1 /**********************************************************************
3 * Copyright (c) 2005-2006 Cryptocom LTD *
4 * This file is distributed under the same license as OpenSSL *
6 * Implementation of GOST R 34.10-94 signature algoritgthm *
8 * Requires OpenSSL 0.9.9 for compilation *
9 **********************************************************************/
11 #include <openssl/rand.h>
12 #include <openssl/bn.h>
13 #include <openssl/dsa.h>
14 #include <openssl/evp.h>
16 #include "gost_params.h"
18 #include "e_gost_err.h"
21 void dump_signature(const char *message,const unsigned char *buffer,size_t len)
24 fprintf(stderr,"signature %s Length=%d",message,len);
27 if (i% 16 ==0) fputc('\n',stderr);
28 fprintf (stderr," %02x",buffer[i]);
30 fprintf(stderr,"\nEnd of signature\n");
33 void dump_dsa_sig(const char *message, DSA_SIG *sig)
35 fprintf(stderr,"%s\nR=",message);
36 BN_print_fp(stderr,sig->r);
37 fprintf(stderr,"\nS=");
38 BN_print_fp(stderr,sig->s);
44 #define dump_signature(a,b,c)
45 #define dump_dsa_sig(a,b)
49 * Computes signature and returns it as DSA_SIG structure
51 DSA_SIG *gost_do_sign(const unsigned char *dgst,int dlen, DSA *dsa)
53 BIGNUM *k=NULL,*tmp=NULL,*tmp2=NULL;
54 DSA_SIG *newsig = DSA_SIG_new();
55 BIGNUM *md = hashsum2bn(dgst);
56 /* check if H(M) mod q is zero */
57 BN_CTX *ctx=BN_CTX_new();
61 GOSTerr(GOST_F_GOST_DO_SIGN,GOST_R_NO_MEMORY);
66 tmp2 = BN_CTX_get(ctx);
67 BN_mod(tmp,md,dsa->q,ctx);
76 /*Generate random number k less than q*/
77 BN_rand_range(k,dsa->q);
78 /* generate r = (a^x mod p) mod q */
79 BN_mod_exp(tmp,dsa->g, k, dsa->p,ctx);
80 if (!(newsig->r)) newsig->r=BN_new();
81 BN_mod(newsig->r,tmp,dsa->q,ctx);
83 while (BN_is_zero(newsig->r));
84 /* generate s = (xr + k(Hm)) mod q */
85 BN_mod_mul(tmp,dsa->priv_key,newsig->r,dsa->q,ctx);
86 BN_mod_mul(tmp2,k,md,dsa->q,ctx);
87 if (!newsig->s) newsig->s=BN_new();
88 BN_mod_add(newsig->s,tmp,tmp2,dsa->q,ctx);
90 while (BN_is_zero(newsig->s));
100 * Packs signature according to Cryptocom rules
101 * and frees up DSA_SIG structure
104 int pack_sign_cc(DSA_SIG *s,int order,unsigned char *sig, size_t *siglen)
107 memset(sig,0,*siglen);
108 store_bignum(s->r, sig,order);
109 store_bignum(s->s, sig + order,order);
110 dump_signature("serialized",sig,*siglen);
115 * Packs signature according to Cryptopro rules
116 * and frees up DSA_SIG structure
118 int pack_sign_cp(DSA_SIG *s,int order,unsigned char *sig, size_t *siglen)
121 memset(sig,0,*siglen);
122 store_bignum(s->s, sig, order);
123 store_bignum(s->r, sig+order,order);
124 dump_signature("serialized",sig,*siglen);
130 * Verifies signature passed as DSA_SIG structure
134 int gost_do_verify(const unsigned char *dgst, int dgst_len,
135 DSA_SIG *sig, DSA *dsa)
137 BIGNUM *md, *tmp=NULL;
139 BIGNUM *u=NULL,*v=NULL,*z1=NULL,*z2=NULL;
140 BIGNUM *tmp2=NULL,*tmp3=NULL;
142 BN_CTX *ctx = BN_CTX_new();
145 if (BN_cmp(sig->s,dsa->q)>=1||
146 BN_cmp(sig->r,dsa->q)>=1)
148 GOSTerr(GOST_F_GOST_DO_VERIFY,GOST_R_SIGNATURE_PARTS_GREATER_THAN_Q);
158 tmp2=BN_CTX_get(ctx);
159 tmp3=BN_CTX_get(ctx);
162 BN_mod(tmp,md,dsa->q,ctx);
169 BN_mod_exp(v,md,q2,dsa->q,ctx);
170 BN_mod_mul(z1,sig->s,v,dsa->q,ctx);
171 BN_sub(tmp,dsa->q,sig->r);
172 BN_mod_mul(z2,tmp,v,dsa->p,ctx);
173 BN_mod_exp(tmp,dsa->g,z1,dsa->p,ctx);
174 BN_mod_exp(tmp2,dsa->pub_key,z2,dsa->p,ctx);
175 BN_mod_mul(tmp3,tmp,tmp2,dsa->p,ctx);
176 BN_mod(u,tmp3,dsa->q,ctx);
177 ok= BN_cmp(u,sig->r);
184 GOSTerr(GOST_F_GOST_DO_VERIFY,GOST_R_SIGNATURE_MISMATCH);
190 * Computes public keys for GOST R 34.10-94 algorithm
193 int gost94_compute_public(DSA *dsa)
195 /* Now fill algorithm parameters with correct values */
196 BN_CTX *ctx = BN_CTX_new();
199 GOSTerr(GOST_F_GOST_COMPUTE_PUBLIC,GOST_R_KEY_IS_NOT_INITALIZED);
202 /* Compute public key y = a^x mod p */
203 dsa->pub_key=BN_new();
204 BN_mod_exp(dsa->pub_key, dsa->g,dsa->priv_key,dsa->p,ctx);
210 * Fill GOST 94 params, searching them in R3410_paramset array
214 int fill_GOST94_params(DSA *dsa,int nid)
216 R3410_params *params=R3410_paramset;
217 while (params->nid!=NID_undef && params->nid !=nid) params++;
218 if (params->nid == NID_undef)
220 GOSTerr(GOST_F_FILL_GOST94_PARAMS,GOST_R_UNSUPPORTED_PARAMETER_SET);
223 #define dump_signature(a,b,c)
224 if (dsa->p) { BN_free(dsa->p); }
226 BN_dec2bn(&(dsa->p),params->p);
227 if (dsa->q) { BN_free(dsa->q); }
229 BN_dec2bn(&(dsa->q),params->q);
230 if (dsa->g) { BN_free(dsa->g); }
232 BN_dec2bn(&(dsa->g),params->a);
237 * Generate GOST R 34.10-94 keypair
241 int gost_sign_keygen(DSA *dsa)
243 dsa->priv_key = BN_new();
244 BN_rand_range(dsa->priv_key,dsa->q);
245 return gost94_compute_public( dsa);
248 /* Unpack signature according to cryptocom rules */
250 DSA_SIG *unpack_cc_signature(const unsigned char *sig,size_t siglen)
256 GOSTerr(GOST_F_UNPACK_CC_SIGNATURE,GOST_R_NO_MEMORY);
259 s->r = getbnfrombuf(sig, siglen/2);
260 s->s = getbnfrombuf(sig + siglen/2, siglen/2);
264 /* Unpack signature according to cryptopro rules */
265 DSA_SIG *unpack_cp_signature(const unsigned char *sig,size_t siglen)
272 GOSTerr(GOST_F_UNPACK_CP_SIGNATURE,GOST_R_NO_MEMORY);
275 s->s = getbnfrombuf(sig , siglen/2);
276 s->r = getbnfrombuf(sig + siglen/2, siglen/2);
280 /* Convert little-endian byte array into bignum */
281 BIGNUM *hashsum2bn(const unsigned char *dgst)
283 unsigned char buf[32];
289 return getbnfrombuf(buf,32);
292 /* Convert byte buffer to bignum, skipping leading zeros*/
293 BIGNUM *getbnfrombuf(const unsigned char *buf,size_t len)
295 while (*buf==0&&len>0)
301 return BN_bin2bn(buf,len,NULL);
311 /* Pack bignum into byte buffer of given size, filling all leading bytes
313 int store_bignum(BIGNUM *bn, unsigned char *buf,int len)
315 int bytes = BN_num_bytes(bn);
316 if (bytes>len) return 0;
318 BN_bn2bin(bn,buf+len-bytes);