diff options
author | lloyd <[email protected]> | 2008-11-08 19:46:52 +0000 |
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committer | lloyd <[email protected]> | 2008-11-08 19:46:52 +0000 |
commit | f1c459725da56fd8ed5766e7779300182fa26bcf (patch) | |
tree | 32295cec92df1155563ae8a535dc695d6800d7f6 /src/block/idea/idea.cpp | |
parent | 8dba7b5264403e781bbb86ff61850e4377dca7b9 (diff) |
Split ciphers into block and stream ciphers. Move base class headers
Diffstat (limited to 'src/block/idea/idea.cpp')
-rw-r--r-- | src/block/idea/idea.cpp | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/src/block/idea/idea.cpp b/src/block/idea/idea.cpp new file mode 100644 index 000000000..a2b076015 --- /dev/null +++ b/src/block/idea/idea.cpp @@ -0,0 +1,172 @@ +/************************************************* +* IDEA Source File * +* (C) 1999-2007 Jack Lloyd * +*************************************************/ + +#include <botan/idea.h> +#include <botan/loadstor.h> + +namespace Botan { + +namespace { + +/************************************************* +* Multiplication modulo 65537 * +*************************************************/ +inline u16bit mul(u16bit x, u16bit y) + { + if(x && y) + { + u32bit T = static_cast<u32bit>(x) * y; + x = static_cast<u16bit>(T >> 16); + y = static_cast<u16bit>(T & 0xFFFF); + return static_cast<u16bit>(y - x + ((y < x) ? 1 : 0)); + } + else + return static_cast<u16bit>(1 - x - y); + } + +/************************************************* +* Find multiplicative inverses modulo 65537 * +*************************************************/ +u16bit mul_inv(u16bit x) + { + if(x <= 1) + return x; + + u16bit t0 = static_cast<u16bit>(65537 / x), t1 = 1; + u16bit y = static_cast<u16bit>(65537 % x); + + while(y != 1) + { + u16bit q = x / y; + x %= y; + t1 += q * t0; + + if(x == 1) + return t1; + + q = y / x; + y %= x; + t0 += q * t1; + } + return (1 - t0); + } + +} + +/************************************************* +* IDEA Encryption * +*************************************************/ +void IDEA::enc(const byte in[], byte out[]) const + { + 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(u32bit j = 0; j != 8; ++j) + { + X1 = mul(X1, EK[6*j+0]); + X2 += EK[6*j+1]; + X3 += EK[6*j+2]; + X4 = mul(X4, EK[6*j+3]); + + u16bit T0 = X3; + X3 = mul(X3 ^ X1, EK[6*j+4]); + + u16bit T1 = X2; + X2 = mul((X2 ^ X4) + X3, EK[6*j+5]); + X3 += X2; + + X1 ^= X2; + X4 ^= X3; + X2 ^= T0; + X3 ^= T1; + } + + X1 = mul(X1, EK[48]); + X2 += EK[50]; + X3 += EK[49]; + X4 = mul(X4, EK[51]); + + store_be(out, X1, X3, X2, X4); + } + +/************************************************* +* IDEA Decryption * +*************************************************/ +void IDEA::dec(const byte in[], byte out[]) const + { + 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(u32bit j = 0; j != 8; ++j) + { + X1 = mul(X1, DK[6*j+0]); + X2 += DK[6*j+1]; + X3 += DK[6*j+2]; + X4 = mul(X4, DK[6*j+3]); + + u16bit T0 = X3; + X3 = mul(X3 ^ X1, DK[6*j+4]); + + u16bit T1 = X2; + X2 = mul((X2 ^ X4) + X3, DK[6*j+5]); + X3 += X2; + + X1 ^= X2; + X4 ^= X3; + X2 ^= T0; + X3 ^= T1; + } + + X1 = mul(X1, DK[48]); + X2 += DK[50]; + X3 += DK[49]; + X4 = mul(X4, DK[51]); + + store_be(out, X1, X3, X2, X4); + } + +/************************************************* +* IDEA Key Schedule * +*************************************************/ +void IDEA::key(const byte key[], u32bit) + { + for(u32bit j = 0; j != 8; ++j) + EK[j] = load_be<u16bit>(key, j); + + for(u32bit j = 1, k = 8, offset = 0; k != 52; j %= 8, ++j, ++k) + { + EK[j+7+offset] = static_cast<u16bit>((EK[(j % 8) + offset] << 9) | + (EK[((j+1) % 8) + offset] >> 7)); + offset += (j == 8) ? 8 : 0; + } + + DK[51] = mul_inv(EK[3]); + DK[50] = -EK[2]; + DK[49] = -EK[1]; + DK[48] = mul_inv(EK[0]); + + for(u32bit j = 1, k = 4, counter = 47; j != 8; ++j, k += 6) + { + DK[counter--] = EK[k+1]; + DK[counter--] = EK[k]; + DK[counter--] = mul_inv(EK[k+5]); + DK[counter--] = -EK[k+3]; + DK[counter--] = -EK[k+4]; + DK[counter--] = mul_inv(EK[k+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]); + } + +} |