diff options
author | lloyd <[email protected]> | 2014-01-01 21:20:55 +0000 |
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committer | lloyd <[email protected]> | 2014-01-01 21:20:55 +0000 |
commit | 197dc467dec28a04c3b2f30da7cef122dfbb13e9 (patch) | |
tree | cdbd3ddaec051c72f0a757db461973d90c37b97a /lib/block/idea/idea.cpp | |
parent | 62faac373c07cfe10bc8c309e89ebdd30d8e5eaa (diff) |
Shuffle things around. Add NIST X.509 test to build.
Diffstat (limited to 'lib/block/idea/idea.cpp')
-rw-r--r-- | lib/block/idea/idea.cpp | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/lib/block/idea/idea.cpp b/lib/block/idea/idea.cpp new file mode 100644 index 000000000..61a938c57 --- /dev/null +++ b/lib/block/idea/idea.cpp @@ -0,0 +1,169 @@ +/* +* IDEA +* (C) 1999-2010 Jack Lloyd +* +* Distributed under the terms of the Botan license +*/ + +#include <botan/idea.h> +#include <botan/loadstor.h> + +namespace Botan { + +namespace { + +/* +* Multiplication modulo 65537 +*/ +inline u16bit mul(u16bit x, u16bit y) + { + const u32bit P = static_cast<u32bit>(x) * y; + + // P ? 0xFFFF : 0 + const u16bit P_mask = !P - 1; + + const u32bit P_hi = P >> 16; + const u32bit P_lo = P & 0xFFFF; + + const u16bit r_1 = (P_lo - P_hi) + (P_lo < P_hi); + const u16bit r_2 = 1 - x - y; + + return (r_1 & P_mask) | (r_2 & ~P_mask); + } + +/* +* Find multiplicative inverses modulo 65537 +* +* 65537 is prime; thus Fermat's little theorem tells us that +* x^65537 == x modulo 65537, which means +* x^(65537-2) == x^-1 modulo 65537 since +* x^(65537-2) * x == 1 mod 65537 +* +* Do the exponentiation with a basic square and multiply: all bits are +* of exponent are 1 so we always multiply +*/ +u16bit mul_inv(u16bit x) + { + u16bit y = x; + + for(size_t i = 0; i != 15; ++i) + { + y = mul(y, y); // square + y = mul(y, x); + } + + return y; + } + +/** +* IDEA is involutional, depending only on the key schedule +*/ +void idea_op(const byte in[], byte out[], size_t blocks, const u16bit K[52]) + { + const size_t BLOCK_SIZE = 8; + + for(size_t i = 0; i != blocks; ++i) + { + u16bit X1 = load_be<u16bit>(in, 0); + u16bit X2 = load_be<u16bit>(in, 1); + u16bit X3 = load_be<u16bit>(in, 2); + u16bit X4 = load_be<u16bit>(in, 3); + + for(size_t j = 0; j != 8; ++j) + { + X1 = mul(X1, K[6*j+0]); + X2 += K[6*j+1]; + X3 += K[6*j+2]; + X4 = mul(X4, K[6*j+3]); + + u16bit T0 = X3; + X3 = mul(X3 ^ X1, K[6*j+4]); + + u16bit T1 = X2; + X2 = mul((X2 ^ X4) + X3, K[6*j+5]); + X3 += X2; + + X1 ^= X2; + X4 ^= X3; + X2 ^= T0; + X3 ^= T1; + } + + X1 = mul(X1, K[48]); + X2 += K[50]; + X3 += K[49]; + X4 = mul(X4, K[51]); + + store_be(out, X1, X3, X2, X4); + + in += BLOCK_SIZE; + out += BLOCK_SIZE; + } + } + +} + +/* +* IDEA Encryption +*/ +void IDEA::encrypt_n(const byte in[], byte out[], size_t blocks) const + { + idea_op(in, out, blocks, &EK[0]); + } + +/* +* IDEA Decryption +*/ +void IDEA::decrypt_n(const byte in[], byte out[], size_t blocks) const + { + idea_op(in, out, blocks, &DK[0]); + } + +/* +* IDEA Key Schedule +*/ +void IDEA::key_schedule(const byte key[], size_t) + { + EK.resize(52); + DK.resize(52); + + for(size_t i = 0; i != 8; ++i) + EK[i] = load_be<u16bit>(key, i); + + for(size_t i = 1, j = 8, offset = 0; j != 52; i %= 8, ++i, ++j) + { + EK[i+7+offset] = static_cast<u16bit>((EK[(i % 8) + offset] << 9) | + (EK[((i+1) % 8) + offset] >> 7)); + offset += (i == 8) ? 8 : 0; + } + + DK[51] = mul_inv(EK[3]); + DK[50] = -EK[2]; + DK[49] = -EK[1]; + DK[48] = mul_inv(EK[0]); + + for(size_t i = 1, j = 4, counter = 47; i != 8; ++i, j += 6) + { + DK[counter--] = EK[j+1]; + DK[counter--] = EK[j]; + DK[counter--] = mul_inv(EK[j+5]); + DK[counter--] = -EK[j+3]; + DK[counter--] = -EK[j+4]; + DK[counter--] = mul_inv(EK[j+2]); + } + + DK[5] = EK[47]; + DK[4] = EK[46]; + DK[3] = mul_inv(EK[51]); + DK[2] = -EK[50]; + DK[1] = -EK[49]; + DK[0] = mul_inv(EK[48]); + } + +void IDEA::clear() + { + zap(EK); + zap(DK); + } + +} |