AddRoundKey(L1,L2,n/L3) *** n — the number of a round Q1 ^ Q3 n8&m^b L1i>16&m^c L1i>24^d L4d

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