Mercurial > dropbear
view libtomcrypt/src/pk/asn1/der/short_integer/der_length_short_integer.c @ 382:0cbe8f6dbf9e
propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f)
to branch 'au.asn.ucc.matt.dropbear' (head 02c413252c90e9de8e03d91e9939dde3029f5c0a)
author | Matt Johnston <matt@ucc.asn.au> |
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date | Thu, 11 Jan 2007 02:41:05 +0000 |
parents | 1b9e69c058d2 |
children | f849a5ca2efc |
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/* 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, [email protected], http://libtomcrypt.com */ #include "tomcrypt.h" /** @file der_length_short_integer.c ASN.1 DER, get length of encoding, Tom St Denis */ #ifdef LTC_DER /** Gets length of DER encoding of num @param num The integer to get the size of @param outlen [out] The length of the DER encoding for the given integer @return CRYPT_OK if successful */ int der_length_short_integer(unsigned long num, unsigned long *outlen) { unsigned long z, y, len; LTC_ARGCHK(outlen != NULL); /* force to 32 bits */ num &= 0xFFFFFFFFUL; /* get the number of bytes */ z = 0; y = num; while (y) { ++z; y >>= 8; } /* handle zero */ if (z == 0) { z = 1; } /* we need a 0x02 to indicate it's INTEGER */ len = 1; /* length byte */ ++len; /* bytes in value */ len += z; /* see if msb is set */ len += (num&(1UL<<((z<<3) - 1))) ? 1 : 0; /* return length */ *outlen = len; return CRYPT_OK; } #endif /* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/short_integer/der_length_short_integer.c,v $ */ /* $Revision: 1.5 $ */ /* $Date: 2006/03/31 14:15:35 $ */