view libtomcrypt/src/encauth/ocb/ocb_ntz.c @ 1638:315fcba6960e

dropbearconvert: keyimport.c: fix BER encoding of secp521r1 keys (#69) keysizes >= 128 octets will be encoded with a 3 byte header which must be accounted by the optional-header Reproduce: master:~/build/dropbear$ ./dropbearkey -t ecdsa -s 521 -f K Generating 521 bit ecdsa key, this may take a while... master:~/build/dropbear$ ./dropbearconvert d o K L Key is a ecdsa-sha2-nistp521 key Wrote key to 'L' master:~/build/dropbear$ openssl ec < L read EC key unable to load Key 139769806448384:error:0D07209B:asn1 encoding routines:ASN1_get_object:too long:crypto/asn1/asn1_lib.c:91:
author Christian Hohnstädt <christian@hohnstaedt.de>
date Wed, 20 Mar 2019 16:42:47 +0100
parents 6dba84798cd5
children
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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.
 */

/**
   @file ocb_ntz.c
   OCB implementation, internal function, by Tom St Denis
*/

#include "tomcrypt.h"

#ifdef LTC_OCB_MODE

/**
   Returns the number of leading zero bits [from lsb up]
   @param x  The 32-bit value to observe
   @return   The number of bits [from the lsb up] that are zero
*/
int ocb_ntz(unsigned long x)
{
   int c;
   x &= 0xFFFFFFFFUL;
   c = 0;
   while ((x & 1) == 0) {
      ++c;
      x >>= 1;
   }
   return c;
}

#endif

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