/************************************************* * RC6 Source File * * (C) 1999-2007 Jack Lloyd * *************************************************/ #include #include #include #include namespace Botan { /************************************************* * RC6 Encryption * *************************************************/ void RC6::enc(const byte in[], byte out[]) const { u32bit A = load_le(in, 0); u32bit B = load_le(in, 1); u32bit C = load_le(in, 2); u32bit D = load_le(in, 3); B += S[0]; D += S[1]; for(u32bit j = 0; j != 20; j += 4) { u32bit T1, T2; T1 = rotate_left(B*(2*B+1), 5); T2 = rotate_left(D*(2*D+1), 5); A = rotate_left(A ^ T1, T2 % 32) + S[2*j+2]; C = rotate_left(C ^ T2, T1 % 32) + S[2*j+3]; T1 = rotate_left(C*(2*C+1), 5); T2 = rotate_left(A*(2*A+1), 5); B = rotate_left(B ^ T1, T2 % 32) + S[2*j+4]; D = rotate_left(D ^ T2, T1 % 32) + S[2*j+5]; T1 = rotate_left(D*(2*D+1), 5); T2 = rotate_left(B*(2*B+1), 5); C = rotate_left(C ^ T1, T2 % 32) + S[2*j+6]; A = rotate_left(A ^ T2, T1 % 32) + S[2*j+7]; T1 = rotate_left(A*(2*A+1), 5); T2 = rotate_left(C*(2*C+1), 5); D = rotate_left(D ^ T1, T2 % 32) + S[2*j+8]; B = rotate_left(B ^ T2, T1 % 32) + S[2*j+9]; } A += S[42]; C += S[43]; store_le(out, A, B, C, D); } /************************************************* * RC6 Decryption * *************************************************/ void RC6::dec(const byte in[], byte out[]) const { u32bit A = load_le(in, 0); u32bit B = load_le(in, 1); u32bit C = load_le(in, 2); u32bit D = load_le(in, 3); C -= S[43]; A -= S[42]; for(u32bit j = 0; j != 20; j += 4) { u32bit T1, T2; T1 = rotate_left(A*(2*A+1), 5); T2 = rotate_left(C*(2*C+1), 5); B = rotate_right(B - S[41 - 2*j], T1 % 32) ^ T2; D = rotate_right(D - S[40 - 2*j], T2 % 32) ^ T1; T1 = rotate_left(D*(2*D+1), 5); T2 = rotate_left(B*(2*B+1), 5); A = rotate_right(A - S[39 - 2*j], T1 % 32) ^ T2; C = rotate_right(C - S[38 - 2*j], T2 % 32) ^ T1; T1 = rotate_left(C*(2*C+1), 5); T2 = rotate_left(A*(2*A+1), 5); D = rotate_right(D - S[37 - 2*j], T1 % 32) ^ T2; B = rotate_right(B - S[36 - 2*j], T2 % 32) ^ T1; T1 = rotate_left(B*(2*B+1), 5); T2 = rotate_left(D*(2*D+1), 5); C = rotate_right(C - S[35 - 2*j], T1 % 32) ^ T2; A = rotate_right(A - S[34 - 2*j], T2 % 32) ^ T1; } D -= S[1]; B -= S[0]; store_le(out, A, B, C, D); } /************************************************* * RC6 Key Schedule * *************************************************/ void RC6::key(const byte key[], u32bit length) { const u32bit WORD_KEYLENGTH = (((length - 1) / 4) + 1), MIX_ROUNDS = 3*std::max(WORD_KEYLENGTH, S.size()); S[0] = 0xB7E15163; for(u32bit j = 1; j != S.size(); ++j) S[j] = S[j-1] + 0x9E3779B9; SecureBuffer K; for(s32bit j = length-1; j >= 0; --j) K[j/4] = (K[j/4] << 8) + key[j]; for(u32bit j = 0, A = 0, B = 0; j != MIX_ROUNDS; ++j) { A = rotate_left(S[j % S.size()] + A + B, 3); B = rotate_left(K[j % WORD_KEYLENGTH] + A + B, (A + B) % 32); S[j % S.size()] = A; K[j % WORD_KEYLENGTH] = B; } } }