src/libstrongswan/plugins/gcrypt/gcrypt_rsa_public_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_public_key.h"
  19
  20 #include <debug.h>
  21 #include <asn1/oid.h>
  22 #include <asn1/asn1.h>
  23 #include <asn1/asn1_parser.h>
  24 #include <asn1/pem.h>
  25 #include <crypto/hashers/hasher.h>
  26
  27 typedef struct private_gcrypt_rsa_public_key_t private_gcrypt_rsa_public_key_t;
  28
  29 /**
  30  * Private data structure with signing context.
  31  */
  32 struct private_gcrypt_rsa_public_key_t {
  33
  34         /**
  35          * Public interface for this signer.
  36          */
  37         gcrypt_rsa_public_key_t public;
  38
  39         /**
  40          * gcrypt S-expression representing an public RSA key
  41          */
  42         gcry_sexp_t key;
  43
  44         /**
  45          * Keyid formed as a SHA-1 hash of a publicKey object
  46          */
  47         identification_t* keyid;
  48
  49         /**
  50          * Keyid formed as a SHA-1 hash of a publicKeyInfo object
  51          */
  52         identification_t* keyid_info;
  53
  54         /**
  55          * reference counter
  56          */
  57         refcount_t ref;
  58 };
  59
  60 /**
  61  * Implemented in gcrypt_rsa_private_key.c
  62  */
  63 chunk_t gcrypt_rsa_find_token(gcry_sexp_t sexp, char *name);
  64 bool gcrypt_rsa_build_keyids(gcry_sexp_t key, identification_t **keyid,
  65                                                          identification_t **keyid_info);
  66
  67 /**
  68  * Verification of an EMPSA PKCS1 signature described in PKCS#1
  69  */
  70 static bool verify_pkcs1(private_gcrypt_rsa_public_key_t *this,
  71                                                  hash_algorithm_t algorithm, char *hash_name,
  72                                                  chunk_t data, chunk_t signature)
  73 {
  74         hasher_t *hasher;
  75         chunk_t hash;
  76         gcry_error_t err;
  77         gcry_sexp_t in, sig;
  78
  79         hasher = lib->crypto->create_hasher(lib->crypto, algorithm);
  80         if (!hasher)
  81         {
  82                 return FALSE;
  83         }
  84         hasher->allocate_hash(hasher, data, &hash);
  85         hasher->destroy(hasher);
  86
  87         err = gcry_sexp_build(&in, NULL, "(data(flags pkcs1)(hash %s %b))",
  88                                                   hash_name, hash.len, hash.ptr);
  89         chunk_free(&hash);
  90         if (err)
  91         {
  92                 DBG1("building data S-expression failed: %s", gpg_strerror(err));
  93                 return FALSE;
  94         }
  95
  96         err = gcry_sexp_build(&sig, NULL, "(sig-val(rsa(s %b)))",
  97                                                   signature.len, signature.ptr);
  98         if (err)
  99         {
 100                 DBG1("building signature S-expression failed: %s", gpg_strerror(err));
 101                 gcry_sexp_release(in);
 102                 return FALSE;
 103         }
 104         err = gcry_pk_verify(sig, in, this->key);
 105         gcry_sexp_release(in);
 106         gcry_sexp_release(sig);
 107         if (err)
 108         {
 109                 DBG1("RSA signature verification failed: %s", gpg_strerror(err));
 110                 return FALSE;
 111         }
 112         return TRUE;
 113 }
 114
 115 /**
 116  * Implementation of public_key_t.get_type.
 117  */
 118 static key_type_t get_type(private_gcrypt_rsa_public_key_t *this)
 119 {
 120         return KEY_RSA;
 121 }
 122
 123 /**
 124  * Implementation of public_key_t.verify.
 125  */
 126 static bool verify(private_gcrypt_rsa_public_key_t *this,
 127                                    signature_scheme_t scheme, chunk_t data, chunk_t signature)
 128 {
 129         switch (scheme)
 130         {
 131                 case SIGN_RSA_EMSA_PKCS1_MD5:
 132                         return verify_pkcs1(this, HASH_MD5, "md5", data, signature);
 133                 case SIGN_RSA_EMSA_PKCS1_SHA1:
 134                         return verify_pkcs1(this, HASH_SHA1, "sha1", data, signature);
 135                 case SIGN_RSA_EMSA_PKCS1_SHA256:
 136                         return verify_pkcs1(this, HASH_SHA256, "sha256", data, signature);
 137                 case SIGN_RSA_EMSA_PKCS1_SHA384:
 138                         return verify_pkcs1(this, HASH_SHA384, "sha384", data, signature);
 139                 case SIGN_RSA_EMSA_PKCS1_SHA512:
 140                         return verify_pkcs1(this, HASH_SHA512, "sha512", data, signature);
 141                 case SIGN_DEFAULT:
 142                         /* parsing hash OID currently not supported by gcrypt, fall */
 143                 default:
 144                         DBG1("signature scheme %N not supported in RSA",
 145                                  signature_scheme_names, scheme);
 146                         return FALSE;
 147         }
 148 }
 149
 150 /**
 151  * Implementation of public_key_t.get_keysize.
 152  */
 153 static bool encrypt_(private_gcrypt_rsa_public_key_t *this, chunk_t crypto,
 154                                         chunk_t *plain)
 155 {
 156         DBG1("RSA public key encryption not implemented");
 157         return FALSE;
 158 }
 159
 160 /**
 161  * Implementation of gcrypt_rsa_public_key.equals.
 162  */
 163 static bool equals(private_gcrypt_rsa_public_key_t *this, public_key_t *other)
 164 {
 165         identification_t *keyid;
 166
 167         if (&this->public.interface == other)
 168         {
 169                 return TRUE;
 170         }
 171         if (other->get_type(other) != KEY_RSA)
 172         {
 173                 return FALSE;
 174         }
 175         keyid = other->get_id(other, ID_PUBKEY_SHA1);
 176         if (keyid && keyid->equals(keyid, this->keyid))
 177         {
 178                 return TRUE;
 179         }
 180         keyid = other->get_id(other, ID_PUBKEY_INFO_SHA1);
 181         if (keyid && keyid->equals(keyid, this->keyid_info))
 182         {
 183                 return TRUE;
 184         }
 185         return FALSE;
 186 }
 187
 188 /**
 189  * Implementation of public_key_t.get_keysize.
 190  */
 191 static size_t get_keysize(private_gcrypt_rsa_public_key_t *this)
 192 {
 193         return gcry_pk_get_nbits(this->key) / 8;
 194 }
 195
 196 /**
 197  * Implementation of public_key_t.get_id.
 198  */
 199 static identification_t *get_id(private_gcrypt_rsa_public_key_t *this,
 200                                                                 id_type_t type)
 201 {
 202         switch (type)
 203         {
 204                 case ID_PUBKEY_INFO_SHA1:
 205                         return this->keyid_info;
 206                 case ID_PUBKEY_SHA1:
 207                         return this->keyid;
 208                 default:
 209                         return NULL;
 210         }
 211 }
 212
 213 /*
 214  * Implementation of public_key_t.get_encoding.
 215  */
 216 static chunk_t get_encoding(private_gcrypt_rsa_public_key_t *this)
 217 {
 218         return asn1_wrap(ASN1_SEQUENCE, "mm",
 219                         asn1_wrap(ASN1_INTEGER, "m", gcrypt_rsa_find_token(this->key, "n")),
 220                         asn1_wrap(ASN1_INTEGER, "m", gcrypt_rsa_find_token(this->key, "e")));
 221 }
 222
 223 /**
 224  * Implementation of public_key_t.get_ref.
 225  */
 226 static public_key_t* get_ref(private_gcrypt_rsa_public_key_t *this)
 227 {
 228         ref_get(&this->ref);
 229         return &this->public.interface;
 230 }
 231
 232 /**
 233  * Implementation of gcrypt_rsa_public_key.destroy.
 234  */
 235 static void destroy(private_gcrypt_rsa_public_key_t *this)
 236 {
 237         if (ref_put(&this->ref))
 238         {
 239                 DESTROY_IF(this->keyid);
 240                 DESTROY_IF(this->keyid_info);
 241                 gcry_sexp_release(this->key);
 242                 free(this);
 243         }
 244 }
 245
 246 /**
 247  * Generic private constructor
 248  */
 249 static private_gcrypt_rsa_public_key_t *gcrypt_rsa_public_key_create_empty()
 250 {
 251         private_gcrypt_rsa_public_key_t *this = malloc_thing(private_gcrypt_rsa_public_key_t);
 252
 253         this->public.interface.get_type = (key_type_t (*)(public_key_t *this))get_type;
 254         this->public.interface.verify = (bool (*)(public_key_t *this, signature_scheme_t scheme, chunk_t data, chunk_t signature))verify;
 255         this->public.interface.encrypt = (bool (*)(public_key_t *this, chunk_t crypto, chunk_t *plain))encrypt_;
 256         this->public.interface.equals = (bool (*) (public_key_t*, public_key_t*))equals;
 257         this->public.interface.get_keysize = (size_t (*) (public_key_t *this))get_keysize;
 258         this->public.interface.get_id = (identification_t* (*) (public_key_t *this,id_type_t))get_id;
 259         this->public.interface.get_encoding = (chunk_t(*)(public_key_t*))get_encoding;
 260         this->public.interface.get_ref = (public_key_t* (*)(public_key_t *this))get_ref;
 261         this->public.interface.destroy = (void (*)(public_key_t *this))destroy;
 262
 263         this->key = NULL;
 264         this->keyid = NULL;
 265         this->keyid_info = NULL;
 266         this->ref = 1;
 267
 268         return this;
 269 }
 270
 271 /**
 272  * Create a public key from a S-expression, used in gcrypt_rsa_private_key
 273  */
 274 public_key_t *gcrypt_rsa_public_key_create_from_sexp(gcry_sexp_t key)
 275 {
 276         private_gcrypt_rsa_public_key_t *this;
 277         gcry_error_t err;
 278         chunk_t n, e;
 279
 280         this = gcrypt_rsa_public_key_create_empty();
 281         n = gcrypt_rsa_find_token(key, "n");
 282         e = gcrypt_rsa_find_token(key, "e");
 283
 284         err = gcry_sexp_build(&this->key, NULL, "(public-key(rsa(n %b)(e %b)))",
 285                                                   n.len, n.ptr, e.len, e.ptr);
 286         chunk_free(&n);
 287         chunk_free(&e);
 288         if (err)
 289         {
 290                 DBG1("loading public key failed: %s", gpg_strerror(err));
 291                 free(this);
 292                 return NULL;
 293         }
 294         if (!gcrypt_rsa_build_keyids(this->key, &this->keyid, &this->keyid_info))
 295         {
 296                 destroy(this);
 297                 return NULL;
 298         }
 299         return &this->public.interface;
 300 }
 301
 302 /**
 303  * ASN.1 definition of RSApublicKey
 304  */
 305 static const asn1Object_t pubkeyObjects[] = {
 306         { 0, "RSAPublicKey",            ASN1_SEQUENCE,  ASN1_OBJ  }, /*  0 */
 307         { 1,   "modulus",                       ASN1_INTEGER,   ASN1_BODY }, /*  1 */
 308         { 1,   "publicExponent",        ASN1_INTEGER,   ASN1_BODY }, /*  2 */
 309         { 0, "exit",                            ASN1_EOC,               ASN1_EXIT }
 310 };
 311 #define PUB_KEY_RSA_PUBLIC_KEY          0
 312 #define PUB_KEY_MODULUS                         1
 313 #define PUB_KEY_EXPONENT                        2
 314
 315 /**
 316  * Load a public key from an ASN1 encoded blob
 317  */
 318 static gcrypt_rsa_public_key_t *load(chunk_t blob)
 319 {
 320         private_gcrypt_rsa_public_key_t *this;
 321         asn1_parser_t *parser;
 322         chunk_t object, n, e;
 323         int objectID;
 324         bool success = FALSE;
 325         gcry_error_t err;
 326
 327         parser = asn1_parser_create(pubkeyObjects, blob);
 328         while (parser->iterate(parser, &objectID, &object))
 329         {
 330                 switch (objectID)
 331                 {
 332                         case PUB_KEY_MODULUS:
 333                                 n = object;
 334                                 break;
 335                         case PUB_KEY_EXPONENT:
 336                                 e = object;
 337                                 break;
 338                 }
 339         }
 340         success = parser->success(parser);
 341         parser->destroy(parser);
 342
 343         if (!success)
 344         {
 345                 return NULL;
 346         }
 347
 348         this = gcrypt_rsa_public_key_create_empty();
 349         err = gcry_sexp_build(&this->key, NULL, "(public-key(rsa(n %b)(e %b)))",
 350                                                   n.len, n.ptr, e.len, e.ptr);
 351         if (err)
 352         {
 353                 DBG1("loading public key failed: %s", gpg_strerror(err));
 354                 free(this);
 355                 return NULL;
 356         }
 357         if (!gcrypt_rsa_build_keyids(this->key, &this->keyid, &this->keyid_info))
 358         {
 359                 destroy(this);
 360                 return NULL;
 361         }
 362         return &this->public;
 363 }
 364
 365 typedef struct private_builder_t private_builder_t;
 366 /**
 367  * Builder implementation for key loading
 368  */
 369 struct private_builder_t {
 370         /** implements the builder interface */
 371         builder_t public;
 372         /** loaded public key */
 373         gcrypt_rsa_public_key_t *key;
 374 };
 375
 376 /**
 377  * Implementation of builder_t.build
 378  */
 379 static gcrypt_rsa_public_key_t *build(private_builder_t *this)
 380 {
 381         gcrypt_rsa_public_key_t *key = this->key;
 382
 383         free(this);
 384         return key;
 385 }
 386
 387 /**
 388  * Implementation of builder_t.add
 389  */
 390 static void add(private_builder_t *this, builder_part_t part, ...)
 391 {
 392         if (!this->key)
 393         {
 394                 va_list args;
 395
 396                 switch (part)
 397                 {
 398                         case BUILD_BLOB_ASN1_DER:
 399                         {
 400                                 va_start(args, part);
 401                                 this->key = load(va_arg(args, chunk_t));
 402                                 va_end(args);
 403                                 return;
 404                         }
 405                         default:
 406                                 break;
 407                 }
 408         }
 409         if (this->key)
 410         {
 411                 destroy((private_gcrypt_rsa_public_key_t*)this->key);
 412         }
 413         builder_cancel(&this->public);
 414 }
 415
 416 /**
 417  * Builder construction function
 418  */
 419 builder_t *gcrypt_rsa_public_key_builder(key_type_t type)
 420 {
 421         private_builder_t *this;
 422
 423         if (type != KEY_RSA)
 424         {
 425                 return NULL;
 426         }
 427
 428         this = malloc_thing(private_builder_t);
 429
 430         this->key = NULL;
 431         this->public.add = (void(*)(builder_t *this, builder_part_t part, ...))add;
 432         this->public.build = (void*(*)(builder_t *this))build;
 433
 434         return &this->public;
 435 }
 436