crypto/ec/ecx_meth.c

   1 /*
   2  * Copyright 2006-2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <stdio.h>
  11 #include "internal/cryptlib.h"
  12 #include <openssl/x509.h>
  13 #include <openssl/ec.h>
  14 #include <openssl/rand.h>
  15 #include "internal/asn1_int.h"
  16 #include "internal/evp_int.h"
  17 #include "ec_lcl.h"
  18
  19 #define X25519_KEYLEN        32
  20 #define X25519_BITS          253
  21 #define X25519_SECURITY_BITS 128
  22
  23 #define ED25519_SIGSIZE      64
  24
  25 typedef struct {
  26     unsigned char pubkey[X25519_KEYLEN];
  27     unsigned char *privkey;
  28 } X25519_KEY;
  29
  30 typedef enum {
  31     X25519_PUBLIC,
  32     X25519_PRIVATE,
  33     X25519_KEYGEN
  34 } ecx_key_op_t;
  35
  36 /* Setup EVP_PKEY using public, private or generation */
  37 static int ecx_key_op(EVP_PKEY *pkey, int id, const X509_ALGOR *palg,
  38                       const unsigned char *p, int plen, ecx_key_op_t op)
  39 {
  40     X25519_KEY *xkey;
  41
  42     if (op != X25519_KEYGEN) {
  43         if (palg != NULL) {
  44             int ptype;
  45
  46             /* Algorithm parameters must be absent */
  47             X509_ALGOR_get0(NULL, &ptype, NULL, palg);
  48             if (ptype != V_ASN1_UNDEF) {
  49                 ECerr(EC_F_ECX_KEY_OP, EC_R_INVALID_ENCODING);
  50                 return 0;
  51             }
  52         }
  53
  54         if (p == NULL || plen != X25519_KEYLEN) {
  55             ECerr(EC_F_ECX_KEY_OP, EC_R_INVALID_ENCODING);
  56             return 0;
  57         }
  58     }
  59
  60     xkey = OPENSSL_zalloc(sizeof(*xkey));
  61     if (xkey == NULL) {
  62         ECerr(EC_F_ECX_KEY_OP, ERR_R_MALLOC_FAILURE);
  63         return 0;
  64     }
  65
  66     if (op == X25519_PUBLIC) {
  67         memcpy(xkey->pubkey, p, plen);
  68     } else {
  69         xkey->privkey = OPENSSL_secure_malloc(X25519_KEYLEN);
  70         if (xkey->privkey == NULL) {
  71             ECerr(EC_F_ECX_KEY_OP, ERR_R_MALLOC_FAILURE);
  72             OPENSSL_free(xkey);
  73             return 0;
  74         }
  75         if (op == X25519_KEYGEN) {
  76             if (RAND_bytes(xkey->privkey, X25519_KEYLEN) <= 0) {
  77                 OPENSSL_secure_free(xkey->privkey);
  78                 OPENSSL_free(xkey);
  79                 return 0;
  80             }
  81             if (id == NID_X25519) {
  82                 xkey->privkey[0] &= 248;
  83                 xkey->privkey[31] &= 127;
  84                 xkey->privkey[31] |= 64;
  85             }
  86         } else {
  87             memcpy(xkey->privkey, p, X25519_KEYLEN);
  88         }
  89         if (id == NID_X25519)
  90             X25519_public_from_private(xkey->pubkey, xkey->privkey);
  91         else
  92             ED25519_public_from_private(xkey->pubkey, xkey->privkey);
  93     }
  94
  95     EVP_PKEY_assign(pkey, id, xkey);
  96     return 1;
  97 }
  98
  99 static int ecx_pub_encode(X509_PUBKEY *pk, const EVP_PKEY *pkey)
 100 {
 101     const X25519_KEY *xkey = pkey->pkey.ptr;
 102     unsigned char *penc;
 103
 104     if (xkey == NULL) {
 105         ECerr(EC_F_ECX_PUB_ENCODE, EC_R_INVALID_KEY);
 106         return 0;
 107     }
 108
 109     penc = OPENSSL_memdup(xkey->pubkey, X25519_KEYLEN);
 110     if (penc == NULL) {
 111         ECerr(EC_F_ECX_PUB_ENCODE, ERR_R_MALLOC_FAILURE);
 112         return 0;
 113     }
 114
 115     if (!X509_PUBKEY_set0_param(pk, OBJ_nid2obj(pkey->ameth->pkey_id),
 116                                 V_ASN1_UNDEF, NULL, penc, X25519_KEYLEN)) {
 117         OPENSSL_free(penc);
 118         ECerr(EC_F_ECX_PUB_ENCODE, ERR_R_MALLOC_FAILURE);
 119         return 0;
 120     }
 121     return 1;
 122 }
 123
 124 static int ecx_pub_decode(EVP_PKEY *pkey, X509_PUBKEY *pubkey)
 125 {
 126     const unsigned char *p;
 127     int pklen;
 128     X509_ALGOR *palg;
 129
 130     if (!X509_PUBKEY_get0_param(NULL, &p, &pklen, &palg, pubkey))
 131         return 0;
 132     return ecx_key_op(pkey, pkey->ameth->pkey_id, palg, p, pklen,
 133                       X25519_PUBLIC);
 134 }
 135
 136 static int ecx_pub_cmp(const EVP_PKEY *a, const EVP_PKEY *b)
 137 {
 138     const X25519_KEY *akey = a->pkey.ptr;
 139     const X25519_KEY *bkey = b->pkey.ptr;
 140
 141     if (akey == NULL || bkey == NULL)
 142         return -2;
 143     return !CRYPTO_memcmp(akey->pubkey, bkey->pubkey, X25519_KEYLEN);
 144 }
 145
 146 static int ecx_priv_decode(EVP_PKEY *pkey, const PKCS8_PRIV_KEY_INFO *p8)
 147 {
 148     const unsigned char *p;
 149     int plen;
 150     ASN1_OCTET_STRING *oct = NULL;
 151     const X509_ALGOR *palg;
 152     int rv;
 153
 154     if (!PKCS8_pkey_get0(NULL, &p, &plen, &palg, p8))
 155         return 0;
 156
 157     oct = d2i_ASN1_OCTET_STRING(NULL, &p, plen);
 158     if (oct == NULL) {
 159         p = NULL;
 160         plen = 0;
 161     } else {
 162         p = ASN1_STRING_get0_data(oct);
 163         plen = ASN1_STRING_length(oct);
 164     }
 165
 166     rv = ecx_key_op(pkey, pkey->ameth->pkey_id, palg, p, plen, X25519_PRIVATE);
 167     ASN1_OCTET_STRING_free(oct);
 168     return rv;
 169 }
 170
 171 static int ecx_priv_encode(PKCS8_PRIV_KEY_INFO *p8, const EVP_PKEY *pkey)
 172 {
 173     const X25519_KEY *xkey = pkey->pkey.ptr;
 174     ASN1_OCTET_STRING oct;
 175     unsigned char *penc = NULL;
 176     int penclen;
 177
 178     if (xkey == NULL || xkey->privkey == NULL) {
 179         ECerr(EC_F_ECX_PRIV_ENCODE, EC_R_INVALID_PRIVATE_KEY);
 180         return 0;
 181     }
 182
 183     oct.data = xkey->privkey;
 184     oct.length = X25519_KEYLEN;
 185     oct.flags = 0;
 186
 187     penclen = i2d_ASN1_OCTET_STRING(&oct, &penc);
 188     if (penclen < 0) {
 189         ECerr(EC_F_ECX_PRIV_ENCODE, ERR_R_MALLOC_FAILURE);
 190         return 0;
 191     }
 192
 193     if (!PKCS8_pkey_set0(p8, OBJ_nid2obj(pkey->ameth->pkey_id), 0,
 194                          V_ASN1_UNDEF, NULL, penc, penclen)) {
 195         OPENSSL_clear_free(penc, penclen);
 196         ECerr(EC_F_ECX_PRIV_ENCODE, ERR_R_MALLOC_FAILURE);
 197         return 0;
 198     }
 199
 200     return 1;
 201 }
 202
 203 static int ecx_size(const EVP_PKEY *pkey)
 204 {
 205     return X25519_KEYLEN;
 206 }
 207
 208 static int ecx_bits(const EVP_PKEY *pkey)
 209 {
 210     return X25519_BITS;
 211 }
 212
 213 static int ecx_security_bits(const EVP_PKEY *pkey)
 214 {
 215     return X25519_SECURITY_BITS;
 216 }
 217
 218 static void ecx_free(EVP_PKEY *pkey)
 219 {
 220     X25519_KEY *xkey = pkey->pkey.ptr;
 221
 222     if (xkey)
 223         OPENSSL_secure_free(xkey->privkey);
 224     OPENSSL_free(xkey);
 225 }
 226
 227 /* "parameters" are always equal */
 228 static int ecx_cmp_parameters(const EVP_PKEY *a, const EVP_PKEY *b)
 229 {
 230     return 1;
 231 }
 232
 233 static int ecx_key_print(BIO *bp, const EVP_PKEY *pkey, int indent,
 234                          ASN1_PCTX *ctx, ecx_key_op_t op)
 235 {
 236     const X25519_KEY *xkey = pkey->pkey.ptr;
 237
 238     const char *nm = OBJ_nid2ln(pkey->ameth->pkey_id);
 239
 240     if (op == X25519_PRIVATE) {
 241         if (xkey == NULL || xkey->privkey == NULL) {
 242             if (BIO_printf(bp, "%*s<INVALID PRIVATE KEY>\n", indent, "") <= 0)
 243                 return 0;
 244             return 1;
 245         }
 246         if (BIO_printf(bp, "%*s%s Private-Key:\n", indent, "", nm) <= 0)
 247             return 0;
 248         if (BIO_printf(bp, "%*spriv:\n", indent, "") <= 0)
 249             return 0;
 250         if (ASN1_buf_print(bp, xkey->privkey, X25519_KEYLEN, indent + 4) == 0)
 251             return 0;
 252     } else {
 253         if (xkey == NULL) {
 254             if (BIO_printf(bp, "%*s<INVALID PUBLIC KEY>\n", indent, "") <= 0)
 255                 return 0;
 256             return 1;
 257         }
 258         if (BIO_printf(bp, "%*s%s Public-Key:\n", indent, "", nm) <= 0)
 259             return 0;
 260     }
 261     if (BIO_printf(bp, "%*spub:\n", indent, "") <= 0)
 262         return 0;
 263     if (ASN1_buf_print(bp, xkey->pubkey, X25519_KEYLEN, indent + 4) == 0)
 264         return 0;
 265     return 1;
 266 }
 267
 268 static int ecx_priv_print(BIO *bp, const EVP_PKEY *pkey, int indent,
 269                           ASN1_PCTX *ctx)
 270 {
 271     return ecx_key_print(bp, pkey, indent, ctx, X25519_PRIVATE);
 272 }
 273
 274 static int ecx_pub_print(BIO *bp, const EVP_PKEY *pkey, int indent,
 275                          ASN1_PCTX *ctx)
 276 {
 277     return ecx_key_print(bp, pkey, indent, ctx, X25519_PUBLIC);
 278 }
 279
 280 static int ecx_ctrl(EVP_PKEY *pkey, int op, long arg1, void *arg2)
 281 {
 282     switch (op) {
 283
 284     case ASN1_PKEY_CTRL_SET1_TLS_ENCPT:
 285         return ecx_key_op(pkey, NID_X25519, NULL, arg2, arg1, X25519_PUBLIC);
 286
 287     case ASN1_PKEY_CTRL_GET1_TLS_ENCPT:
 288         if (pkey->pkey.ptr != NULL) {
 289             const X25519_KEY *xkey = pkey->pkey.ptr;
 290             unsigned char **ppt = arg2;
 291             *ppt = OPENSSL_memdup(xkey->pubkey, X25519_KEYLEN);
 292             if (*ppt != NULL)
 293                 return X25519_KEYLEN;
 294         }
 295         return 0;
 296
 297     case ASN1_PKEY_CTRL_DEFAULT_MD_NID:
 298         *(int *)arg2 = NID_sha256;
 299         return 2;
 300
 301     default:
 302         return -2;
 303
 304     }
 305 }
 306
 307 const EVP_PKEY_ASN1_METHOD ecx25519_asn1_meth = {
 308     NID_X25519,
 309     NID_X25519,
 310     0,
 311     "X25519",
 312     "OpenSSL X25519 algorithm",
 313
 314     ecx_pub_decode,
 315     ecx_pub_encode,
 316     ecx_pub_cmp,
 317     ecx_pub_print,
 318
 319     ecx_priv_decode,
 320     ecx_priv_encode,
 321     ecx_priv_print,
 322
 323     ecx_size,
 324     ecx_bits,
 325     ecx_security_bits,
 326
 327     0, 0, 0, 0,
 328     ecx_cmp_parameters,
 329     0, 0,
 330
 331     ecx_free,
 332     ecx_ctrl,
 333     NULL,
 334     NULL
 335 };
 336
 337 static int ecd_size(const EVP_PKEY *pkey)
 338 {
 339     return ED25519_SIGSIZE;
 340 }
 341
 342 const EVP_PKEY_ASN1_METHOD ed25519_asn1_meth = {
 343     NID_ED25519,
 344     NID_ED25519,
 345     0,
 346     "ED25519",
 347     "OpenSSL ED25519 algorithm",
 348
 349     ecx_pub_decode,
 350     ecx_pub_encode,
 351     ecx_pub_cmp,
 352     ecx_pub_print,
 353
 354     ecx_priv_decode,
 355     ecx_priv_encode,
 356     ecx_priv_print,
 357
 358     ecd_size,
 359     ecx_bits,
 360     ecx_security_bits,
 361
 362     0, 0, 0, 0,
 363     ecx_cmp_parameters,
 364     0, 0,
 365
 366     ecx_free,
 367     0,
 368     NULL,
 369     NULL
 370 };
 371
 372 static int pkey_ecx_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
 373 {
 374     return ecx_key_op(pkey, ctx->pmeth->pkey_id, NULL, NULL, 0, X25519_KEYGEN);
 375 }
 376
 377 static int pkey_ecx_derive(EVP_PKEY_CTX *ctx, unsigned char *key,
 378                            size_t *keylen)
 379 {
 380     const X25519_KEY *pkey, *peerkey;
 381
 382     if (ctx->pkey == NULL || ctx->peerkey == NULL) {
 383         ECerr(EC_F_PKEY_ECX_DERIVE, EC_R_KEYS_NOT_SET);
 384         return 0;
 385     }
 386     pkey = ctx->pkey->pkey.ptr;
 387     peerkey = ctx->peerkey->pkey.ptr;
 388     if (pkey == NULL || pkey->privkey == NULL) {
 389         ECerr(EC_F_PKEY_ECX_DERIVE, EC_R_INVALID_PRIVATE_KEY);
 390         return 0;
 391     }
 392     if (peerkey == NULL) {
 393         ECerr(EC_F_PKEY_ECX_DERIVE, EC_R_INVALID_PEER_KEY);
 394         return 0;
 395     }
 396     *keylen = X25519_KEYLEN;
 397     if (key != NULL && X25519(key, pkey->privkey, peerkey->pubkey) == 0)
 398         return 0;
 399     return 1;
 400 }
 401
 402 static int pkey_ecx_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
 403 {
 404     /* Only need to handle peer key for derivation */
 405     if (type == EVP_PKEY_CTRL_PEER_KEY)
 406         return 1;
 407     return -2;
 408 }
 409
 410 const EVP_PKEY_METHOD ecx25519_pkey_meth = {
 411     NID_X25519,
 412     0, 0, 0, 0, 0, 0, 0,
 413     pkey_ecx_keygen,
 414     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 415     pkey_ecx_derive,
 416     pkey_ecx_ctrl,
 417     0
 418 };
 419
 420 static int pkey_ecd_digestsign(EVP_MD_CTX *ctx, unsigned char *sig,
 421                                size_t *siglen, const unsigned char *tbs,
 422                                size_t tbslen)
 423 {
 424     const X25519_KEY *edkey = EVP_MD_CTX_pkey_ctx(ctx)->pkey->pkey.ptr;
 425
 426     if (sig == NULL) {
 427         *siglen = ED25519_SIGSIZE;
 428         return 1;
 429     }
 430     if (*siglen < ED25519_SIGSIZE) {
 431         ECerr(EC_F_PKEY_ECD_DIGESTSIGN, EC_R_BUFFER_TOO_SMALL);
 432         return 0;
 433     }
 434
 435     if (ED25519_sign(sig, tbs, tbslen, edkey->pubkey, edkey->privkey) == 0)
 436         return 0;
 437     *siglen = ED25519_SIGSIZE;
 438     return 1;
 439 }
 440
 441 static int pkey_ecd_digestverify(EVP_MD_CTX *ctx, const unsigned char *sig,
 442                                  size_t siglen, const unsigned char *tbs,
 443                                  size_t tbslen)
 444 {
 445     const X25519_KEY *edkey = EVP_MD_CTX_pkey_ctx(ctx)->pkey->pkey.ptr;
 446
 447     if (siglen != ED25519_SIGSIZE)
 448         return 0;
 449
 450     return ED25519_verify(tbs, tbslen, sig, edkey->pubkey);
 451 }
 452
 453 static int pkey_ecd_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
 454 {
 455     switch (type) {
 456     case EVP_PKEY_CTRL_MD:
 457         /* Only NULL allowed as digest */
 458         if (p2 == NULL)
 459             return 1;
 460         ECerr(EC_F_PKEY_ECD_CTRL, EC_R_INVALID_DIGEST_TYPE);
 461         return 0;
 462
 463     case EVP_PKEY_CTRL_DIGESTINIT:
 464         return 1;
 465     }
 466     return -2;
 467 }
 468
 469 const EVP_PKEY_METHOD ed25519_pkey_meth = {
 470     NID_ED25519, EVP_PKEY_FLAG_SIGCTX_CUSTOM,
 471     0, 0, 0, 0, 0, 0,
 472     pkey_ecx_keygen,
 473     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 474     pkey_ecd_ctrl,
 475     0,
 476     pkey_ecd_digestsign,
 477     pkey_ecd_digestverify
 478 };