path: root/src/libzrtpcpp/crypto/openssl/ZrtpDH.cpp

/*
  Copyright (C) 2006, 2009 by Werner Dittmann

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA

 * In addition, as a special exception, the copyright holders give
 * permission to link the code of portions of this program with the
 * OpenSSL library under certain conditions as described in each
 * individual source file, and distribute linked combinations
 * including the two.
 * You must obey the GNU General Public License in all respects
 * for all of the code used other than OpenSSL.  If you modify
 * file(s) with this exception, you may extend this exception to your
 * version of the file(s), but you are not obligated to do so.  If you
 * do not wish to do so, delete this exception statement from your
 * version.  If you delete this exception statement from all source
 * files in the program, then also delete it here.
 */

/** Copyright (C) 2006, 2009
 *
 * @author  Werner Dittmann <Werner.Dittmann@t-online.de>
 */

#include <string.h>

#include <openssl/crypto.h>
#include <openssl/bio.h>
#include <openssl/bn.h>
#include <openssl/rand.h>
#include <openssl/err.h>
#include <openssl/dh.h>
#include <openssl/evp.h>
#include <openssl/ec.h>
#include <openssl/ecdh.h>

#include <libzrtpcpp/crypto/ZrtpDH.h>
#include <libzrtpcpp/ZrtpTextData.h>

// extern void initializeOpenSSL();

static BIGNUM* bnP2048 = NULL;
static BIGNUM* bnP3072 = NULL;
// static BIGNUM* bnP4096 = NULL;

static BIGNUM* bnP2048MinusOne = NULL;
static BIGNUM* bnP3072MinusOne = NULL;
// static BIGNUM* bnP4096MinusOne = NULL;

static uint8_t dhinit = 0;

void randomZRTP(uint8_t *buf, int32_t length)
{
//    initializeOpenSSL();
    RAND_bytes(buf, length);
}

static const uint8_t P2048[] =
{
    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
    0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
    0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
    0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
    0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
    0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
    0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
    0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
    0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
    0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE4, 0x5B, 0x3D,
    0xC2, 0x00, 0x7C, 0xB8, 0xA1, 0x63, 0xBF, 0x05, 0x98, 0xDA, 0x48, 0x36,
    0x1C, 0x55, 0xD3, 0x9A, 0x69, 0x16, 0x3F, 0xA8, 0xFD, 0x24, 0xCF, 0x5F,
    0x83, 0x65, 0x5D, 0x23, 0xDC, 0xA3, 0xAD, 0x96, 0x1C, 0x62, 0xF3, 0x56,
    0x20, 0x85, 0x52, 0xBB, 0x9E, 0xD5, 0x29, 0x07, 0x70, 0x96, 0x96, 0x6D,
    0x67, 0x0C, 0x35, 0x4E, 0x4A, 0xBC, 0x98, 0x04, 0xF1, 0x74, 0x6C, 0x08,
    0xCA, 0x18, 0x21, 0x7C, 0x32, 0x90, 0x5E, 0x46, 0x2E, 0x36, 0xCE, 0x3B,
    0xE3, 0x9E, 0x77, 0x2C, 0x18, 0x0E, 0x86, 0x03, 0x9B, 0x27, 0x83, 0xA2,
    0xEC, 0x07, 0xA2, 0x8F, 0xB5, 0xC5, 0x5D, 0xF0, 0x6F, 0x4C, 0x52, 0xC9,
    0xDE, 0x2B, 0xCB, 0xF6, 0x95, 0x58, 0x17, 0x18, 0x39, 0x95, 0x49, 0x7C,
    0xEA, 0x95, 0x6A, 0xE5, 0x15, 0xD2, 0x26, 0x18, 0x98, 0xFA, 0x05, 0x10,
    0x15, 0x72, 0x8E, 0x5A, 0x8A, 0xAC, 0xAA, 0x68, 0xFF, 0xFF, 0xFF, 0xFF,
    0xFF, 0xFF, 0xFF, 0xFF
};

static const uint8_t P3072[] =
{
    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
    0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
    0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
    0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
    0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
    0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
    0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
    0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
    0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
    0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE4, 0x5B, 0x3D,
    0xC2, 0x00, 0x7C, 0xB8, 0xA1, 0x63, 0xBF, 0x05, 0x98, 0xDA, 0x48, 0x36,
    0x1C, 0x55, 0xD3, 0x9A, 0x69, 0x16, 0x3F, 0xA8, 0xFD, 0x24, 0xCF, 0x5F,
    0x83, 0x65, 0x5D, 0x23, 0xDC, 0xA3, 0xAD, 0x96, 0x1C, 0x62, 0xF3, 0x56,
    0x20, 0x85, 0x52, 0xBB, 0x9E, 0xD5, 0x29, 0x07, 0x70, 0x96, 0x96, 0x6D,
    0x67, 0x0C, 0x35, 0x4E, 0x4A, 0xBC, 0x98, 0x04, 0xF1, 0x74, 0x6C, 0x08,
    0xCA, 0x18, 0x21, 0x7C, 0x32, 0x90, 0x5E, 0x46, 0x2E, 0x36, 0xCE, 0x3B,
    0xE3, 0x9E, 0x77, 0x2C, 0x18, 0x0E, 0x86, 0x03, 0x9B, 0x27, 0x83, 0xA2,
    0xEC, 0x07, 0xA2, 0x8F, 0xB5, 0xC5, 0x5D, 0xF0, 0x6F, 0x4C, 0x52, 0xC9,
    0xDE, 0x2B, 0xCB, 0xF6, 0x95, 0x58, 0x17, 0x18, 0x39, 0x95, 0x49, 0x7C,
    0xEA, 0x95, 0x6A, 0xE5, 0x15, 0xD2, 0x26, 0x18, 0x98, 0xFA, 0x05, 0x10,
    0x15, 0x72, 0x8E, 0x5A, 0x8A, 0xAA, 0xC4, 0x2D, 0xAD, 0x33, 0x17, 0x0D,
    0x04, 0x50, 0x7A, 0x33, 0xA8, 0x55, 0x21, 0xAB, 0xDF, 0x1C, 0xBA, 0x64,
    0xEC, 0xFB, 0x85, 0x04, 0x58, 0xDB, 0xEF, 0x0A, 0x8A, 0xEA, 0x71, 0x57,
    0x5D, 0x06, 0x0C, 0x7D, 0xB3, 0x97, 0x0F, 0x85, 0xA6, 0xE1, 0xE4, 0xC7,
    0xAB, 0xF5, 0xAE, 0x8C, 0xDB, 0x09, 0x33, 0xD7, 0x1E, 0x8C, 0x94, 0xE0,
    0x4A, 0x25, 0x61, 0x9D, 0xCE, 0xE3, 0xD2, 0x26, 0x1A, 0xD2, 0xEE, 0x6B,
    0xF1, 0x2F, 0xFA, 0x06, 0xD9, 0x8A, 0x08, 0x64, 0xD8, 0x76, 0x02, 0x73,
    0x3E, 0xC8, 0x6A, 0x64, 0x52, 0x1F, 0x2B, 0x18, 0x17, 0x7B, 0x20, 0x0C,
    0xBB, 0xE1, 0x17, 0x57, 0x7A, 0x61, 0x5D, 0x6C, 0x77, 0x09, 0x88, 0xC0,
    0xBA, 0xD9, 0x46, 0xE2, 0x08, 0xE2, 0x4F, 0xA0, 0x74, 0xE5, 0xAB, 0x31,
    0x43, 0xDB, 0x5B, 0xFC, 0xE0, 0xFD, 0x10, 0x8E, 0x4B, 0x82, 0xD1, 0x20,
    0xA9, 0x3A, 0xD2, 0xCA, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
};

/* **************
static const uint8_t P4096[] =
{
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE4, 0x5B, 0x3D,
0xC2, 0x00, 0x7C, 0xB8, 0xA1, 0x63, 0xBF, 0x05, 0x98, 0xDA, 0x48, 0x36,
0x1C, 0x55, 0xD3, 0x9A, 0x69, 0x16, 0x3F, 0xA8, 0xFD, 0x24, 0xCF, 0x5F,
0x83, 0x65, 0x5D, 0x23, 0xDC, 0xA3, 0xAD, 0x96, 0x1C, 0x62, 0xF3, 0x56,
0x20, 0x85, 0x52, 0xBB, 0x9E, 0xD5, 0x29, 0x07, 0x70, 0x96, 0x96, 0x6D,
0x67, 0x0C, 0x35, 0x4E, 0x4A, 0xBC, 0x98, 0x04, 0xF1, 0x74, 0x6C, 0x08,
0xCA, 0x18, 0x21, 0x7C, 0x32, 0x90, 0x5E, 0x46, 0x2E, 0x36, 0xCE, 0x3B,
0xE3, 0x9E, 0x77, 0x2C, 0x18, 0x0E, 0x86, 0x03, 0x9B, 0x27, 0x83, 0xA2,
0xEC, 0x07, 0xA2, 0x8F, 0xB5, 0xC5, 0x5D, 0xF0, 0x6F, 0x4C, 0x52, 0xC9,
0xDE, 0x2B, 0xCB, 0xF6, 0x95, 0x58, 0x17, 0x18, 0x39, 0x95, 0x49, 0x7C,
0xEA, 0x95, 0x6A, 0xE5, 0x15, 0xD2, 0x26, 0x18, 0x98, 0xFA, 0x05, 0x10,
0x15, 0x72, 0x8E, 0x5A, 0x8A, 0xAA, 0xC4, 0x2D, 0xAD, 0x33, 0x17, 0x0D,
0x04, 0x50, 0x7A, 0x33, 0xA8, 0x55, 0x21, 0xAB, 0xDF, 0x1C, 0xBA, 0x64,
0xEC, 0xFB, 0x85, 0x04, 0x58, 0xDB, 0xEF, 0x0A, 0x8A, 0xEA, 0x71, 0x57,
0x5D, 0x06, 0x0C, 0x7D, 0xB3, 0x97, 0x0F, 0x85, 0xA6, 0xE1, 0xE4, 0xC7,
0xAB, 0xF5, 0xAE, 0x8C, 0xDB, 0x09, 0x33, 0xD7, 0x1E, 0x8C, 0x94, 0xE0,
0x4A, 0x25, 0x61, 0x9D, 0xCE, 0xE3, 0xD2, 0x26, 0x1A, 0xD2, 0xEE, 0x6B,
0xF1, 0x2F, 0xFA, 0x06, 0xD9, 0x8A, 0x08, 0x64, 0xD8, 0x76, 0x02, 0x73,
0x3E, 0xC8, 0x6A, 0x64, 0x52, 0x1F, 0x2B, 0x18, 0x17, 0x7B, 0x20, 0x0C,
0xBB, 0xE1, 0x17, 0x57, 0x7A, 0x61, 0x5D, 0x6C, 0x77, 0x09, 0x88, 0xC0,
0xBA, 0xD9, 0x46, 0xE2, 0x08, 0xE2, 0x4F, 0xA0, 0x74, 0xE5, 0xAB, 0x31,
0x43, 0xDB, 0x5B, 0xFC, 0xE0, 0xFD, 0x10, 0x8E, 0x4B, 0x82, 0xD1, 0x20,
0xA9, 0x21, 0x08, 0x01, 0x1A, 0x72, 0x3C, 0x12, 0xA7, 0x87, 0xE6, 0xD7,
0x88, 0x71, 0x9A, 0x10, 0xBD, 0xBA, 0x5B, 0x26, 0x99, 0xC3, 0x27, 0x18,
0x6A, 0xF4, 0xE2, 0x3C, 0x1A, 0x94, 0x68, 0x34, 0xB6, 0x15, 0x0B, 0xDA,
0x25, 0x83, 0xE9, 0xCA, 0x2A, 0xD4, 0x4C, 0xE8, 0xDB, 0xBB, 0xC2, 0xDB,
0x04, 0xDE, 0x8E, 0xF9, 0x2E, 0x8E, 0xFC, 0x14, 0x1F, 0xBE, 0xCA, 0xA6,
0x28, 0x7C, 0x59, 0x47, 0x4E, 0x6B, 0xC0, 0x5D, 0x99, 0xB2, 0x96, 0x4F,
0xA0, 0x90, 0xC3, 0xA2, 0x23, 0x3B, 0xA1, 0x86, 0x51, 0x5B, 0xE7, 0xED,
0x1F, 0x61, 0x29, 0x70, 0xCE, 0xE2, 0xD7, 0xAF, 0xB8, 0x1B, 0xDD, 0x76,
0x21, 0x70, 0x48, 0x1C, 0xD0, 0x06, 0x91, 0x27, 0xD5, 0xB0, 0x5A, 0xA9,
0x93, 0xB4, 0xEA, 0x98, 0x8D, 0x8F, 0xDD, 0xC1, 0x86, 0xFF, 0xB7, 0xDC,
0x90, 0xA6, 0xC0, 0x8F, 0x4D, 0xF4, 0x35, 0xC9, 0x34, 0x06, 0x31, 0x99,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
};
*************** */

ZrtpDH::ZrtpDH(const char* type) {

    uint8_t random[64];

    // Well - the algo type is only 4 char thus cast to int32 and compare
    if (*(int32_t*)type == *(int32_t*)dh2k) {
        pkType = DH2K;
    }
    else if (*(int32_t*)type == *(int32_t*)dh3k) {
        pkType = DH3K;
    }
    else if (*(int32_t*)type == *(int32_t*)ec25) {
        pkType = EC25;
    }
    else if (*(int32_t*)type == *(int32_t*)ec38) {
        pkType = EC38;
    }
    else {
        return;
    }

//  initializeOpenSSL();

    if (!dhinit) {
        bnP2048 = BN_bin2bn(P2048,sizeof(P2048),NULL);
        bnP3072 = BN_bin2bn(P3072,sizeof(P3072),NULL);
//      bnP4096 = BN_bin2bn(P4096,sizeof(P4096),NULL);

        bnP2048MinusOne = BN_dup(bnP2048);
        BN_sub_word(bnP2048MinusOne, 1);

        bnP3072MinusOne = BN_dup(bnP3072);
        BN_sub_word(bnP3072MinusOne, 1);

//      bnP4096MinusOne = BN_dup(bnP4096);
//      BN_sub_word(bnP4096MinusOne, 1);
        dhinit = 1;
    }

    DH* tmpCtx = NULL;
    switch (pkType) {
    case DH2K:
    case DH3K:
        ctx = static_cast<void*>(DH_new());
        tmpCtx = static_cast<DH*>(ctx);
        tmpCtx->g = BN_new();
        BN_set_word(tmpCtx->g, DH_GENERATOR_2);

        if (pkType == DH2K) {
            tmpCtx->p = BN_dup(bnP2048);
            RAND_bytes(random, 32);
            tmpCtx->priv_key = BN_bin2bn(random, 32, NULL);
        }
        else if (pkType == DH3K) {
            tmpCtx->p = BN_dup(bnP3072);
            RAND_bytes(random, 64);
            tmpCtx->priv_key = BN_bin2bn(random, 32, NULL);
        }
        break;

    case EC25:
        ctx = static_cast<void*>(EC_KEY_new_by_curve_name(NID_X9_62_prime256v1));
        break;
    case EC38:
        ctx = static_cast<void*>(EC_KEY_new_by_curve_name(NID_secp384r1));
        break;
    }
}

ZrtpDH::~ZrtpDH() {
    if (ctx == NULL)
        return;

    switch (pkType) {
    case DH2K:
    case DH3K:
        DH_free(static_cast<DH*>(ctx));
        break;

    case EC25:
    case EC38:
        EC_KEY_free(static_cast<EC_KEY*>(ctx));
        break;
    }
}

int32_t ZrtpDH::computeSecretKey(uint8_t *pubKeyBytes, uint8_t *secret) {

    if (pkType == DH2K || pkType == DH3K) {
        DH* tmpCtx = static_cast<DH*>(ctx);

        if (tmpCtx->pub_key != NULL) {
            BN_free(tmpCtx->pub_key);
        }
        tmpCtx->pub_key = BN_bin2bn(pubKeyBytes, getDhSize(), NULL);
        return DH_compute_key(secret, tmpCtx->pub_key, tmpCtx);
    }
    if (pkType == EC25 || pkType == EC38) {
        uint8_t buffer[100];
        int32_t ret;
        int32_t len = getPubKeySize();

        buffer[0] = POINT_CONVERSION_UNCOMPRESSED;
        memcpy(buffer+1, pubKeyBytes, len);
        
        EC_POINT* point = EC_POINT_new(EC_KEY_get0_group(static_cast<EC_KEY*>(ctx)));
        EC_POINT_oct2point(EC_KEY_get0_group(static_cast<EC_KEY*>(ctx)),
                                             point, buffer, len+1, NULL);
        ret = ECDH_compute_key(secret, getDhSize(), point, static_cast<EC_KEY*>(ctx), NULL);
        EC_POINT_free(point);
        return ret;
    }
    return -1;
}

int32_t ZrtpDH::generatePublicKey()
{
    if (pkType == DH2K || pkType == DH3K)
        return DH_generate_key(static_cast<DH*>(ctx));

    if (pkType == EC25 || pkType == EC38)
        return EC_KEY_generate_key(static_cast<EC_KEY*>(ctx));
    return 0;
}

int32_t ZrtpDH::getDhSize() const
{
    if (pkType == DH2K || pkType == DH3K)
        return DH_size(static_cast<DH*>(ctx));

    if (pkType == EC25)
        return 32;
    if (pkType == EC38)
        return 48;

    return 0;
}

int32_t ZrtpDH::getPubKeySize() const
{
    if (pkType == DH2K || pkType == DH3K)
        return BN_num_bytes(static_cast<DH*>(ctx)->pub_key);

    if (pkType == EC25 || pkType == EC38)
        return EC_POINT_point2oct(EC_KEY_get0_group(static_cast<EC_KEY*>(ctx)),
                                  EC_KEY_get0_public_key(static_cast<EC_KEY*>(ctx)),
                                  POINT_CONVERSION_UNCOMPRESSED, NULL, 0, NULL) - 1;
    return 0;

}

int32_t ZrtpDH::getPubKeyBytes(uint8_t *buf) const
{

    if (pkType == DH2K || pkType == DH3K) {
        // get len of pub_key, prepend with zeros to DH size
        int32_t prepend = getDhSize() - getPubKeySize();
        if (prepend > 0) {
            memset(buf, 0, prepend);
        }
        return BN_bn2bin(static_cast<DH*>(ctx)->pub_key, buf + prepend);
    }
    if (pkType == EC25 || pkType == EC38) {
        uint8_t buffer[100];

        int len = EC_POINT_point2oct(EC_KEY_get0_group(static_cast<EC_KEY*>(ctx)),
                                     EC_KEY_get0_public_key(static_cast<EC_KEY*>(ctx)),
                                     POINT_CONVERSION_UNCOMPRESSED, buffer, 100, NULL);
        memcpy(buf, buffer+1, len-1);
        return len-1;
    }
    return 0;
}

int32_t ZrtpDH::checkPubKey(uint8_t *pubKeyBytes) const
{
    if (pkType == EC25 || pkType == EC38) {
        uint8_t buffer[100];
        int32_t ret;
        int32_t len = getPubKeySize();

        buffer[0] = POINT_CONVERSION_UNCOMPRESSED;
        memcpy(buffer+1, pubKeyBytes, len);

        EC_POINT* point = EC_POINT_new(EC_KEY_get0_group(static_cast<EC_KEY*>(ctx)));
        EC_POINT_oct2point(EC_KEY_get0_group(static_cast<EC_KEY*>(ctx)),
                                             point, buffer, len+1, NULL);
        EC_KEY* chkKey = EC_KEY_new();
        EC_KEY_set_group(chkKey, EC_KEY_get0_group(static_cast<EC_KEY*>(ctx)));
        EC_KEY_set_public_key(chkKey, point);
        ret = EC_KEY_check_key(chkKey);

        EC_POINT_free(point);
        EC_KEY_free(chkKey);
        
        return ret;
    }

    BIGNUM* pubKeyOther = BN_bin2bn(pubKeyBytes, getDhSize(), NULL);

    if (pkType == DH2K) {
        if (BN_cmp(bnP2048MinusOne, pubKeyOther) == 0)
            return 0;
    }
    else if (pkType == DH3K) {
        if (BN_cmp(bnP3072MinusOne, pubKeyOther) == 0)
            return 0;
    }
    else {
//        if (BN_cmp(bnP4096MinusOne, pubKeyOther) == 0)
        return 0;
    }
    int one = BN_is_one(pubKeyOther);
    if (one == 1)
        return 0;

    BN_free(pubKeyOther);
    return 1;
}

const char* ZrtpDH::getDHtype()
{
    switch (pkType) {
    case DH2K:
        return dh2k;
        break;
    case DH3K:
        return dh3k;
        break;
    case EC25:
        return ec25;
        break;
    case EC38:
        return ec38;
        break;
    }
    return NULL;
}

/** EMACS **
 * Local variables:
 * mode: c++
 * c-default-style: ellemtel
 * c-basic-offset: 4
 * End:
 */