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/*
* Copyright (c) 2001-2007, Tom St Denis
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/* 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://libtom.org
*/
#include "tomcrypt.h"
/**
@file der_decode_bit_string.c
ASN.1 DER, encode a BIT STRING, Tom St Denis
*/
#ifdef LTC_DER
#define SETBIT(v, n) (v=((unsigned char)(v) | (1U << (unsigned char)(n))))
/**
Store a BIT STRING
@param in The DER encoded BIT STRING
@param inlen The size of the DER BIT STRING
@param out [out] The array of bits stored (8 per char)
@param outlen [in/out] The number of bits stored
@return CRYPT_OK if successful
*/
int der_decode_raw_bit_string(const unsigned char *in, unsigned long inlen,
unsigned char *out, unsigned long *outlen)
{
unsigned long dlen, blen, x, y;
LTC_ARGCHK(in != NULL);
LTC_ARGCHK(out != NULL);
LTC_ARGCHK(outlen != NULL);
/* packet must be at least 4 bytes */
if (inlen < 4) {
return CRYPT_INVALID_ARG;
}
/* check for 0x03 */
if ((in[0]&0x1F) != 0x03) {
return CRYPT_INVALID_PACKET;
}
/* offset in the data */
x = 1;
/* get the length of the data */
if (in[x] & 0x80) {
/* long format get number of length bytes */
y = in[x++] & 0x7F;
/* invalid if 0 or > 2 */
if (y == 0 || y > 2) {
return CRYPT_INVALID_PACKET;
}
/* read the data len */
dlen = 0;
while (y--) {
dlen = (dlen << 8) | (unsigned long)in[x++];
}
} else {
/* short format */
dlen = in[x++] & 0x7F;
}
/* is the data len too long or too short? */
if ((dlen == 0) || (dlen + x > inlen)) {
return CRYPT_INVALID_PACKET;
}
/* get padding count */
blen = ((dlen - 1) << 3) - (in[x++] & 7);
/* too many bits? */
if (blen > *outlen) {
*outlen = blen;
return CRYPT_BUFFER_OVERFLOW;
}
/* decode/store the bits */
for (y = 0; y < blen; y++) {
if (in[x] & (1 << (7 - (y & 7)))) {
SETBIT(out[y/8], 7-(y%8));
}
if ((y & 7) == 7) {
++x;
}
}
/* we done */
*outlen = blen;
return CRYPT_OK;
}
#endif
/* $Source$ */
/* $Revision$ */
/* $Date$ */
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