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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_octet_string.c |
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15 ASN.1 DER, encode a OCTET STRING, Tom St Denis |
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16 */ |
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17 |
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18 |
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19 #ifdef LTC_DER |
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20 |
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21 /** |
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22 Store a OCTET STRING |
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23 @param in The DER encoded OCTET STRING |
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24 @param inlen The size of the DER OCTET STRING |
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25 @param out [out] The array of octets stored (one per char) |
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26 @param outlen [in/out] The number of octets stored |
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27 @return CRYPT_OK if successful |
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28 */ |
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29 int der_decode_octet_string(const unsigned char *in, unsigned long inlen, |
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30 unsigned char *out, unsigned long *outlen) |
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31 { |
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32 unsigned long x, y, len; |
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33 |
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34 LTC_ARGCHK(in != NULL); |
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35 LTC_ARGCHK(out != NULL); |
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36 LTC_ARGCHK(outlen != NULL); |
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37 |
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38 /* must have header at least */ |
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39 if (inlen < 2) { |
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40 return CRYPT_INVALID_PACKET; |
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41 } |
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42 |
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43 /* check for 0x04 */ |
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44 if ((in[0] & 0x1F) != 0x04) { |
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45 return CRYPT_INVALID_PACKET; |
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46 } |
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47 x = 1; |
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48 |
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49 /* decode the length */ |
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50 if (in[x] & 0x80) { |
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51 /* valid # of bytes in length are 1,2,3 */ |
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52 y = in[x] & 0x7F; |
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53 if ((y == 0) || (y > 3) || ((x + y) > inlen)) { |
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54 return CRYPT_INVALID_PACKET; |
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55 } |
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56 |
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57 /* read the length in */ |
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58 len = 0; |
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59 ++x; |
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60 while (y--) { |
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61 len = (len << 8) | in[x++]; |
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62 } |
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63 } else { |
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64 len = in[x++] & 0x7F; |
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65 } |
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66 |
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67 /* is it too long? */ |
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68 if (len > *outlen) { |
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69 return CRYPT_BUFFER_OVERFLOW; |
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70 } |
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71 |
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72 if (len + x > inlen) { |
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73 return CRYPT_INVALID_PACKET; |
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74 } |
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75 |
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76 /* read the data */ |
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77 for (y = 0; y < len; y++) { |
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78 out[y] = in[x++]; |
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79 } |
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80 |
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81 *outlen = y; |
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82 |
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83 return CRYPT_OK; |
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84 } |
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85 |
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86 #endif |
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87 |
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88 /* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/octet/der_decode_octet_string.c,v $ */ |
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89 /* $Revision: 1.1 $ */ |
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90 /* $Date: 2005/05/16 15:08:11 $ */ |
