| /* 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.org |
| */ |
| #include "tomcrypt.h" |
| |
| /** |
| @file der_length_bit_string.c |
| ASN.1 DER, get length of BIT STRING, Tom St Denis |
| */ |
| |
| #ifdef LTC_DER |
| /** |
| Gets length of DER encoding of BIT STRING |
| @param nbits The number of bits in the string to encode |
| @param outlen [out] The length of the DER encoding for the given string |
| @return CRYPT_OK if successful |
| */ |
| int der_length_bit_string(unsigned long nbits, unsigned long *outlen) |
| { |
| unsigned long nbytes; |
| LTC_ARGCHK(outlen != NULL); |
| |
| /* get the number of the bytes */ |
| nbytes = (nbits >> 3) + ((nbits & 7) ? 1 : 0) + 1; |
| |
| if (nbytes < 128) { |
| /* 03 LL PP DD DD DD ... */ |
| *outlen = 2 + nbytes; |
| } else if (nbytes < 256) { |
| /* 03 81 LL PP DD DD DD ... */ |
| *outlen = 3 + nbytes; |
| } else if (nbytes < 65536) { |
| /* 03 82 LL LL PP DD DD DD ... */ |
| *outlen = 4 + nbytes; |
| } else { |
| return CRYPT_INVALID_ARG; |
| } |
| |
| return CRYPT_OK; |
| } |
| |
| #endif |
| |
| |
| /* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/bit/der_length_bit_string.c,v $ */ |
| /* $Revision: 1.1 $ */ |
| /* $Date: 2005/05/16 15:08:11 $ */ |