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1 /* ====================================================================
2  * Copyright (c) 1998-2005 The OpenSSL Project.  All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  *
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  *
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in
13  *    the documentation and/or other materials provided with the
14  *    distribution.
15  *
16  * 3. All advertising materials mentioning features or use of this
17  *    software must display the following acknowledgment:
18  *    "This product includes software developed by the OpenSSL Project
19  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
20  *
21  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
22  *    endorse or promote products derived from this software without
23  *    prior written permission. For written permission, please contact
24  *    openssl-core@OpenSSL.org.
25  *
26  * 5. Products derived from this software may not be called "OpenSSL"
27  *    nor may "OpenSSL" appear in their names without prior written
28  *    permission of the OpenSSL Project.
29  *
30  * 6. Redistributions of any form whatsoever must retain the following
31  *    acknowledgment:
32  *    "This product includes software developed by the OpenSSL Project
33  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
34  *
35  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
36  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
37  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
38  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
39  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
40  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
41  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
42  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
43  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
44  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
45  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
46  * OF THE POSSIBILITY OF SUCH DAMAGE.
47  * ====================================================================
48  *
49  * This product includes cryptographic software written by Eric Young
50  * (eay@cryptsoft.com).  This product includes software written by Tim
51  * Hudson (tjh@cryptsoft.com). */
52 
53 #include <openssl/ecdsa.h>
54 
55 #include <vector>
56 
57 #include <openssl/bn.h>
58 #include <openssl/crypto.h>
59 #include <openssl/ec.h>
60 #include <openssl/err.h>
61 #include <openssl/mem.h>
62 #include <openssl/obj.h>
63 #include <openssl/rand.h>
64 
65 #include "../test/scoped_types.h"
66 
67 enum Api {
68   kEncodedApi,
69   kRawApi,
70 };
71 
72 // VerifyECDSASig returns true on success, false on failure.
VerifyECDSASig(Api api,const uint8_t * digest,size_t digest_len,const ECDSA_SIG * ecdsa_sig,EC_KEY * eckey,int expected_result)73 static bool VerifyECDSASig(Api api, const uint8_t *digest,
74                            size_t digest_len, const ECDSA_SIG *ecdsa_sig,
75                            EC_KEY *eckey, int expected_result) {
76   int actual_result;
77 
78   switch (api) {
79     case kEncodedApi: {
80       uint8_t *der;
81       size_t der_len;
82       if (!ECDSA_SIG_to_bytes(&der, &der_len, ecdsa_sig)) {
83         return false;
84       }
85       ScopedOpenSSLBytes delete_der(der);
86       actual_result = ECDSA_verify(0, digest, digest_len, der, der_len, eckey);
87       break;
88     }
89 
90     case kRawApi:
91       actual_result = ECDSA_do_verify(digest, digest_len, ecdsa_sig, eckey);
92       break;
93 
94     default:
95       return false;
96   }
97   return expected_result == actual_result;
98 }
99 
100 // TestTamperedSig verifies that signature verification fails when a valid
101 // signature is tampered with. |ecdsa_sig| must be a valid signature, which will
102 // be modified. TestTamperedSig returns true on success, false on failure.
TestTamperedSig(FILE * out,Api api,const uint8_t * digest,size_t digest_len,ECDSA_SIG * ecdsa_sig,EC_KEY * eckey,const BIGNUM * order)103 static bool TestTamperedSig(FILE *out, Api api, const uint8_t *digest,
104                             size_t digest_len, ECDSA_SIG *ecdsa_sig,
105                             EC_KEY *eckey, const BIGNUM *order) {
106   // Modify a single byte of the signature: to ensure we don't
107   // garble the ASN1 structure, we read the raw signature and
108   // modify a byte in one of the bignums directly.
109 
110   // Store the two BIGNUMs in raw_buf.
111   size_t r_len = BN_num_bytes(ecdsa_sig->r);
112   size_t s_len = BN_num_bytes(ecdsa_sig->s);
113   size_t bn_len = BN_num_bytes(order);
114   if (r_len > bn_len || s_len > bn_len) {
115     return false;
116   }
117   size_t buf_len = 2 * bn_len;
118   std::vector<uint8_t> raw_buf(buf_len);
119   // Pad the bignums with leading zeroes.
120   if (!BN_bn2bin_padded(raw_buf.data(), bn_len, ecdsa_sig->r) ||
121       !BN_bn2bin_padded(raw_buf.data() + bn_len, bn_len, ecdsa_sig->s)) {
122     return false;
123   }
124 
125   // Modify a single byte in the buffer.
126   size_t offset = raw_buf[10] % buf_len;
127   uint8_t dirt = raw_buf[11] ? raw_buf[11] : 1;
128   raw_buf[offset] ^= dirt;
129   // Now read the BIGNUMs back in from raw_buf.
130   if (BN_bin2bn(raw_buf.data(), bn_len, ecdsa_sig->r) == NULL ||
131       BN_bin2bn(raw_buf.data() + bn_len, bn_len, ecdsa_sig->s) == NULL ||
132       !VerifyECDSASig(api, digest, digest_len, ecdsa_sig, eckey, 0)) {
133     return false;
134   }
135 
136   // Sanity check: Undo the modification and verify signature.
137   raw_buf[offset] ^= dirt;
138   if (BN_bin2bn(raw_buf.data(), bn_len, ecdsa_sig->r) == NULL ||
139       BN_bin2bn(raw_buf.data() + bn_len, bn_len, ecdsa_sig->s) == NULL ||
140       !VerifyECDSASig(api, digest, digest_len, ecdsa_sig, eckey, 1)) {
141     return false;
142   }
143 
144   return true;
145 }
146 
TestBuiltin(FILE * out)147 static bool TestBuiltin(FILE *out) {
148   // Fill digest values with some random data.
149   uint8_t digest[20], wrong_digest[20];
150   if (!RAND_bytes(digest, 20) || !RAND_bytes(wrong_digest, 20)) {
151     fprintf(out, "ERROR: unable to get random data\n");
152     return false;
153   }
154 
155   static const struct {
156     int nid;
157     const char *name;
158   } kCurves[] = {
159       { NID_secp224r1, "secp224r1" },
160       { NID_X9_62_prime256v1, "secp256r1" },
161       { NID_secp384r1, "secp384r1" },
162       { NID_secp521r1, "secp521r1" },
163       { NID_undef, NULL }
164   };
165 
166   // Create and verify ECDSA signatures with every available curve.
167   fputs("\ntesting ECDSA_sign(), ECDSA_verify(), ECDSA_do_sign(), and "
168         "ECDSA_do_verify() with some internal curves:\n", out);
169 
170   for (size_t n = 0; kCurves[n].nid != NID_undef; n++) {
171     fprintf(out, "%s: ", kCurves[n].name);
172 
173     int nid = kCurves[n].nid;
174     ScopedEC_GROUP group(EC_GROUP_new_by_curve_name(nid));
175     if (!group) {
176       fprintf(out, " failed\n");
177       return false;
178     }
179     const BIGNUM *order = EC_GROUP_get0_order(group.get());
180     if (BN_num_bits(order) < 160) {
181       // Too small to test.
182       fprintf(out, " skipped\n");
183       continue;
184     }
185 
186     // Create a new ECDSA key.
187     ScopedEC_KEY eckey(EC_KEY_new());
188     if (!eckey || !EC_KEY_set_group(eckey.get(), group.get()) ||
189         !EC_KEY_generate_key(eckey.get())) {
190       fprintf(out, " failed\n");
191       return false;
192     }
193     // Create a second key.
194     ScopedEC_KEY wrong_eckey(EC_KEY_new());
195     if (!wrong_eckey || !EC_KEY_set_group(wrong_eckey.get(), group.get()) ||
196         !EC_KEY_generate_key(wrong_eckey.get())) {
197       fprintf(out, " failed\n");
198       return false;
199     }
200 
201     fprintf(out, ".");
202     fflush(out);
203 
204     // Check the key.
205     if (!EC_KEY_check_key(eckey.get())) {
206       fprintf(out, " failed\n");
207       return false;
208     }
209     fprintf(out, ".");
210     fflush(out);
211 
212     // Test ASN.1-encoded signatures.
213     // Create a signature.
214     unsigned sig_len = ECDSA_size(eckey.get());
215     std::vector<uint8_t> signature(sig_len);
216     if (!ECDSA_sign(0, digest, 20, signature.data(), &sig_len, eckey.get())) {
217       fprintf(out, " failed\n");
218       return false;
219     }
220     signature.resize(sig_len);
221     fprintf(out, ".");
222     fflush(out);
223     // Verify the signature.
224     if (!ECDSA_verify(0, digest, 20, signature.data(), signature.size(),
225                       eckey.get())) {
226       fprintf(out, " failed\n");
227       return false;
228     }
229     fprintf(out, ".");
230     fflush(out);
231     // Verify the signature with the wrong key.
232     if (ECDSA_verify(0, digest, 20, signature.data(), signature.size(),
233                      wrong_eckey.get())) {
234       fprintf(out, " failed\n");
235       return false;
236     }
237     fprintf(out, ".");
238     fflush(out);
239     // Verify the signature using the wrong digest.
240     if (ECDSA_verify(0, wrong_digest, 20, signature.data(), signature.size(),
241                      eckey.get())) {
242       fprintf(out, " failed\n");
243       return false;
244     }
245     fprintf(out, ".");
246     fflush(out);
247     // Verify a truncated signature.
248     if (ECDSA_verify(0, digest, 20, signature.data(), signature.size() - 1,
249                      eckey.get())) {
250       fprintf(out, " failed\n");
251       return false;
252     }
253     fprintf(out, ".");
254     fflush(out);
255     // Verify a tampered signature.
256     ScopedECDSA_SIG ecdsa_sig(ECDSA_SIG_from_bytes(
257         signature.data(), signature.size()));
258     if (!ecdsa_sig ||
259         !TestTamperedSig(out, kEncodedApi, digest, 20, ecdsa_sig.get(),
260                          eckey.get(), order)) {
261       fprintf(out, " failed\n");
262       return false;
263     }
264     fprintf(out, ".");
265     fflush(out);
266 
267     // Test ECDSA_SIG signing and verification.
268     // Create a signature.
269     ecdsa_sig.reset(ECDSA_do_sign(digest, 20, eckey.get()));
270     if (!ecdsa_sig) {
271       fprintf(out, " failed\n");
272       return false;
273     }
274     fprintf(out, ".");
275     fflush(out);
276     // Verify the signature using the correct key.
277     if (!ECDSA_do_verify(digest, 20, ecdsa_sig.get(), eckey.get())) {
278       fprintf(out, " failed\n");
279       return false;
280     }
281     fprintf(out, ".");
282     fflush(out);
283     // Verify the signature with the wrong key.
284     if (ECDSA_do_verify(digest, 20, ecdsa_sig.get(), wrong_eckey.get())) {
285       fprintf(out, " failed\n");
286       return false;
287     }
288     fprintf(out, ".");
289     fflush(out);
290     // Verify the signature using the wrong digest.
291     if (ECDSA_do_verify(wrong_digest, 20, ecdsa_sig.get(), eckey.get())) {
292       fprintf(out, " failed\n");
293       return false;
294     }
295     fprintf(out, ".");
296     fflush(out);
297     // Verify a tampered signature.
298     if (!TestTamperedSig(out, kRawApi, digest, 20, ecdsa_sig.get(), eckey.get(),
299                          order)) {
300       fprintf(out, " failed\n");
301       return false;
302     }
303     fprintf(out, ".");
304     fflush(out);
305 
306     fprintf(out, " ok\n");
307     // Clear bogus errors.
308     ERR_clear_error();
309   }
310 
311   return true;
312 }
313 
TestECDSA_SIG_max_len(size_t order_len)314 static bool TestECDSA_SIG_max_len(size_t order_len) {
315   /* Create the largest possible |ECDSA_SIG| of the given constraints. */
316   ScopedECDSA_SIG sig(ECDSA_SIG_new());
317   if (!sig) {
318     return false;
319   }
320   std::vector<uint8_t> bytes(order_len, 0xff);
321   if (!BN_bin2bn(bytes.data(), bytes.size(), sig->r) ||
322       !BN_bin2bn(bytes.data(), bytes.size(), sig->s)) {
323     return false;
324   }
325   /* Serialize it. */
326   uint8_t *der;
327   size_t der_len;
328   if (!ECDSA_SIG_to_bytes(&der, &der_len, sig.get())) {
329     return false;
330   }
331   ScopedOpenSSLBytes delete_der(der);
332 
333   size_t max_len = ECDSA_SIG_max_len(order_len);
334   if (max_len != der_len) {
335     fprintf(stderr, "ECDSA_SIG_max_len(%u) returned %u, wanted %u\n",
336             static_cast<unsigned>(order_len), static_cast<unsigned>(max_len),
337             static_cast<unsigned>(der_len));
338     return false;
339   }
340   return true;
341 }
342 
main(void)343 int main(void) {
344   CRYPTO_library_init();
345   ERR_load_crypto_strings();
346 
347   if (!TestBuiltin(stdout) ||
348       !TestECDSA_SIG_max_len(224/8) ||
349       !TestECDSA_SIG_max_len(256/8) ||
350       !TestECDSA_SIG_max_len(384/8) ||
351       !TestECDSA_SIG_max_len(512/8) ||
352       !TestECDSA_SIG_max_len(10000)) {
353     printf("\nECDSA test failed\n");
354     ERR_print_errors_fp(stdout);
355     return 1;
356   }
357 
358   printf("\nPASS\n");
359   return 0;
360 }
361