des.c (12621B)
1 /********************************************************************* 2 * Filename: des.c 3 * Author: Brad Conte (brad AT radconte.com) 4 * Copyright: 5 * Disclaimer: This code is presented "as is" without any guarantees. 6 * Details: Implementation of the DES encryption algorithm. 7 Modes of operation (such as CBC) are not included. 8 The formal NIST algorithm specification can be found here: 9 * http://csrc.nist.gov/publications/fips/fips46-3/fips46-3.pdf 10 *********************************************************************/ 11 12 /*************************** HEADER FILES ***************************/ 13 #include <stdlib.h> 14 #include <memory.h> 15 #include "des.h" 16 17 /****************************** MACROS ******************************/ 18 // Obtain bit "b" from the left and shift it "c" places from the right 19 #define BITNUM(a,b,c) (((a[(b)/8] >> (7 - (b%8))) & 0x01) << (c)) 20 #define BITNUMINTR(a,b,c) ((((a) >> (31 - (b))) & 0x00000001) << (c)) 21 #define BITNUMINTL(a,b,c) ((((a) << (b)) & 0x80000000) >> (c)) 22 23 // This macro converts a 6 bit block with the S-Box row defined as the first and last 24 // bits to a 6 bit block with the row defined by the first two bits. 25 #define SBOXBIT(a) (((a) & 0x20) | (((a) & 0x1f) >> 1) | (((a) & 0x01) << 4)) 26 27 /**************************** VARIABLES *****************************/ 28 static const BYTE sbox1[64] = { 29 14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7, 30 0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8, 31 4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0, 32 15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13 33 }; 34 static const BYTE sbox2[64] = { 35 15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10, 36 3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5, 37 0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15, 38 13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9 39 }; 40 static const BYTE sbox3[64] = { 41 10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8, 42 13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1, 43 13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7, 44 1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12 45 }; 46 static const BYTE sbox4[64] = { 47 7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15, 48 13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9, 49 10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4, 50 3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14 51 }; 52 static const BYTE sbox5[64] = { 53 2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9, 54 14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6, 55 4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14, 56 11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3 57 }; 58 static const BYTE sbox6[64] = { 59 12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11, 60 10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8, 61 9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6, 62 4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13 63 }; 64 static const BYTE sbox7[64] = { 65 4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1, 66 13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6, 67 1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2, 68 6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12 69 }; 70 static const BYTE sbox8[64] = { 71 13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7, 72 1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2, 73 7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8, 74 2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11 75 }; 76 77 /*********************** FUNCTION DEFINITIONS ***********************/ 78 // Initial (Inv)Permutation step 79 void IP(WORD state[], const BYTE in[]) 80 { 81 state[0] = BITNUM(in,57,31) | BITNUM(in,49,30) | BITNUM(in,41,29) | BITNUM(in,33,28) | 82 BITNUM(in,25,27) | BITNUM(in,17,26) | BITNUM(in,9,25) | BITNUM(in,1,24) | 83 BITNUM(in,59,23) | BITNUM(in,51,22) | BITNUM(in,43,21) | BITNUM(in,35,20) | 84 BITNUM(in,27,19) | BITNUM(in,19,18) | BITNUM(in,11,17) | BITNUM(in,3,16) | 85 BITNUM(in,61,15) | BITNUM(in,53,14) | BITNUM(in,45,13) | BITNUM(in,37,12) | 86 BITNUM(in,29,11) | BITNUM(in,21,10) | BITNUM(in,13,9) | BITNUM(in,5,8) | 87 BITNUM(in,63,7) | BITNUM(in,55,6) | BITNUM(in,47,5) | BITNUM(in,39,4) | 88 BITNUM(in,31,3) | BITNUM(in,23,2) | BITNUM(in,15,1) | BITNUM(in,7,0); 89 90 state[1] = BITNUM(in,56,31) | BITNUM(in,48,30) | BITNUM(in,40,29) | BITNUM(in,32,28) | 91 BITNUM(in,24,27) | BITNUM(in,16,26) | BITNUM(in,8,25) | BITNUM(in,0,24) | 92 BITNUM(in,58,23) | BITNUM(in,50,22) | BITNUM(in,42,21) | BITNUM(in,34,20) | 93 BITNUM(in,26,19) | BITNUM(in,18,18) | BITNUM(in,10,17) | BITNUM(in,2,16) | 94 BITNUM(in,60,15) | BITNUM(in,52,14) | BITNUM(in,44,13) | BITNUM(in,36,12) | 95 BITNUM(in,28,11) | BITNUM(in,20,10) | BITNUM(in,12,9) | BITNUM(in,4,8) | 96 BITNUM(in,62,7) | BITNUM(in,54,6) | BITNUM(in,46,5) | BITNUM(in,38,4) | 97 BITNUM(in,30,3) | BITNUM(in,22,2) | BITNUM(in,14,1) | BITNUM(in,6,0); 98 } 99 100 void InvIP(WORD state[], BYTE in[]) 101 { 102 in[0] = BITNUMINTR(state[1],7,7) | BITNUMINTR(state[0],7,6) | BITNUMINTR(state[1],15,5) | 103 BITNUMINTR(state[0],15,4) | BITNUMINTR(state[1],23,3) | BITNUMINTR(state[0],23,2) | 104 BITNUMINTR(state[1],31,1) | BITNUMINTR(state[0],31,0); 105 106 in[1] = BITNUMINTR(state[1],6,7) | BITNUMINTR(state[0],6,6) | BITNUMINTR(state[1],14,5) | 107 BITNUMINTR(state[0],14,4) | BITNUMINTR(state[1],22,3) | BITNUMINTR(state[0],22,2) | 108 BITNUMINTR(state[1],30,1) | BITNUMINTR(state[0],30,0); 109 110 in[2] = BITNUMINTR(state[1],5,7) | BITNUMINTR(state[0],5,6) | BITNUMINTR(state[1],13,5) | 111 BITNUMINTR(state[0],13,4) | BITNUMINTR(state[1],21,3) | BITNUMINTR(state[0],21,2) | 112 BITNUMINTR(state[1],29,1) | BITNUMINTR(state[0],29,0); 113 114 in[3] = BITNUMINTR(state[1],4,7) | BITNUMINTR(state[0],4,6) | BITNUMINTR(state[1],12,5) | 115 BITNUMINTR(state[0],12,4) | BITNUMINTR(state[1],20,3) | BITNUMINTR(state[0],20,2) | 116 BITNUMINTR(state[1],28,1) | BITNUMINTR(state[0],28,0); 117 118 in[4] = BITNUMINTR(state[1],3,7) | BITNUMINTR(state[0],3,6) | BITNUMINTR(state[1],11,5) | 119 BITNUMINTR(state[0],11,4) | BITNUMINTR(state[1],19,3) | BITNUMINTR(state[0],19,2) | 120 BITNUMINTR(state[1],27,1) | BITNUMINTR(state[0],27,0); 121 122 in[5] = BITNUMINTR(state[1],2,7) | BITNUMINTR(state[0],2,6) | BITNUMINTR(state[1],10,5) | 123 BITNUMINTR(state[0],10,4) | BITNUMINTR(state[1],18,3) | BITNUMINTR(state[0],18,2) | 124 BITNUMINTR(state[1],26,1) | BITNUMINTR(state[0],26,0); 125 126 in[6] = BITNUMINTR(state[1],1,7) | BITNUMINTR(state[0],1,6) | BITNUMINTR(state[1],9,5) | 127 BITNUMINTR(state[0],9,4) | BITNUMINTR(state[1],17,3) | BITNUMINTR(state[0],17,2) | 128 BITNUMINTR(state[1],25,1) | BITNUMINTR(state[0],25,0); 129 130 in[7] = BITNUMINTR(state[1],0,7) | BITNUMINTR(state[0],0,6) | BITNUMINTR(state[1],8,5) | 131 BITNUMINTR(state[0],8,4) | BITNUMINTR(state[1],16,3) | BITNUMINTR(state[0],16,2) | 132 BITNUMINTR(state[1],24,1) | BITNUMINTR(state[0],24,0); 133 } 134 135 WORD f(WORD state, const BYTE key[]) 136 { 137 BYTE lrgstate[6]; //,i; 138 WORD t1,t2; 139 140 // Expantion Permutation 141 t1 = BITNUMINTL(state,31,0) | ((state & 0xf0000000) >> 1) | BITNUMINTL(state,4,5) | 142 BITNUMINTL(state,3,6) | ((state & 0x0f000000) >> 3) | BITNUMINTL(state,8,11) | 143 BITNUMINTL(state,7,12) | ((state & 0x00f00000) >> 5) | BITNUMINTL(state,12,17) | 144 BITNUMINTL(state,11,18) | ((state & 0x000f0000) >> 7) | BITNUMINTL(state,16,23); 145 146 t2 = BITNUMINTL(state,15,0) | ((state & 0x0000f000) << 15) | BITNUMINTL(state,20,5) | 147 BITNUMINTL(state,19,6) | ((state & 0x00000f00) << 13) | BITNUMINTL(state,24,11) | 148 BITNUMINTL(state,23,12) | ((state & 0x000000f0) << 11) | BITNUMINTL(state,28,17) | 149 BITNUMINTL(state,27,18) | ((state & 0x0000000f) << 9) | BITNUMINTL(state,0,23); 150 151 lrgstate[0] = (t1 >> 24) & 0x000000ff; 152 lrgstate[1] = (t1 >> 16) & 0x000000ff; 153 lrgstate[2] = (t1 >> 8) & 0x000000ff; 154 lrgstate[3] = (t2 >> 24) & 0x000000ff; 155 lrgstate[4] = (t2 >> 16) & 0x000000ff; 156 lrgstate[5] = (t2 >> 8) & 0x000000ff; 157 158 // Key XOR 159 lrgstate[0] ^= key[0]; 160 lrgstate[1] ^= key[1]; 161 lrgstate[2] ^= key[2]; 162 lrgstate[3] ^= key[3]; 163 lrgstate[4] ^= key[4]; 164 lrgstate[5] ^= key[5]; 165 166 // S-Box Permutation 167 state = (sbox1[SBOXBIT(lrgstate[0] >> 2)] << 28) | 168 (sbox2[SBOXBIT(((lrgstate[0] & 0x03) << 4) | (lrgstate[1] >> 4))] << 24) | 169 (sbox3[SBOXBIT(((lrgstate[1] & 0x0f) << 2) | (lrgstate[2] >> 6))] << 20) | 170 (sbox4[SBOXBIT(lrgstate[2] & 0x3f)] << 16) | 171 (sbox5[SBOXBIT(lrgstate[3] >> 2)] << 12) | 172 (sbox6[SBOXBIT(((lrgstate[3] & 0x03) << 4) | (lrgstate[4] >> 4))] << 8) | 173 (sbox7[SBOXBIT(((lrgstate[4] & 0x0f) << 2) | (lrgstate[5] >> 6))] << 4) | 174 sbox8[SBOXBIT(lrgstate[5] & 0x3f)]; 175 176 // P-Box Permutation 177 state = BITNUMINTL(state,15,0) | BITNUMINTL(state,6,1) | BITNUMINTL(state,19,2) | 178 BITNUMINTL(state,20,3) | BITNUMINTL(state,28,4) | BITNUMINTL(state,11,5) | 179 BITNUMINTL(state,27,6) | BITNUMINTL(state,16,7) | BITNUMINTL(state,0,8) | 180 BITNUMINTL(state,14,9) | BITNUMINTL(state,22,10) | BITNUMINTL(state,25,11) | 181 BITNUMINTL(state,4,12) | BITNUMINTL(state,17,13) | BITNUMINTL(state,30,14) | 182 BITNUMINTL(state,9,15) | BITNUMINTL(state,1,16) | BITNUMINTL(state,7,17) | 183 BITNUMINTL(state,23,18) | BITNUMINTL(state,13,19) | BITNUMINTL(state,31,20) | 184 BITNUMINTL(state,26,21) | BITNUMINTL(state,2,22) | BITNUMINTL(state,8,23) | 185 BITNUMINTL(state,18,24) | BITNUMINTL(state,12,25) | BITNUMINTL(state,29,26) | 186 BITNUMINTL(state,5,27) | BITNUMINTL(state,21,28) | BITNUMINTL(state,10,29) | 187 BITNUMINTL(state,3,30) | BITNUMINTL(state,24,31); 188 189 // Return the final state value 190 return(state); 191 } 192 193 void des_key_setup(const BYTE key[], BYTE schedule[][6], DES_MODE mode) 194 { 195 WORD i, j, to_gen, C, D; 196 const WORD key_rnd_shift[16] = {1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1}; 197 const WORD key_perm_c[28] = {56,48,40,32,24,16,8,0,57,49,41,33,25,17, 198 9,1,58,50,42,34,26,18,10,2,59,51,43,35}; 199 const WORD key_perm_d[28] = {62,54,46,38,30,22,14,6,61,53,45,37,29,21, 200 13,5,60,52,44,36,28,20,12,4,27,19,11,3}; 201 const WORD key_compression[48] = {13,16,10,23,0,4,2,27,14,5,20,9, 202 22,18,11,3,25,7,15,6,26,19,12,1, 203 40,51,30,36,46,54,29,39,50,44,32,47, 204 43,48,38,55,33,52,45,41,49,35,28,31}; 205 206 // Permutated Choice #1 (copy the key in, ignoring parity bits). 207 for (i = 0, j = 31, C = 0; i < 28; ++i, --j) 208 C |= BITNUM(key,key_perm_c[i],j); 209 for (i = 0, j = 31, D = 0; i < 28; ++i, --j) 210 D |= BITNUM(key,key_perm_d[i],j); 211 212 // Generate the 16 subkeys. 213 for (i = 0; i < 16; ++i) { 214 C = ((C << key_rnd_shift[i]) | (C >> (28-key_rnd_shift[i]))) & 0xfffffff0; 215 D = ((D << key_rnd_shift[i]) | (D >> (28-key_rnd_shift[i]))) & 0xfffffff0; 216 217 // Decryption subkeys are reverse order of encryption subkeys so 218 // generate them in reverse if the key schedule is for decryption useage. 219 if (mode == DES_DECRYPT) 220 to_gen = 15 - i; 221 else /*(if mode == DES_ENCRYPT)*/ 222 to_gen = i; 223 // Initialize the array 224 for (j = 0; j < 6; ++j) 225 schedule[to_gen][j] = 0; 226 for (j = 0; j < 24; ++j) 227 schedule[to_gen][j/8] |= BITNUMINTR(C,key_compression[j],7 - (j%8)); 228 for ( ; j < 48; ++j) 229 schedule[to_gen][j/8] |= BITNUMINTR(D,key_compression[j] - 28,7 - (j%8)); 230 } 231 } 232 233 void des_crypt(const BYTE in[], BYTE out[], const BYTE key[][6]) 234 { 235 WORD state[2],idx,t; 236 237 IP(state,in); 238 239 for (idx=0; idx < 15; ++idx) { 240 t = state[1]; 241 state[1] = f(state[1],key[idx]) ^ state[0]; 242 state[0] = t; 243 } 244 // Perform the final loop manually as it doesn't switch sides 245 state[0] = f(state[1],key[15]) ^ state[0]; 246 247 InvIP(state,out); 248 } 249 250 void three_des_key_setup(const BYTE key[], BYTE schedule[][16][6], DES_MODE mode) 251 { 252 if (mode == DES_ENCRYPT) { 253 des_key_setup(&key[0],schedule[0],mode); 254 des_key_setup(&key[8],schedule[1],!mode); 255 des_key_setup(&key[16],schedule[2],mode); 256 } 257 else /*if (mode == DES_DECRYPT*/ { 258 des_key_setup(&key[16],schedule[0],mode); 259 des_key_setup(&key[8],schedule[1],!mode); 260 des_key_setup(&key[0],schedule[2],mode); 261 } 262 } 263 264 void three_des_crypt(const BYTE in[], BYTE out[], const BYTE key[][16][6]) 265 { 266 des_crypt(in,out,key[0]); 267 des_crypt(out,out,key[1]); 268 des_crypt(out,out,key[2]); 269 }