view libtomcrypt/src/pk/pkcs1/pkcs_1_i2osp.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.
 */
#include "tomcrypt.h"

/**
  @file pkcs_1_i2osp.c
  Integer to Octet I2OSP, Tom St Denis
*/

#ifdef LTC_PKCS_1

/* always stores the same # of bytes, pads with leading zero bytes
   as required
 */

/**
   PKCS #1 Integer to binary
   @param n             The integer to store
   @param modulus_len   The length of the RSA modulus
   @param out           [out] The destination for the integer
   @return CRYPT_OK if successful
*/
int pkcs_1_i2osp(void *n, unsigned long modulus_len, unsigned char *out)
{
   unsigned long size;

   size = mp_unsigned_bin_size(n);

   if (size > modulus_len) {
      return CRYPT_BUFFER_OVERFLOW;
   }

   /* store it */
   zeromem(out, modulus_len);
   return mp_to_unsigned_bin(n, out+(modulus_len-size));
}

#endif /* LTC_PKCS_1 */


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