src/libstrongswan/plugins/gcrypt/gcrypt_rsa_private_key.c

   1 /*
   2  * Copyright (C) 2005-2009 Martin Willi
   3  * Hochschule fuer Technik Rapperswil
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the
   7  * Free Software Foundation; either version 2 of the License, or (at your
   8  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  12  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * for more details.
  14  */
  15
  16 #include <gcrypt.h>
  17
  18 #include "gcrypt_rsa_private_key.h"
  19
  20 #include <debug.h>
  21 #include <asn1/oid.h>
  22 #include <asn1/asn1.h>
  23 #include <asn1/asn1_parser.h>
  24
  25 typedef struct private_gcrypt_rsa_private_key_t private_gcrypt_rsa_private_key_t;
  26
  27 /**
  28  * Private data of a gcrypt_rsa_private_key_t object.
  29  */
  30 struct private_gcrypt_rsa_private_key_t {
  31
  32         /**
  33          * Public interface
  34          */
  35         gcrypt_rsa_private_key_t public;
  36
  37         /**
  38          * gcrypt S-expression representing an RSA key
  39          */
  40         gcry_sexp_t key;
  41
  42         /**
  43          * Keyid formed as a SHA-1 hash of a publicKey object
  44          */
  45         identification_t* keyid;
  46
  47         /**
  48          * Keyid formed as a SHA-1 hash of a publicKeyInfo object
  49          */
  50         identification_t* keyid_info;
  51
  52         /**
  53          * reference count
  54          */
  55         refcount_t ref;
  56 };
  57
  58 /**
  59  * Implemented in gcrypt_rsa_public_key.c
  60  */
  61 public_key_t *gcrypt_rsa_public_key_create_from_sexp(gcry_sexp_t key);
  62
  63 /**
  64  * find a token in a S-expression
  65  */
  66 chunk_t gcrypt_rsa_find_token(gcry_sexp_t sexp, char *name)
  67 {
  68         gcry_sexp_t token;
  69         chunk_t data = chunk_empty;
  70
  71         token = gcry_sexp_find_token(sexp, name, 1);
  72         if (token)
  73         {
  74                 data.ptr = (char*)gcry_sexp_nth_data(token, 1, &data.len);
  75                 if (!data.ptr)
  76                 {
  77                         data.len = 0;
  78                 }
  79                 data = chunk_clone(data);
  80                 gcry_sexp_release(token);
  81         }
  82         return data;
  83 }
  84
  85 /**
  86  * Sign a chunk of data with direct PKCS#1 encoding, no hash OID
  87  */
  88 static bool sign_raw(private_gcrypt_rsa_private_key_t *this,
  89                                          chunk_t data, chunk_t *signature)
  90 {
  91         gcry_sexp_t in, out;
  92         gcry_error_t err;
  93         chunk_t em;
  94         size_t k;
  95
  96         /* EM = 0x00 || 0x01 || PS || 0x00 || T
  97          * PS = 0xFF padding, with length to fill em
  98          * T  = data
  99          */
 100         k = gcry_pk_get_nbits(this->key) / 8;
 101         if (data.len > k - 3)
 102         {
 103                 return FALSE;
 104         }
 105         em = chunk_alloc(k);
 106         memset(em.ptr, 0xFF, em.len);
 107         em.ptr[0] = 0x00;
 108         em.ptr[1] = 0x01;
 109         em.ptr[em.len - data.len - 1] = 0x00;
 110         memcpy(em.ptr + em.len - data.len, data.ptr, data.len);
 111
 112         err = gcry_sexp_build(&in, NULL, "(data(flags raw)(value %b))",
 113                                                   em.len, em.ptr);
 114         chunk_free(&em);
 115         if (err)
 116         {
 117                 DBG1("building signature S-expression failed: %s", gpg_strerror(err));
 118                 return FALSE;
 119         }
 120         err = gcry_pk_sign(&out, in, this->key);
 121         gcry_sexp_release(in);
 122         if (err)
 123         {
 124                 DBG1("creating pkcs1 signature failed: %s", gpg_strerror(err));
 125                 return FALSE;
 126         }
 127         *signature = gcrypt_rsa_find_token(out, "s");
 128         gcry_sexp_release(out);
 129         return !!signature->len;
 130 }
 131
 132 /**
 133  * Sign a chunk of data using hashing and PKCS#1 encoding
 134  */
 135 static bool sign_pkcs1(private_gcrypt_rsa_private_key_t *this,
 136                                            hash_algorithm_t hash_algorithm, char *hash_name,
 137                                            chunk_t data, chunk_t *signature)
 138 {
 139         hasher_t *hasher;
 140         chunk_t hash;
 141         gcry_error_t err;
 142         gcry_sexp_t in, out;
 143         int hash_oid;
 144
 145         hash_oid = hasher_algorithm_to_oid(hash_algorithm);
 146         if (hash_oid == OID_UNKNOWN)
 147         {
 148                 return FALSE;
 149         }
 150         hasher = lib->crypto->create_hasher(lib->crypto, hash_algorithm);
 151         if (!hasher)
 152         {
 153                 return FALSE;
 154         }
 155         hasher->allocate_hash(hasher, data, &hash);
 156         hasher->destroy(hasher);
 157
 158         err = gcry_sexp_build(&in, NULL, "(data(flags pkcs1)(hash %s %b))",
 159                                                   hash_name, hash.len, hash.ptr);
 160         chunk_free(&hash);
 161         if (err)
 162         {
 163                 DBG1("building signature S-expression failed: %s", gpg_strerror(err));
 164                 return FALSE;
 165         }
 166         err = gcry_pk_sign(&out, in, this->key);
 167         gcry_sexp_release(in);
 168         if (err)
 169         {
 170                 DBG1("creating pkcs1 signature failed: %s", gpg_strerror(err));
 171                 return FALSE;
 172         }
 173         *signature = gcrypt_rsa_find_token(out, "s");
 174         gcry_sexp_release(out);
 175         return !!signature->len;
 176 }
 177
 178 /**
 179  * Implementation of gcrypt_rsa_private_key.destroy.
 180  */
 181 static key_type_t get_type(private_gcrypt_rsa_private_key_t *this)
 182 {
 183         return KEY_RSA;
 184 }
 185
 186 /**
 187  * Implementation of gcrypt_rsa_private_key.destroy.
 188  */
 189 static bool sign(private_gcrypt_rsa_private_key_t *this, signature_scheme_t scheme,
 190                                  chunk_t data, chunk_t *sig)
 191 {
 192         switch (scheme)
 193         {
 194                 case SIGN_RSA_EMSA_PKCS1_NULL:
 195                         return sign_raw(this, data, sig);
 196                 case SIGN_RSA_EMSA_PKCS1_SHA1:
 197                         return sign_pkcs1(this, HASH_SHA1, "sha1", data, sig);
 198                 case SIGN_RSA_EMSA_PKCS1_SHA256:
 199                         return sign_pkcs1(this, HASH_SHA256, "sha256", data, sig);
 200                 case SIGN_RSA_EMSA_PKCS1_SHA384:
 201                         return sign_pkcs1(this, HASH_SHA384, "sha384", data, sig);
 202                 case SIGN_RSA_EMSA_PKCS1_SHA512:
 203                         return sign_pkcs1(this, HASH_SHA512, "sha512", data, sig);
 204                 case SIGN_RSA_EMSA_PKCS1_MD5:
 205                         return sign_pkcs1(this, HASH_MD5, "md5", data, sig);
 206                 default:
 207                         DBG1("signature scheme %N not supported in RSA",
 208                                  signature_scheme_names, scheme);
 209                         return FALSE;
 210         }
 211 }
 212
 213 /**
 214  * Implementation of gcrypt_rsa_private_key.destroy.
 215  */
 216 static bool decrypt(private_gcrypt_rsa_private_key_t *this,
 217                                         chunk_t crypto, chunk_t *plain)
 218 {
 219         DBG1("RSA private key decryption not implemented");
 220         return FALSE;
 221 }
 222
 223 /**
 224  * Implementation of gcrypt_rsa_private_key.get_keysize.
 225  */
 226 static size_t get_keysize(private_gcrypt_rsa_private_key_t *this)
 227 {
 228         return gcry_pk_get_nbits(this->key) / 8;
 229 }
 230
 231 /**
 232  * Implementation of gcrypt_rsa_private_key.destroy.
 233  */
 234 static identification_t* get_id(private_gcrypt_rsa_private_key_t *this,
 235                                                                 id_type_t type)
 236 {
 237         switch (type)
 238         {
 239                 case ID_PUBKEY_INFO_SHA1:
 240                         return this->keyid_info;
 241                 case ID_PUBKEY_SHA1:
 242                         return this->keyid;
 243                 default:
 244                         return NULL;
 245         }
 246 }
 247
 248 /**
 249  * Implementation of gcrypt_rsa_private_key.get_public_key.
 250  */
 251 static public_key_t* get_public_key(private_gcrypt_rsa_private_key_t *this)
 252 {
 253         return gcrypt_rsa_public_key_create_from_sexp(this->key);
 254 }
 255
 256 /**
 257  * Implementation of gcrypt_rsa_private_key.equals.
 258  */
 259 static bool equals(private_gcrypt_rsa_private_key_t *this, private_key_t *other)
 260 {
 261         identification_t *keyid;
 262
 263         if (&this->public.interface == other)
 264         {
 265                 return TRUE;
 266         }
 267         if (other->get_type(other) != KEY_RSA)
 268         {
 269                 return FALSE;
 270         }
 271         keyid = other->get_id(other, ID_PUBKEY_SHA1);
 272         if (keyid && keyid->equals(keyid, this->keyid))
 273         {
 274                 return TRUE;
 275         }
 276         keyid = other->get_id(other, ID_PUBKEY_INFO_SHA1);
 277         if (keyid && keyid->equals(keyid, this->keyid_info))
 278         {
 279                 return TRUE;
 280         }
 281         return FALSE;
 282 }
 283
 284 /**
 285  * Implementation of gcrypt_rsa_private_key.belongs_to.
 286  */
 287 static bool belongs_to(private_gcrypt_rsa_private_key_t *this,
 288                                            public_key_t *public)
 289 {
 290         identification_t *keyid;
 291
 292         if (public->get_type(public) != KEY_RSA)
 293         {
 294                 return FALSE;
 295         }
 296         keyid = public->get_id(public, ID_PUBKEY_SHA1);
 297         if (keyid && keyid->equals(keyid, this->keyid))
 298         {
 299                 return TRUE;
 300         }
 301         keyid = public->get_id(public, ID_PUBKEY_INFO_SHA1);
 302         if (keyid && keyid->equals(keyid, this->keyid_info))
 303         {
 304                 return TRUE;
 305         }
 306         return FALSE;
 307 }
 308
 309 /**
 310  * Implementation of private_key_t.get_encoding.
 311  */
 312 static chunk_t get_encoding(private_gcrypt_rsa_private_key_t *this)
 313 {
 314         chunk_t cp, cq, cd, cexp1 = chunk_empty, cexp2 = chunk_empty;
 315         gcry_mpi_t p = NULL, q = NULL, d = NULL, exp1, exp2;
 316         gcry_error_t err;
 317
 318         /* p and q are swapped, gcrypt expects p < q */
 319         cp = gcrypt_rsa_find_token(this->key, "q");
 320         cq = gcrypt_rsa_find_token(this->key, "p");
 321         cd = gcrypt_rsa_find_token(this->key, "d");
 322
 323         err = gcry_mpi_scan(&p, GCRYMPI_FMT_USG, cp.ptr, cp.len, NULL)
 324                 | gcry_mpi_scan(&q, GCRYMPI_FMT_USG, cq.ptr, cq.len, NULL)
 325                 | gcry_mpi_scan(&d, GCRYMPI_FMT_USG, cd.ptr, cd.len, NULL);
 326         if (err)
 327         {
 328                 gcry_mpi_release(p);
 329                 gcry_mpi_release(q);
 330                 gcry_mpi_release(d);
 331                 chunk_clear(&cp);
 332                 chunk_clear(&cq);
 333                 chunk_clear(&cd);
 334                 DBG1("scanning mpi for export failed: %s", gpg_strerror(err));
 335                 return chunk_empty;
 336         }
 337
 338         gcry_mpi_sub_ui(p, p, 1);
 339         exp1 = gcry_mpi_new(gcry_pk_get_nbits(this->key));
 340         gcry_mpi_mod(exp1, d, p);
 341         gcry_mpi_release(p);
 342
 343         gcry_mpi_sub_ui(q, q, 1);
 344         exp2 = gcry_mpi_new(gcry_pk_get_nbits(this->key));
 345         gcry_mpi_mod(exp1, d, q);
 346         gcry_mpi_release(q);
 347
 348         err = gcry_mpi_aprint(GCRYMPI_FMT_USG, &cexp1.ptr, &cexp1.len, exp1)
 349                 | gcry_mpi_aprint(GCRYMPI_FMT_USG, &cexp2.ptr, &cexp2.len, exp2);
 350
 351         gcry_mpi_release(d);
 352         gcry_mpi_release(exp1);
 353         gcry_mpi_release(exp2);
 354
 355         if (err)
 356         {
 357                 DBG1("printing mpi for export failed: %s", gpg_strerror(err));
 358                 chunk_clear(&cp);
 359                 chunk_clear(&cq);
 360                 chunk_clear(&cd);
 361                 chunk_clear(&cexp1);
 362                 chunk_clear(&cexp2);
 363                 return chunk_empty;
 364         }
 365
 366         return asn1_wrap(ASN1_SEQUENCE, "cmmmmmmmm", ASN1_INTEGER_0,
 367                         asn1_integer("m", gcrypt_rsa_find_token(this->key, "n")),
 368                         asn1_integer("m", gcrypt_rsa_find_token(this->key, "e")),
 369                         asn1_integer("m", cd),
 370                         asn1_integer("m", cp),
 371                         asn1_integer("m", cq),
 372                         asn1_integer("m", cexp1),
 373                         asn1_integer("m", cexp2),
 374                         asn1_integer("m", gcrypt_rsa_find_token(this->key, "u")));
 375 }
 376
 377 /**
 378  * Implementation of gcrypt_rsa_private_key.get_ref.
 379  */
 380 static private_key_t* get_ref(private_gcrypt_rsa_private_key_t *this)
 381 {
 382         ref_get(&this->ref);
 383         return &this->public.interface;
 384 }
 385
 386 /**
 387  * Implementation of gcrypt_rsa_private_key.destroy.
 388  */
 389 static void destroy(private_gcrypt_rsa_private_key_t *this)
 390 {
 391         if (ref_put(&this->ref))
 392         {
 393                 DESTROY_IF(this->keyid);
 394                 DESTROY_IF(this->keyid_info);
 395                 gcry_sexp_release(this->key);
 396                 free(this);
 397         }
 398 }
 399
 400 /**
 401  * Internal generic constructor
 402  */
 403 static private_gcrypt_rsa_private_key_t *gcrypt_rsa_private_key_create_empty()
 404 {
 405         private_gcrypt_rsa_private_key_t *this = malloc_thing(private_gcrypt_rsa_private_key_t);
 406
 407         this->public.interface.get_type = (key_type_t (*)(private_key_t *this))get_type;
 408         this->public.interface.sign = (bool (*)(private_key_t *this, signature_scheme_t scheme, chunk_t data, chunk_t *signature))sign;
 409         this->public.interface.decrypt = (bool (*)(private_key_t *this, chunk_t crypto, chunk_t *plain))decrypt;
 410         this->public.interface.get_keysize = (size_t (*) (private_key_t *this))get_keysize;
 411         this->public.interface.get_id = (identification_t* (*) (private_key_t *this,id_type_t))get_id;
 412         this->public.interface.get_public_key = (public_key_t* (*)(private_key_t *this))get_public_key;
 413         this->public.interface.equals = (bool (*) (private_key_t*, private_key_t*))equals;
 414         this->public.interface.belongs_to = (bool (*) (private_key_t *this, public_key_t *public))belongs_to;
 415         this->public.interface.get_encoding = (chunk_t(*)(private_key_t*))get_encoding;
 416         this->public.interface.get_ref = (private_key_t* (*)(private_key_t *this))get_ref;
 417         this->public.interface.destroy = (void (*)(private_key_t *this))destroy;
 418
 419         this->key = NULL;
 420         this->keyid = NULL;
 421         this->keyid_info = NULL;
 422         this->ref = 1;
 423
 424         return this;
 425 }
 426
 427 /**
 428  * build the keyids of a private/public key
 429  */
 430 bool gcrypt_rsa_build_keyids(gcry_sexp_t key, identification_t **keyid,
 431                                                          identification_t **keyid_info)
 432 {
 433         chunk_t publicKeyInfo, publicKey, hash;
 434         hasher_t *hasher;
 435
 436         hasher = lib->crypto->create_hasher(lib->crypto, HASH_SHA1);
 437         if (!hasher)
 438         {
 439                 DBG1("SHA1 hash algorithm not supported, unable to use RSA");
 440                 return FALSE;
 441         }
 442         publicKey = asn1_wrap(ASN1_SEQUENCE, "mm",
 443                                  asn1_integer("m", gcrypt_rsa_find_token(key, "n")),
 444                                  asn1_integer("m", gcrypt_rsa_find_token(key, "e")));
 445         hasher->allocate_hash(hasher, publicKey, &hash);
 446         *keyid = identification_create_from_encoding(ID_PUBKEY_SHA1, hash);
 447         chunk_free(&hash);
 448
 449         publicKeyInfo = asn1_wrap(ASN1_SEQUENCE, "cm",
 450                                                 asn1_algorithmIdentifier(OID_RSA_ENCRYPTION),
 451                                                 asn1_bitstring("m", publicKey));
 452         hasher->allocate_hash(hasher, publicKeyInfo, &hash);
 453         *keyid_info = identification_create_from_encoding(ID_PUBKEY_INFO_SHA1, hash);
 454         chunk_free(&hash);
 455
 456         hasher->destroy(hasher);
 457         chunk_free(&publicKeyInfo);
 458
 459         return TRUE;
 460 }
 461
 462 /**
 463  * Generate an RSA key of specified key size
 464  */
 465 static gcrypt_rsa_private_key_t *generate(size_t key_size)
 466 {
 467         private_gcrypt_rsa_private_key_t *this;
 468         gcry_sexp_t param, key;
 469         gcry_error_t err;
 470
 471         err = gcry_sexp_build(&param, NULL, "(genkey(rsa(nbits %d)))", key_size);
 472         if (err)
 473         {
 474                 DBG1("building S-expression failed: %s", gpg_strerror(err));
 475                 return NULL;
 476         }
 477
 478         err = gcry_pk_genkey(&key, param);
 479         gcry_sexp_release(param);
 480         if (err)
 481         {
 482                 DBG1("generating RSA key failed: %s", gpg_strerror(err));
 483                 return NULL;
 484         }
 485         this = gcrypt_rsa_private_key_create_empty();
 486         this->key = key;
 487
 488         if (!gcrypt_rsa_build_keyids(this->key, &this->keyid, &this->keyid_info))
 489         {
 490                 destroy(this);
 491                 return NULL;
 492         }
 493
 494         return &this->public;
 495 }
 496
 497 /**
 498  * ASN.1 definition of a PKCS#1 RSA private key
 499  */
 500 static const asn1Object_t privkeyObjects[] = {
 501         { 0, "RSAPrivateKey",           ASN1_SEQUENCE,     ASN1_NONE }, /*  0 */
 502         { 1,   "version",                       ASN1_INTEGER,      ASN1_BODY }, /*  1 */
 503         { 1,   "modulus",                       ASN1_INTEGER,      ASN1_BODY }, /*  2 */
 504         { 1,   "publicExponent",        ASN1_INTEGER,      ASN1_BODY }, /*  3 */
 505         { 1,   "privateExponent",       ASN1_INTEGER,      ASN1_BODY }, /*  4 */
 506         { 1,   "prime1",                        ASN1_INTEGER,      ASN1_BODY }, /*  5 */
 507         { 1,   "prime2",                        ASN1_INTEGER,      ASN1_BODY }, /*  6 */
 508         { 1,   "exponent1",                     ASN1_INTEGER,      ASN1_BODY }, /*  7 */
 509         { 1,   "exponent2",                     ASN1_INTEGER,      ASN1_BODY }, /*  8 */
 510         { 1,   "coefficient",           ASN1_INTEGER,      ASN1_BODY }, /*  9 */
 511         { 1,   "otherPrimeInfos",       ASN1_SEQUENCE,     ASN1_OPT |
 512                                                                                                    ASN1_LOOP }, /* 10 */
 513         { 2,     "otherPrimeInfo",      ASN1_SEQUENCE,     ASN1_NONE }, /* 11 */
 514         { 3,       "prime",                     ASN1_INTEGER,      ASN1_BODY }, /* 12 */
 515         { 3,       "exponent",          ASN1_INTEGER,      ASN1_BODY }, /* 13 */
 516         { 3,       "coefficient",       ASN1_INTEGER,      ASN1_BODY }, /* 14 */
 517         { 1,   "end opt or loop",       ASN1_EOC,          ASN1_END  }, /* 15 */
 518         { 0, "exit",                            ASN1_EOC,          ASN1_EXIT }
 519 };
 520 #define PRIV_KEY_VERSION                 1
 521 #define PRIV_KEY_MODULUS                 2
 522 #define PRIV_KEY_PUB_EXP                 3
 523 #define PRIV_KEY_PRIV_EXP                4
 524 #define PRIV_KEY_PRIME1                  5
 525 #define PRIV_KEY_PRIME2                  6
 526 #define PRIV_KEY_EXP1                    7
 527 #define PRIV_KEY_EXP2                    8
 528 #define PRIV_KEY_COEFF                   9
 529
 530 /**
 531  * load private key from a ASN1 encoded blob
 532  */
 533 static gcrypt_rsa_private_key_t *load(chunk_t blob)
 534 {
 535         private_gcrypt_rsa_private_key_t *this;
 536         asn1_parser_t *parser;
 537         chunk_t object;
 538         int objectID ;
 539         bool success = FALSE;
 540         chunk_t n, e, d, u, p, q;
 541         gcry_error_t err;
 542
 543         parser = asn1_parser_create(privkeyObjects, blob);
 544         parser->set_flags(parser, FALSE, TRUE);
 545
 546         while (parser->iterate(parser, &objectID, &object))
 547         {
 548                 switch (objectID)
 549                 {
 550                         case PRIV_KEY_VERSION:
 551                                 if (object.len > 0 && *object.ptr != 0)
 552                                 {
 553                                         goto end;
 554                                 }
 555                                 break;
 556                         case PRIV_KEY_MODULUS:
 557                                 n = object;
 558                                 break;
 559                         case PRIV_KEY_PUB_EXP:
 560                                 e = object;
 561                                 break;
 562                         case PRIV_KEY_PRIV_EXP:
 563                                 d = object;
 564                                 break;
 565                         case PRIV_KEY_PRIME1:
 566                                 /* p and q are swapped, as gcrypt expects p < q */
 567                                 q = object;
 568                                 break;
 569                         case PRIV_KEY_PRIME2:
 570                                 p = object;
 571                                 break;
 572                         case PRIV_KEY_EXP1:
 573                         case PRIV_KEY_EXP2:
 574                                 break;
 575                         case PRIV_KEY_COEFF:
 576                                 u = object;
 577                                 break;
 578                 }
 579         }
 580         success = parser->success(parser);
 581
 582 end:
 583         parser->destroy(parser);
 584
 585         if (!success)
 586         {
 587                 return NULL;
 588         }
 589
 590         this = gcrypt_rsa_private_key_create_empty();
 591         err = gcry_sexp_build(&this->key, NULL,
 592                                         "(private-key(rsa(n %b)(e %b)(d %b)(p %b)(q %b)(u %b)))",
 593                                         n.len, n.ptr, e.len, e.ptr, d.len, d.ptr,
 594                                         p.len, p.ptr, q.len, q.ptr, u.len, u.ptr);
 595         if (err)
 596         {
 597                 DBG1("loading private key failed: %s", gpg_strerror(err));
 598                 free(this);
 599                 return NULL;
 600         }
 601         err = gcry_pk_testkey(this->key);
 602         if (err)
 603         {
 604                 DBG1("private key sanity check failed: %s", gpg_strerror(err));
 605                 destroy(this);
 606                 return NULL;
 607         }
 608         if (!gcrypt_rsa_build_keyids(this->key, &this->keyid, &this->keyid_info))
 609         {
 610                 destroy(this);
 611                 return NULL;
 612         }
 613         return &this->public;
 614 }
 615
 616 typedef struct private_builder_t private_builder_t;
 617
 618 /**
 619  * Builder implementation for key loading/generation
 620  */
 621 struct private_builder_t {
 622         /** implements the builder interface */
 623         builder_t public;
 624         /** loaded/generated private key */
 625         gcrypt_rsa_private_key_t *key;
 626 };
 627
 628 /**
 629  * Implementation of builder_t.build
 630  */
 631 static gcrypt_rsa_private_key_t *build(private_builder_t *this)
 632 {
 633         gcrypt_rsa_private_key_t *key = this->key;
 634
 635         free(this);
 636         return key;
 637 }
 638
 639 /**
 640  * Implementation of builder_t.add
 641  */
 642 static void add(private_builder_t *this, builder_part_t part, ...)
 643 {
 644         if (!this->key)
 645         {
 646                 va_list args;
 647
 648                 switch (part)
 649                 {
 650                         case BUILD_BLOB_ASN1_DER:
 651                         {
 652                                 va_start(args, part);
 653                                 this->key = load(va_arg(args, chunk_t));
 654                                 va_end(args);
 655                                 return;
 656                         }
 657                         case BUILD_KEY_SIZE:
 658                         {
 659                                 va_start(args, part);
 660                                 this->key = generate(va_arg(args, u_int));
 661                                 va_end(args);
 662                                 return;
 663                         }
 664                         default:
 665                                 break;
 666                 }
 667         }
 668         if (this->key)
 669         {
 670                 destroy((private_gcrypt_rsa_private_key_t*)this->key);
 671         }
 672         builder_cancel(&this->public);
 673 }
 674
 675 /**
 676  * Builder construction function
 677  */
 678 builder_t *gcrypt_rsa_private_key_builder(key_type_t type)
 679 {
 680         private_builder_t *this;
 681
 682         if (type != KEY_RSA)
 683         {
 684                 return NULL;
 685         }
 686
 687         this = malloc_thing(private_builder_t);
 688
 689         this->key = NULL;
 690         this->public.add = (void(*)(builder_t *this, builder_part_t part, ...))add;
 691         this->public.build = (void*(*)(builder_t *this))build;
 692
 693         return &this->public;
 694 }
 695