view libtomcrypt/src/pk/dsa/dsa_export.c @ 994:5c5ade336926

Prefer stronger algorithms in algorithm negotiation. Prefer diffie-hellman-group14-sha1 (2048 bit) over diffie-hellman-group1-sha1 (1024 bit). Due to meet-in-the-middle attacks the effective key length of three key 3DES is 112 bits. AES is stronger and faster then 3DES. Prefer to delay the start of compression until after authentication has completed. This avoids exposing compression code to attacks from unauthenticated users. (github pull request #9)
author Fedor Brunner <fedor.brunner@azet.sk>
date Fri, 23 Jan 2015 23:00:25 +0800
parents 0cbe8f6dbf9e
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 dsa_export.c
   DSA implementation, export key, Tom St Denis
*/

#ifdef MDSA

/**
  Export a DSA key to a binary packet
  @param out    [out] Where to store the packet
  @param outlen [in/out] The max size and resulting size of the packet
  @param type   The type of key to export (PK_PRIVATE or PK_PUBLIC)
  @param key    The key to export
  @return CRYPT_OK if successful
*/
int dsa_export(unsigned char *out, unsigned long *outlen, int type, dsa_key *key)
{
   unsigned char flags[1];

   LTC_ARGCHK(out    != NULL);
   LTC_ARGCHK(outlen != NULL);
   LTC_ARGCHK(key    != NULL);

   /* can we store the static header?  */
   if (type == PK_PRIVATE && key->type != PK_PRIVATE) {
      return CRYPT_PK_TYPE_MISMATCH;
   }

   if (type != PK_PUBLIC && type != PK_PRIVATE) {
      return CRYPT_INVALID_ARG;
   }

   flags[0] = (type != PK_PUBLIC) ? 1 : 0;

   if (type == PK_PRIVATE) {
      return der_encode_sequence_multi(out, outlen,
                                 LTC_ASN1_BIT_STRING,   1UL, flags,
                                 LTC_ASN1_INTEGER,      1UL, key->g,
                                 LTC_ASN1_INTEGER,      1UL, key->p,
                                 LTC_ASN1_INTEGER,      1UL, key->q,
                                 LTC_ASN1_INTEGER,      1UL, key->y,
                                 LTC_ASN1_INTEGER,      1UL, key->x,
                                 LTC_ASN1_EOL,          0UL, NULL);
   } else {
      return der_encode_sequence_multi(out, outlen,
                                 LTC_ASN1_BIT_STRING,   1UL, flags,
                                 LTC_ASN1_INTEGER,      1UL, key->g,
                                 LTC_ASN1_INTEGER,      1UL, key->p,
                                 LTC_ASN1_INTEGER,      1UL, key->q,
                                 LTC_ASN1_INTEGER,      1UL, key->y,
                                 LTC_ASN1_EOL,          0UL, NULL);
   }
}

#endif


/* $Source: /cvs/libtom/libtomcrypt/src/pk/dsa/dsa_export.c,v $ */
/* $Revision: 1.8 $ */
/* $Date: 2006/03/31 14:15:35 $ */