/* * Data Encryption Standard * D.P.Mitchell 83/06/08. * * block_cipher(key, block, decrypting) */ #include #include static long ip_low(char [8]); static long ip_high(char [8]); static void fp(long, long, char[8]); static void key_setup(char[DESKEYLEN], char[128]); static void block_cipher(char[DESKEYLEN], char[8], int); /* * destructively encrypt the buffer, which * must be at least 8 characters long. */ int encrypt(void *key, void *vbuf, int n) { char *buf; int i, r; if(n < 8) return 0; buf = vbuf; n--; r = n % 7; n /= 7; for(i = 0; i < n; i++){ block_cipher(key, buf, 0); buf += 7; } if(r) block_cipher(key, buf - 7 + r, 0); return 1; } /* * destructively decrypt the buffer, which * must be at least 8 characters long. */ int decrypt(void *key, void *vbuf, int n) { char *buf; int i, r; if(n < 8) return 0; buf = vbuf; n--; r = n % 7; n /= 7; buf += n * 7; if(r) block_cipher(key, buf - 7 + r, 1); for(i = 0; i < n; i++){ buf -= 7; block_cipher(key, buf, 1); } return 1; } /* * Tables for Combined S and P Boxes */ static long s0p[] = { 0x00410100,0x00010000,0x40400000,0x40410100,0x00400000,0x40010100,0x40010000,0x40400000, 0x40010100,0x00410100,0x00410000,0x40000100,0x40400100,0x00400000,0x00000000,0x40010000, 0x00010000,0x40000000,0x00400100,0x00010100,0x40410100,0x00410000,0x40000100,0x00400100, 0x40000000,0x00000100,0x00010100,0x40410000,0x00000100,0x40400100,0x40410000,0x00000000, 0x00000000,0x40410100,0x00400100,0x40010000,0x00410100,0x00010000,0x40000100,0x00400100, 0x40410000,0x00000100,0x00010100,0x40400000,0x40010100,0x40000000,0x40400000,0x00410000, 0x40410100,0x00010100,0x00410000,0x40400100,0x00400000,0x40000100,0x40010000,0x00000000, 0x00010000,0x00400000,0x40400100,0x00410100,0x40000000,0x40410000,0x00000100,0x40010100, }; static long s1p[] = { 0x08021002,0x00000000,0x00021000,0x08020000,0x08000002,0x00001002,0x08001000,0x00021000, 0x00001000,0x08020002,0x00000002,0x08001000,0x00020002,0x08021000,0x08020000,0x00000002, 0x00020000,0x08001002,0x08020002,0x00001000,0x00021002,0x08000000,0x00000000,0x00020002, 0x08001002,0x00021002,0x08021000,0x08000002,0x08000000,0x00020000,0x00001002,0x08021002, 0x00020002,0x08021000,0x08001000,0x00021002,0x08021002,0x00020002,0x08000002,0x00000000, 0x08000000,0x00001002,0x00020000,0x08020002,0x00001000,0x08000000,0x00021002,0x08001002, 0x08021000,0x00001000,0x00000000,0x08000002,0x00000002,0x08021002,0x00021000,0x08020000, 0x08020002,0x00020000,0x00001002,0x08001000,0x08001002,0x00000002,0x08020000,0x00021000, }; static long s2p[] = { 0x20800000,0x00808020,0x00000020,0x20800020,0x20008000,0x00800000,0x20800020,0x00008020, 0x00800020,0x00008000,0x00808000,0x20000000,0x20808020,0x20000020,0x20000000,0x20808000, 0x00000000,0x20008000,0x00808020,0x00000020,0x20000020,0x20808020,0x00008000,0x20800000, 0x20808000,0x00800020,0x20008020,0x00808000,0x00008020,0x00000000,0x00800000,0x20008020, 0x00808020,0x00000020,0x20000000,0x00008000,0x20000020,0x20008000,0x00808000,0x20800020, 0x00000000,0x00808020,0x00008020,0x20808000,0x20008000,0x00800000,0x20808020,0x20000000, 0x20008020,0x20800000,0x00800000,0x20808020,0x00008000,0x00800020,0x20800020,0x00008020, 0x00800020,0x00000000,0x20808000,0x20000020,0x20800000,0x20008020,0x00000020,0x00808000, }; static long s3p[] = { 0x00080201,0x02000200,0x00000001,0x02080201,0x00000000,0x02080000,0x02000201,0x00080001, 0x02080200,0x02000001,0x02000000,0x00000201,0x02000001,0x00080201,0x00080000,0x02000000, 0x02080001,0x00080200,0x00000200,0x00000001,0x00080200,0x02000201,0x02080000,0x00000200, 0x00000201,0x00000000,0x00080001,0x02080200,0x02000200,0x02080001,0x02080201,0x00080000, 0x02080001,0x00000201,0x00080000,0x02000001,0x00080200,0x02000200,0x00000001,0x02080000, 0x02000201,0x00000000,0x00000200,0x00080001,0x00000000,0x02080001,0x02080200,0x00000200, 0x02000000,0x02080201,0x00080201,0x00080000,0x02080201,0x00000001,0x02000200,0x00080201, 0x00080001,0x00080200,0x02080000,0x02000201,0x00000201,0x02000000,0x02000001,0x02080200, }; static long s4p[] = { 0x01000000,0x00002000,0x00000080,0x01002084,0x01002004,0x01000080,0x00002084,0x01002000, 0x00002000,0x00000004,0x01000004,0x00002080,0x01000084,0x01002004,0x01002080,0x00000000, 0x00002080,0x01000000,0x00002004,0x00000084,0x01000080,0x00002084,0x00000000,0x01000004, 0x00000004,0x01000084,0x01002084,0x00002004,0x01002000,0x00000080,0x00000084,0x01002080, 0x01002080,0x01000084,0x00002004,0x01002000,0x00002000,0x00000004,0x01000004,0x01000080, 0x01000000,0x00002080,0x01002084,0x00000000,0x00002084,0x01000000,0x00000080,0x00002004, 0x01000084,0x00000080,0x00000000,0x01002084,0x01002004,0x01002080,0x00000084,0x00002000, 0x00002080,0x01002004,0x01000080,0x00000084,0x00000004,0x00002084,0x01002000,0x01000004, }; static long s5p[] = { 0x10000008,0x00040008,0x00000000,0x10040400,0x00040008,0x00000400,0x10000408,0x00040000, 0x00000408,0x10040408,0x00040400,0x10000000,0x10000400,0x10000008,0x10040000,0x00040408, 0x00040000,0x10000408,0x10040008,0x00000000,0x00000400,0x00000008,0x10040400,0x10040008, 0x10040408,0x10040000,0x10000000,0x00000408,0x00000008,0x00040400,0x00040408,0x10000400, 0x00000408,0x10000000,0x10000400,0x00040408,0x10040400,0x00040008,0x00000000,0x10000400, 0x10000000,0x00000400,0x10040008,0x00040000,0x00040008,0x10040408,0x00040400,0x00000008, 0x10040408,0x00040400,0x00040000,0x10000408,0x10000008,0x10040000,0x00040408,0x00000000, 0x00000400,0x10000008,0x10000408,0x10040400,0x10040000,0x00000408,0x00000008,0x10040008, }; static long s6p[] = { 0x00000800,0x00000040,0x00200040,0x80200000,0x80200840,0x80000800,0x00000840,0x00000000, 0x00200000,0x80200040,0x80000040,0x00200800,0x80000000,0x00200840,0x00200800,0x80000040, 0x80200040,0x00000800,0x80000800,0x80200840,0x00000000,0x00200040,0x80200000,0x00000840, 0x80200800,0x80000840,0x00200840,0x80000000,0x80000840,0x80200800,0x00000040,0x00200000, 0x80000840,0x00200800,0x80200800,0x80000040,0x00000800,0x00000040,0x00200000,0x80200800, 0x80200040,0x80000840,0x00000840,0x00000000,0x00000040,0x80200000,0x80000000,0x00200040, 0x00000000,0x80200040,0x00200040,0x00000840,0x80000040,0x00000800,0x80200840,0x00200000, 0x00200840,0x80000000,0x80000800,0x80200840,0x80200000,0x00200840,0x00200800,0x80000800, }; static long s7p[] = { 0x04100010,0x04104000,0x00004010,0x00000000,0x04004000,0x00100010,0x04100000,0x04104010, 0x00000010,0x04000000,0x00104000,0x00004010,0x00104010,0x04004010,0x04000010,0x04100000, 0x00004000,0x00104010,0x00100010,0x04004000,0x04104010,0x04000010,0x00000000,0x00104000, 0x04000000,0x00100000,0x04004010,0x04100010,0x00100000,0x00004000,0x04104000,0x00000010, 0x00100000,0x00004000,0x04000010,0x04104010,0x00004010,0x04000000,0x00000000,0x00104000, 0x04100010,0x04004010,0x04004000,0x00100010,0x04104000,0x00000010,0x00100010,0x04004000, 0x04104010,0x00100000,0x04100000,0x04000010,0x00104000,0x00004010,0x04004010,0x04100000, 0x00000010,0x04104000,0x00104010,0x00000000,0x04000000,0x04100010,0x00004000,0x00104010, }; /* * DES electronic codebook encryption of one block */ static void block_cipher(char short_key[DESKEYLEN], char text[8], int decrypting) { register char *key; register long crypto, temp; register long right, left; register i; register key_offset; static char lastkey[DESKEYLEN]; static char expanded_key[128]; temp = 0; for (i = 0; i < DESKEYLEN; i++) if (lastkey[i] != short_key[i]) { lastkey[i] = short_key[i]; temp = 1; } if (temp) key_setup(short_key, expanded_key); key = expanded_key; left = ip_low(text); right = ip_high(text); if (decrypting) { key_offset = 16; key = key + 128 - 8; } else key_offset = 0; for (i = 0; i < 16; i++) { temp = (right << 1) | ((right >> 31) & 1); crypto = s0p[(temp & 0x3f) ^ *key++]; crypto |= s1p[((temp >> 4) & 0x3f) ^ *key++]; crypto |= s2p[((temp >> 8) & 0x3f) ^ *key++]; crypto |= s3p[((temp >> 12) & 0x3f) ^ *key++]; crypto |= s4p[((temp >> 16) & 0x3f) ^ *key++]; crypto |= s5p[((temp >> 20) & 0x3f) ^ *key++]; crypto |= s6p[((temp >> 24) & 0x3f) ^ *key++]; temp = ((right & 1) << 5) | ((right >> 27) & 0x1f); crypto |= s7p[temp ^ *key++]; temp = left; left = right; right = temp ^ crypto; key -= key_offset; } /* * standard final permutation (IPI) * left and right are reversed here */ fp(right, left, text); } /* * Initial Permutation */ static long iptab[] = { 0x00000000, 0x00008000, 0x00000000, 0x00008000, 0x00000080, 0x00008080, 0x00000080, 0x00008080 }; static long ip_low(char block[8]) { int i; register long l; l = 0; for(i = 0; i < 8; i++){ l |= iptab[(block[i] >> 4) & 7] >> i; l |= iptab[block[i] & 7] << (16 - i); } return l; } static long ip_high(char block[8]) { int i; register long l; l = 0; for(i = 0; i < 8; i++){ l |= iptab[(block[i] >> 5) & 7] >> i; l |= iptab[(block[i] >> 1) & 7] << (16 - i); } return l; } /* * Final Permutation */ static unsigned long fptab[] = { 0x00000000,0x80000000,0x00800000,0x80800000,0x00008000,0x80008000,0x00808000,0x80808000, 0x00000080,0x80000080,0x00800080,0x80800080,0x00008080,0x80008080,0x00808080,0x80808080, }; static void fp(long left, long right, char text[8]) { unsigned long ta[2], t, v[2]; int i, j, sh; ta[0] = right; ta[1] = left; v[0] = v[1] = 0; for(i = 0; i < 2; i++){ t = ta[i]; sh = i; for(j = 0; j < 4; j++){ v[1] |= fptab[t & 0xf] >> sh; t >>= 4; v[0] |= fptab[t & 0xf] >> sh; t >>= 4; sh += 2; } } for(i = 0; i < 2; i++) for(j = 0; j < 4; j++){ *text++ = v[i]; v[i] >>= 8; } } /* * Key set-up */ static uchar keyexpand[][15][2] = { { 3, 2, 9, 8, 18, 8, 27, 32, 33, 2, 42, 16, 48, 8, 65, 16, 74, 2, 80, 2, 89, 4, 99, 16, 104, 4, 122, 32, 0, 0, }, { 1, 4, 8, 1, 18, 4, 25, 32, 34, 32, 41, 8, 50, 8, 59, 32, 64, 16, 75, 4, 90, 1, 97, 16, 106, 2, 112, 2, 123, 1, }, { 2, 1, 19, 8, 35, 1, 40, 1, 50, 4, 57, 32, 75, 2, 80, 32, 89, 1, 96, 16, 107, 4, 120, 8, 0, 0, 0, 0, 0, 0, }, { 4, 32, 20, 2, 31, 4, 37, 32, 47, 1, 54, 1, 63, 2, 68, 1, 78, 4, 84, 8, 101, 16, 108, 4, 119, 16, 126, 8, 0, 0, }, { 5, 4, 15, 4, 21, 32, 31, 1, 38, 1, 47, 2, 53, 2, 68, 8, 85, 16, 92, 4, 103, 16, 108, 32, 118, 32, 124, 2, 0, 0, }, { 15, 2, 21, 2, 39, 8, 46, 16, 55, 32, 61, 1, 71, 16, 76, 32, 86, 32, 93, 4, 102, 2, 108, 16, 117, 8, 126, 1, 0, 0, }, { 14, 16, 23, 32, 29, 1, 38, 8, 52, 2, 63, 4, 70, 2, 76, 16, 85, 8, 100, 1, 110, 4, 116, 8, 127, 8, 0, 0, 0, 0, }, { 1, 8, 8, 32, 17, 1, 24, 16, 35, 4, 50, 1, 57, 16, 67, 8, 83, 1, 88, 1, 98, 4, 105, 32, 114, 32, 123, 2, 0, 0, }, { 0, 1, 11, 16, 16, 4, 35, 2, 40, 32, 49, 1, 56, 16, 65, 2, 74, 16, 80, 8, 99, 8, 115, 1, 121, 4, 0, 0, 0, 0, }, { 9, 16, 18, 2, 24, 2, 33, 4, 43, 16, 48, 4, 66, 32, 73, 8, 82, 8, 91, 32, 97, 2, 106, 16, 112, 8, 122, 1, 0, 0, }, { 14, 32, 21, 4, 30, 2, 36, 16, 45, 8, 60, 1, 69, 2, 87, 8, 94, 16, 103, 32, 109, 1, 118, 8, 124, 32, 0, 0, 0, 0, }, { 7, 4, 14, 2, 20, 16, 29, 8, 44, 1, 54, 4, 60, 8, 71, 8, 78, 16, 87, 32, 93, 1, 102, 8, 116, 2, 125, 4, 0, 0, }, { 7, 2, 12, 1, 22, 4, 28, 8, 45, 16, 52, 4, 63, 16, 70, 8, 84, 2, 95, 4, 101, 32, 111, 1, 118, 1, 0, 0, 0, 0, }, { 6, 16, 13, 16, 20, 4, 31, 16, 36, 32, 46, 32, 53, 4, 62, 2, 69, 32, 79, 1, 86, 1, 95, 2, 101, 2, 119, 8, 0, 0, }, { 0, 32, 10, 8, 19, 32, 25, 2, 34, 16, 40, 8, 59, 8, 66, 2, 72, 2, 81, 4, 91, 16, 96, 4, 115, 2, 121, 8, 0, 0, }, { 3, 16, 10, 4, 17, 32, 26, 32, 33, 8, 42, 8, 51, 32, 57, 2, 67, 4, 82, 1, 89, 16, 98, 2, 104, 2, 113, 4, 120, 1, }, { 1, 16, 11, 8, 27, 1, 32, 1, 42, 4, 49, 32, 58, 32, 67, 2, 72, 32, 81, 1, 88, 16, 99, 4, 114, 1, 0, 0, 0, 0, }, { 6, 32, 12, 2, 23, 4, 29, 32, 39, 1, 46, 1, 55, 2, 61, 2, 70, 4, 76, 8, 93, 16, 100, 4, 111, 16, 116, 32, 0, 0, }, { 6, 2, 13, 32, 23, 1, 30, 1, 39, 2, 45, 2, 63, 8, 77, 16, 84, 4, 95, 16, 100, 32, 110, 32, 117, 4, 127, 4, 0, 0, }, { 4, 1, 13, 2, 31, 8, 38, 16, 47, 32, 53, 1, 62, 8, 68, 32, 78, 32, 85, 4, 94, 2, 100, 16, 109, 8, 127, 2, 0, 0, }, { 5, 16, 15, 32, 21, 1, 30, 8, 44, 2, 55, 4, 61, 32, 68, 16, 77, 8, 92, 1, 102, 4, 108, 8, 126, 16, 0, 0, 0, 0, }, { 2, 8, 9, 1, 16, 16, 27, 4, 42, 1, 49, 16, 58, 2, 75, 1, 80, 1, 90, 4, 97, 32, 106, 32, 113, 8, 120, 32, 0, 0, }, { 2, 4, 8, 4, 27, 2, 32, 32, 41, 1, 48, 16, 59, 4, 66, 16, 72, 8, 91, 8, 107, 1, 112, 1, 123, 16, 0, 0, 0, 0, }, { 3, 8, 10, 2, 16, 2, 25, 4, 35, 16, 40, 4, 59, 2, 65, 8, 74, 8, 83, 32, 89, 2, 98, 16, 104, 8, 121, 16, 0, 0, }, { 4, 2, 13, 4, 22, 2, 28, 16, 37, 8, 52, 1, 62, 4, 79, 8, 86, 16, 95, 32, 101, 1, 110, 8, 126, 32, 0, 0, 0, 0, }, { 5, 32, 12, 16, 21, 8, 36, 1, 46, 4, 52, 8, 70, 16, 79, 32, 85, 1, 94, 8, 108, 2, 119, 4, 126, 2, 0, 0, 0, 0, }, { 5, 2, 14, 4, 20, 8, 37, 16, 44, 4, 55, 16, 60, 32, 76, 2, 87, 4, 93, 32, 103, 1, 110, 1, 119, 2, 124, 1, 0, 0, }, { 7, 32, 12, 4, 23, 16, 28, 32, 38, 32, 45, 4, 54, 2, 60, 16, 71, 1, 78, 1, 87, 2, 93, 2, 111, 8, 118, 16, 125, 16, }, { 1, 1, 11, 32, 17, 2, 26, 16, 32, 8, 51, 8, 64, 2, 73, 4, 83, 16, 88, 4, 107, 2, 112, 32, 122, 8, 0, 0, 0, 0, }, { 0, 4, 9, 32, 18, 32, 25, 8, 34, 8, 43, 32, 49, 2, 58, 16, 74, 1, 81, 16, 90, 2, 96, 2, 105, 4, 115, 16, 122, 4, }, { 2, 2, 19, 1, 24, 1, 34, 4, 41, 32, 50, 32, 57, 8, 64, 32, 73, 1, 80, 16, 91, 4, 106, 1, 113, 16, 123, 8, 0, 0, }, { 3, 4, 10, 16, 16, 8, 35, 8, 51, 1, 56, 1, 67, 16, 72, 4, 91, 2, 96, 32, 105, 1, 112, 16, 121, 2, 0, 0, 0, 0, }, { 4, 16, 15, 1, 22, 1, 31, 2, 37, 2, 55, 8, 62, 16, 69, 16, 76, 4, 87, 16, 92, 32, 102, 32, 109, 4, 118, 2, 125, 32, }, { 6, 4, 23, 8, 30, 16, 39, 32, 45, 1, 54, 8, 70, 32, 77, 4, 86, 2, 92, 16, 101, 8, 116, 1, 125, 2, 0, 0, 0, 0, }, { 4, 4, 13, 1, 22, 8, 36, 2, 47, 4, 53, 32, 63, 1, 69, 8, 84, 1, 94, 4, 100, 8, 117, 16, 127, 32, 0, 0, 0, 0, }, { 3, 32, 8, 16, 19, 4, 34, 1, 41, 16, 50, 2, 56, 2, 67, 1, 72, 1, 82, 4, 89, 32, 98, 32, 105, 8, 114, 8, 121, 1, }, { 1, 32, 19, 2, 24, 32, 33, 1, 40, 16, 51, 4, 64, 8, 83, 8, 99, 1, 104, 1, 114, 4, 120, 4, 0, 0, 0, 0, 0, 0, }, { 8, 2, 17, 4, 27, 16, 32, 4, 51, 2, 56, 32, 66, 8, 75, 32, 81, 2, 90, 16, 96, 8, 115, 8, 122, 2, 0, 0, 0, 0, }, { 2, 16, 18, 1, 25, 16, 34, 2, 40, 2, 49, 4, 59, 16, 66, 4, 73, 32, 82, 32, 89, 8, 98, 8, 107, 32, 113, 2, 123, 4, }, { 7, 1, 13, 8, 28, 1, 38, 4, 44, 8, 61, 16, 71, 32, 77, 1, 86, 8, 100, 2, 111, 4, 117, 32, 124, 16, 0, 0, 0, 0, }, { 12, 8, 29, 16, 36, 4, 47, 16, 52, 32, 62, 32, 68, 2, 79, 4, 85, 32, 95, 1, 102, 1, 111, 2, 117, 2, 126, 4, 0, 0, }, { 5, 1, 15, 16, 20, 32, 30, 32, 37, 4, 46, 2, 52, 16, 61, 8, 70, 1, 79, 2, 85, 2, 103, 8, 110, 16, 119, 32, 124, 4, }, { 0, 16, 9, 2, 18, 16, 24, 8, 43, 8, 59, 1, 65, 4, 75, 16, 80, 4, 99, 2, 104, 32, 113, 1, 123, 32, 0, 0, 0, 0, }, { 10, 32, 17, 8, 26, 8, 35, 32, 41, 2, 50, 16, 56, 8, 66, 1, 73, 16, 82, 2, 88, 2, 97, 4, 107, 16, 112, 4, 121, 32, }, { 0, 2, 11, 1, 16, 1, 26, 4, 33, 32, 42, 32, 49, 8, 58, 8, 65, 1, 72, 16, 83, 4, 98, 1, 105, 16, 114, 2, 0, 0, }, { 8, 8, 27, 8, 43, 1, 48, 1, 58, 4, 64, 4, 83, 2, 88, 32, 97, 1, 104, 16, 115, 4, 122, 16, 0, 0, 0, 0, 0, 0, }, { 5, 8, 14, 1, 23, 2, 29, 2, 47, 8, 54, 16, 63, 32, 68, 4, 79, 16, 84, 32, 94, 32, 101, 4, 110, 2, 116, 16, 127, 1, }, { 4, 8, 15, 8, 22, 16, 31, 32, 37, 1, 46, 8, 60, 2, 69, 4, 78, 2, 84, 16, 93, 8, 108, 1, 118, 4, 0, 0, 0, 0, }, { 7, 16, 14, 8, 28, 2, 39, 4, 45, 32, 55, 1, 62, 1, 76, 1, 86, 4, 92, 8, 109, 16, 116, 4, 125, 1, 0, 0, 0, 0, }, { 1, 2, 11, 4, 26, 1, 33, 16, 42, 2, 48, 2, 57, 4, 64, 1, 74, 4, 81, 32, 90, 32, 97, 8, 106, 8, 115, 32, 120, 16, }, { 2, 32, 11, 2, 16, 32, 25, 1, 32, 16, 43, 4, 58, 1, 75, 8, 91, 1, 96, 1, 106, 4, 113, 32, 0, 0, 0, 0, 0, 0, }, { 3, 1, 9, 4, 19, 16, 24, 4, 43, 2, 48, 32, 57, 1, 67, 32, 73, 2, 82, 16, 88, 8, 107, 8, 120, 2, 0, 0, 0, 0, }, { 0, 8, 10, 1, 17, 16, 26, 2, 32, 2, 41, 4, 51, 16, 56, 4, 65, 32, 74, 32, 81, 8, 90, 8, 99, 32, 105, 2, 114, 16, }, { 6, 1, 20, 1, 30, 4, 36, 8, 53, 16, 60, 4, 69, 1, 78, 8, 92, 2, 103, 4, 109, 32, 119, 1, 125, 8, 0, 0, 0, 0, }, { 7, 8, 21, 16, 28, 4, 39, 16, 44, 32, 54, 32, 61, 4, 71, 4, 77, 32, 87, 1, 94, 1, 103, 2, 109, 2, 124, 8, 0, 0, }, { 6, 8, 12, 32, 22, 32, 29, 4, 38, 2, 44, 16, 53, 8, 71, 2, 77, 2, 95, 8, 102, 16, 111, 32, 117, 1, 127, 16, 0, 0, } }; static void key_setup(char key[DESKEYLEN], char *ek) { int i, j, k, mask; uchar (*x)[2]; memset(ek, 0, 128); x = keyexpand[0]; for(i = 0; i < 7; i++){ k = key[i]; for(mask = 0x80; mask; mask >>= 1){ if(k & mask) for(j = 0; j < 15; j++) ek[x[j][0]] |= x[j][1]; x += 15; } } }