gost2001_keyx.c

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/**********************************************************************
 *                          gost_keyx.c                               *
 *             Copyright (c) 2005-2006 Cryptocom LTD                  *
 *         This file is distributed under the same license as OpenSSL *
 *                                                                    *
 *   VK0 34.10-2001 key exchange and GOST R 34.10-2001                *
 *   based PKCS7/SMIME support                                        *
 *          Requires OpenSSL 0.9.9 for compilation                    *
 **********************************************************************/
#include <openssl/evp.h>
#include <openssl/rand.h>
#include <string.h>
#include <openssl/objects.h>
#include "gost89.h"
#include "gosthash.h"
#include "e_gost_err.h"
#include "gost_keywrap.h"
#include "gost_lcl.h"
#include "gost2001_keyx.h"



/* Implementation of CryptoPro VKO 34.10-2001 algorithm */
static int VKO_compute_key(unsigned char *shared_key,size_t shared_key_size,const EC_POINT *pub_key,EC_KEY *priv_key,const unsigned char *ukm)
    {
    unsigned char ukm_be[8],databuf[64],hashbuf[64];
    BIGNUM *UKM=NULL,*p=NULL,*order=NULL,*X=NULL,*Y=NULL;
    const BIGNUM* key=EC_KEY_get0_private_key(priv_key);
    EC_POINT *pnt=EC_POINT_new(EC_KEY_get0_group(priv_key));
    int i;
    gost_hash_ctx hash_ctx;
    BN_CTX *ctx = BN_CTX_new();

    for (i=0;i<8;i++)
        {
        ukm_be[7-i]=ukm[i];
        }
    BN_CTX_start(ctx);
    UKM=getbnfrombuf(ukm_be,8);
    p=BN_CTX_get(ctx);
    order = BN_CTX_get(ctx);
    X=BN_CTX_get(ctx);
    Y=BN_CTX_get(ctx);
    EC_GROUP_get_order(EC_KEY_get0_group(priv_key),order,ctx);
    BN_mod_mul(p,key,UKM,order,ctx);    
    EC_POINT_mul(EC_KEY_get0_group(priv_key),pnt,NULL,pub_key,p,ctx);
    EC_POINT_get_affine_coordinates_GFp(EC_KEY_get0_group(priv_key),
        pnt,X,Y,ctx);
    /*Serialize elliptic curve point same way as we do it when saving
     * key */
    store_bignum(Y,databuf,32);
    store_bignum(X,databuf+32,32);
    /* And reverse byte order of whole buffer */
    for (i=0;i<64;i++)
        {
        hashbuf[63-i]=databuf[i];
        }
    init_gost_hash_ctx(&hash_ctx,&GostR3411_94_CryptoProParamSet);
    start_hash(&hash_ctx);
    hash_block(&hash_ctx,hashbuf,64);
    finish_hash(&hash_ctx,shared_key);
    done_gost_hash_ctx(&hash_ctx);
    BN_free(UKM);
    BN_CTX_end(ctx);
    BN_CTX_free(ctx);
    EC_POINT_free(pnt);
    return 32;
    }


/*
 * EVP_PKEY_METHOD callback derive. Implements VKO R 34.10-2001
 * algorithm
 */
int pkey_gost2001_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
{
    /* Public key of peer in the ctx field peerkey
     * Our private key in the ctx pkey
     * ukm is in the algorithm specific context data
     */
    EVP_PKEY *my_key = EVP_PKEY_CTX_get0_pkey(ctx);
    EVP_PKEY *peer_key = EVP_PKEY_CTX_get0_peerkey(ctx);
    struct gost_pmeth_data *data = EVP_PKEY_CTX_get_data(ctx);
    
    if (!data->shared_ukm) {
        GOSTerr(GOST_F_PKEY_GOST2001_DERIVE, GOST_R_UKM_NOT_SET);
        return 0;
    }   

    if (key == NULL) {
        *keylen = 32;
        return 32;
    }   
    
    *keylen=VKO_compute_key(key, 32, EC_KEY_get0_public_key(EVP_PKEY_get0(peer_key)),
        (EC_KEY *)EVP_PKEY_get0(my_key),data->shared_ukm);
    return 1;   
}




/*  
 * EVP_PKEY_METHOD callback encrypt  
 * Implementation of GOST2001 key transport, cryptocom variation 
 */
/* Generates ephemeral key based on pubk algorithm
 * computes shared key using VKO and returns filled up
 * GOST_KEY_TRANSPORT structure
 */

/*  
 * EVP_PKEY_METHOD callback encrypt  
 * Implementation of GOST2001 key transport, cryptopo variation 
 */

int pkey_GOST01cp_encrypt(EVP_PKEY_CTX *pctx, unsigned char *out, size_t *out_len, const unsigned char *key,size_t key_len) 
    {
    GOST_KEY_TRANSPORT *gkt=NULL; 
    EVP_PKEY *pubk = EVP_PKEY_CTX_get0_pkey(pctx);
    struct gost_pmeth_data *data = EVP_PKEY_CTX_get_data(pctx);
    const struct gost_cipher_info *param=get_encryption_params(NULL);
    unsigned char ukm[8], shared_key[32], crypted_key[44];
    int ret=0;
    int key_is_ephemeral=1;
    gost_ctx cctx;
    EVP_PKEY *sec_key=EVP_PKEY_CTX_get0_peerkey(pctx);
    if (data->shared_ukm) 
        {
        memcpy(ukm, data->shared_ukm,8);
        } 
    else if (out) 
        {
        
        if (RAND_bytes(ukm,8)<=0)
            {
            GOSTerr(GOST_F_PKEY_GOST01CP_ENCRYPT,
                GOST_R_RANDOM_GENERATOR_FAILURE);
            return 0;
            }   
        }   
    /* Check for private key in the peer_key of context */  
    if (sec_key) 
        {
        key_is_ephemeral=0;
        if (!gost_get0_priv_key(sec_key)) 
            {
            GOSTerr(GOST_F_PKEY_GOST01CP_ENCRYPT,
            GOST_R_NO_PRIVATE_PART_OF_NON_EPHEMERAL_KEYPAIR);
            goto err;
            }   
        } 
    else 
        {
        key_is_ephemeral=1;
        if (out) 
            {
            sec_key = EVP_PKEY_new();
            EVP_PKEY_assign(sec_key,EVP_PKEY_base_id(pubk),EC_KEY_new());
            EVP_PKEY_copy_parameters(sec_key,pubk);
            if (!gost2001_keygen(EVP_PKEY_get0(sec_key))) 
                {
                goto err;
                }   
            }
        }
    if (!get_gost_engine_param(GOST_PARAM_CRYPT_PARAMS) && param ==  gost_cipher_list)
        {
        param= gost_cipher_list+1;
        }   
    if (out) 
        {
        VKO_compute_key(shared_key,32,EC_KEY_get0_public_key(EVP_PKEY_get0(pubk)),EVP_PKEY_get0(sec_key),ukm);
        gost_init(&cctx,param->sblock); 
        keyWrapCryptoPro(&cctx,shared_key,ukm,key,crypted_key);
        }
    gkt = GOST_KEY_TRANSPORT_new();
    if (!gkt)
        {
        goto err;
        }   
    if(!ASN1_OCTET_STRING_set(gkt->key_agreement_info->eph_iv,
            ukm,8))
        {
        goto err;
        }   
    if (!ASN1_OCTET_STRING_set(gkt->key_info->imit,crypted_key+40,4))
        {
        goto err;
        }
    if (!ASN1_OCTET_STRING_set(gkt->key_info->encrypted_key,crypted_key+8,32))
        {
        goto err;
        }
    if (key_is_ephemeral) { 
        if (!X509_PUBKEY_set(&gkt->key_agreement_info->ephem_key,out?sec_key:pubk))
            {
            GOSTerr(GOST_F_PKEY_GOST01CP_ENCRYPT,
                    GOST_R_CANNOT_PACK_EPHEMERAL_KEY);
            goto err;
            }   
    }       
    ASN1_OBJECT_free(gkt->key_agreement_info->cipher);
    gkt->key_agreement_info->cipher = OBJ_nid2obj(param->nid);
    if (key_is_ephemeral && sec_key) EVP_PKEY_free(sec_key);
    if (!key_is_ephemeral)
        {
        /* Set control "public key from client certificate used" */
        if (EVP_PKEY_CTX_ctrl(pctx, -1, -1, EVP_PKEY_CTRL_PEER_KEY, 3, NULL) <= 0)
            {
            GOSTerr(GOST_F_PKEY_GOST01CP_ENCRYPT,
                GOST_R_CTRL_CALL_FAILED);
            goto err;
            }
        }
    if ((*out_len = i2d_GOST_KEY_TRANSPORT(gkt,out?&out:NULL))>0) ret =1;
    GOST_KEY_TRANSPORT_free(gkt);
    return ret; 
    err:        
    if (key_is_ephemeral && sec_key) EVP_PKEY_free(sec_key);
    GOST_KEY_TRANSPORT_free(gkt);
    return -1;
    }
/*  
 * EVP_PKEY_METHOD callback decrypt  
 * Implementation of GOST2001 key transport, cryptopo variation 
 */
int pkey_GOST01cp_decrypt(EVP_PKEY_CTX *pctx, unsigned char *key, size_t * key_len, const unsigned char *in, size_t in_len)
    {
    const unsigned char *p = in;
    EVP_PKEY *priv = EVP_PKEY_CTX_get0_pkey(pctx);
    GOST_KEY_TRANSPORT *gkt = NULL;
    int ret=0;  
    unsigned char wrappedKey[44];
    unsigned char sharedKey[32];
    gost_ctx ctx;
    const struct gost_cipher_info *param=NULL;
    EVP_PKEY *eph_key=NULL, *peerkey=NULL;

    if (!key)
        {
        *key_len = 32;
        return 1;
        }   
    gkt = d2i_GOST_KEY_TRANSPORT(NULL,(const unsigned char **)&p,
        in_len);
    if (!gkt)
        {
        GOSTerr(GOST_F_PKEY_GOST01CP_DECRYPT,GOST_R_ERROR_PARSING_KEY_TRANSPORT_INFO);
        return -1;
        }   

    /* If key transport structure contains public key, use it */
    eph_key = X509_PUBKEY_get(gkt->key_agreement_info->ephem_key);
    if (eph_key)
        {
        if (EVP_PKEY_derive_set_peer(pctx, eph_key) <= 0)
            {
            GOSTerr(GOST_F_PKEY_GOST01CP_DECRYPT,
                GOST_R_INCOMPATIBLE_PEER_KEY);
            goto err;
            }
        }
    else
        {
        /* Set control "public key from client certificate used" */
        if (EVP_PKEY_CTX_ctrl(pctx, -1, -1, EVP_PKEY_CTRL_PEER_KEY, 3, NULL) <= 0)
            {
            GOSTerr(GOST_F_PKEY_GOST01CP_DECRYPT,
                GOST_R_CTRL_CALL_FAILED);
            goto err;
            }
        }
    peerkey = EVP_PKEY_CTX_get0_peerkey(pctx);
    if (!peerkey)
        {
        GOSTerr(GOST_F_PKEY_GOST01CP_DECRYPT,
            GOST_R_NO_PEER_KEY);
        goto err;
        }
        
    param = get_encryption_params(gkt->key_agreement_info->cipher);
    if(!param){
        goto err;
    }

    gost_init(&ctx,param->sblock);  
    OPENSSL_assert(gkt->key_agreement_info->eph_iv->length==8);
    memcpy(wrappedKey,gkt->key_agreement_info->eph_iv->data,8);
    OPENSSL_assert(gkt->key_info->encrypted_key->length==32);
    memcpy(wrappedKey+8,gkt->key_info->encrypted_key->data,32);
    OPENSSL_assert(gkt->key_info->imit->length==4);
    memcpy(wrappedKey+40,gkt->key_info->imit->data,4);  
    VKO_compute_key(sharedKey,32,EC_KEY_get0_public_key(EVP_PKEY_get0(peerkey)),
        EVP_PKEY_get0(priv),wrappedKey);
    if (!keyUnwrapCryptoPro(&ctx,sharedKey,wrappedKey,key))
        {
        GOSTerr(GOST_F_PKEY_GOST01CP_DECRYPT,
            GOST_R_ERROR_COMPUTING_SHARED_KEY);
        goto err;
        }   
                
    ret=1;
err:    
    if (eph_key) EVP_PKEY_free(eph_key);
    if (gkt) GOST_KEY_TRANSPORT_free(gkt);
    return ret;
    }