ssl/tls_srp.c

   1 /* ssl/tls_srp.c */
   2 /* Written by Christophe Renou (christophe.renou@edelweb.fr) with
   3  * the precious help of Peter Sylvester (peter.sylvester@edelweb.fr)
   4  * for the EdelKey project and contributed to the OpenSSL project 2004.
   5  */
   6 /* ====================================================================
   7  * Copyright (c) 2004 The OpenSSL Project.  All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  *
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  *
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in
  18  *    the documentation and/or other materials provided with the
  19  *    distribution.
  20  *
  21  * 3. All advertising materials mentioning features or use of this
  22  *    software must display the following acknowledgment:
  23  *    "This product includes software developed by the OpenSSL Project
  24  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
  25  *
  26  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  27  *    endorse or promote products derived from this software without
  28  *    prior written permission. For written permission, please contact
  29  *    licensing@OpenSSL.org.
  30  *
  31  * 5. Products derived from this software may not be called "OpenSSL"
  32  *    nor may "OpenSSL" appear in their names without prior written
  33  *    permission of the OpenSSL Project.
  34  *
  35  * 6. Redistributions of any form whatsoever must retain the following
  36  *    acknowledgment:
  37  *    "This product includes software developed by the OpenSSL Project
  38  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
  39  *
  40  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  41  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  43  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  44  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  45  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  46  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  47  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  49  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  50  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  51  * OF THE POSSIBILITY OF SUCH DAMAGE.
  52  * ====================================================================
  53  *
  54  * This product includes cryptographic software written by Eric Young
  55  * (eay@cryptsoft.com).  This product includes software written by Tim
  56  * Hudson (tjh@cryptsoft.com).
  57  *
  58  */
  59 #include "ssl_locl.h"
  60 #ifndef OPENSSL_NO_SRP
  61
  62 #include <openssl/rand.h>
  63 #include <openssl/srp.h>
  64 #include <openssl/err.h>
  65
  66 int SSL_CTX_SRP_CTX_free(struct ssl_ctx_st *ctx)
  67         {
  68         if (ctx == NULL)
  69                 return 0;
  70         OPENSSL_free(ctx->srp_ctx.login);
  71         BN_free(ctx->srp_ctx.N);
  72         BN_free(ctx->srp_ctx.g);
  73         BN_free(ctx->srp_ctx.s);
  74         BN_free(ctx->srp_ctx.B);
  75         BN_free(ctx->srp_ctx.A);
  76         BN_free(ctx->srp_ctx.a);
  77         BN_free(ctx->srp_ctx.b);
  78         BN_free(ctx->srp_ctx.v);
  79         ctx->srp_ctx.TLS_ext_srp_username_callback = NULL;
  80         ctx->srp_ctx.SRP_cb_arg = NULL;
  81         ctx->srp_ctx.SRP_verify_param_callback = NULL;
  82         ctx->srp_ctx.SRP_give_srp_client_pwd_callback = NULL;
  83         ctx->srp_ctx.SRP_TLS_ext_missing_srp_client_username_callback = NULL;
  84         ctx->srp_ctx.N = NULL;
  85         ctx->srp_ctx.g = NULL;
  86         ctx->srp_ctx.s = NULL;
  87         ctx->srp_ctx.B = NULL;
  88         ctx->srp_ctx.A = NULL;
  89         ctx->srp_ctx.a = NULL;
  90         ctx->srp_ctx.b = NULL;
  91         ctx->srp_ctx.v = NULL;
  92         ctx->srp_ctx.login = NULL;
  93         ctx->srp_ctx.info = NULL;
  94         ctx->srp_ctx.strength = SRP_MINIMAL_N;
  95         ctx->srp_ctx.srp_Mask = 0;
  96         return (1);
  97         }
  98
  99 int SSL_SRP_CTX_free(struct ssl_st *s)
 100         {
 101         if (s == NULL)
 102                 return 0;
 103         OPENSSL_free(s->srp_ctx.login);
 104         BN_free(s->srp_ctx.N);
 105         BN_free(s->srp_ctx.g);
 106         BN_free(s->srp_ctx.s);
 107         BN_free(s->srp_ctx.B);
 108         BN_free(s->srp_ctx.A);
 109         BN_free(s->srp_ctx.a);
 110         BN_free(s->srp_ctx.b);
 111         BN_free(s->srp_ctx.v);
 112         s->srp_ctx.TLS_ext_srp_username_callback = NULL;
 113         s->srp_ctx.SRP_cb_arg = NULL;
 114         s->srp_ctx.SRP_verify_param_callback = NULL;
 115         s->srp_ctx.SRP_give_srp_client_pwd_callback = NULL;
 116         s->srp_ctx.SRP_TLS_ext_missing_srp_client_username_callback = NULL;
 117         s->srp_ctx.N = NULL;
 118         s->srp_ctx.g = NULL;
 119         s->srp_ctx.s = NULL;
 120         s->srp_ctx.B = NULL;
 121         s->srp_ctx.A = NULL;
 122         s->srp_ctx.a = NULL;
 123         s->srp_ctx.b = NULL;
 124         s->srp_ctx.v = NULL;
 125         s->srp_ctx.login = NULL;
 126         s->srp_ctx.info = NULL;
 127         s->srp_ctx.strength = SRP_MINIMAL_N;
 128         s->srp_ctx.srp_Mask = 0;
 129         return (1);
 130         }
 131
 132 int SSL_SRP_CTX_init(struct ssl_st *s)
 133         {
 134         SSL_CTX *ctx;
 135
 136         if ((s == NULL) || ((ctx = s->ctx) == NULL))
 137                 return 0;
 138         s->srp_ctx.SRP_cb_arg = ctx->srp_ctx.SRP_cb_arg;
 139         /* set client Hello login callback */
 140         s->srp_ctx.TLS_ext_srp_username_callback = ctx->srp_ctx.TLS_ext_srp_username_callback;
 141         /* set SRP N/g param callback for verification */
 142         s->srp_ctx.SRP_verify_param_callback = ctx->srp_ctx.SRP_verify_param_callback;
 143         /* set SRP client passwd callback */
 144         s->srp_ctx.SRP_give_srp_client_pwd_callback = ctx->srp_ctx.SRP_give_srp_client_pwd_callback;
 145         s->srp_ctx.SRP_TLS_ext_missing_srp_client_username_callback = ctx->srp_ctx.SRP_TLS_ext_missing_srp_client_username_callback;
 146
 147         s->srp_ctx.N = NULL;
 148         s->srp_ctx.g = NULL;
 149         s->srp_ctx.s = NULL;
 150         s->srp_ctx.B = NULL;
 151         s->srp_ctx.A = NULL;
 152         s->srp_ctx.a = NULL;
 153         s->srp_ctx.b = NULL;
 154         s->srp_ctx.v = NULL;
 155         s->srp_ctx.login = NULL;
 156         s->srp_ctx.info = ctx->srp_ctx.info;
 157         s->srp_ctx.strength = ctx->srp_ctx.strength;
 158
 159         if (((ctx->srp_ctx.N != NULL) &&
 160                  ((s->srp_ctx.N = BN_dup(ctx->srp_ctx.N)) == NULL)) ||
 161                 ((ctx->srp_ctx.g != NULL) &&
 162                  ((s->srp_ctx.g = BN_dup(ctx->srp_ctx.g)) == NULL)) ||
 163                 ((ctx->srp_ctx.s != NULL) &&
 164                  ((s->srp_ctx.s = BN_dup(ctx->srp_ctx.s)) == NULL)) ||
 165                 ((ctx->srp_ctx.B != NULL) &&
 166                  ((s->srp_ctx.B = BN_dup(ctx->srp_ctx.B)) == NULL)) ||
 167                 ((ctx->srp_ctx.A != NULL) &&
 168                  ((s->srp_ctx.A = BN_dup(ctx->srp_ctx.A)) == NULL)) ||
 169                 ((ctx->srp_ctx.a != NULL) &&
 170                  ((s->srp_ctx.a = BN_dup(ctx->srp_ctx.a)) == NULL)) ||
 171                 ((ctx->srp_ctx.v != NULL) &&
 172                  ((s->srp_ctx.v = BN_dup(ctx->srp_ctx.v)) == NULL)) ||
 173                 ((ctx->srp_ctx.b != NULL) &&
 174                  ((s->srp_ctx.b = BN_dup(ctx->srp_ctx.b)) == NULL)))
 175                 {
 176                 SSLerr(SSL_F_SSL_SRP_CTX_INIT,ERR_R_BN_LIB);
 177                 goto err;
 178                 }
 179         if ((ctx->srp_ctx.login != NULL) &&
 180                 ((s->srp_ctx.login = BUF_strdup(ctx->srp_ctx.login)) == NULL))
 181                 {
 182                 SSLerr(SSL_F_SSL_SRP_CTX_INIT,ERR_R_INTERNAL_ERROR);
 183                 goto err;
 184                 }
 185         s->srp_ctx.srp_Mask = ctx->srp_ctx.srp_Mask;
 186
 187         return (1);
 188 err:
 189         OPENSSL_free(s->srp_ctx.login);
 190         BN_free(s->srp_ctx.N);
 191         BN_free(s->srp_ctx.g);
 192         BN_free(s->srp_ctx.s);
 193         BN_free(s->srp_ctx.B);
 194         BN_free(s->srp_ctx.A);
 195         BN_free(s->srp_ctx.a);
 196         BN_free(s->srp_ctx.b);
 197         BN_free(s->srp_ctx.v);
 198         return (0);
 199         }
 200
 201 int SSL_CTX_SRP_CTX_init(struct ssl_ctx_st *ctx)
 202         {
 203         if (ctx == NULL)
 204                 return 0;
 205
 206         ctx->srp_ctx.SRP_cb_arg = NULL;
 207         /* set client Hello login callback */
 208         ctx->srp_ctx.TLS_ext_srp_username_callback = NULL;
 209         /* set SRP N/g param callback for verification */
 210         ctx->srp_ctx.SRP_verify_param_callback = NULL;
 211         /* set SRP client passwd callback */
 212         ctx->srp_ctx.SRP_give_srp_client_pwd_callback = NULL;
 213         ctx->srp_ctx.SRP_TLS_ext_missing_srp_client_username_callback = NULL;
 214
 215         ctx->srp_ctx.N = NULL;
 216         ctx->srp_ctx.g = NULL;
 217         ctx->srp_ctx.s = NULL;
 218         ctx->srp_ctx.B = NULL;
 219         ctx->srp_ctx.A = NULL;
 220         ctx->srp_ctx.a = NULL;
 221         ctx->srp_ctx.b = NULL;
 222         ctx->srp_ctx.v = NULL;
 223         ctx->srp_ctx.login = NULL;
 224         ctx->srp_ctx.srp_Mask = 0;
 225         ctx->srp_ctx.info = NULL;
 226         ctx->srp_ctx.strength = SRP_MINIMAL_N;
 227
 228         return (1);
 229         }
 230
 231 /* server side */
 232 int SSL_srp_server_param_with_username(SSL *s, int *ad)
 233         {
 234         unsigned char b[SSL_MAX_MASTER_KEY_LENGTH];
 235         int al;
 236
 237         *ad = SSL_AD_UNKNOWN_SRP_USERNAME;
 238         if ((s->srp_ctx.TLS_ext_srp_username_callback !=NULL) &&
 239                 ((al = s->srp_ctx.TLS_ext_srp_username_callback(s, ad, s->srp_ctx.SRP_cb_arg))!=SSL_ERROR_NONE))
 240                         return al;
 241
 242         *ad = SSL_AD_INTERNAL_ERROR;
 243         if ((s->srp_ctx.N == NULL) ||
 244                 (s->srp_ctx.g == NULL) ||
 245                 (s->srp_ctx.s == NULL) ||
 246                 (s->srp_ctx.v == NULL))
 247                 return SSL3_AL_FATAL;
 248
 249         if (RAND_bytes(b, sizeof(b)) <= 0)
 250                 return SSL3_AL_FATAL;
 251         s->srp_ctx.b = BN_bin2bn(b,sizeof(b),NULL);
 252         OPENSSL_cleanse(b,sizeof(b));
 253
 254         /* Calculate:  B = (kv + g^b) % N  */
 255
 256         return ((s->srp_ctx.B = SRP_Calc_B(s->srp_ctx.b, s->srp_ctx.N, s->srp_ctx.g, s->srp_ctx.v)) != NULL)?
 257                         SSL_ERROR_NONE:SSL3_AL_FATAL;
 258         }
 259
 260 /* If the server just has the raw password, make up a verifier entry on the fly */
 261 int SSL_set_srp_server_param_pw(SSL *s, const char *user, const char *pass, const char *grp)
 262         {
 263         SRP_gN *GN = SRP_get_default_gN(grp);
 264         if(GN == NULL) return -1;
 265         s->srp_ctx.N = BN_dup(GN->N);
 266         s->srp_ctx.g = BN_dup(GN->g);
 267         if(s->srp_ctx.v != NULL)
 268                 {
 269                 BN_clear_free(s->srp_ctx.v);
 270                 s->srp_ctx.v = NULL;
 271                 }
 272         if(s->srp_ctx.s != NULL)
 273                 {
 274                 BN_clear_free(s->srp_ctx.s);
 275                 s->srp_ctx.s = NULL;
 276                 }
 277         if(!SRP_create_verifier_BN(user, pass, &s->srp_ctx.s, &s->srp_ctx.v, GN->N, GN->g)) return -1;
 278
 279         return 1;
 280         }
 281
 282 int SSL_set_srp_server_param(SSL *s, const BIGNUM *N, const BIGNUM *g,
 283                              BIGNUM *sa, BIGNUM *v, char *info)
 284         {
 285         if (N!= NULL)
 286                 {
 287                 if (s->srp_ctx.N != NULL)
 288                         {
 289                         if (!BN_copy(s->srp_ctx.N,N))
 290                                 {
 291                                 BN_free(s->srp_ctx.N);
 292                                 s->srp_ctx.N = NULL;
 293                                 }
 294                         }
 295                 else
 296                         s->srp_ctx.N = BN_dup(N);
 297                 }
 298         if (g!= NULL)
 299                 {
 300                 if (s->srp_ctx.g != NULL)
 301                         {
 302                         if (!BN_copy(s->srp_ctx.g,g))
 303                                 {
 304                                 BN_free(s->srp_ctx.g);
 305                                 s->srp_ctx.g = NULL;
 306                                 }
 307                         }
 308                 else
 309                         s->srp_ctx.g = BN_dup(g);
 310                 }
 311         if (sa!= NULL)
 312                 {
 313                 if (s->srp_ctx.s != NULL)
 314                         {
 315                         if (!BN_copy(s->srp_ctx.s,sa))
 316                                 {
 317                                 BN_free(s->srp_ctx.s);
 318                                 s->srp_ctx.s = NULL;
 319                                 }
 320                         }
 321                 else
 322                         s->srp_ctx.s = BN_dup(sa);
 323                 }
 324         if (v!= NULL)
 325                 {
 326                 if (s->srp_ctx.v != NULL)
 327                         {
 328                         if (!BN_copy(s->srp_ctx.v,v))
 329                                 {
 330                                 BN_free(s->srp_ctx.v);
 331                                 s->srp_ctx.v = NULL;
 332                                 }
 333                         }
 334                 else
 335                         s->srp_ctx.v = BN_dup(v);
 336                 }
 337         s->srp_ctx.info = info;
 338
 339         if (!(s->srp_ctx.N) ||
 340                 !(s->srp_ctx.g) ||
 341                 !(s->srp_ctx.s) ||
 342                 !(s->srp_ctx.v))
 343                 return -1;
 344
 345         return 1;
 346         }
 347
 348 int SRP_generate_server_master_secret(SSL *s,unsigned char *master_key)
 349         {
 350         BIGNUM *K = NULL, *u = NULL;
 351         int ret = -1, tmp_len;
 352         unsigned char *tmp = NULL;
 353
 354         if (!SRP_Verify_A_mod_N(s->srp_ctx.A,s->srp_ctx.N))
 355                 goto err;
 356         if (!(u = SRP_Calc_u(s->srp_ctx.A,s->srp_ctx.B,s->srp_ctx.N)))
 357                 goto err;
 358         if (!(K = SRP_Calc_server_key(s->srp_ctx.A, s->srp_ctx.v, u, s->srp_ctx.b, s->srp_ctx.N)))
 359                 goto err;
 360
 361         tmp_len = BN_num_bytes(K);
 362         if ((tmp = OPENSSL_malloc(tmp_len)) == NULL)
 363                 goto err;
 364         BN_bn2bin(K, tmp);
 365         ret = s->method->ssl3_enc->generate_master_secret(s,master_key,tmp,tmp_len);
 366 err:
 367         if (tmp)
 368                 {
 369                 OPENSSL_cleanse(tmp,tmp_len) ;
 370                 OPENSSL_free(tmp);
 371                 }
 372         BN_clear_free(K);
 373         BN_clear_free(u);
 374         return ret;
 375         }
 376
 377 /* client side */
 378 int SRP_generate_client_master_secret(SSL *s,unsigned char *master_key)
 379         {
 380         BIGNUM *x = NULL, *u = NULL, *K = NULL;
 381         int ret = -1, tmp_len;
 382         char *passwd = NULL;
 383         unsigned char *tmp = NULL;
 384
 385         /* Checks if b % n == 0
 386          */
 387         if (SRP_Verify_B_mod_N(s->srp_ctx.B,s->srp_ctx.N)==0) goto err;
 388         if (!(u = SRP_Calc_u(s->srp_ctx.A,s->srp_ctx.B,s->srp_ctx.N))) goto err;
 389         if (s->srp_ctx.SRP_give_srp_client_pwd_callback == NULL) goto err;
 390         if (!(passwd = s->srp_ctx.SRP_give_srp_client_pwd_callback(s, s->srp_ctx.SRP_cb_arg))) goto err;
 391         if (!(x = SRP_Calc_x(s->srp_ctx.s,s->srp_ctx.login,passwd))) goto err;
 392         if (!(K = SRP_Calc_client_key(s->srp_ctx.N, s->srp_ctx.B, s->srp_ctx.g, x, s->srp_ctx.a, u))) goto err;
 393
 394         tmp_len = BN_num_bytes(K);
 395         if ((tmp = OPENSSL_malloc(tmp_len)) == NULL) goto err;
 396         BN_bn2bin(K, tmp);
 397         ret = s->method->ssl3_enc->generate_master_secret(s,master_key,tmp,tmp_len);
 398 err:
 399         if (tmp)
 400                 {
 401                 OPENSSL_cleanse(tmp,tmp_len) ;
 402                 OPENSSL_free(tmp);
 403                 }
 404         BN_clear_free(K);
 405         BN_clear_free(x);
 406         if (passwd)
 407                 {
 408                 OPENSSL_cleanse(passwd,strlen(passwd)) ;
 409                 OPENSSL_free(passwd);
 410                 }
 411         BN_clear_free(u);
 412         return ret;
 413         }
 414
 415 int SRP_Calc_A_param(SSL *s)
 416         {
 417         unsigned char rnd[SSL_MAX_MASTER_KEY_LENGTH];
 418
 419         if (BN_num_bits(s->srp_ctx.N) < s->srp_ctx.strength)
 420                 return 0;
 421
 422         if (s->srp_ctx.SRP_verify_param_callback ==NULL &&
 423                 !SRP_check_known_gN_param(s->srp_ctx.g,s->srp_ctx.N))
 424                 return 0;
 425
 426         if (RAND_bytes(rnd, sizeof(rnd)) <= 0)
 427                 return 0;
 428         s->srp_ctx.a = BN_bin2bn(rnd,sizeof(rnd), s->srp_ctx.a);
 429         OPENSSL_cleanse(rnd,sizeof(rnd));
 430
 431         if (!(s->srp_ctx.A = SRP_Calc_A(s->srp_ctx.a,s->srp_ctx.N,s->srp_ctx.g)))
 432                 return 0;
 433
 434         /* We can have a callback to verify SRP param!! */
 435         if (s->srp_ctx.SRP_verify_param_callback !=NULL)
 436                 return s->srp_ctx.SRP_verify_param_callback(s,s->srp_ctx.SRP_cb_arg);
 437
 438         return 1;
 439         }
 440
 441 int SRP_have_to_put_srp_username(SSL *s)
 442         {
 443         if (s->srp_ctx.SRP_TLS_ext_missing_srp_client_username_callback == NULL)
 444                 return 0;
 445         if ((s->srp_ctx.login = s->srp_ctx.SRP_TLS_ext_missing_srp_client_username_callback(s,s->srp_ctx.SRP_cb_arg)) == NULL)
 446                 return 0;
 447         s->srp_ctx.srp_Mask|=SSL_kSRP;
 448         return 1;
 449         }
 450
 451 BIGNUM *SSL_get_srp_g(SSL *s)
 452         {
 453         if (s->srp_ctx.g != NULL)
 454                 return s->srp_ctx.g;
 455         return s->ctx->srp_ctx.g;
 456         }
 457
 458 BIGNUM *SSL_get_srp_N(SSL *s)
 459         {
 460         if (s->srp_ctx.N != NULL)
 461                 return s->srp_ctx.N;
 462         return s->ctx->srp_ctx.N;
 463         }
 464
 465 char *SSL_get_srp_username(SSL *s)
 466         {
 467         if (s->srp_ctx.login != NULL)
 468                 return s->srp_ctx.login;
 469         return s->ctx->srp_ctx.login;
 470         }
 471
 472 char *SSL_get_srp_userinfo(SSL *s)
 473         {
 474         if (s->srp_ctx.info != NULL)
 475                 return s->srp_ctx.info;
 476         return s->ctx->srp_ctx.info;
 477         }
 478
 479 #define tls1_ctx_ctrl ssl3_ctx_ctrl
 480 #define tls1_ctx_callback_ctrl ssl3_ctx_callback_ctrl
 481
 482 int SSL_CTX_set_srp_username(SSL_CTX *ctx,char *name)
 483         {
 484         return tls1_ctx_ctrl(ctx,SSL_CTRL_SET_TLS_EXT_SRP_USERNAME,0,name);
 485         }
 486
 487 int SSL_CTX_set_srp_password(SSL_CTX *ctx,char *password)
 488         {
 489         return tls1_ctx_ctrl(ctx,SSL_CTRL_SET_TLS_EXT_SRP_PASSWORD,0,password);
 490         }
 491
 492 int SSL_CTX_set_srp_strength(SSL_CTX *ctx, int strength)
 493         {
 494         return tls1_ctx_ctrl(ctx, SSL_CTRL_SET_TLS_EXT_SRP_STRENGTH, strength,
 495                              NULL);
 496         }
 497
 498 int SSL_CTX_set_srp_verify_param_callback(SSL_CTX *ctx, int (*cb)(SSL *,void *))
 499         {
 500         return tls1_ctx_callback_ctrl(ctx,SSL_CTRL_SET_SRP_VERIFY_PARAM_CB,
 501                                       (void (*)(void))cb);
 502         }
 503
 504 int SSL_CTX_set_srp_cb_arg(SSL_CTX *ctx, void *arg)
 505         {
 506         return tls1_ctx_ctrl(ctx,SSL_CTRL_SET_SRP_ARG,0,arg);
 507         }
 508
 509 int SSL_CTX_set_srp_username_callback(SSL_CTX *ctx,
 510                                       int (*cb)(SSL *,int *,void *))
 511         {
 512         return tls1_ctx_callback_ctrl(ctx,SSL_CTRL_SET_TLS_EXT_SRP_USERNAME_CB,
 513                                       (void (*)(void))cb);
 514         }
 515
 516 int SSL_CTX_set_srp_client_pwd_callback(SSL_CTX *ctx, char *(*cb)(SSL *,void *))
 517         {
 518         return tls1_ctx_callback_ctrl(ctx,SSL_CTRL_SET_SRP_GIVE_CLIENT_PWD_CB,
 519                                       (void (*)(void))cb);
 520         }
 521
 522 int SSL_CTX_set_srp_missing_srp_username_callback(SSL_CTX *ctx,
 523                                                   char *(*cb)(SSL *,void *))
 524         {
 525         return tls1_ctx_callback_ctrl(ctx,
 526                             SSL_CTRL_SET_TLS_EXT_SRP_MISSING_CLIENT_USERNAME_CB,
 527                                       (void (*)(void))cb);
 528         }
 529 #endif