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