Mercurial > dropbear
view libtomcrypt/src/pk/asn1/der/short_integer/der_length_short_integer.c @ 1446:b8764eee6bdb
add --enable-static configure argument. disable conflicting harden flags
author | Matt Johnston <matt@ucc.asn.au> |
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date | Tue, 27 Jun 2017 22:37:46 +0800 |
parents | f849a5ca2efc |
children | 6dba84798cd5 |
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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://libtom.org */ #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 /* $Source$ */ /* $Revision$ */ /* $Date$ */