gost_sign.c revision 238405
1/********************************************************************** 2 * gost_sign.c * 3 * Copyright (c) 2005-2006 Cryptocom LTD * 4 * This file is distributed under the same license as OpenSSL * 5 * * 6 * Implementation of GOST R 34.10-94 signature algorithm * 7 * for OpenSSL * 8 * Requires OpenSSL 0.9.9 for compilation * 9 **********************************************************************/ 10#include <string.h> 11#include <openssl/rand.h> 12#include <openssl/bn.h> 13#include <openssl/dsa.h> 14#include <openssl/evp.h> 15 16#include "gost_params.h" 17#include "gost_lcl.h" 18#include "e_gost_err.h" 19 20#ifdef DEBUG_SIGN 21void dump_signature(const char *message,const unsigned char *buffer,size_t len) 22 { 23 size_t i; 24 fprintf(stderr,"signature %s Length=%d",message,len); 25 for (i=0; i<len; i++) 26 { 27 if (i% 16 ==0) fputc('\n',stderr); 28 fprintf (stderr," %02x",buffer[i]); 29 } 30 fprintf(stderr,"\nEnd of signature\n"); 31 } 32 33void dump_dsa_sig(const char *message, DSA_SIG *sig) 34 { 35 fprintf(stderr,"%s\nR=",message); 36 BN_print_fp(stderr,sig->r); 37 fprintf(stderr,"\nS="); 38 BN_print_fp(stderr,sig->s); 39 fprintf(stderr,"\n"); 40 } 41 42#else 43 44#define dump_signature(a,b,c) 45#define dump_dsa_sig(a,b) 46#endif 47 48/* 49 * Computes signature and returns it as DSA_SIG structure 50 */ 51DSA_SIG *gost_do_sign(const unsigned char *dgst,int dlen, DSA *dsa) 52 { 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(); 58 BN_CTX_start(ctx); 59 if (!newsig) 60 { 61 GOSTerr(GOST_F_GOST_DO_SIGN,GOST_R_NO_MEMORY); 62 goto err; 63 } 64 tmp=BN_CTX_get(ctx); 65 k = BN_CTX_get(ctx); 66 tmp2 = BN_CTX_get(ctx); 67 BN_mod(tmp,md,dsa->q,ctx); 68 if (BN_is_zero(tmp)) 69 { 70 BN_one(md); 71 } 72 do 73 { 74 do 75 { 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); 82 } 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); 89 } 90 while (BN_is_zero(newsig->s)); 91 err: 92 BN_free(md); 93 BN_CTX_end(ctx); 94 BN_CTX_free(ctx); 95 return newsig; 96 } 97 98 99/* 100 * Packs signature according to Cryptocom rules 101 * and frees up DSA_SIG structure 102 */ 103/* 104int pack_sign_cc(DSA_SIG *s,int order,unsigned char *sig, size_t *siglen) 105 { 106 *siglen = 2*order; 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); 111 DSA_SIG_free(s); 112 return 1; 113 } 114*/ 115/* 116 * Packs signature according to Cryptopro rules 117 * and frees up DSA_SIG structure 118 */ 119int pack_sign_cp(DSA_SIG *s,int order,unsigned char *sig, size_t *siglen) 120 { 121 *siglen = 2*order; 122 memset(sig,0,*siglen); 123 store_bignum(s->s, sig, order); 124 store_bignum(s->r, sig+order,order); 125 dump_signature("serialized",sig,*siglen); 126 DSA_SIG_free(s); 127 return 1; 128 } 129 130/* 131 * Verifies signature passed as DSA_SIG structure 132 * 133 */ 134 135int gost_do_verify(const unsigned char *dgst, int dgst_len, 136 DSA_SIG *sig, DSA *dsa) 137 { 138 BIGNUM *md, *tmp=NULL; 139 BIGNUM *q2=NULL; 140 BIGNUM *u=NULL,*v=NULL,*z1=NULL,*z2=NULL; 141 BIGNUM *tmp2=NULL,*tmp3=NULL; 142 int ok; 143 BN_CTX *ctx = BN_CTX_new(); 144 145 BN_CTX_start(ctx); 146 if (BN_cmp(sig->s,dsa->q)>=1|| 147 BN_cmp(sig->r,dsa->q)>=1) 148 { 149 GOSTerr(GOST_F_GOST_DO_VERIFY,GOST_R_SIGNATURE_PARTS_GREATER_THAN_Q); 150 return 0; 151 } 152 md=hashsum2bn(dgst); 153 154 tmp=BN_CTX_get(ctx); 155 v=BN_CTX_get(ctx); 156 q2=BN_CTX_get(ctx); 157 z1=BN_CTX_get(ctx); 158 z2=BN_CTX_get(ctx); 159 tmp2=BN_CTX_get(ctx); 160 tmp3=BN_CTX_get(ctx); 161 u = BN_CTX_get(ctx); 162 163 BN_mod(tmp,md,dsa->q,ctx); 164 if (BN_is_zero(tmp)) 165 { 166 BN_one(md); 167 } 168 BN_copy(q2,dsa->q); 169 BN_sub_word(q2,2); 170 BN_mod_exp(v,md,q2,dsa->q,ctx); 171 BN_mod_mul(z1,sig->s,v,dsa->q,ctx); 172 BN_sub(tmp,dsa->q,sig->r); 173 BN_mod_mul(z2,tmp,v,dsa->p,ctx); 174 BN_mod_exp(tmp,dsa->g,z1,dsa->p,ctx); 175 BN_mod_exp(tmp2,dsa->pub_key,z2,dsa->p,ctx); 176 BN_mod_mul(tmp3,tmp,tmp2,dsa->p,ctx); 177 BN_mod(u,tmp3,dsa->q,ctx); 178 ok= BN_cmp(u,sig->r); 179 180 BN_free(md); 181 BN_CTX_end(ctx); 182 BN_CTX_free(ctx); 183 if (ok!=0) 184 { 185 GOSTerr(GOST_F_GOST_DO_VERIFY,GOST_R_SIGNATURE_MISMATCH); 186 } 187 return (ok==0); 188 } 189 190/* 191 * Computes public keys for GOST R 34.10-94 algorithm 192 * 193 */ 194int gost94_compute_public(DSA *dsa) 195 { 196 /* Now fill algorithm parameters with correct values */ 197 BN_CTX *ctx = BN_CTX_new(); 198 if (!dsa->g) 199 { 200 GOSTerr(GOST_F_GOST94_COMPUTE_PUBLIC,GOST_R_KEY_IS_NOT_INITALIZED); 201 return 0; 202 } 203 /* Compute public key y = a^x mod p */ 204 dsa->pub_key=BN_new(); 205 BN_mod_exp(dsa->pub_key, dsa->g,dsa->priv_key,dsa->p,ctx); 206 BN_CTX_free(ctx); 207 return 1; 208 } 209 210/* 211 * Fill GOST 94 params, searching them in R3410_paramset array 212 * by nid of paramset 213 * 214 */ 215int fill_GOST94_params(DSA *dsa,int nid) 216 { 217 R3410_params *params=R3410_paramset; 218 while (params->nid!=NID_undef && params->nid !=nid) params++; 219 if (params->nid == NID_undef) 220 { 221 GOSTerr(GOST_F_FILL_GOST94_PARAMS,GOST_R_UNSUPPORTED_PARAMETER_SET); 222 return 0; 223 } 224#define dump_signature(a,b,c) 225 if (dsa->p) { BN_free(dsa->p); } 226 dsa->p=NULL; 227 BN_dec2bn(&(dsa->p),params->p); 228 if (dsa->q) { BN_free(dsa->q); } 229 dsa->q=NULL; 230 BN_dec2bn(&(dsa->q),params->q); 231 if (dsa->g) { BN_free(dsa->g); } 232 dsa->g=NULL; 233 BN_dec2bn(&(dsa->g),params->a); 234 return 1; 235 } 236 237/* 238 * Generate GOST R 34.10-94 keypair 239 * 240 * 241 */ 242int gost_sign_keygen(DSA *dsa) 243 { 244 dsa->priv_key = BN_new(); 245 BN_rand_range(dsa->priv_key,dsa->q); 246 return gost94_compute_public( dsa); 247 } 248 249/* Unpack signature according to cryptocom rules */ 250/* 251DSA_SIG *unpack_cc_signature(const unsigned char *sig,size_t siglen) 252 { 253 DSA_SIG *s; 254 s = DSA_SIG_new(); 255 if (s == NULL) 256 { 257 GOSTerr(GOST_F_UNPACK_CC_SIGNATURE,GOST_R_NO_MEMORY); 258 return(NULL); 259 } 260 s->r = getbnfrombuf(sig, siglen/2); 261 s->s = getbnfrombuf(sig + siglen/2, siglen/2); 262 return s; 263 } 264*/ 265/* Unpack signature according to cryptopro rules */ 266DSA_SIG *unpack_cp_signature(const unsigned char *sig,size_t siglen) 267 { 268 DSA_SIG *s; 269 270 s = DSA_SIG_new(); 271 if (s == NULL) 272 { 273 GOSTerr(GOST_F_UNPACK_CP_SIGNATURE,GOST_R_NO_MEMORY); 274 return NULL; 275 } 276 s->s = getbnfrombuf(sig , siglen/2); 277 s->r = getbnfrombuf(sig + siglen/2, siglen/2); 278 return s; 279 } 280 281/* Convert little-endian byte array into bignum */ 282BIGNUM *hashsum2bn(const unsigned char *dgst) 283 { 284 unsigned char buf[32]; 285 int i; 286 for (i=0;i<32;i++) 287 { 288 buf[31-i]=dgst[i]; 289 } 290 return getbnfrombuf(buf,32); 291 } 292 293/* Convert byte buffer to bignum, skipping leading zeros*/ 294BIGNUM *getbnfrombuf(const unsigned char *buf,size_t len) 295 { 296 while (*buf==0&&len>0) 297 { 298 buf++; len--; 299 } 300 if (len) 301 { 302 return BN_bin2bn(buf,len,NULL); 303 } 304 else 305 { 306 BIGNUM *b=BN_new(); 307 BN_zero(b); 308 return b; 309 } 310 } 311 312/* Pack bignum into byte buffer of given size, filling all leading bytes 313 * by zeros */ 314int store_bignum(BIGNUM *bn, unsigned char *buf,int len) 315 { 316 int bytes = BN_num_bytes(bn); 317 if (bytes>len) return 0; 318 memset(buf,0,len); 319 BN_bn2bin(bn,buf+len-bytes); 320 return 1; 321 } 322