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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 #include "tomcrypt.h" |
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12 |
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13 /** |
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14 @file der_decode_utctime.c |
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15 ASN.1 DER, decode a UTCTIME, Tom St Denis |
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16 */ |
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17 |
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18 #ifdef LTC_DER |
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19 |
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20 static int char_to_int(unsigned char x) |
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21 { |
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22 switch (x) { |
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23 case '0': return 0; |
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24 case '1': return 1; |
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25 case '2': return 2; |
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26 case '3': return 3; |
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27 case '4': return 4; |
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28 case '5': return 5; |
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29 case '6': return 6; |
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30 case '7': return 7; |
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31 case '8': return 8; |
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32 case '9': return 9; |
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33 } |
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34 return 100; |
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35 } |
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36 |
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37 #define DECODE_V(y, max) \ |
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38 y = char_to_int(buf[x])*10 + char_to_int(buf[x+1]); \ |
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39 if (y >= max) return CRYPT_INVALID_PACKET; \ |
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40 x += 2; |
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41 |
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42 int der_decode_utctime(const unsigned char *in, unsigned long *inlen, |
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43 ltc_utctime *out) |
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44 { |
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45 unsigned char buf[32]; |
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46 unsigned long x; |
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47 int y; |
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48 |
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49 LTC_ARGCHK(in != NULL); |
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50 LTC_ARGCHK(inlen != NULL); |
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51 LTC_ARGCHK(out != NULL); |
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52 |
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53 /* check header */ |
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54 if (*inlen < 2UL || (in[1] >= sizeof(buf)) || ((in[1] + 2UL) > *inlen)) { |
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55 return CRYPT_INVALID_PACKET; |
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56 } |
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57 |
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58 /* decode the string */ |
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59 for (x = 0; x < in[1]; x++) { |
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60 y = der_ia5_value_decode(in[x+2]); |
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61 if (y == -1) { |
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62 return CRYPT_INVALID_PACKET; |
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63 } |
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64 buf[x] = y; |
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65 } |
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66 *inlen = 2 + x; |
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67 |
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68 |
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69 /* possible encodings are |
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70 YYMMDDhhmmZ |
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71 YYMMDDhhmm+hh'mm' |
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72 YYMMDDhhmm-hh'mm' |
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73 YYMMDDhhmmssZ |
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74 YYMMDDhhmmss+hh'mm' |
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75 YYMMDDhhmmss-hh'mm' |
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76 |
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77 So let's do a trivial decode upto [including] mm |
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78 */ |
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79 |
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80 x = 0; |
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81 DECODE_V(out->YY, 100); |
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82 DECODE_V(out->MM, 13); |
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83 DECODE_V(out->DD, 32); |
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84 DECODE_V(out->hh, 24); |
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85 DECODE_V(out->mm, 60); |
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86 |
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87 /* clear timezone and seconds info */ |
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88 out->off_dir = out->off_hh = out->off_mm = out->ss = 0; |
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89 |
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90 /* now is it Z, +, - or 0-9 */ |
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91 if (buf[x] == 'Z') { |
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92 return CRYPT_OK; |
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93 } else if (buf[x] == '+' || buf[x] == '-') { |
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94 out->off_dir = (buf[x++] == '+') ? 0 : 1; |
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95 DECODE_V(out->off_hh, 24); |
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96 DECODE_V(out->off_mm, 60); |
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97 return CRYPT_OK; |
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98 } |
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99 |
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100 /* decode seconds */ |
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101 DECODE_V(out->ss, 60); |
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102 |
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103 /* now is it Z, +, - */ |
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104 if (buf[x] == 'Z') { |
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105 return CRYPT_OK; |
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106 } else if (buf[x] == '+' || buf[x] == '-') { |
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107 out->off_dir = (buf[x++] == '+') ? 0 : 1; |
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108 DECODE_V(out->off_hh, 24); |
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109 DECODE_V(out->off_mm, 60); |
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110 return CRYPT_OK; |
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111 } else { |
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112 return CRYPT_INVALID_PACKET; |
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113 } |
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114 } |
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115 |
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116 #endif |
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117 |
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118 /* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/utctime/der_decode_utctime.c,v $ */ |
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119 /* $Revision: 1.6 $ */ |
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120 /* $Date: 2005/06/19 12:07:00 $ */ |
