Mercurial > dropbear

annotate src/pk/asn1/der/bit/der_decode_bit_string.c @ 390:d8e44bef7917 libtomcrypt-dropbear

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Replace // with /* */
author Matt Johnston <matt@ucc.asn.au>
date Thu, 11 Jan 2007 04:28:09 +0000
parents d5faf4814ddb
children
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rev   line source
280
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
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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.com
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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_bit_string.c
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15 ASN.1 DER, encode a BIT 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 BIT STRING
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23 @param in The DER encoded BIT STRING
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24 @param inlen The size of the DER BIT STRING
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25 @param out [out] The array of bits stored (one per char)
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26 @param outlen [in/out] The number of bits stored
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27 @return CRYPT_OK if successful
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28 */
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29 int der_decode_bit_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 dlen, blen, x, y;
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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 /* packet must be at least 4 bytes */
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39 if (inlen < 4) {
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40 return CRYPT_INVALID_ARG;
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41 }
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42
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43 /* check for 0x03 */
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44 if ((in[0]&0x1F) != 0x03) {
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45 return CRYPT_INVALID_PACKET;
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46 }
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47
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48 /* offset in the data */
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49 x = 1;
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50
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51 /* get the length of the data */
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52 if (in[x] & 0x80) {
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53 /* long format get number of length bytes */
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54 y = in[x++] & 0x7F;
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55
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56 /* invalid if 0 or > 2 */
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57 if (y == 0 || y > 2) {
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58 return CRYPT_INVALID_PACKET;
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59 }
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60
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61 /* read the data len */
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62 dlen = 0;
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63 while (y--) {
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64 dlen = (dlen << 8) | (unsigned long)in[x++];
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65 }
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66 } else {
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67 /* short format */
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68 dlen = in[x++] & 0x7F;
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69 }
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70
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71 /* is the data len too long or too short? */
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72 if ((dlen == 0) || (dlen + 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 /* get padding count */
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77 blen = ((dlen - 1) << 3) - (in[x++] & 7);
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78
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79 /* too many bits? */
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80 if (blen > *outlen) {
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81 *outlen = blen;
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82 return CRYPT_BUFFER_OVERFLOW;
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83 }
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84
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85 /* decode/store the bits */
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86 for (y = 0; y < blen; y++) {
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87 out[y] = (in[x] & (1 << (7 - (y & 7)))) ? 1 : 0;
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88 if ((y & 7) == 7) {
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89 ++x;
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90 }
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91 }
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92
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93 /* we done */
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94 *outlen = blen;
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95 return CRYPT_OK;
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96 }
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97
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98 #endif
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99
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100 /* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/bit/der_decode_bit_string.c,v $ */
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101 /* $Revision: 1.4 $ */
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102 /* $Date: 2006/06/16 21:53:41 $ */