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Diffstat (limited to 'src/common/des.c')
| -rw-r--r-- | src/common/des.c | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/src/common/des.c b/src/common/des.c new file mode 100644 index 000000000..67a3a38d1 --- /dev/null +++ b/src/common/des.c @@ -0,0 +1,218 @@ +// Copyright (c) Athena Dev Teams - Licensed under GNU GPL +// For more information, see LICENCE in the main folder +#include "../common/cbasetypes.h" +#include "../common/des.h" + + +/// DES (Data Encryption Standard) algorithm, modified version. +/// @see http://www.eathena.ws/board/index.php?autocom=bugtracker&showbug=5099. +/// @see http://en.wikipedia.org/wiki/Data_Encryption_Standard +/// @see http://en.wikipedia.org/wiki/DES_supplementary_material + + +/// Bitmask for accessing individual bits of a byte. +static const uint8_t mask[8] = { + 0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01 +}; + + +/// Initial permutation (IP). +static void IP(BIT64* src) +{ + BIT64 tmp = {0}; + + static const uint8_t ip_table[64] = { + 58, 50, 42, 34, 26, 18, 10, 2, + 60, 52, 44, 36, 28, 20, 12, 4, + 62, 54, 46, 38, 30, 22, 14, 6, + 64, 56, 48, 40, 32, 24, 16, 8, + 57, 49, 41, 33, 25, 17, 9, 1, + 59, 51, 43, 35, 27, 19, 11, 3, + 61, 53, 45, 37, 29, 21, 13, 5, + 63, 55, 47, 39, 31, 23, 15, 7, + }; + + size_t i; + for( i = 0; i < ARRAYLENGTH(ip_table); ++i ) + { + uint8_t j = ip_table[i] - 1; + if( src->b[(j >> 3) & 7] & mask[j & 7] ) + tmp .b[(i >> 3) & 7] |= mask[i & 7]; + } + + *src = tmp; +} + + +/// Final permutation (IP^-1). +static void FP(BIT64* src) +{ + BIT64 tmp = {0}; + + static const uint8_t fp_table[64] = { + 40, 8, 48, 16, 56, 24, 64, 32, + 39, 7, 47, 15, 55, 23, 63, 31, + 38, 6, 46, 14, 54, 22, 62, 30, + 37, 5, 45, 13, 53, 21, 61, 29, + 36, 4, 44, 12, 52, 20, 60, 28, + 35, 3, 43, 11, 51, 19, 59, 27, + 34, 2, 42, 10, 50, 18, 58, 26, + 33, 1, 41, 9, 49, 17, 57, 25, + }; + + size_t i; + for( i = 0; i < ARRAYLENGTH(fp_table); ++i ) + { + uint8_t j = fp_table[i] - 1; + if( src->b[(j >> 3) & 7] & mask[j & 7] ) + tmp .b[(i >> 3) & 7] |= mask[i & 7]; + } + + *src = tmp; +} + + +/// Expansion (E). +/// Expands upper four 8-bits (32b) into eight 6-bits (48b). +static void E(BIT64* src) +{ + BIT64 tmp = {0}; + +if( false ) +{// original + static const uint8_t expand_table[48] = { + 32, 1, 2, 3, 4, 5, + 4, 5, 6, 7, 8, 9, + 8, 9, 10, 11, 12, 13, + 12, 13, 14, 15, 16, 17, + 16, 17, 18, 19, 20, 21, + 20, 21, 22, 23, 24, 25, + 24, 25, 26, 27, 28, 29, + 28, 29, 30, 31, 32, 1, + }; + + size_t i; + for( i = 0; i < ARRAYLENGTH(expand_table); ++i ) + { + uint8_t j = expand_table[i] - 1; + if( src->b[j / 8 + 4] & mask[j % 8] ) + tmp .b[i / 6 + 0] |= mask[i % 6]; + } +} +else +{// optimized + tmp.b[0] = ((src->b[7]<<5) | (src->b[4]>>3)) & 0x3f; // ..0 vutsr + tmp.b[1] = ((src->b[4]<<1) | (src->b[5]>>7)) & 0x3f; // ..srqpo n + tmp.b[2] = ((src->b[4]<<5) | (src->b[5]>>3)) & 0x3f; // ..o nmlkj + tmp.b[3] = ((src->b[5]<<1) | (src->b[6]>>7)) & 0x3f; // ..kjihg f + tmp.b[4] = ((src->b[5]<<5) | (src->b[6]>>3)) & 0x3f; // ..g fedcb + tmp.b[5] = ((src->b[6]<<1) | (src->b[7]>>7)) & 0x3f; // ..cba98 7 + tmp.b[6] = ((src->b[6]<<5) | (src->b[7]>>3)) & 0x3f; // ..8 76543 + tmp.b[7] = ((src->b[7]<<1) | (src->b[4]>>7)) & 0x3f; // ..43210 v +} + + *src = tmp; +} + + +/// Transposition (P-BOX). +static void TP(BIT64* src) +{ + BIT64 tmp = {0}; + + static const uint8_t tp_table[32] = { + 16, 7, 20, 21, + 29, 12, 28, 17, + 1, 15, 23, 26, + 5, 18, 31, 10, + 2, 8, 24, 14, + 32, 27, 3, 9, + 19, 13, 30, 6, + 22, 11, 4, 25, + }; + + size_t i; + for( i = 0; i < ARRAYLENGTH(tp_table); ++i ) + { + uint8_t j = tp_table[i] - 1; + if( src->b[(j >> 3) + 0] & mask[j & 7] ) + tmp .b[(i >> 3) + 4] |= mask[i & 7]; + } + + *src = tmp; +} + + +/// Substitution boxes (S-boxes). +/// NOTE: This implementation was optimized to process two nibbles in one step (twice as fast). +static void SBOX(BIT64* src) +{ + BIT64 tmp = {0}; + + static const uint8_t s_table[4][64] = { + { + 0xef, 0x03, 0x41, 0xfd, 0xd8, 0x74, 0x1e, 0x47, 0x26, 0xef, 0xfb, 0x22, 0xb3, 0xd8, 0x84, 0x1e, + 0x39, 0xac, 0xa7, 0x60, 0x62, 0xc1, 0xcd, 0xba, 0x5c, 0x96, 0x90, 0x59, 0x05, 0x3b, 0x7a, 0x85, + 0x40, 0xfd, 0x1e, 0xc8, 0xe7, 0x8a, 0x8b, 0x21, 0xda, 0x43, 0x64, 0x9f, 0x2d, 0x14, 0xb1, 0x72, + 0xf5, 0x5b, 0xc8, 0xb6, 0x9c, 0x37, 0x76, 0xec, 0x39, 0xa0, 0xa3, 0x05, 0x52, 0x6e, 0x0f, 0xd9, + },{ + 0xa7, 0xdd, 0x0d, 0x78, 0x9e, 0x0b, 0xe3, 0x95, 0x60, 0x36, 0x36, 0x4f, 0xf9, 0x60, 0x5a, 0xa3, + 0x11, 0x24, 0xd2, 0x87, 0xc8, 0x52, 0x75, 0xec, 0xbb, 0xc1, 0x4c, 0xba, 0x24, 0xfe, 0x8f, 0x19, + 0xda, 0x13, 0x66, 0xaf, 0x49, 0xd0, 0x90, 0x06, 0x8c, 0x6a, 0xfb, 0x91, 0x37, 0x8d, 0x0d, 0x78, + 0xbf, 0x49, 0x11, 0xf4, 0x23, 0xe5, 0xce, 0x3b, 0x55, 0xbc, 0xa2, 0x57, 0xe8, 0x22, 0x74, 0xce, + },{ + 0x2c, 0xea, 0xc1, 0xbf, 0x4a, 0x24, 0x1f, 0xc2, 0x79, 0x47, 0xa2, 0x7c, 0xb6, 0xd9, 0x68, 0x15, + 0x80, 0x56, 0x5d, 0x01, 0x33, 0xfd, 0xf4, 0xae, 0xde, 0x30, 0x07, 0x9b, 0xe5, 0x83, 0x9b, 0x68, + 0x49, 0xb4, 0x2e, 0x83, 0x1f, 0xc2, 0xb5, 0x7c, 0xa2, 0x19, 0xd8, 0xe5, 0x7c, 0x2f, 0x83, 0xda, + 0xf7, 0x6b, 0x90, 0xfe, 0xc4, 0x01, 0x5a, 0x97, 0x61, 0xa6, 0x3d, 0x40, 0x0b, 0x58, 0xe6, 0x3d, + },{ + 0x4d, 0xd1, 0xb2, 0x0f, 0x28, 0xbd, 0xe4, 0x78, 0xf6, 0x4a, 0x0f, 0x93, 0x8b, 0x17, 0xd1, 0xa4, + 0x3a, 0xec, 0xc9, 0x35, 0x93, 0x56, 0x7e, 0xcb, 0x55, 0x20, 0xa0, 0xfe, 0x6c, 0x89, 0x17, 0x62, + 0x17, 0x62, 0x4b, 0xb1, 0xb4, 0xde, 0xd1, 0x87, 0xc9, 0x14, 0x3c, 0x4a, 0x7e, 0xa8, 0xe2, 0x7d, + 0xa0, 0x9f, 0xf6, 0x5c, 0x6a, 0x09, 0x8d, 0xf0, 0x0f, 0xe3, 0x53, 0x25, 0x95, 0x36, 0x28, 0xcb, + } + }; + + size_t i; + for( i = 0; i < ARRAYLENGTH(s_table); ++i ) + { + tmp.b[i] = (s_table[i][src->b[i*2+0]] & 0xf0) + | (s_table[i][src->b[i*2+1]] & 0x0f); + } + + *src = tmp; +} + + +/// DES round function. +/// XORs src[0..3] with TP(SBOX(E(src[4..7]))). +static void RoundFunction(BIT64* src) +{ + BIT64 tmp = *src; + E(&tmp); + SBOX(&tmp); + TP(&tmp); + + src->b[0] ^= tmp.b[4]; + src->b[1] ^= tmp.b[5]; + src->b[2] ^= tmp.b[6]; + src->b[3] ^= tmp.b[7]; +} + + +void des_decrypt_block(BIT64* block) +{ + IP(block); + RoundFunction(block); + FP(block); +} + + +void des_decrypt(unsigned char* data, size_t size) +{ + BIT64* p = (BIT64*)data; + size_t i; + + for( i = 0; i*8 < size; i += 8 ) + des_decrypt_block(p); +} |