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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 /* Skipjack Implementation by Tom St Denis */ |
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13 #include "mycrypt.h" |
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14 |
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15 #ifdef SKIPJACK |
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16 |
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17 const struct _cipher_descriptor skipjack_desc = |
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18 { |
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19 "skipjack", |
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20 17, |
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21 10, 10, 8, 32, |
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22 &skipjack_setup, |
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23 &skipjack_ecb_encrypt, |
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24 &skipjack_ecb_decrypt, |
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25 &skipjack_test, |
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26 &skipjack_keysize |
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27 }; |
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28 |
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29 static const unsigned char sbox[256] = { |
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30 0xa3,0xd7,0x09,0x83,0xf8,0x48,0xf6,0xf4,0xb3,0x21,0x15,0x78,0x99,0xb1,0xaf,0xf9, |
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31 0xe7,0x2d,0x4d,0x8a,0xce,0x4c,0xca,0x2e,0x52,0x95,0xd9,0x1e,0x4e,0x38,0x44,0x28, |
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32 0x0a,0xdf,0x02,0xa0,0x17,0xf1,0x60,0x68,0x12,0xb7,0x7a,0xc3,0xe9,0xfa,0x3d,0x53, |
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33 0x96,0x84,0x6b,0xba,0xf2,0x63,0x9a,0x19,0x7c,0xae,0xe5,0xf5,0xf7,0x16,0x6a,0xa2, |
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34 0x39,0xb6,0x7b,0x0f,0xc1,0x93,0x81,0x1b,0xee,0xb4,0x1a,0xea,0xd0,0x91,0x2f,0xb8, |
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35 0x55,0xb9,0xda,0x85,0x3f,0x41,0xbf,0xe0,0x5a,0x58,0x80,0x5f,0x66,0x0b,0xd8,0x90, |
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36 0x35,0xd5,0xc0,0xa7,0x33,0x06,0x65,0x69,0x45,0x00,0x94,0x56,0x6d,0x98,0x9b,0x76, |
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37 0x97,0xfc,0xb2,0xc2,0xb0,0xfe,0xdb,0x20,0xe1,0xeb,0xd6,0xe4,0xdd,0x47,0x4a,0x1d, |
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38 0x42,0xed,0x9e,0x6e,0x49,0x3c,0xcd,0x43,0x27,0xd2,0x07,0xd4,0xde,0xc7,0x67,0x18, |
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39 0x89,0xcb,0x30,0x1f,0x8d,0xc6,0x8f,0xaa,0xc8,0x74,0xdc,0xc9,0x5d,0x5c,0x31,0xa4, |
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40 0x70,0x88,0x61,0x2c,0x9f,0x0d,0x2b,0x87,0x50,0x82,0x54,0x64,0x26,0x7d,0x03,0x40, |
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41 0x34,0x4b,0x1c,0x73,0xd1,0xc4,0xfd,0x3b,0xcc,0xfb,0x7f,0xab,0xe6,0x3e,0x5b,0xa5, |
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42 0xad,0x04,0x23,0x9c,0x14,0x51,0x22,0xf0,0x29,0x79,0x71,0x7e,0xff,0x8c,0x0e,0xe2, |
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43 0x0c,0xef,0xbc,0x72,0x75,0x6f,0x37,0xa1,0xec,0xd3,0x8e,0x62,0x8b,0x86,0x10,0xe8, |
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44 0x08,0x77,0x11,0xbe,0x92,0x4f,0x24,0xc5,0x32,0x36,0x9d,0xcf,0xf3,0xa6,0xbb,0xac, |
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45 0x5e,0x6c,0xa9,0x13,0x57,0x25,0xb5,0xe3,0xbd,0xa8,0x3a,0x01,0x05,0x59,0x2a,0x46 |
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46 }; |
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47 |
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48 /* simple x + 1 (mod 10) in one step. */ |
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49 static const int keystep[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 }; |
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50 |
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51 /* simple x - 1 (mod 10) in one step */ |
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52 static const int ikeystep[] = { 9, 0, 1, 2, 3, 4, 5, 6, 7, 8 }; |
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53 |
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54 int skipjack_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey) |
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55 { |
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56 int x; |
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57 |
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58 _ARGCHK(key != NULL); |
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59 _ARGCHK(skey != NULL); |
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60 |
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61 if (keylen != 10) { |
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62 return CRYPT_INVALID_KEYSIZE; |
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63 } |
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64 |
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65 if (num_rounds != 32 && num_rounds != 0) { |
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66 return CRYPT_INVALID_ROUNDS; |
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67 } |
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68 |
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69 /* make sure the key is in range for platforms where CHAR_BIT != 8 */ |
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70 for (x = 0; x < 10; x++) { |
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71 skey->skipjack.key[x] = key[x] & 255; |
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72 } |
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73 |
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74 return CRYPT_OK; |
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75 } |
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76 |
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77 #define RULE_A \ |
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78 tmp = g_func(w1, &kp, key->skipjack.key); \ |
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79 w1 = tmp ^ w4 ^ x; \ |
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80 w4 = w3; w3 = w2; \ |
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81 w2 = tmp; |
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82 |
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83 #define RULE_B \ |
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84 tmp = g_func(w1, &kp, key->skipjack.key); \ |
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85 tmp1 = w4; w4 = w3; \ |
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86 w3 = w1 ^ w2 ^ x; \ |
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87 w1 = tmp1; w2 = tmp; |
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88 |
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89 #define RULE_A1 \ |
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90 tmp = w1 ^ w2 ^ x; \ |
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91 w1 = ig_func(w2, &kp, key->skipjack.key); \ |
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92 w2 = w3; w3 = w4; w4 = tmp; |
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93 |
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94 #define RULE_B1 \ |
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95 tmp = ig_func(w2, &kp, key->skipjack.key); \ |
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96 w2 = tmp ^ w3 ^ x; \ |
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97 w3 = w4; w4 = w1; w1 = tmp; |
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98 |
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99 static unsigned g_func(unsigned w, int *kp, unsigned char *key) |
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100 { |
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101 unsigned char g1,g2; |
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102 |
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103 g1 = (w >> 8) & 255; g2 = w & 255; |
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104 g1 ^= sbox[g2^key[*kp]]; *kp = keystep[*kp]; |
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105 g2 ^= sbox[g1^key[*kp]]; *kp = keystep[*kp]; |
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106 g1 ^= sbox[g2^key[*kp]]; *kp = keystep[*kp]; |
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107 g2 ^= sbox[g1^key[*kp]]; *kp = keystep[*kp]; |
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108 return ((unsigned)g1<<8)|(unsigned)g2; |
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109 } |
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110 |
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111 static unsigned ig_func(unsigned w, int *kp, unsigned char *key) |
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112 { |
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113 unsigned char g1,g2; |
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114 |
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115 g1 = (w >> 8) & 255; g2 = w & 255; |
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116 *kp = ikeystep[*kp]; g2 ^= sbox[g1^key[*kp]]; |
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117 *kp = ikeystep[*kp]; g1 ^= sbox[g2^key[*kp]]; |
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118 *kp = ikeystep[*kp]; g2 ^= sbox[g1^key[*kp]]; |
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119 *kp = ikeystep[*kp]; g1 ^= sbox[g2^key[*kp]]; |
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120 return ((unsigned)g1<<8)|(unsigned)g2; |
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121 } |
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122 |
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123 #ifdef CLEAN_STACK |
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124 static void _skipjack_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key) |
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125 #else |
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126 void skipjack_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key) |
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127 #endif |
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128 { |
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129 unsigned w1,w2,w3,w4,tmp,tmp1; |
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130 int x, kp; |
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131 |
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132 _ARGCHK(pt != NULL); |
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133 _ARGCHK(ct != NULL); |
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134 _ARGCHK(key != NULL); |
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135 |
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136 /* load block */ |
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137 w1 = ((unsigned)pt[0]<<8)|pt[1]; |
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138 w2 = ((unsigned)pt[2]<<8)|pt[3]; |
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139 w3 = ((unsigned)pt[4]<<8)|pt[5]; |
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140 w4 = ((unsigned)pt[6]<<8)|pt[7]; |
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141 |
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142 /* 8 rounds of RULE A */ |
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143 for (x = 1, kp = 0; x < 9; x++) { |
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144 RULE_A; |
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145 } |
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146 |
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147 /* 8 rounds of RULE B */ |
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148 for (; x < 17; x++) { |
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149 RULE_B; |
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150 } |
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151 |
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152 /* 8 rounds of RULE A */ |
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153 for (; x < 25; x++) { |
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154 RULE_A; |
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155 } |
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156 |
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157 /* 8 rounds of RULE B */ |
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158 for (; x < 33; x++) { |
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159 RULE_B; |
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160 } |
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161 |
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162 /* store block */ |
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163 ct[0] = (w1>>8)&255; ct[1] = w1&255; |
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164 ct[2] = (w2>>8)&255; ct[3] = w2&255; |
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165 ct[4] = (w3>>8)&255; ct[5] = w3&255; |
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166 ct[6] = (w4>>8)&255; ct[7] = w4&255; |
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167 } |
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168 |
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169 #ifdef CLEAN_STACK |
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170 void skipjack_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key) |
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171 { |
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172 _skipjack_ecb_encrypt(pt, ct, key); |
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173 burn_stack(sizeof(unsigned) * 8 + sizeof(int) * 2); |
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174 } |
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175 #endif |
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176 |
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177 #ifdef CLEAN_STACK |
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178 static void _skipjack_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key) |
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179 #else |
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180 void skipjack_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key) |
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181 #endif |
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182 { |
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183 unsigned w1,w2,w3,w4,tmp; |
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184 int x, kp; |
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185 |
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186 _ARGCHK(pt != NULL); |
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187 _ARGCHK(ct != NULL); |
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188 _ARGCHK(key != NULL); |
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189 |
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190 /* load block */ |
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191 w1 = ((unsigned)ct[0]<<8)|ct[1]; |
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192 w2 = ((unsigned)ct[2]<<8)|ct[3]; |
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193 w3 = ((unsigned)ct[4]<<8)|ct[5]; |
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194 w4 = ((unsigned)ct[6]<<8)|ct[7]; |
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195 |
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196 /* 8 rounds of RULE B^-1 |
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197 |
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198 Note the value "kp = 8" comes from "kp = (32 * 4) mod 10" where 32*4 is 128 which mod 10 is 8 |
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199 */ |
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200 for (x = 32, kp = 8; x > 24; x--) { |
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201 RULE_B1; |
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202 } |
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203 |
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204 /* 8 rounds of RULE A^-1 */ |
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205 for (; x > 16; x--) { |
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206 RULE_A1; |
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207 } |
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208 |
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209 |
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210 /* 8 rounds of RULE B^-1 */ |
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211 for (; x > 8; x--) { |
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212 RULE_B1; |
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213 } |
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214 |
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215 /* 8 rounds of RULE A^-1 */ |
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216 for (; x > 0; x--) { |
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217 RULE_A1; |
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218 } |
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219 |
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220 /* store block */ |
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221 pt[0] = (w1>>8)&255; pt[1] = w1&255; |
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222 pt[2] = (w2>>8)&255; pt[3] = w2&255; |
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223 pt[4] = (w3>>8)&255; pt[5] = w3&255; |
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224 pt[6] = (w4>>8)&255; pt[7] = w4&255; |
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225 } |
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226 |
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227 #ifdef CLEAN_STACK |
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228 void skipjack_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key) |
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229 { |
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230 _skipjack_ecb_decrypt(ct, pt, key); |
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231 burn_stack(sizeof(unsigned) * 7 + sizeof(int) * 2); |
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232 } |
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233 #endif |
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234 |
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235 int skipjack_test(void) |
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236 { |
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237 #ifndef LTC_TEST |
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238 return CRYPT_NOP; |
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239 #else |
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240 static const struct { |
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241 unsigned char key[10], pt[8], ct[8]; |
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242 } tests[] = { |
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243 { |
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244 { 0x00, 0x99, 0x88, 0x77, 0x66, 0x55, 0x44, 0x33, 0x22, 0x11 }, |
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245 { 0x33, 0x22, 0x11, 0x00, 0xdd, 0xcc, 0xbb, 0xaa }, |
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246 { 0x25, 0x87, 0xca, 0xe2, 0x7a, 0x12, 0xd3, 0x00 } |
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247 } |
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248 }; |
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249 unsigned char buf[2][8]; |
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250 int x, y, err; |
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251 symmetric_key key; |
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252 |
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253 for (x = 0; x < (int)(sizeof(tests) / sizeof(tests[0])); x++) { |
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254 /* setup key */ |
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255 if ((err = skipjack_setup(tests[x].key, 10, 0, &key)) != CRYPT_OK) { |
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256 return err; |
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257 } |
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258 |
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259 /* encrypt and decrypt */ |
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260 skipjack_ecb_encrypt(tests[x].pt, buf[0], &key); |
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261 skipjack_ecb_decrypt(buf[0], buf[1], &key); |
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262 |
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263 /* compare */ |
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264 if (memcmp(buf[0], tests[x].ct, 8) != 0 || memcmp(buf[1], tests[x].pt, 8) != 0) { |
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265 return CRYPT_FAIL_TESTVECTOR; |
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266 } |
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267 |
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268 /* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */ |
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269 for (y = 0; y < 8; y++) buf[0][y] = 0; |
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270 for (y = 0; y < 1000; y++) skipjack_ecb_encrypt(buf[0], buf[0], &key); |
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271 for (y = 0; y < 1000; y++) skipjack_ecb_decrypt(buf[0], buf[0], &key); |
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272 for (y = 0; y < 8; y++) if (buf[0][y] != 0) return CRYPT_FAIL_TESTVECTOR; |
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273 } |
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274 |
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275 return CRYPT_OK; |
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276 #endif |
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277 } |
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278 |
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279 int skipjack_keysize(int *desired_keysize) |
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280 { |
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281 _ARGCHK(desired_keysize != NULL); |
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282 if (*desired_keysize < 10) { |
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283 return CRYPT_INVALID_KEYSIZE; |
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284 } else if (*desired_keysize > 10) { |
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285 *desired_keysize = 10; |
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286 } |
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287 return CRYPT_OK; |
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288 } |
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289 |
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290 #endif |
