| /* LibTomCrypt, modular cryptographic library -- Tom St Denis |
| * |
| * LibTomCrypt is a library that provides various cryptographic |
| * algorithms in a highly modular and flexible manner. |
| * |
| * The library is free for all purposes without any express |
| * guarantee it works. |
| * |
| * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com |
| */ |
| #include "tomcrypt.h" |
| |
| /** |
| @file der_decode_short_integer.c |
| ASN.1 DER, decode an integer, Tom St Denis |
| */ |
| |
| |
| #ifdef LTC_DER |
| |
| /** |
| Read a short integer |
| @param in The DER encoded data |
| @param inlen Size of data |
| @param num [out] The integer to decode |
| @return CRYPT_OK if successful |
| */ |
| int der_decode_short_integer(const unsigned char *in, unsigned long inlen, unsigned long *num) |
| { |
| unsigned long len, x, y; |
| |
| LTC_ARGCHK(num != NULL); |
| LTC_ARGCHK(in != NULL); |
| |
| /* check length */ |
| if (inlen < 2) { |
| return CRYPT_INVALID_PACKET; |
| } |
| |
| /* check header */ |
| x = 0; |
| if ((in[x++] & 0x1F) != 0x02) { |
| return CRYPT_INVALID_PACKET; |
| } |
| |
| /* get the packet len */ |
| len = in[x++]; |
| |
| if (x + len > inlen) { |
| return CRYPT_INVALID_PACKET; |
| } |
| |
| /* read number */ |
| y = 0; |
| while (len--) { |
| y = (y<<8) | (unsigned long)in[x++]; |
| } |
| *num = y; |
| |
| return CRYPT_OK; |
| |
| } |
| |
| #endif |
| |
| /* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/short_integer/der_decode_short_integer.c,v $ */ |
| /* $Revision: 1.6 $ */ |
| /* $Date: 2006/03/31 14:15:35 $ */ |