test/ecdsatest.c

   1 /*
   2  * Copyright 2002-2018 The OpenSSL Project Authors. All Rights Reserved.
   3  * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
   4  *
   5  * Licensed under the Apache License 2.0 (the "License").  You may not use
   6  * this file except in compliance with the License.  You can obtain a copy
   7  * in the file LICENSE in the source distribution or at
   8  * https://www.openssl.org/source/license.html
   9  */
  10
  11 #include <openssl/opensslconf.h> /* To see if OPENSSL_NO_EC is defined */
  12 #include "testutil.h"
  13
  14 #ifndef OPENSSL_NO_EC
  15
  16 # include <openssl/evp.h>
  17 # include <openssl/bn.h>
  18 # include <openssl/ec.h>
  19 # include <openssl/rand.h>
  20 # include "internal/nelem.h"
  21 # include "ecdsatest.h"
  22
  23 /* functions to change the RAND_METHOD */
  24 static int fbytes(unsigned char *buf, int num);
  25
  26 static RAND_METHOD fake_rand;
  27 static const RAND_METHOD *old_rand;
  28 static int use_fake = 0;
  29 static const char *numbers[2];
  30 static size_t crv_len = 0;
  31 static EC_builtin_curve *curves = NULL;
  32
  33 static int change_rand(void)
  34 {
  35     /* save old rand method */
  36     if (!TEST_ptr(old_rand = RAND_get_rand_method()))
  37         return 0;
  38
  39     fake_rand = *old_rand;
  40     /* use own random function */
  41     fake_rand.bytes = fbytes;
  42     /* set new RAND_METHOD */
  43     if (!TEST_true(RAND_set_rand_method(&fake_rand)))
  44         return 0;
  45     return 1;
  46 }
  47
  48 static int restore_rand(void)
  49 {
  50     if (!TEST_true(RAND_set_rand_method(old_rand)))
  51         return 0;
  52     return 1;
  53 }
  54
  55 static int fbytes(unsigned char *buf, int num)
  56 {
  57     int ret = 0;
  58     static int fbytes_counter = 0;
  59     BIGNUM *tmp = NULL;
  60
  61     if (use_fake == 0)
  62         return old_rand->bytes(buf, num);
  63
  64     use_fake = 0;
  65
  66     if (!TEST_ptr(tmp = BN_new())
  67         || !TEST_int_lt(fbytes_counter, OSSL_NELEM(numbers))
  68         || !TEST_true(BN_hex2bn(&tmp, numbers[fbytes_counter]))
  69         /* tmp might need leading zeros so pad it out */
  70         || !TEST_int_le(BN_num_bytes(tmp), num)
  71         || !TEST_true(BN_bn2binpad(tmp, buf, num)))
  72         goto err;
  73
  74     fbytes_counter = (fbytes_counter + 1) % OSSL_NELEM(numbers);
  75     ret = 1;
  76  err:
  77     BN_free(tmp);
  78     return ret;
  79 }
  80
  81 /*-
  82  * This function hijacks the RNG to feed it the chosen ECDSA key and nonce.
  83  * The ECDSA KATs are from:
  84  * - the X9.62 draft (4)
  85  * - NIST CAVP (720)
  86  *
  87  * It uses the low-level ECDSA_sign_setup instead of EVP to control the RNG.
  88  * NB: This is not how applications should use ECDSA; this is only for testing.
  89  *
  90  * Tests the library can successfully:
  91  * - generate public keys that matches those KATs
  92  * - create ECDSA signatures that match those KATs
  93  * - accept those signatures as valid
  94  */
  95 static int x9_62_tests(int n)
  96 {
  97     int nid, md_nid, ret = 0;
  98     const char *r_in = NULL, *s_in = NULL, *tbs = NULL;
  99     unsigned char *pbuf = NULL, *qbuf = NULL, *message = NULL;
 100     unsigned char digest[EVP_MAX_MD_SIZE];
 101     unsigned int dgst_len = 0;
 102     long q_len, msg_len = 0;
 103     size_t p_len;
 104     EVP_MD_CTX *mctx = NULL;
 105     EC_KEY *key = NULL;
 106     ECDSA_SIG *signature = NULL;
 107     BIGNUM *r = NULL, *s = NULL;
 108     BIGNUM *kinv = NULL, *rp = NULL;
 109     const BIGNUM *sig_r = NULL, *sig_s = NULL;
 110
 111     nid = ecdsa_cavs_kats[n].nid;
 112     md_nid = ecdsa_cavs_kats[n].md_nid;
 113     r_in = ecdsa_cavs_kats[n].r;
 114     s_in = ecdsa_cavs_kats[n].s;
 115     tbs = ecdsa_cavs_kats[n].msg;
 116     numbers[0] = ecdsa_cavs_kats[n].d;
 117     numbers[1] = ecdsa_cavs_kats[n].k;
 118
 119     TEST_info("ECDSA KATs for curve %s", OBJ_nid2sn(nid));
 120
 121     if (!TEST_ptr(mctx = EVP_MD_CTX_new())
 122         /* get the message digest */
 123         || !TEST_ptr(message = OPENSSL_hexstr2buf(tbs, &msg_len))
 124         || !TEST_true(EVP_DigestInit_ex(mctx, EVP_get_digestbynid(md_nid), NULL))
 125         || !TEST_true(EVP_DigestUpdate(mctx, message, msg_len))
 126         || !TEST_true(EVP_DigestFinal_ex(mctx, digest, &dgst_len))
 127         /* create the key */
 128         || !TEST_ptr(key = EC_KEY_new_by_curve_name(nid))
 129         /* load KAT variables */
 130         || !TEST_ptr(r = BN_new())
 131         || !TEST_ptr(s = BN_new())
 132         || !TEST_true(BN_hex2bn(&r, r_in))
 133         || !TEST_true(BN_hex2bn(&s, s_in))
 134         /* swap the RNG source */
 135         || !TEST_true(change_rand()))
 136         goto err;
 137
 138     /* public key must match KAT */
 139     use_fake = 1;
 140     if (!TEST_true(EC_KEY_generate_key(key))
 141         || !TEST_true(p_len = EC_KEY_key2buf(key, POINT_CONVERSION_UNCOMPRESSED,
 142                                              &pbuf, NULL))
 143         || !TEST_ptr(qbuf = OPENSSL_hexstr2buf(ecdsa_cavs_kats[n].Q, &q_len))
 144         || !TEST_int_eq(q_len, p_len)
 145         || !TEST_mem_eq(qbuf, q_len, pbuf, p_len))
 146         goto err;
 147
 148     /* create the signature via ECDSA_sign_setup to avoid use of ECDSA nonces */
 149     use_fake = 1;
 150     if (!TEST_true(ECDSA_sign_setup(key, NULL, &kinv, &rp))
 151         || !TEST_ptr(signature = ECDSA_do_sign_ex(digest, dgst_len,
 152                                                   kinv, rp, key))
 153         /* verify the signature */
 154         || !TEST_int_eq(ECDSA_do_verify(digest, dgst_len, signature, key), 1))
 155         goto err;
 156
 157     /* compare the created signature with the expected signature */
 158     ECDSA_SIG_get0(signature, &sig_r, &sig_s);
 159     if (!TEST_BN_eq(sig_r, r)
 160         || !TEST_BN_eq(sig_s, s))
 161         goto err;
 162
 163     ret = 1;
 164
 165  err:
 166     /* restore the RNG source */
 167     if (!TEST_true(restore_rand()))
 168         ret = 0;
 169
 170     OPENSSL_free(message);
 171     OPENSSL_free(pbuf);
 172     OPENSSL_free(qbuf);
 173     EC_KEY_free(key);
 174     ECDSA_SIG_free(signature);
 175     BN_free(r);
 176     BN_free(s);
 177     EVP_MD_CTX_free(mctx);
 178     BN_clear_free(kinv);
 179     BN_clear_free(rp);
 180     return ret;
 181 }
 182
 183 /*-
 184  * Positive and negative ECDSA testing through EVP interface:
 185  * - EVP_DigestSign (this is the one-shot version)
 186  * - EVP_DigestVerify
 187  *
 188  * Tests the library can successfully:
 189  * - create a key
 190  * - create a signature
 191  * - accept that signature
 192  * - reject that signature with a different public key
 193  * - reject that signature if its length is not correct
 194  * - reject that signature after modifying the message
 195  * - accept that signature after un-modifying the message
 196  * - reject that signature after modifying the signature
 197  * - accept that signature after un-modifying the signature
 198  */
 199 static int test_builtin(int n)
 200 {
 201     EC_KEY *eckey_neg = NULL, *eckey = NULL;
 202     unsigned char dirt, offset, tbs[128];
 203     unsigned char *sig = NULL;
 204     EVP_PKEY *pkey_neg = NULL, *pkey = NULL;
 205     EVP_MD_CTX *mctx = NULL;
 206     size_t sig_len;
 207     int nid, ret = 0;
 208
 209     nid = curves[n].nid;
 210
 211     /* skip built-in curves where ord(G) is not prime */
 212     if (nid == NID_ipsec4 || nid == NID_ipsec3) {
 213         TEST_info("skipped: ECDSA unsupported for curve %s", OBJ_nid2sn(nid));
 214         return 1;
 215     }
 216
 217     TEST_info("testing ECDSA for curve %s", OBJ_nid2sn(nid));
 218
 219     if (!TEST_ptr(mctx = EVP_MD_CTX_new())
 220         /* get some random message data */
 221         || !TEST_true(RAND_bytes(tbs, sizeof(tbs)))
 222         /* real key */
 223         || !TEST_ptr(eckey = EC_KEY_new_by_curve_name(nid))
 224         || !TEST_true(EC_KEY_generate_key(eckey))
 225         || !TEST_ptr(pkey = EVP_PKEY_new())
 226         || !TEST_true(EVP_PKEY_assign_EC_KEY(pkey, eckey))
 227         /* fake key for negative testing */
 228         || !TEST_ptr(eckey_neg = EC_KEY_new_by_curve_name(nid))
 229         || !TEST_true(EC_KEY_generate_key(eckey_neg))
 230         || !TEST_ptr(pkey_neg = EVP_PKEY_new())
 231         || !TEST_true(EVP_PKEY_assign_EC_KEY(pkey_neg, eckey_neg)))
 232         goto err;
 233
 234     sig_len = ECDSA_size(eckey);
 235
 236     if (!TEST_ptr(sig = OPENSSL_malloc(sig_len))
 237         /* create a signature */
 238         || !TEST_true(EVP_DigestSignInit(mctx, NULL, NULL, NULL, pkey))
 239         || !TEST_true(EVP_DigestSign(mctx, sig, &sig_len, tbs, sizeof(tbs)))
 240         || !TEST_int_le(sig_len, ECDSA_size(eckey))
 241         /* negative test, verify with wrong key, 0 return */
 242         || !TEST_true(EVP_MD_CTX_reset(mctx))
 243         || !TEST_true(EVP_DigestVerifyInit(mctx, NULL, NULL, NULL, pkey_neg))
 244         || !TEST_int_eq(EVP_DigestVerify(mctx, sig, sig_len, tbs, sizeof(tbs)), 0)
 245         /* negative test, verify with wrong signature length, -1 return */
 246         || !TEST_true(EVP_MD_CTX_reset(mctx))
 247         || !TEST_true(EVP_DigestVerifyInit(mctx, NULL, NULL, NULL, pkey))
 248         || !TEST_int_eq(EVP_DigestVerify(mctx, sig, sig_len - 1, tbs, sizeof(tbs)), -1)
 249         /* positive test, verify with correct key, 1 return */
 250         || !TEST_true(EVP_MD_CTX_reset(mctx))
 251         || !TEST_true(EVP_DigestVerifyInit(mctx, NULL, NULL, NULL, pkey))
 252         || !TEST_int_eq(EVP_DigestVerify(mctx, sig, sig_len, tbs, sizeof(tbs)), 1))
 253         goto err;
 254
 255     /* muck with the message, test it fails with 0 return */
 256     tbs[0] ^= 1;
 257     if (!TEST_true(EVP_MD_CTX_reset(mctx))
 258         || !TEST_true(EVP_DigestVerifyInit(mctx, NULL, NULL, NULL, pkey))
 259         || !TEST_int_eq(EVP_DigestVerify(mctx, sig, sig_len, tbs, sizeof(tbs)), 0))
 260         goto err;
 261     /* un-muck and test it verifies */
 262     tbs[0] ^= 1;
 263     if (!TEST_true(EVP_MD_CTX_reset(mctx))
 264         || !TEST_true(EVP_DigestVerifyInit(mctx, NULL, NULL, NULL, pkey))
 265         || !TEST_int_eq(EVP_DigestVerify(mctx, sig, sig_len, tbs, sizeof(tbs)), 1))
 266         goto err;
 267
 268     /*-
 269      * Muck with the ECDSA signature. The DER encoding is one of:
 270      * - 30 LL 02 ..
 271      * - 30 81 LL 02 ..
 272      *
 273      * - Sometimes this mucks with the high level DER sequence wrapper:
 274      *   in that case, DER-parsing of the whole signature should fail.
 275      *
 276      * - Sometimes this mucks with the DER-encoding of ECDSA.r:
 277      *   in that case, DER-parsing of ECDSA.r should fail.
 278      *
 279      * - Sometimes this mucks with the DER-encoding of ECDSA.s:
 280      *   in that case, DER-parsing of ECDSA.s should fail.
 281      *
 282      * - Sometimes this mucks with ECDSA.r:
 283      *   in that case, the signature verification should fail.
 284      *
 285      * - Sometimes this mucks with ECDSA.s:
 286      *   in that case, the signature verification should fail.
 287      *
 288      * The usual case is changing the integer value of ECDSA.r or ECDSA.s.
 289      * Because the ratio of DER overhead to signature bytes is small.
 290      * So most of the time it will be one of the last two cases.
 291      *
 292      * In any case, EVP_PKEY_verify should not return 1 for valid.
 293      */
 294     offset = tbs[0] % sig_len;
 295     dirt = tbs[1] ? tbs[1] : 1;
 296     sig[offset] ^= dirt;
 297     if (!TEST_true(EVP_MD_CTX_reset(mctx))
 298         || !TEST_true(EVP_DigestVerifyInit(mctx, NULL, NULL, NULL, pkey))
 299         || !TEST_int_ne(EVP_DigestVerify(mctx, sig, sig_len, tbs, sizeof(tbs)), 1))
 300         goto err;
 301     /* un-muck and test it verifies */
 302     sig[offset] ^= dirt;
 303     if (!TEST_true(EVP_MD_CTX_reset(mctx))
 304         || !TEST_true(EVP_DigestVerifyInit(mctx, NULL, NULL, NULL, pkey))
 305         || !TEST_int_eq(EVP_DigestVerify(mctx, sig, sig_len, tbs, sizeof(tbs)), 1))
 306         goto err;
 307
 308     ret = 1;
 309  err:
 310     EVP_PKEY_free(pkey);
 311     EVP_PKEY_free(pkey_neg);
 312     EVP_MD_CTX_free(mctx);
 313     OPENSSL_free(sig);
 314     return ret;
 315 }
 316 #endif
 317
 318 int setup_tests(void)
 319 {
 320 #ifdef OPENSSL_NO_EC
 321     TEST_note("Elliptic curves are disabled.");
 322 #else
 323     /* get a list of all internal curves */
 324     crv_len = EC_get_builtin_curves(NULL, 0);
 325     if (!TEST_ptr(curves = OPENSSL_malloc(sizeof(*curves) * crv_len))
 326         || !TEST_true(EC_get_builtin_curves(curves, crv_len)))
 327         return 0;
 328     ADD_ALL_TESTS(test_builtin, crv_len);
 329     ADD_ALL_TESTS(x9_62_tests, OSSL_NELEM(ecdsa_cavs_kats));
 330 #endif
 331     return 1;
 332 }
 333
 334 void cleanup_tests(void)
 335 {
 336 #ifndef OPENSSL_NO_EC
 337     OPENSSL_free(curves);
 338 #endif
 339 }