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1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis |
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2 * |
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3 * LibTomCrypt is a library that provides various cryptographic |
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4 * algorithms in a highly modular and flexible manner. |
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5 * |
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6 * The library is free for all purposes without any express |
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7 * guarantee it works. |
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8 * |
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9 * Tom St Denis, [email protected], http://libtomcrypt.org |
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10 */ |
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11 /**********************************************************************\ |
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12 * To commemorate the 1996 RSA Data Security Conference, the following * |
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13 * code is released into the public domain by its author. Prost! * |
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14 * * |
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15 * This cipher uses 16-bit words and little-endian byte ordering. * |
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16 * I wonder which processor it was optimized for? * |
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17 * * |
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18 * Thanks to CodeView, SoftIce, and D86 for helping bring this code to * |
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19 * the public. * |
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20 \**********************************************************************/ |
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21 |
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22 #include <mycrypt.h> |
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23 |
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24 #ifdef RC2 |
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25 |
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26 const struct _cipher_descriptor rc2_desc = { |
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27 "rc2", |
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28 12, 8, 128, 8, 16, |
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29 &rc2_setup, |
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30 &rc2_ecb_encrypt, |
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31 &rc2_ecb_decrypt, |
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32 &rc2_test, |
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33 &rc2_keysize |
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34 }; |
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35 |
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36 |
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37 /**********************************************************************\ |
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38 * Expand a variable-length user key (between 1 and 128 bytes) to a * |
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39 * 64-short working rc2 key, of at most "bits" effective key bits. * |
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40 * The effective key bits parameter looks like an export control hack. * |
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41 * For normal use, it should always be set to 1024. For convenience, * |
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42 * zero is accepted as an alias for 1024. * |
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43 \**********************************************************************/ |
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44 |
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45 /* 256-entry permutation table, probably derived somehow from pi */ |
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46 static const unsigned char permute[256] = { |
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47 217,120,249,196, 25,221,181,237, 40,233,253,121, 74,160,216,157, |
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48 198,126, 55,131, 43,118, 83,142, 98, 76,100,136, 68,139,251,162, |
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49 23,154, 89,245,135,179, 79, 19, 97, 69,109,141, 9,129,125, 50, |
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50 189,143, 64,235,134,183,123, 11,240,149, 33, 34, 92,107, 78,130, |
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51 84,214,101,147,206, 96,178, 28,115, 86,192, 20,167,140,241,220, |
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52 18,117,202, 31, 59,190,228,209, 66, 61,212, 48,163, 60,182, 38, |
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53 111,191, 14,218, 70,105, 7, 87, 39,242, 29,155,188,148, 67, 3, |
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54 248, 17,199,246,144,239, 62,231, 6,195,213, 47,200,102, 30,215, |
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55 8,232,234,222,128, 82,238,247,132,170,114,172, 53, 77,106, 42, |
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56 150, 26,210,113, 90, 21, 73,116, 75,159,208, 94, 4, 24,164,236, |
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57 194,224, 65,110, 15, 81,203,204, 36,145,175, 80,161,244,112, 57, |
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58 153,124, 58,133, 35,184,180,122,252, 2, 54, 91, 37, 85,151, 49, |
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59 45, 93,250,152,227,138,146,174, 5,223, 41, 16,103,108,186,201, |
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60 211, 0,230,207,225,158,168, 44, 99, 22, 1, 63, 88,226,137,169, |
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61 13, 56, 52, 27,171, 51,255,176,187, 72, 12, 95,185,177,205, 46, |
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62 197,243,219, 71,229,165,156,119, 10,166, 32,104,254,127,193,173 |
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63 }; |
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64 |
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65 int rc2_setup(const unsigned char *key, int keylen, int rounds, symmetric_key *skey) |
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66 { |
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67 unsigned *xkey = skey->rc2.xkey; |
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68 unsigned char tmp[128]; |
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69 unsigned T8, TM; |
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70 int i, bits; |
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71 |
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72 _ARGCHK(key != NULL); |
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73 _ARGCHK(skey != NULL); |
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74 |
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75 if (keylen < 8 || keylen > 128) { |
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76 return CRYPT_INVALID_KEYSIZE; |
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77 } |
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78 |
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79 if (rounds != 0 && rounds != 16) { |
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80 return CRYPT_INVALID_ROUNDS; |
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81 } |
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82 |
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83 for (i = 0; i < keylen; i++) { |
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84 tmp[i] = key[i] & 255; |
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85 } |
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86 |
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87 /* Phase 1: Expand input key to 128 bytes */ |
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88 if (keylen < 128) { |
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89 for (i = keylen; i < 128; i++) { |
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90 tmp[i] = permute[(int)((tmp[i - 1] + tmp[i - keylen]) & 255)]; |
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91 } |
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92 } |
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93 |
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94 /* Phase 2 - reduce effective key size to "bits" */ |
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95 bits = keylen*8; |
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96 T8 = (unsigned)(bits+7)>>3; |
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97 TM = (255 >> (unsigned)(7 & -bits)); |
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98 tmp[128 - T8] = permute[(int)(tmp[128 - T8] & TM)]; |
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99 for (i = 127 - T8; i >= 0; i--) { |
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100 tmp[i] = permute[(int)(tmp[i + 1] ^ tmp[i + T8])]; |
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101 } |
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102 |
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103 /* Phase 3 - copy to xkey in little-endian order */ |
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104 i = 63; |
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105 do { |
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106 xkey[i] = (unsigned)tmp[2*i] + ((unsigned)tmp[2*i+1] << 8); |
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107 } while (i-- > 0); |
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108 |
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109 #ifdef CLEAN_STACK |
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110 zeromem(tmp, sizeof(tmp)); |
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111 #endif |
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112 |
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113 return CRYPT_OK; |
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114 } |
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115 |
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116 /**********************************************************************\ |
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117 * Encrypt an 8-byte block of plaintext using the given key. * |
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118 \**********************************************************************/ |
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119 #ifdef CLEAN_STACK |
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120 static void _rc2_ecb_encrypt( const unsigned char *plain, |
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121 unsigned char *cipher, |
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122 symmetric_key *skey) |
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123 #else |
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124 void rc2_ecb_encrypt( const unsigned char *plain, |
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125 unsigned char *cipher, |
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126 symmetric_key *skey) |
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127 #endif |
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128 { |
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129 unsigned *xkey; |
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130 unsigned x76, x54, x32, x10, i; |
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131 |
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132 _ARGCHK(plain != NULL); |
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133 _ARGCHK(cipher != NULL); |
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134 _ARGCHK(skey != NULL); |
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135 |
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136 xkey = skey->rc2.xkey; |
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137 |
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138 x76 = ((unsigned)plain[7] << 8) + (unsigned)plain[6]; |
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139 x54 = ((unsigned)plain[5] << 8) + (unsigned)plain[4]; |
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140 x32 = ((unsigned)plain[3] << 8) + (unsigned)plain[2]; |
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141 x10 = ((unsigned)plain[1] << 8) + (unsigned)plain[0]; |
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142 |
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143 for (i = 0; i < 16; i++) { |
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144 x10 = (x10 + (x32 & ~x76) + (x54 & x76) + xkey[4*i+0]) & 0xFFFF; |
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145 x10 = ((x10 << 1) | (x10 >> 15)) & 0xFFFF; |
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146 |
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147 x32 = (x32 + (x54 & ~x10) + (x76 & x10) + xkey[4*i+1]) & 0xFFFF; |
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148 x32 = ((x32 << 2) | (x32 >> 14)) & 0xFFFF; |
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149 |
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150 x54 = (x54 + (x76 & ~x32) + (x10 & x32) + xkey[4*i+2]) & 0xFFFF; |
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151 x54 = ((x54 << 3) | (x54 >> 13)) & 0xFFFF; |
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152 |
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153 x76 = (x76 + (x10 & ~x54) + (x32 & x54) + xkey[4*i+3]) & 0xFFFF; |
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154 x76 = ((x76 << 5) | (x76 >> 11)) & 0xFFFF; |
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155 |
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156 if (i == 4 || i == 10) { |
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157 x10 = (x10 + xkey[x76 & 63]) & 0xFFFF; |
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158 x32 = (x32 + xkey[x10 & 63]) & 0xFFFF; |
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159 x54 = (x54 + xkey[x32 & 63]) & 0xFFFF; |
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160 x76 = (x76 + xkey[x54 & 63]) & 0xFFFF; |
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161 } |
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162 } |
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163 |
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164 cipher[0] = (unsigned char)x10; |
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165 cipher[1] = (unsigned char)(x10 >> 8); |
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166 cipher[2] = (unsigned char)x32; |
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167 cipher[3] = (unsigned char)(x32 >> 8); |
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168 cipher[4] = (unsigned char)x54; |
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169 cipher[5] = (unsigned char)(x54 >> 8); |
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170 cipher[6] = (unsigned char)x76; |
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171 cipher[7] = (unsigned char)(x76 >> 8); |
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172 } |
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173 |
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174 #ifdef CLEAN_STACK |
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175 void rc2_ecb_encrypt( const unsigned char *plain, |
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176 unsigned char *cipher, |
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177 symmetric_key *skey) |
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178 { |
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179 _rc2_ecb_encrypt(plain, cipher, skey); |
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180 burn_stack(sizeof(unsigned *) + sizeof(unsigned) * 5); |
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181 } |
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182 #endif |
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183 |
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184 /**********************************************************************\ |
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185 * Decrypt an 8-byte block of ciphertext using the given key. * |
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186 \**********************************************************************/ |
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187 |
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188 #ifdef CLEAN_STACK |
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189 static void _rc2_ecb_decrypt( const unsigned char *cipher, |
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190 unsigned char *plain, |
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191 symmetric_key *skey) |
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192 #else |
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193 void rc2_ecb_decrypt( const unsigned char *cipher, |
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194 unsigned char *plain, |
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195 symmetric_key *skey) |
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196 #endif |
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197 { |
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198 unsigned x76, x54, x32, x10; |
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199 unsigned *xkey; |
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200 int i; |
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201 |
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202 _ARGCHK(plain != NULL); |
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203 _ARGCHK(cipher != NULL); |
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204 _ARGCHK(skey != NULL); |
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205 |
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206 xkey = skey->rc2.xkey; |
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207 |
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208 x76 = ((unsigned)cipher[7] << 8) + (unsigned)cipher[6]; |
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209 x54 = ((unsigned)cipher[5] << 8) + (unsigned)cipher[4]; |
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210 x32 = ((unsigned)cipher[3] << 8) + (unsigned)cipher[2]; |
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211 x10 = ((unsigned)cipher[1] << 8) + (unsigned)cipher[0]; |
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212 |
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213 for (i = 15; i >= 0; i--) { |
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214 if (i == 4 || i == 10) { |
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215 x76 = (x76 - xkey[x54 & 63]) & 0xFFFF; |
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216 x54 = (x54 - xkey[x32 & 63]) & 0xFFFF; |
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217 x32 = (x32 - xkey[x10 & 63]) & 0xFFFF; |
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218 x10 = (x10 - xkey[x76 & 63]) & 0xFFFF; |
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219 } |
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220 |
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221 x76 = ((x76 << 11) | (x76 >> 5)) & 0xFFFF; |
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222 x76 = (x76 - ((x10 & ~x54) + (x32 & x54) + xkey[4*i+3])) & 0xFFFF; |
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223 |
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224 x54 = ((x54 << 13) | (x54 >> 3)) & 0xFFFF; |
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225 x54 = (x54 - ((x76 & ~x32) + (x10 & x32) + xkey[4*i+2])) & 0xFFFF; |
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226 |
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227 x32 = ((x32 << 14) | (x32 >> 2)) & 0xFFFF; |
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228 x32 = (x32 - ((x54 & ~x10) + (x76 & x10) + xkey[4*i+1])) & 0xFFFF; |
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229 |
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230 x10 = ((x10 << 15) | (x10 >> 1)) & 0xFFFF; |
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231 x10 = (x10 - ((x32 & ~x76) + (x54 & x76) + xkey[4*i+0])) & 0xFFFF; |
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232 } |
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233 |
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234 plain[0] = (unsigned char)x10; |
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235 plain[1] = (unsigned char)(x10 >> 8); |
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236 plain[2] = (unsigned char)x32; |
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237 plain[3] = (unsigned char)(x32 >> 8); |
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238 plain[4] = (unsigned char)x54; |
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239 plain[5] = (unsigned char)(x54 >> 8); |
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240 plain[6] = (unsigned char)x76; |
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241 plain[7] = (unsigned char)(x76 >> 8); |
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242 } |
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243 |
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244 #ifdef CLEAN_STACK |
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245 void rc2_ecb_decrypt( const unsigned char *cipher, |
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246 unsigned char *plain, |
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247 symmetric_key *skey) |
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248 { |
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249 _rc2_ecb_decrypt(cipher, plain, skey); |
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250 burn_stack(sizeof(unsigned *) + sizeof(unsigned) * 4 + sizeof(int)); |
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251 } |
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252 #endif |
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253 |
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254 int rc2_test(void) |
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255 { |
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256 #ifndef LTC_TEST |
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257 return CRYPT_NOP; |
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258 #else |
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259 static const struct { |
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260 int keylen; |
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261 unsigned char key[16], pt[8], ct[8]; |
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262 } tests[] = { |
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263 |
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264 { 8, |
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265 { 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, |
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266 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, |
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267 { 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 }, |
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268 { 0x30, 0x64, 0x9e, 0xdf, 0x9b, 0xe7, 0xd2, 0xc2 } |
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269 |
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270 }, |
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271 { 16, |
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272 { 0x88, 0xbc, 0xa9, 0x0e, 0x90, 0x87, 0x5a, 0x7f, |
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273 0x0f, 0x79, 0xc3, 0x84, 0x62, 0x7b, 0xaf, 0xb2 }, |
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274 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, |
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275 { 0x22, 0x69, 0x55, 0x2a, 0xb0, 0xf8, 0x5c, 0xa6 } |
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276 } |
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277 }; |
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278 int x, y, err; |
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279 symmetric_key skey; |
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280 unsigned char tmp[2][8]; |
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281 |
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282 for (x = 0; x < (int)(sizeof(tests) / sizeof(tests[0])); x++) { |
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283 zeromem(tmp, sizeof(tmp)); |
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284 if ((err = rc2_setup(tests[x].key, tests[x].keylen, 0, &skey)) != CRYPT_OK) { |
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285 return err; |
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286 } |
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287 |
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288 rc2_ecb_encrypt(tests[x].pt, tmp[0], &skey); |
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289 rc2_ecb_decrypt(tmp[0], tmp[1], &skey); |
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290 |
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291 if (memcmp(tmp[0], tests[x].ct, 8) != 0 || memcmp(tmp[1], tests[x].pt, 8) != 0) { |
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292 return CRYPT_FAIL_TESTVECTOR; |
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293 } |
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294 |
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295 /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */ |
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296 for (y = 0; y < 8; y++) tmp[0][y] = 0; |
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297 for (y = 0; y < 1000; y++) rc2_ecb_encrypt(tmp[0], tmp[0], &skey); |
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298 for (y = 0; y < 1000; y++) rc2_ecb_decrypt(tmp[0], tmp[0], &skey); |
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299 for (y = 0; y < 8; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR; |
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300 } |
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301 return CRYPT_OK; |
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302 #endif |
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303 } |
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304 |
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305 int rc2_keysize(int *keysize) |
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306 { |
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307 _ARGCHK(keysize != NULL); |
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308 if (*keysize < 8) { |
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309 return CRYPT_INVALID_KEYSIZE; |
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310 } else if (*keysize > 128) { |
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311 *keysize = 128; |
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312 } |
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313 return CRYPT_OK; |
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314 } |
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315 |
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316 #endif |
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317 |
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318 |
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319 |
