/************************************************* * CAST-256 Source File * * (C) 1999-2007 The Botan Project * *************************************************/ #include #include namespace Botan { namespace { /************************************************* * CAST-256 Round Type 1 * *************************************************/ void round1(u32bit& out, u32bit in, u32bit mask, u32bit rot) { u32bit temp = rotate_left(mask + in, rot); out ^= (CAST_SBOX1[get_byte(0, temp)] ^ CAST_SBOX2[get_byte(1, temp)]) - CAST_SBOX3[get_byte(2, temp)] + CAST_SBOX4[get_byte(3, temp)]; } /************************************************* * CAST-256 Round Type 2 * *************************************************/ void round2(u32bit& out, u32bit in, u32bit mask, u32bit rot) { u32bit temp = rotate_left(mask ^ in, rot); out ^= (CAST_SBOX1[get_byte(0, temp)] - CAST_SBOX2[get_byte(1, temp)] + CAST_SBOX3[get_byte(2, temp)]) ^ CAST_SBOX4[get_byte(3, temp)]; } /************************************************* * CAST-256 Round Type 3 * *************************************************/ void round3(u32bit& out, u32bit in, u32bit mask, u32bit rot) { u32bit temp = rotate_left(mask - in, rot); out ^= ((CAST_SBOX1[get_byte(0, temp)] + CAST_SBOX2[get_byte(1, temp)]) ^ CAST_SBOX3[get_byte(2, temp)]) - CAST_SBOX4[get_byte(3, temp)]; } } /************************************************* * CAST-256 Encryption * *************************************************/ void CAST_256::enc(const byte in[], byte out[]) const { u32bit A = load_be(in, 0); u32bit B = load_be(in, 1); u32bit C = load_be(in, 2); u32bit D = load_be(in, 3); round1(C, D, MK[ 0], RK[ 0]); round2(B, C, MK[ 1], RK[ 1]); round3(A, B, MK[ 2], RK[ 2]); round1(D, A, MK[ 3], RK[ 3]); round1(C, D, MK[ 4], RK[ 4]); round2(B, C, MK[ 5], RK[ 5]); round3(A, B, MK[ 6], RK[ 6]); round1(D, A, MK[ 7], RK[ 7]); round1(C, D, MK[ 8], RK[ 8]); round2(B, C, MK[ 9], RK[ 9]); round3(A, B, MK[10], RK[10]); round1(D, A, MK[11], RK[11]); round1(C, D, MK[12], RK[12]); round2(B, C, MK[13], RK[13]); round3(A, B, MK[14], RK[14]); round1(D, A, MK[15], RK[15]); round1(C, D, MK[16], RK[16]); round2(B, C, MK[17], RK[17]); round3(A, B, MK[18], RK[18]); round1(D, A, MK[19], RK[19]); round1(C, D, MK[20], RK[20]); round2(B, C, MK[21], RK[21]); round3(A, B, MK[22], RK[22]); round1(D, A, MK[23], RK[23]); round1(D, A, MK[27], RK[27]); round3(A, B, MK[26], RK[26]); round2(B, C, MK[25], RK[25]); round1(C, D, MK[24], RK[24]); round1(D, A, MK[31], RK[31]); round3(A, B, MK[30], RK[30]); round2(B, C, MK[29], RK[29]); round1(C, D, MK[28], RK[28]); round1(D, A, MK[35], RK[35]); round3(A, B, MK[34], RK[34]); round2(B, C, MK[33], RK[33]); round1(C, D, MK[32], RK[32]); round1(D, A, MK[39], RK[39]); round3(A, B, MK[38], RK[38]); round2(B, C, MK[37], RK[37]); round1(C, D, MK[36], RK[36]); round1(D, A, MK[43], RK[43]); round3(A, B, MK[42], RK[42]); round2(B, C, MK[41], RK[41]); round1(C, D, MK[40], RK[40]); round1(D, A, MK[47], RK[47]); round3(A, B, MK[46], RK[46]); round2(B, C, MK[45], RK[45]); round1(C, D, MK[44], RK[44]); store_be(out, A, B, C, D); } /************************************************* * CAST-256 Decryption * *************************************************/ void CAST_256::dec(const byte in[], byte out[]) const { u32bit A = load_be(in, 0); u32bit B = load_be(in, 1); u32bit C = load_be(in, 2); u32bit D = load_be(in, 3); round1(C, D, MK[44], RK[44]); round2(B, C, MK[45], RK[45]); round3(A, B, MK[46], RK[46]); round1(D, A, MK[47], RK[47]); round1(C, D, MK[40], RK[40]); round2(B, C, MK[41], RK[41]); round3(A, B, MK[42], RK[42]); round1(D, A, MK[43], RK[43]); round1(C, D, MK[36], RK[36]); round2(B, C, MK[37], RK[37]); round3(A, B, MK[38], RK[38]); round1(D, A, MK[39], RK[39]); round1(C, D, MK[32], RK[32]); round2(B, C, MK[33], RK[33]); round3(A, B, MK[34], RK[34]); round1(D, A, MK[35], RK[35]); round1(C, D, MK[28], RK[28]); round2(B, C, MK[29], RK[29]); round3(A, B, MK[30], RK[30]); round1(D, A, MK[31], RK[31]); round1(C, D, MK[24], RK[24]); round2(B, C, MK[25], RK[25]); round3(A, B, MK[26], RK[26]); round1(D, A, MK[27], RK[27]); round1(D, A, MK[23], RK[23]); round3(A, B, MK[22], RK[22]); round2(B, C, MK[21], RK[21]); round1(C, D, MK[20], RK[20]); round1(D, A, MK[19], RK[19]); round3(A, B, MK[18], RK[18]); round2(B, C, MK[17], RK[17]); round1(C, D, MK[16], RK[16]); round1(D, A, MK[15], RK[15]); round3(A, B, MK[14], RK[14]); round2(B, C, MK[13], RK[13]); round1(C, D, MK[12], RK[12]); round1(D, A, MK[11], RK[11]); round3(A, B, MK[10], RK[10]); round2(B, C, MK[ 9], RK[ 9]); round1(C, D, MK[ 8], RK[ 8]); round1(D, A, MK[ 7], RK[ 7]); round3(A, B, MK[ 6], RK[ 6]); round2(B, C, MK[ 5], RK[ 5]); round1(C, D, MK[ 4], RK[ 4]); round1(D, A, MK[ 3], RK[ 3]); round3(A, B, MK[ 2], RK[ 2]); round2(B, C, MK[ 1], RK[ 1]); round1(C, D, MK[ 0], RK[ 0]); store_be(out, A, B, C, D); } /************************************************* * CAST-256 Key Schedule * *************************************************/ void CAST_256::key(const byte key[], u32bit length) { SecureBuffer TMP; for(u32bit j = 0; j != length; ++j) TMP[j/4] = (TMP[j/4] << 8) + key[j]; u32bit A = TMP[0], B = TMP[1], C = TMP[2], D = TMP[3], E = TMP[4], F = TMP[5], G = TMP[6], H = TMP[7]; for(u32bit j = 0; j != 48; j += 4) { round1(G, H, KEY_MASK[4*j+ 0], KEY_ROT[(4*j+ 0) % 32]); round2(F, G, KEY_MASK[4*j+ 1], KEY_ROT[(4*j+ 1) % 32]); round3(E, F, KEY_MASK[4*j+ 2], KEY_ROT[(4*j+ 2) % 32]); round1(D, E, KEY_MASK[4*j+ 3], KEY_ROT[(4*j+ 3) % 32]); round2(C, D, KEY_MASK[4*j+ 4], KEY_ROT[(4*j+ 4) % 32]); round3(B, C, KEY_MASK[4*j+ 5], KEY_ROT[(4*j+ 5) % 32]); round1(A, B, KEY_MASK[4*j+ 6], KEY_ROT[(4*j+ 6) % 32]); round2(H, A, KEY_MASK[4*j+ 7], KEY_ROT[(4*j+ 7) % 32]); round1(G, H, KEY_MASK[4*j+ 8], KEY_ROT[(4*j+ 8) % 32]); round2(F, G, KEY_MASK[4*j+ 9], KEY_ROT[(4*j+ 9) % 32]); round3(E, F, KEY_MASK[4*j+10], KEY_ROT[(4*j+10) % 32]); round1(D, E, KEY_MASK[4*j+11], KEY_ROT[(4*j+11) % 32]); round2(C, D, KEY_MASK[4*j+12], KEY_ROT[(4*j+12) % 32]); round3(B, C, KEY_MASK[4*j+13], KEY_ROT[(4*j+13) % 32]); round1(A, B, KEY_MASK[4*j+14], KEY_ROT[(4*j+14) % 32]); round2(H, A, KEY_MASK[4*j+15], KEY_ROT[(4*j+15) % 32]); RK[j ] = (A % 32); RK[j+1] = (C % 32); RK[j+2] = (E % 32); RK[j+3] = (G % 32); MK[j ] = H; MK[j+1] = F; MK[j+2] = D; MK[j+3] = B; } } }