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1 /* Aes.c -- AES encryption / decryption
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2 2008-08-05
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3 Igor Pavlov
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4 Public domain */
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5
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6 #include "Aes.h"
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7 #include "CpuArch.h"
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8
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9 static UInt32 T[256 * 4];
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10 static Byte Sbox[256] = {
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11 0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
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12 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
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13 0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
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14 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
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15 0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
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16 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
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17 0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
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18 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
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19 0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
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20 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
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21 0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
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22 0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
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23 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
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24 0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
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25 0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
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26 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16};
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27
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28 static UInt32 D[256 * 4];
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29 static Byte InvS[256];
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30
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31 static Byte Rcon[11] = { 0x00, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36 };
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32
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33 #define xtime(x) ((((x) << 1) ^ (((x) & 0x80) != 0 ? 0x1B : 0)) & 0xFF)
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34
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35 #define Ui32(a0, a1, a2, a3) ((UInt32)(a0) | ((UInt32)(a1) << 8) | ((UInt32)(a2) << 16) | ((UInt32)(a3) << 24))
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36
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37 #define gb0(x) ( (x) & 0xFF)
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38 #define gb1(x) (((x) >> ( 8)) & 0xFF)
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39 #define gb2(x) (((x) >> (16)) & 0xFF)
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40 #define gb3(x) (((x) >> (24)) & 0xFF)
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41
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42 void AesGenTables(void)
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43 {
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44 unsigned i;
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45 for (i = 0; i < 256; i++)
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46 InvS[Sbox[i]] = (Byte)i;
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47 for (i = 0; i < 256; i++)
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48 {
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49 {
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50 UInt32 a1 = Sbox[i];
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51 UInt32 a2 = xtime(a1);
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52 UInt32 a3 = xtime(a1) ^ a1;
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53 T[ i] = Ui32(a2, a1, a1, a3);
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54 T[0x100 + i] = Ui32(a3, a2, a1, a1);
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55 T[0x200 + i] = Ui32(a1, a3, a2, a1);
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56 T[0x300 + i] = Ui32(a1, a1, a3, a2);
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57 }
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58 {
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59 UInt32 a1 = InvS[i];
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60 UInt32 a2 = xtime(a1);
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61 UInt32 a4 = xtime(a2);
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62 UInt32 a8 = xtime(a4);
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63 UInt32 a9 = a8 ^ a1;
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64 UInt32 aB = a8 ^ a2 ^ a1;
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65 UInt32 aD = a8 ^ a4 ^ a1;
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66 UInt32 aE = a8 ^ a4 ^ a2;
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67 D[ i] = Ui32(aE, a9, aD, aB);
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68 D[0x100 + i] = Ui32(aB, aE, a9, aD);
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69 D[0x200 + i] = Ui32(aD, aB, aE, a9);
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70 D[0x300 + i] = Ui32(a9, aD, aB, aE);
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71 }
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72 }
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73 }
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74
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75 #define HT(i, x, s) (T + (x << 8))[gb ## x(s[(i + x) & 3])]
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76 #define HT4(m, i, s, p) m[i] = \
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77 HT(i, 0, s) ^ \
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78 HT(i, 1, s) ^ \
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79 HT(i, 2, s) ^ \
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80 HT(i, 3, s) ^ w[p + i]
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81 /* such order (2031) in HT16 is for VC6/K8 speed optimization) */
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82 #define HT16(m, s, p) \
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83 HT4(m, 2, s, p); \
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84 HT4(m, 0, s, p); \
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85 HT4(m, 3, s, p); \
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86 HT4(m, 1, s, p); \
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87
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88 #define FT(i, x) Sbox[gb ## x(m[(i + x) & 3])]
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89 #define FT4(i) dest[i] = Ui32(FT(i, 0), FT(i, 1), FT(i, 2), FT(i, 3)) ^ w[i];
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90
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91 #define HD(i, x, s) (D + (x << 8))[gb ## x(s[(i - x) & 3])]
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92 #define HD4(m, i, s, p) m[i] = \
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93 HD(i, 0, s) ^ \
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94 HD(i, 1, s) ^ \
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95 HD(i, 2, s) ^ \
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96 HD(i, 3, s) ^ w[p + i];
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97 /* such order (0231) in HD16 is for VC6/K8 speed optimization) */
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98 #define HD16(m, s, p) \
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99 HD4(m, 0, s, p); \
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100 HD4(m, 2, s, p); \
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101 HD4(m, 3, s, p); \
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102 HD4(m, 1, s, p); \
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103
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104 #define FD(i, x) InvS[gb ## x(m[(i - x) & 3])]
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105 #define FD4(i) dest[i] = Ui32(FD(i, 0), FD(i, 1), FD(i, 2), FD(i, 3)) ^ w[i];
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106
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107 void Aes_SetKeyEncode(CAes *p, const Byte *key, unsigned keySize)
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108 {
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109 unsigned i, wSize;
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110 UInt32 *w;
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111 keySize /= 4;
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112 p->numRounds2 = keySize / 2 + 3;
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113
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114 wSize = (p->numRounds2 * 2 + 1) * 4;
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115 w = p->rkey;
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116
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117 for (i = 0; i < keySize; i++, key += 4)
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118 w[i] = Ui32(key[0], key[1], key[2], key[3]);
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119
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120 for (; i < wSize; i++)
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121 {
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122 UInt32 t = w[i - 1];
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123 unsigned rem = i % keySize;
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124 if (rem == 0)
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125 t = Ui32(Sbox[gb1(t)] ^ Rcon[i / keySize], Sbox[gb2(t)], Sbox[gb3(t)], Sbox[gb0(t)]);
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126 else if (keySize > 6 && rem == 4)
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127 t = Ui32(Sbox[gb0(t)], Sbox[gb1(t)], Sbox[gb2(t)], Sbox[gb3(t)]);
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128 w[i] = w[i - keySize] ^ t;
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129 }
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130 }
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131
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132 void Aes_SetKeyDecode(CAes *p, const Byte *key, unsigned keySize)
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133 {
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134 unsigned i, num;
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135 UInt32 *w;
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136 Aes_SetKeyEncode(p, key, keySize);
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137 num = p->numRounds2 * 8 - 4;
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138 w = p->rkey + 4;
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139 for (i = 0; i < num; i++)
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140 {
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141 UInt32 r = w[i];
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142 w[i] =
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143 D[ Sbox[gb0(r)]] ^
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144 D[0x100 + Sbox[gb1(r)]] ^
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145 D[0x200 + Sbox[gb2(r)]] ^
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146 D[0x300 + Sbox[gb3(r)]];
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147 }
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148 }
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149
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150 static void AesEncode32(UInt32 *dest, const UInt32 *src, const UInt32 *w, unsigned numRounds2)
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151 {
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152 UInt32 s[4];
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153 UInt32 m[4];
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154 s[0] = src[0] ^ w[0];
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155 s[1] = src[1] ^ w[1];
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156 s[2] = src[2] ^ w[2];
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157 s[3] = src[3] ^ w[3];
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158 w += 4;
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159 for (;;)
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160 {
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161 HT16(m, s, 0);
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162 if (--numRounds2 == 0)
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163 break;
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164 HT16(s, m, 4);
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165 w += 8;
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166 }
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167 w += 4;
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168 FT4(0); FT4(1); FT4(2); FT4(3);
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169 }
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170
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171 static void AesDecode32(UInt32 *dest, const UInt32 *src, const UInt32 *w, unsigned numRounds2)
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172 {
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173 UInt32 s[4];
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174 UInt32 m[4];
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175 w += numRounds2 * 8;
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176 s[0] = src[0] ^ w[0];
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177 s[1] = src[1] ^ w[1];
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178 s[2] = src[2] ^ w[2];
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179 s[3] = src[3] ^ w[3];
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180 for (;;)
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181 {
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182 w -= 8;
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183 HD16(m, s, 4);
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184 if (--numRounds2 == 0)
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185 break;
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186 HD16(s, m, 0);
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187 }
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188 FD4(0); FD4(1); FD4(2); FD4(3);
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189 }
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190
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191 void Aes_Encode32(const CAes *p, UInt32 *dest, const UInt32 *src)
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192 {
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193 AesEncode32(dest, src, p->rkey, p->numRounds2);
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194 }
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195
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196 void Aes_Decode32(const CAes *p, UInt32 *dest, const UInt32 *src)
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197 {
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198 AesDecode32(dest, src, p->rkey, p->numRounds2);
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199 }
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200
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201 void AesCbc_Init(CAesCbc *p, const Byte *iv)
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202 {
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203 unsigned i;
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204 for (i = 0; i < 4; i++)
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205 p->prev[i] = GetUi32(iv + i * 4);
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206 }
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207
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208 SizeT AesCbc_Encode(CAesCbc *p, Byte *data, SizeT size)
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209 {
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210 SizeT i;
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211 if (size == 0)
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212 return 0;
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213 if (size < AES_BLOCK_SIZE)
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214 return AES_BLOCK_SIZE;
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215 size -= AES_BLOCK_SIZE;
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216 for (i = 0; i <= size; i += AES_BLOCK_SIZE, data += AES_BLOCK_SIZE)
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217 {
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218 p->prev[0] ^= GetUi32(data);
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219 p->prev[1] ^= GetUi32(data + 4);
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220 p->prev[2] ^= GetUi32(data + 8);
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221 p->prev[3] ^= GetUi32(data + 12);
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222
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223 AesEncode32(p->prev, p->prev, p->aes.rkey, p->aes.numRounds2);
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224
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225 SetUi32(data, p->prev[0]);
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226 SetUi32(data + 4, p->prev[1]);
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227 SetUi32(data + 8, p->prev[2]);
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228 SetUi32(data + 12, p->prev[3]);
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229 }
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230 return i;
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231 }
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232
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233 SizeT AesCbc_Decode(CAesCbc *p, Byte *data, SizeT size)
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234 {
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235 SizeT i;
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236 UInt32 in[4], out[4];
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237 if (size == 0)
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238 return 0;
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239 if (size < AES_BLOCK_SIZE)
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240 return AES_BLOCK_SIZE;
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241 size -= AES_BLOCK_SIZE;
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242 for (i = 0; i <= size; i += AES_BLOCK_SIZE, data += AES_BLOCK_SIZE)
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243 {
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244 in[0] = GetUi32(data);
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245 in[1] = GetUi32(data + 4);
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246 in[2] = GetUi32(data + 8);
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247 in[3] = GetUi32(data + 12);
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248
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249 AesDecode32(out, in, p->aes.rkey, p->aes.numRounds2);
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250
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251 SetUi32(data, p->prev[0] ^ out[0]);
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252 SetUi32(data + 4, p->prev[1] ^ out[1]);
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253 SetUi32(data + 8, p->prev[2] ^ out[2]);
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254 SetUi32(data + 12, p->prev[3] ^ out[3]);
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255
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256 p->prev[0] = in[0];
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257 p->prev[1] = in[1];
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258 p->prev[2] = in[2];
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259 p->prev[3] = in[3];
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260 }
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261 return i;
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262 }
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