1 | /* |
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2 | * Copyright (c) 2011 The FreeBSD Project. All rights reserved. |
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3 | * |
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4 | * Redistribution and use in source and binary forms, with or without |
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5 | * modification, are permitted provided that the following conditions |
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6 | * are met: |
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7 | * 1. Redistributions of source code must retain the above copyright |
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8 | * notice, this list of conditions and the following disclaimer. |
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9 | * 2. Redistributions in binary form must reproduce the above copyright |
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10 | * notice, this list of conditions and the following disclaimer in the |
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11 | * documentation and/or other materials provided with the distribution. |
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12 | * |
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13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
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14 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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15 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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16 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
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17 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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18 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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19 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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20 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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21 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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22 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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23 | * SUCH DAMAGE. |
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24 | */ |
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25 | |
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26 | /* Based on: |
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27 | * SHA512-based Unix crypt implementation. Released into the Public Domain by |
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28 | * Ulrich Drepper <drepper@redhat.com>. */ |
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29 | |
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30 | #include <sys/cdefs.h> |
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31 | __FBSDID("$FreeBSD$"); |
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32 | |
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33 | #include <sys/endian.h> |
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34 | #include <sys/param.h> |
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35 | |
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36 | #include <errno.h> |
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37 | #include <limits.h> |
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38 | #include <sha512.h> |
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39 | #include <stdbool.h> |
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40 | #include <stdint.h> |
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41 | #include <stdio.h> |
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42 | #include <stdlib.h> |
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43 | #include <string.h> |
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44 | |
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45 | #include <crypt.h> |
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46 | |
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47 | /* Define our magic string to mark salt for SHA512 "encryption" replacement. */ |
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48 | static const char sha512_salt_prefix[] = "$6$"; |
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49 | |
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50 | /* Prefix for optional rounds specification. */ |
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51 | static const char sha512_rounds_prefix[] = "rounds="; |
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52 | |
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53 | /* Maximum salt string length. */ |
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54 | #define SALT_LEN_MAX 16 |
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55 | /* Default number of rounds if not explicitly specified. */ |
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56 | #define ROUNDS_DEFAULT 5000 |
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57 | /* Minimum number of rounds. */ |
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58 | #define ROUNDS_MIN 1000 |
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59 | /* Maximum number of rounds. */ |
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60 | #define ROUNDS_MAX 999999999 |
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61 | |
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62 | char * |
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63 | crypt_sha512_r(const char *key, const char *salt, struct crypt_data *data) |
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64 | { |
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65 | u_long srounds; |
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66 | int n; |
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67 | uint8_t alt_result[64], temp_result[64]; |
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68 | SHA512_CTX ctx, alt_ctx; |
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69 | size_t salt_len, key_len, cnt, rounds; |
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70 | char *cp, *copied_key, *copied_salt, *p_bytes, *s_bytes, *endp; |
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71 | const char *num; |
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72 | bool rounds_custom; |
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73 | char *buffer = &data->buffer[0]; |
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74 | int buflen = (int)sizeof(data->buffer); |
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75 | |
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76 | copied_key = NULL; |
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77 | copied_salt = NULL; |
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78 | |
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79 | /* Default number of rounds. */ |
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80 | rounds = ROUNDS_DEFAULT; |
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81 | rounds_custom = false; |
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82 | |
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83 | /* Find beginning of salt string. The prefix should normally always |
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84 | * be present. Just in case it is not. */ |
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85 | if (strncmp(sha512_salt_prefix, salt, sizeof(sha512_salt_prefix) - 1) == 0) |
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86 | /* Skip salt prefix. */ |
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87 | salt += sizeof(sha512_salt_prefix) - 1; |
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88 | |
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89 | if (strncmp(salt, sha512_rounds_prefix, sizeof(sha512_rounds_prefix) - 1) |
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90 | == 0) { |
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91 | num = salt + sizeof(sha512_rounds_prefix) - 1; |
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92 | srounds = strtoul(num, &endp, 10); |
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93 | |
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94 | if (*endp == '$') { |
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95 | salt = endp + 1; |
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96 | rounds = MAX(ROUNDS_MIN, MIN(srounds, ROUNDS_MAX)); |
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97 | rounds_custom = true; |
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98 | } |
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99 | } |
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100 | |
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101 | salt_len = MIN(strcspn(salt, "$"), SALT_LEN_MAX); |
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102 | key_len = strlen(key); |
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103 | |
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104 | /* Prepare for the real work. */ |
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105 | SHA512_Init(&ctx); |
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106 | |
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107 | /* Add the key string. */ |
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108 | SHA512_Update(&ctx, key, key_len); |
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109 | |
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110 | /* The last part is the salt string. This must be at most 8 |
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111 | * characters and it ends at the first `$' character (for |
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112 | * compatibility with existing implementations). */ |
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113 | SHA512_Update(&ctx, salt, salt_len); |
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114 | |
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115 | /* Compute alternate SHA512 sum with input KEY, SALT, and KEY. The |
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116 | * final result will be added to the first context. */ |
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117 | SHA512_Init(&alt_ctx); |
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118 | |
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119 | /* Add key. */ |
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120 | SHA512_Update(&alt_ctx, key, key_len); |
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121 | |
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122 | /* Add salt. */ |
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123 | SHA512_Update(&alt_ctx, salt, salt_len); |
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124 | |
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125 | /* Add key again. */ |
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126 | SHA512_Update(&alt_ctx, key, key_len); |
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127 | |
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128 | /* Now get result of this (64 bytes) and add it to the other context. */ |
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129 | SHA512_Final(alt_result, &alt_ctx); |
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130 | |
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131 | /* Add for any character in the key one byte of the alternate sum. */ |
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132 | for (cnt = key_len; cnt > 64; cnt -= 64) |
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133 | SHA512_Update(&ctx, alt_result, 64); |
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134 | SHA512_Update(&ctx, alt_result, cnt); |
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135 | |
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136 | /* Take the binary representation of the length of the key and for |
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137 | * every 1 add the alternate sum, for every 0 the key. */ |
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138 | for (cnt = key_len; cnt > 0; cnt >>= 1) |
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139 | if ((cnt & 1) != 0) |
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140 | SHA512_Update(&ctx, alt_result, 64); |
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141 | else |
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142 | SHA512_Update(&ctx, key, key_len); |
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143 | |
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144 | /* Create intermediate result. */ |
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145 | SHA512_Final(alt_result, &ctx); |
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146 | |
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147 | /* Start computation of P byte sequence. */ |
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148 | SHA512_Init(&alt_ctx); |
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149 | |
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150 | /* For every character in the password add the entire password. */ |
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151 | for (cnt = 0; cnt < key_len; ++cnt) |
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152 | SHA512_Update(&alt_ctx, key, key_len); |
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153 | |
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154 | /* Finish the digest. */ |
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155 | SHA512_Final(temp_result, &alt_ctx); |
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156 | |
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157 | /* Create byte sequence P. */ |
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158 | cp = p_bytes = alloca(key_len); |
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159 | for (cnt = key_len; cnt >= 64; cnt -= 64) { |
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160 | memcpy(cp, temp_result, 64); |
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161 | cp += 64; |
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162 | } |
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163 | memcpy(cp, temp_result, cnt); |
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164 | |
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165 | /* Start computation of S byte sequence. */ |
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166 | SHA512_Init(&alt_ctx); |
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167 | |
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168 | /* For every character in the password add the entire password. */ |
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169 | for (cnt = 0; cnt < 16 + alt_result[0]; ++cnt) |
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170 | SHA512_Update(&alt_ctx, salt, salt_len); |
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171 | |
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172 | /* Finish the digest. */ |
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173 | SHA512_Final(temp_result, &alt_ctx); |
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174 | |
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175 | /* Create byte sequence S. */ |
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176 | cp = s_bytes = alloca(salt_len); |
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177 | for (cnt = salt_len; cnt >= 64; cnt -= 64) { |
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178 | memcpy(cp, temp_result, 64); |
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179 | cp += 64; |
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180 | } |
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181 | memcpy(cp, temp_result, cnt); |
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182 | |
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183 | /* Repeatedly run the collected hash value through SHA512 to burn CPU |
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184 | * cycles. */ |
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185 | for (cnt = 0; cnt < rounds; ++cnt) { |
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186 | /* New context. */ |
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187 | SHA512_Init(&ctx); |
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188 | |
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189 | /* Add key or last result. */ |
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190 | if ((cnt & 1) != 0) |
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191 | SHA512_Update(&ctx, p_bytes, key_len); |
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192 | else |
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193 | SHA512_Update(&ctx, alt_result, 64); |
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194 | |
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195 | /* Add salt for numbers not divisible by 3. */ |
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196 | if (cnt % 3 != 0) |
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197 | SHA512_Update(&ctx, s_bytes, salt_len); |
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198 | |
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199 | /* Add key for numbers not divisible by 7. */ |
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200 | if (cnt % 7 != 0) |
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201 | SHA512_Update(&ctx, p_bytes, key_len); |
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202 | |
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203 | /* Add key or last result. */ |
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204 | if ((cnt & 1) != 0) |
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205 | SHA512_Update(&ctx, alt_result, 64); |
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206 | else |
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207 | SHA512_Update(&ctx, p_bytes, key_len); |
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208 | |
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209 | /* Create intermediate result. */ |
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210 | SHA512_Final(alt_result, &ctx); |
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211 | } |
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212 | |
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213 | /* Now we can construct the result string. It consists of three |
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214 | * parts. */ |
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215 | cp = stpncpy(buffer, sha512_salt_prefix, MAX(0, buflen)); |
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216 | buflen -= sizeof(sha512_salt_prefix) - 1; |
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217 | |
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218 | if (rounds_custom) { |
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219 | n = snprintf(cp, MAX(0, buflen), "%s%zu$", |
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220 | sha512_rounds_prefix, rounds); |
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221 | |
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222 | cp += n; |
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223 | buflen -= n; |
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224 | } |
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225 | |
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226 | cp = stpncpy(cp, salt, MIN((size_t)MAX(0, buflen), salt_len)); |
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227 | buflen -= MIN((size_t)MAX(0, buflen), salt_len); |
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228 | |
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229 | if (buflen > 0) { |
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230 | *cp++ = '$'; |
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231 | --buflen; |
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232 | } |
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233 | |
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234 | b64_from_24bit(alt_result[0], alt_result[21], alt_result[42], 4, &buflen, &cp); |
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235 | b64_from_24bit(alt_result[22], alt_result[43], alt_result[1], 4, &buflen, &cp); |
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236 | b64_from_24bit(alt_result[44], alt_result[2], alt_result[23], 4, &buflen, &cp); |
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237 | b64_from_24bit(alt_result[3], alt_result[24], alt_result[45], 4, &buflen, &cp); |
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238 | b64_from_24bit(alt_result[25], alt_result[46], alt_result[4], 4, &buflen, &cp); |
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239 | b64_from_24bit(alt_result[47], alt_result[5], alt_result[26], 4, &buflen, &cp); |
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240 | b64_from_24bit(alt_result[6], alt_result[27], alt_result[48], 4, &buflen, &cp); |
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241 | b64_from_24bit(alt_result[28], alt_result[49], alt_result[7], 4, &buflen, &cp); |
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242 | b64_from_24bit(alt_result[50], alt_result[8], alt_result[29], 4, &buflen, &cp); |
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243 | b64_from_24bit(alt_result[9], alt_result[30], alt_result[51], 4, &buflen, &cp); |
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244 | b64_from_24bit(alt_result[31], alt_result[52], alt_result[10], 4, &buflen, &cp); |
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245 | b64_from_24bit(alt_result[53], alt_result[11], alt_result[32], 4, &buflen, &cp); |
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246 | b64_from_24bit(alt_result[12], alt_result[33], alt_result[54], 4, &buflen, &cp); |
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247 | b64_from_24bit(alt_result[34], alt_result[55], alt_result[13], 4, &buflen, &cp); |
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248 | b64_from_24bit(alt_result[56], alt_result[14], alt_result[35], 4, &buflen, &cp); |
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249 | b64_from_24bit(alt_result[15], alt_result[36], alt_result[57], 4, &buflen, &cp); |
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250 | b64_from_24bit(alt_result[37], alt_result[58], alt_result[16], 4, &buflen, &cp); |
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251 | b64_from_24bit(alt_result[59], alt_result[17], alt_result[38], 4, &buflen, &cp); |
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252 | b64_from_24bit(alt_result[18], alt_result[39], alt_result[60], 4, &buflen, &cp); |
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253 | b64_from_24bit(alt_result[40], alt_result[61], alt_result[19], 4, &buflen, &cp); |
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254 | b64_from_24bit(alt_result[62], alt_result[20], alt_result[41], 4, &buflen, &cp); |
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255 | b64_from_24bit(0, 0, alt_result[63], 2, &buflen, &cp); |
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256 | |
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257 | if (buflen <= 0) { |
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258 | errno = ERANGE; |
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259 | buffer = NULL; |
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260 | } |
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261 | else |
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262 | *cp = '\0'; /* Terminate the string. */ |
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263 | |
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264 | /* Clear the buffer for the intermediate result so that people |
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265 | * attaching to processes or reading core dumps cannot get any |
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266 | * information. We do it in this way to clear correct_words[] inside |
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267 | * the SHA512 implementation as well. */ |
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268 | SHA512_Init(&ctx); |
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269 | SHA512_Final(alt_result, &ctx); |
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270 | memset(temp_result, '\0', sizeof(temp_result)); |
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271 | memset(p_bytes, '\0', key_len); |
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272 | memset(s_bytes, '\0', salt_len); |
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273 | memset(&ctx, '\0', sizeof(ctx)); |
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274 | memset(&alt_ctx, '\0', sizeof(alt_ctx)); |
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275 | if (copied_key != NULL) |
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276 | memset(copied_key, '\0', key_len); |
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277 | if (copied_salt != NULL) |
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278 | memset(copied_salt, '\0', salt_len); |
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279 | |
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280 | return buffer; |
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281 | } |
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282 | |
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283 | struct crypt_format crypt_sha512_format = |
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284 | CRYPT_FORMAT_INITIALIZER(crypt_sha512_r, "$6$"); |
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