374 lines
9.6 KiB
C
374 lines
9.6 KiB
C
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/**********************************************************************
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* gost_sign.c *
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* Copyright (c) 2005-2006 Cryptocom LTD *
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* This file is distributed under the same license as OpenSSL *
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* *
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* Implementation of GOST R 34.10-94 signature algorithm *
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* for OpenSSL *
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* Requires OpenSSL 0.9.9 for compilation *
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**********************************************************************/
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#include <string.h>
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#include <openssl/rand.h>
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#include <openssl/bn.h>
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#include <openssl/dsa.h>
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#include <openssl/evp.h>
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#include <openssl/err.h>
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#include "gost_params.h"
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#include "gost_lcl.h"
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#include "e_gost_err.h"
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#ifdef DEBUG_SIGN
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void dump_signature(const char *message, const unsigned char *buffer,
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size_t len)
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{
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size_t i;
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fprintf(stderr, "signature %s Length=%d", message, len);
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for (i = 0; i < len; i++) {
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if (i % 16 == 0)
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fputc('\n', stderr);
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fprintf(stderr, " %02x", buffer[i]);
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}
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fprintf(stderr, "\nEnd of signature\n");
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}
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void dump_dsa_sig(const char *message, DSA_SIG *sig)
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{
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fprintf(stderr, "%s\nR=", message);
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BN_print_fp(stderr, sig->r);
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fprintf(stderr, "\nS=");
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BN_print_fp(stderr, sig->s);
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fprintf(stderr, "\n");
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}
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#else
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# define dump_signature(a,b,c)
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# define dump_dsa_sig(a,b)
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#endif
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/*
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* Computes signature and returns it as DSA_SIG structure
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*/
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DSA_SIG *gost_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)
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{
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BIGNUM *k = NULL, *tmp = NULL, *tmp2 = NULL;
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DSA_SIG *newsig = NULL, *ret = NULL;
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BIGNUM *md = hashsum2bn(dgst);
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/* check if H(M) mod q is zero */
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BN_CTX *ctx = BN_CTX_new();
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if(!ctx) {
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GOSTerr(GOST_F_GOST_DO_SIGN, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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BN_CTX_start(ctx);
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newsig = DSA_SIG_new();
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if (!newsig) {
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GOSTerr(GOST_F_GOST_DO_SIGN, GOST_R_NO_MEMORY);
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goto err;
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}
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tmp = BN_CTX_get(ctx);
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k = BN_CTX_get(ctx);
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tmp2 = BN_CTX_get(ctx);
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if(!tmp || !k || !tmp2) {
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GOSTerr(GOST_F_GOST_DO_SIGN, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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BN_mod(tmp, md, dsa->q, ctx);
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if (BN_is_zero(tmp)) {
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BN_one(md);
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}
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do {
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do {
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/*
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* Generate random number k less than q
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*/
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BN_rand_range(k, dsa->q);
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/* generate r = (a^x mod p) mod q */
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BN_mod_exp(tmp, dsa->g, k, dsa->p, ctx);
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if (!(newsig->r)) {
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newsig->r = BN_new();
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if(!newsig->r) {
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GOSTerr(GOST_F_GOST_DO_SIGN, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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}
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BN_mod(newsig->r, tmp, dsa->q, ctx);
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}
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while (BN_is_zero(newsig->r));
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/* generate s = (xr + k(Hm)) mod q */
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BN_mod_mul(tmp, dsa->priv_key, newsig->r, dsa->q, ctx);
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BN_mod_mul(tmp2, k, md, dsa->q, ctx);
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if (!newsig->s) {
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newsig->s = BN_new();
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if(!newsig->s) {
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GOSTerr(GOST_F_GOST_DO_SIGN, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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}
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BN_mod_add(newsig->s, tmp, tmp2, dsa->q, ctx);
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}
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while (BN_is_zero(newsig->s));
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ret = newsig;
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err:
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BN_free(md);
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if(ctx) {
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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}
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if(!ret && newsig) {
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DSA_SIG_free(newsig);
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}
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return ret;
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}
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/*
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* Packs signature according to Cryptocom rules
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* and frees up DSA_SIG structure
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*/
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/*-
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int pack_sign_cc(DSA_SIG *s,int order,unsigned char *sig, size_t *siglen)
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{
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*siglen = 2*order;
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memset(sig,0,*siglen);
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store_bignum(s->r, sig,order);
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store_bignum(s->s, sig + order,order);
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dump_signature("serialized",sig,*siglen);
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DSA_SIG_free(s);
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return 1;
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}
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*/
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/*
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* Packs signature according to Cryptopro rules
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* and frees up DSA_SIG structure
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*/
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int pack_sign_cp(DSA_SIG *s, int order, unsigned char *sig, size_t *siglen)
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{
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*siglen = 2 * order;
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memset(sig, 0, *siglen);
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store_bignum(s->s, sig, order);
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store_bignum(s->r, sig + order, order);
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dump_signature("serialized", sig, *siglen);
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DSA_SIG_free(s);
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return 1;
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}
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/*
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* Verifies signature passed as DSA_SIG structure
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*
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*/
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int gost_do_verify(const unsigned char *dgst, int dgst_len,
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DSA_SIG *sig, DSA *dsa)
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{
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BIGNUM *md = NULL, *tmp = NULL;
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BIGNUM *q2 = NULL;
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BIGNUM *u = NULL, *v = NULL, *z1 = NULL, *z2 = NULL;
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BIGNUM *tmp2 = NULL, *tmp3 = NULL;
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int ok = 0;
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BN_CTX *ctx = BN_CTX_new();
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if(!ctx) {
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GOSTerr(GOST_F_GOST_DO_VERIFY, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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BN_CTX_start(ctx);
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if (BN_cmp(sig->s, dsa->q) >= 1 || BN_cmp(sig->r, dsa->q) >= 1) {
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GOSTerr(GOST_F_GOST_DO_VERIFY, GOST_R_SIGNATURE_PARTS_GREATER_THAN_Q);
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goto err;
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}
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md = hashsum2bn(dgst);
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tmp = BN_CTX_get(ctx);
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v = BN_CTX_get(ctx);
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q2 = BN_CTX_get(ctx);
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z1 = BN_CTX_get(ctx);
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z2 = BN_CTX_get(ctx);
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tmp2 = BN_CTX_get(ctx);
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tmp3 = BN_CTX_get(ctx);
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u = BN_CTX_get(ctx);
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if(!tmp || !v || !q2 || !z1 || !z2 || !tmp2 || !tmp3 || !u) {
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GOSTerr(GOST_F_GOST_DO_VERIFY, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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BN_mod(tmp, md, dsa->q, ctx);
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if (BN_is_zero(tmp)) {
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BN_one(md);
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}
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BN_copy(q2, dsa->q);
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BN_sub_word(q2, 2);
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BN_mod_exp(v, md, q2, dsa->q, ctx);
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BN_mod_mul(z1, sig->s, v, dsa->q, ctx);
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BN_sub(tmp, dsa->q, sig->r);
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BN_mod_mul(z2, tmp, v, dsa->p, ctx);
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BN_mod_exp(tmp, dsa->g, z1, dsa->p, ctx);
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BN_mod_exp(tmp2, dsa->pub_key, z2, dsa->p, ctx);
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BN_mod_mul(tmp3, tmp, tmp2, dsa->p, ctx);
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BN_mod(u, tmp3, dsa->q, ctx);
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ok = (BN_cmp(u, sig->r) == 0);
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if (!ok) {
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GOSTerr(GOST_F_GOST_DO_VERIFY, GOST_R_SIGNATURE_MISMATCH);
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}
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err:
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if(md) BN_free(md);
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if(ctx) {
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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}
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return ok;
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}
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/*
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* Computes public keys for GOST R 34.10-94 algorithm
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*
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*/
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int gost94_compute_public(DSA *dsa)
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{
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/* Now fill algorithm parameters with correct values */
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BN_CTX *ctx;
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if (!dsa->g) {
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GOSTerr(GOST_F_GOST94_COMPUTE_PUBLIC, GOST_R_KEY_IS_NOT_INITALIZED);
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return 0;
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}
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ctx = BN_CTX_new();
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if(!ctx) {
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GOSTerr(GOST_F_GOST94_COMPUTE_PUBLIC, ERR_R_MALLOC_FAILURE);
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return 0;
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}
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dsa->pub_key = BN_new();
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if(!dsa->pub_key) {
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GOSTerr(GOST_F_GOST94_COMPUTE_PUBLIC, ERR_R_MALLOC_FAILURE);
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BN_CTX_free(ctx);
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return 0;
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}
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/* Compute public key y = a^x mod p */
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BN_mod_exp(dsa->pub_key, dsa->g, dsa->priv_key, dsa->p, ctx);
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BN_CTX_free(ctx);
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return 1;
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}
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/*
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* Fill GOST 94 params, searching them in R3410_paramset array
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* by nid of paramset
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*
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*/
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int fill_GOST94_params(DSA *dsa, int nid)
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{
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R3410_params *params = R3410_paramset;
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while (params->nid != NID_undef && params->nid != nid)
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params++;
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if (params->nid == NID_undef) {
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GOSTerr(GOST_F_FILL_GOST94_PARAMS, GOST_R_UNSUPPORTED_PARAMETER_SET);
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return 0;
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}
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#define dump_signature(a,b,c)
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if (dsa->p) {
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BN_free(dsa->p);
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}
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dsa->p = NULL;
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BN_dec2bn(&(dsa->p), params->p);
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if (dsa->q) {
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BN_free(dsa->q);
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}
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dsa->q = NULL;
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BN_dec2bn(&(dsa->q), params->q);
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if (dsa->g) {
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BN_free(dsa->g);
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}
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dsa->g = NULL;
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BN_dec2bn(&(dsa->g), params->a);
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return 1;
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}
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/*
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* Generate GOST R 34.10-94 keypair
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*
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*
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*/
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int gost_sign_keygen(DSA *dsa)
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{
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dsa->priv_key = BN_new();
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if(!dsa->priv_key) {
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GOSTerr(GOST_F_GOST_SIGN_KEYGEN, ERR_R_MALLOC_FAILURE);
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return 0;
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}
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BN_rand_range(dsa->priv_key, dsa->q);
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return gost94_compute_public(dsa);
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}
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/* Unpack signature according to cryptocom rules */
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/*-
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DSA_SIG *unpack_cc_signature(const unsigned char *sig,size_t siglen)
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{
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DSA_SIG *s;
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s = DSA_SIG_new();
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if (s == NULL)
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{
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GOSTerr(GOST_F_UNPACK_CC_SIGNATURE,GOST_R_NO_MEMORY);
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return(NULL);
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}
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s->r = getbnfrombuf(sig, siglen/2);
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s->s = getbnfrombuf(sig + siglen/2, siglen/2);
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return s;
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}
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*/
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/* Unpack signature according to cryptopro rules */
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DSA_SIG *unpack_cp_signature(const unsigned char *sig, size_t siglen)
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{
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DSA_SIG *s;
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s = DSA_SIG_new();
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if (s == NULL) {
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GOSTerr(GOST_F_UNPACK_CP_SIGNATURE, GOST_R_NO_MEMORY);
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return NULL;
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}
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s->s = getbnfrombuf(sig, siglen / 2);
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s->r = getbnfrombuf(sig + siglen / 2, siglen / 2);
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return s;
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}
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/* Convert little-endian byte array into bignum */
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BIGNUM *hashsum2bn(const unsigned char *dgst)
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{
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unsigned char buf[32];
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int i;
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for (i = 0; i < 32; i++) {
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buf[31 - i] = dgst[i];
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}
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return getbnfrombuf(buf, 32);
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}
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/* Convert byte buffer to bignum, skipping leading zeros*/
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BIGNUM *getbnfrombuf(const unsigned char *buf, size_t len)
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{
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while (*buf == 0 && len > 0) {
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buf++;
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len--;
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}
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if (len) {
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return BN_bin2bn(buf, len, NULL);
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} else {
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BIGNUM *b = BN_new();
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BN_zero(b);
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return b;
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}
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}
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/*
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* Pack bignum into byte buffer of given size, filling all leading bytes by
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|
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* zeros
|
||
|
|
*/
|
||
|
|
int store_bignum(BIGNUM *bn, unsigned char *buf, int len)
|
||
|
|
{
|
||
|
|
int bytes = BN_num_bytes(bn);
|
||
|
|
if (bytes > len)
|
||
|
|
return 0;
|
||
|
|
memset(buf, 0, len);
|
||
|
|
BN_bn2bin(bn, buf + len - bytes);
|
||
|
|
return 1;
|
||
|
|
}
|