annotate src/pk/asn1/der/short_integer/der_decode_short_integer.c @ 380:d5faf4814ddb libtomcrypt-orig libtomcrypt-1.16

Update to LibTomCrypt 1.16
author Matt Johnston <matt@ucc.asn.au>
date Thu, 11 Jan 2007 02:22:00 +0000
parents 59400faa4b44
children
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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_short_integer.c
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15 ASN.1 DER, decode an integer, 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 Read a short integer
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23 @param in The DER encoded data
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24 @param inlen Size of data
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25 @param num [out] The integer to decode
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26 @return CRYPT_OK if successful
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27 */
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28 int der_decode_short_integer(const unsigned char *in, unsigned long inlen, unsigned long *num)
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29 {
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30 unsigned long len, x, y;
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31
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32 LTC_ARGCHK(num != NULL);
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33 LTC_ARGCHK(in != NULL);
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34
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35 /* check length */
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36 if (inlen < 2) {
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37 return CRYPT_INVALID_PACKET;
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38 }
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39
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40 /* check header */
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41 x = 0;
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42 if ((in[x++] & 0x1F) != 0x02) {
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43 return CRYPT_INVALID_PACKET;
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44 }
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45
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46 /* get the packet len */
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47 len = in[x++];
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48
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49 if (x + len > inlen) {
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50 return CRYPT_INVALID_PACKET;
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51 }
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52
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53 /* read number */
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54 y = 0;
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55 while (len--) {
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56 y = (y<<8) | (unsigned long)in[x++];
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57 }
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58 *num = y;
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59
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60 return CRYPT_OK;
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61
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62 }
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63
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64 #endif
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65
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66 /* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/short_integer/der_decode_short_integer.c,v $ */
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67 /* $Revision: 1.6 $ */
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68 /* $Date: 2006/03/31 14:15:35 $ */