/* 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_bit_string.c  ASN.1 DER, encode a BIT STRING, Tom St Denis*/#ifdef LTC_DER/**  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 (one per char)  @param outlen  [in/out] The number of bits stored  @return CRYPT_OK if successful*/int der_decode_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++) {       out[y] = (in[x] & (1 << (7 - (y & 7)))) ? 1 : 0;       if ((y & 7) == 7) {          ++x;       }   }   /* we done */   *outlen = blen;   return CRYPT_OK;}#endif/* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/bit/der_decode_bit_string.c,v $ *//* $Revision: 1.4 $ *//* $Date: 2006/06/16 21:53:41 $ */