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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_object_identifier.c |
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15 ASN.1 DER, Decode Object Identifier, 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 Decode OID data and store the array of integers in words |
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21 @param in The OID DER encoded data |
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22 @param inlen The length of the OID data |
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23 @param words [out] The destination of the OID words |
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24 @param outlen [in/out] The number of OID words |
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25 @return CRYPT_OK if successful |
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26 */ |
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27 int der_decode_object_identifier(const unsigned char *in, unsigned long inlen, |
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28 unsigned long *words, unsigned long *outlen) |
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29 { |
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30 unsigned long x, y, t, len; |
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31 |
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32 LTC_ARGCHK(in != NULL); |
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33 LTC_ARGCHK(words != NULL); |
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34 LTC_ARGCHK(outlen != NULL); |
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35 |
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36 /* header is at least 3 bytes */ |
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37 if (inlen < 3) { |
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38 return CRYPT_INVALID_PACKET; |
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39 } |
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40 |
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41 /* must be room for at least two words */ |
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42 if (*outlen < 2) { |
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43 return CRYPT_BUFFER_OVERFLOW; |
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44 } |
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45 |
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46 /* decode the packet header */ |
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47 x = 0; |
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48 if ((in[x++] & 0x1F) != 0x06) { |
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49 return CRYPT_INVALID_PACKET; |
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50 } |
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51 |
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52 /* get the length */ |
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53 if (in[x] < 128) { |
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54 len = in[x++]; |
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55 } else { |
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56 if (in[x] < 0x81 || in[x] > 0x82) { |
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57 return CRYPT_INVALID_PACKET; |
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58 } |
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59 y = in[x++] & 0x7F; |
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60 len = 0; |
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61 while (y--) { |
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62 len = (len << 8) | (unsigned long)in[x++]; |
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63 } |
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64 } |
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65 |
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66 if (len < 1 || (len + x) > inlen) { |
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67 return CRYPT_INVALID_PACKET; |
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68 } |
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69 |
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70 /* decode word1 and word2 */ |
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71 --len; |
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72 t = in[x++]; |
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73 words[0] = t/40; |
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74 words[1] = t%40; |
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75 |
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76 /* decode rest */ |
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77 y = 2; |
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78 t = 0; |
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79 while (len--) { |
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80 t = (t << 7) | (in[x] & 0x7F); |
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81 if (!(in[x++] & 0x80)) { |
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82 /* store t */ |
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83 if (y >= *outlen) { |
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84 return CRYPT_BUFFER_OVERFLOW; |
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85 } |
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86 words[y++] = t; |
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87 t = 0; |
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88 } |
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89 } |
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90 |
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91 *outlen = y; |
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92 return CRYPT_OK; |
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93 } |
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94 |
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95 #endif |
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96 |
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97 /* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/object_identifier/der_decode_object_identifier.c,v $ */ |
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98 /* $Revision: 1.1 $ */ |
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99 /* $Date: 2005/05/16 15:08:11 $ */ |
