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annotate libtomcrypt/src/pk/asn1/der/bit/der_decode_raw_bit_string.c @ 1934:83b6a47759a8

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Add m_snprintf() that won't return negative
author Matt Johnston <matt@ucc.asn.au>
date Fri, 01 Apr 2022 12:10:48 +0800
parents 6dba84798cd5
children
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1471
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
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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 #include "tomcrypt.h"
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10
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11 /**
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12 @file der_decode_bit_string.c
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13 ASN.1 DER, encode a BIT STRING, Tom St Denis
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14 */
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15
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16
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17 #ifdef LTC_DER
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18
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19 #define SETBIT(v, n) (v=((unsigned char)(v) | (1U << (unsigned char)(n))))
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20 #define CLRBIT(v, n) (v=((unsigned char)(v) & ~(1U << (unsigned char)(n))))
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21
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22 /**
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23 Store a BIT STRING
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24 @param in The DER encoded BIT STRING
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25 @param inlen The size of the DER BIT STRING
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26 @param out [out] The array of bits stored (8 per char)
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27 @param outlen [in/out] The number of bits stored
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28 @return CRYPT_OK if successful
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29 */
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30 int der_decode_raw_bit_string(const unsigned char *in, unsigned long inlen,
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31 unsigned char *out, unsigned long *outlen)
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32 {
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33 unsigned long dlen, blen, x, y;
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34
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35 LTC_ARGCHK(in != NULL);
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36 LTC_ARGCHK(out != NULL);
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37 LTC_ARGCHK(outlen != NULL);
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38
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39 /* packet must be at least 4 bytes */
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40 if (inlen < 4) {
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41 return CRYPT_INVALID_ARG;
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42 }
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43
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44 /* check for 0x03 */
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45 if ((in[0]&0x1F) != 0x03) {
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46 return CRYPT_INVALID_PACKET;
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47 }
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48
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49 /* offset in the data */
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50 x = 1;
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51
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52 /* get the length of the data */
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53 if (in[x] & 0x80) {
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54 /* long format get number of length bytes */
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55 y = in[x++] & 0x7F;
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56
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57 /* invalid if 0 or > 2 */
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58 if (y == 0 || y > 2) {
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59 return CRYPT_INVALID_PACKET;
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60 }
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61
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62 /* read the data len */
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63 dlen = 0;
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64 while (y--) {
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65 dlen = (dlen << 8) | (unsigned long)in[x++];
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66 }
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67 } else {
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68 /* short format */
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69 dlen = in[x++] & 0x7F;
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70 }
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71
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72 /* is the data len too long or too short? */
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73 if ((dlen == 0) || (dlen + x > inlen)) {
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74 return CRYPT_INVALID_PACKET;
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75 }
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76
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77 /* get padding count */
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78 blen = ((dlen - 1) << 3) - (in[x++] & 7);
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79
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80 /* too many bits? */
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81 if (blen > *outlen) {
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82 *outlen = blen;
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83 return CRYPT_BUFFER_OVERFLOW;
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84 }
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85
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86 /* decode/store the bits */
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87 for (y = 0; y < blen; y++) {
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88 if (in[x] & (1 << (7 - (y & 7)))) {
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89 SETBIT(out[y/8], 7-(y%8));
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90 } else {
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91 CLRBIT(out[y/8], 7-(y%8));
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92 }
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93 if ((y & 7) == 7) {
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94 ++x;
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95 }
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96 }
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97
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98 /* we done */
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99 *outlen = blen;
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100 return CRYPT_OK;
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101 }
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102
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103 #endif
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104
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105 /* ref: $Format:%D$ */
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106 /* git commit: $Format:%H$ */
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107 /* commit time: $Format:%ai$ */