src/libstrongswan/plugins/openssl/openssl_ec_private_key.c

   1 /*
   2  * Copyright (C) 2008 Tobias Brunner
   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 "openssl_ec_private_key.h"
  17 #include "openssl_ec_public_key.h"
  18 #include "openssl_util.h"
  19
  20 #include <debug.h>
  21
  22 #include <openssl/evp.h>
  23 #include <openssl/ecdsa.h>
  24
  25 typedef struct private_openssl_ec_private_key_t private_openssl_ec_private_key_t;
  26
  27 /**
  28  * Private data of a openssl_ec_private_key_t object.
  29  */
  30 struct private_openssl_ec_private_key_t {
  31         /**
  32          * Public interface for this signer.
  33          */
  34         openssl_ec_private_key_t public;
  35
  36         /**
  37          * EC key object
  38          */
  39         EC_KEY *ec;
  40
  41         /**
  42          * Keyid formed as a SHA-1 hash of a privateKey object
  43          */
  44         identification_t* keyid;
  45
  46         /**
  47          * Keyid formed as a SHA-1 hash of a privateKeyInfo object
  48          */
  49         identification_t* keyid_info;
  50
  51         /**
  52          * reference count
  53          */
  54         refcount_t ref;
  55 };
  56
  57 /**
  58  * Mapping from the signature scheme defined in (RFC 4754) to the elliptic
  59  * curve and the hash algorithm
  60  */
  61 typedef struct {
  62         /**
  63          * Scheme specified in RFC 4754
  64          */
  65         int scheme;
  66
  67         /**
  68          * NID of the hash
  69          */
  70         int hash;
  71
  72         /**
  73          * NID of the curve
  74          */
  75         int curve;
  76 } openssl_ecdsa_scheme_t;
  77
  78 #define END_OF_LIST -1
  79
  80 /**
  81  * Signature schemes
  82  */
  83 static openssl_ecdsa_scheme_t ecdsa_schemes[] = {
  84         {SIGN_ECDSA_256, NID_sha256, NID_X9_62_prime256v1},
  85         {SIGN_ECDSA_384, NID_sha384, NID_secp384r1},
  86         {SIGN_ECDSA_521, NID_sha512, NID_secp521r1},
  87         {END_OF_LIST,    0,          0},
  88 };
  89
  90 /**
  91  * Look up the hash and curve of a signature scheme
  92  */
  93 static bool lookup_scheme(int scheme, int *hash, int *curve)
  94 {
  95         openssl_ecdsa_scheme_t *ecdsa_scheme = ecdsa_schemes;
  96         while (ecdsa_scheme->scheme != END_OF_LIST)
  97         {
  98                 if (scheme == ecdsa_scheme->scheme)
  99                 {
 100                         *hash = ecdsa_scheme->hash;
 101                         *curve = ecdsa_scheme->curve;
 102                         return TRUE;
 103                 }
 104                 ecdsa_scheme++;
 105         }
 106         return FALSE;
 107 }
 108
 109 /**
 110  * shared functions, implemented in openssl_ec_public_key.c
 111  */
 112 bool openssl_ec_public_key_build_id(EC_KEY *ec, identification_t **keyid,
 113                                                                  identification_t **keyid_info);
 114
 115 openssl_ec_public_key_t *openssl_ec_public_key_create_from_private_key(EC_KEY *ec);
 116
 117
 118 /**
 119  * Convert an ECDSA_SIG to a chunk by concatenating r and s.
 120  * This function allocates memory for the chunk.
 121  */
 122 static bool sig2chunk(const EC_GROUP *group, ECDSA_SIG *sig, chunk_t *chunk)
 123 {
 124         return openssl_bn_cat(EC_FIELD_ELEMENT_LEN(group), sig->r, sig->s, chunk);
 125 }
 126
 127 /**
 128  * Build the signature
 129  */
 130 static bool build_signature(private_openssl_ec_private_key_t *this,
 131                                                         chunk_t hash, chunk_t *signature)
 132 {
 133         ECDSA_SIG *sig = ECDSA_do_sign(hash.ptr, hash.len, this->ec);
 134         bool success;
 135
 136         if (!sig)
 137         {
 138                 return FALSE;
 139         }
 140         success = sig2chunk(EC_KEY_get0_group(this->ec), sig, signature);
 141         ECDSA_SIG_free(sig);
 142         return success;
 143 }
 144
 145 /**
 146  * Implementation of private_key_t.get_type.
 147  */
 148 static key_type_t get_type(private_openssl_ec_private_key_t *this)
 149 {
 150         return KEY_ECDSA;
 151 }
 152
 153 /**
 154  * Implementation of private_key_t.sign.
 155  */
 156 static bool sign(private_openssl_ec_private_key_t *this, signature_scheme_t scheme,
 157                                  chunk_t data, chunk_t *signature)
 158 {
 159         bool success;
 160
 161         if (scheme == SIGN_ECDSA_WITH_NULL)
 162         {
 163                 success = build_signature(this, data, signature);
 164         }
 165         else
 166         {
 167                 EC_GROUP *req_group;
 168                 const EC_GROUP *my_group;
 169                 chunk_t hash = chunk_empty;
 170                 int hash_type, curve;
 171
 172                 if (!lookup_scheme(scheme, &hash_type, &curve))
 173                 {
 174                         DBG1("signature scheme %N not supported in EC",
 175                                          signature_scheme_names, scheme);
 176                         return FALSE;
 177                 }
 178
 179                 req_group = EC_GROUP_new_by_curve_name(curve);
 180                 if (!req_group)
 181                 {
 182                         DBG1("signature scheme %N not supported in EC (required curve not supported)",
 183                                          signature_scheme_names, scheme);
 184                         return FALSE;
 185                 }
 186
 187                 my_group = EC_KEY_get0_group(this->ec);
 188                 if (EC_GROUP_cmp(my_group, req_group, NULL) != 0)
 189                 {
 190                         DBG1("signature scheme %N not supported by private key",
 191                                          signature_scheme_names, scheme);
 192                         return FALSE;
 193                 }
 194                 EC_GROUP_free(req_group);
 195
 196                 if (!openssl_hash_chunk(hash_type, data, &hash))
 197                 {
 198                         return FALSE;
 199                 }
 200                 success = build_signature(this, hash, signature);
 201                 chunk_free(&hash);
 202         }
 203         return success;
 204 }
 205
 206 /**
 207  * Implementation of private_key_t.destroy.
 208  */
 209 static bool decrypt(private_openssl_ec_private_key_t *this,
 210                                         chunk_t crypto, chunk_t *plain)
 211 {
 212         DBG1("EC private key decryption not implemented");
 213         return FALSE;
 214 }
 215
 216 /**
 217  * Implementation of private_key_t.get_keysize.
 218  */
 219 static size_t get_keysize(private_openssl_ec_private_key_t *this)
 220 {
 221         return EC_FIELD_ELEMENT_LEN(EC_KEY_get0_group(this->ec));
 222 }
 223
 224 /**
 225  * Implementation of private_key_t.get_id.
 226  */
 227 static identification_t* get_id(private_openssl_ec_private_key_t *this,
 228                                                                 id_type_t type)
 229 {
 230         switch (type)
 231         {
 232                 case ID_PUBKEY_INFO_SHA1:
 233                         return this->keyid_info;
 234                 case ID_PUBKEY_SHA1:
 235                         return this->keyid;
 236                 default:
 237                         return NULL;
 238         }
 239 }
 240
 241 /**
 242  * Implementation of private_key_t.get_public_key.
 243  */
 244 static openssl_ec_public_key_t* get_public_key(private_openssl_ec_private_key_t *this)
 245 {
 246         return openssl_ec_public_key_create_from_private_key(this->ec);
 247 }
 248
 249 /**
 250  * Implementation of private_key_t.belongs_to.
 251  */
 252 static bool belongs_to(private_openssl_ec_private_key_t *this, public_key_t *public)
 253 {
 254         identification_t *keyid;
 255
 256         if (public->get_type(public) != KEY_ECDSA)
 257         {
 258                 return FALSE;
 259         }
 260         keyid = public->get_id(public, ID_PUBKEY_SHA1);
 261         if (keyid && keyid->equals(keyid, this->keyid))
 262         {
 263                 return TRUE;
 264         }
 265         keyid = public->get_id(public, ID_PUBKEY_INFO_SHA1);
 266         if (keyid && keyid->equals(keyid, this->keyid_info))
 267         {
 268                 return TRUE;
 269         }
 270         return FALSE;
 271 }
 272
 273 /**
 274  * Implementation of private_key_t.get_encoding.
 275  */
 276 static chunk_t get_encoding(private_openssl_ec_private_key_t *this)
 277 {
 278         chunk_t enc = chunk_alloc(i2d_ECPrivateKey(this->ec, NULL));
 279         u_char *p = enc.ptr;
 280         i2d_ECPrivateKey(this->ec, &p);
 281         return enc;
 282 }
 283
 284 /**
 285  * Implementation of private_key_t.get_ref.
 286  */
 287 static private_openssl_ec_private_key_t* get_ref(private_openssl_ec_private_key_t *this)
 288 {
 289         ref_get(&this->ref);
 290         return this;
 291
 292 }
 293
 294 /**
 295  * Implementation of private_key_t.destroy.
 296  */
 297 static void destroy(private_openssl_ec_private_key_t *this)
 298 {
 299         if (ref_put(&this->ref))
 300         {
 301                 if (this->ec)
 302                 {
 303                         EC_KEY_free(this->ec);
 304                 }
 305                 DESTROY_IF(this->keyid);
 306                 DESTROY_IF(this->keyid_info);
 307                 free(this);
 308         }
 309 }
 310
 311 /**
 312  * Internal generic constructor
 313  */
 314 static private_openssl_ec_private_key_t *openssl_ec_private_key_create_empty(void)
 315 {
 316         private_openssl_ec_private_key_t *this = malloc_thing(private_openssl_ec_private_key_t);
 317
 318         this->public.interface.get_type = (key_type_t (*)(private_key_t *this))get_type;
 319         this->public.interface.sign = (bool (*)(private_key_t *this, signature_scheme_t scheme, chunk_t data, chunk_t *signature))sign;
 320         this->public.interface.decrypt = (bool (*)(private_key_t *this, chunk_t crypto, chunk_t *plain))decrypt;
 321         this->public.interface.get_keysize = (size_t (*) (private_key_t *this))get_keysize;
 322         this->public.interface.get_id = (identification_t* (*) (private_key_t *this,id_type_t))get_id;
 323         this->public.interface.get_public_key = (public_key_t* (*)(private_key_t *this))get_public_key;
 324         this->public.interface.belongs_to = (bool (*) (private_key_t *this, public_key_t *public))belongs_to;
 325         this->public.interface.get_encoding = (chunk_t(*)(private_key_t*))get_encoding;
 326         this->public.interface.get_ref = (private_key_t* (*)(private_key_t *this))get_ref;
 327         this->public.interface.destroy = (void (*)(private_key_t *this))destroy;
 328
 329         this->ec = NULL;
 330         this->keyid = NULL;
 331         this->keyid_info = NULL;
 332         this->ref = 1;
 333
 334         return this;
 335 }
 336
 337 /**
 338  * load private key from an ASN1 encoded blob
 339  */
 340 static openssl_ec_private_key_t *load(chunk_t blob)
 341 {
 342         u_char *p = blob.ptr;
 343         private_openssl_ec_private_key_t *this = openssl_ec_private_key_create_empty();
 344
 345         this->ec = d2i_ECPrivateKey(NULL, (const u_char**)&p, blob.len);
 346
 347         chunk_clear(&blob);
 348
 349         if (!this->ec)
 350         {
 351                 destroy(this);
 352                 return NULL;
 353         }
 354
 355         if (!openssl_ec_public_key_build_id(this->ec, &this->keyid, &this->keyid_info))
 356         {
 357                 destroy(this);
 358                 return NULL;
 359         }
 360
 361         if (!EC_KEY_check_key(this->ec))
 362         {
 363                 destroy(this);
 364                 return NULL;
 365         }
 366
 367         return &this->public;
 368 }
 369
 370 typedef struct private_builder_t private_builder_t;
 371 /**
 372  * Builder implementation for key loading/generation
 373  */
 374 struct private_builder_t {
 375         /** implements the builder interface */
 376         builder_t public;
 377         /** loaded/generated private key */
 378         openssl_ec_private_key_t *key;
 379 };
 380
 381 /**
 382  * Implementation of builder_t.build
 383  */
 384 static openssl_ec_private_key_t *build(private_builder_t *this)
 385 {
 386         openssl_ec_private_key_t *key = this->key;
 387
 388         free(this);
 389         return key;
 390 }
 391
 392 /**
 393  * Implementation of builder_t.add
 394  */
 395 static void add(private_builder_t *this, builder_part_t part, ...)
 396 {
 397         if (!this->key)
 398         {
 399                 va_list args;
 400                 chunk_t chunk;
 401
 402                 switch (part)
 403                 {
 404                         case BUILD_BLOB_ASN1_DER:
 405                         {
 406                                 va_start(args, part);
 407                                 chunk = va_arg(args, chunk_t);
 408                                 this->key = load(chunk_clone(chunk));
 409                                 va_end(args);
 410                                 return;
 411                         }
 412                         default:
 413                                 break;
 414                 }
 415         }
 416         if (this->key)
 417         {
 418                 destroy((private_openssl_ec_private_key_t*)this->key);
 419         }
 420         builder_cancel(&this->public);
 421 }
 422
 423 /**
 424  * Builder construction function
 425  */
 426 builder_t *openssl_ec_private_key_builder(key_type_t type)
 427 {
 428         private_builder_t *this;
 429
 430         if (type != KEY_ECDSA)
 431         {
 432                 return NULL;
 433         }
 434
 435         this = malloc_thing(private_builder_t);
 436
 437         this->key = NULL;
 438         this->public.add = (void(*)(builder_t *this, builder_part_t part, ...))add;
 439         this->public.build = (void*(*)(builder_t *this))build;
 440
 441         return &this->public;
 442 }
 443