1 // Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved.
2 // Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved.
3 //
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at
7 //
8 //     https://www.apache.org/licenses/LICENSE-2.0
9 //
10 // Unless required by applicable law or agreed to in writing, software
11 // distributed under the License is distributed on an "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 // See the License for the specific language governing permissions and
14 // limitations under the License.
15 
16 #include <openssl/ecdsa.h>
17 
18 #include <vector>
19 
20 #include <gtest/gtest.h>
21 
22 #include <openssl/bn.h>
23 #include <openssl/crypto.h>
24 #include <openssl/ec.h>
25 #include <openssl/err.h>
26 #include <openssl/mem.h>
27 #include <openssl/nid.h>
28 #include <openssl/rand.h>
29 
30 #include "../ec/internal.h"
31 #include "../../test/file_test.h"
32 #include "../../test/test_util.h"
33 
34 
HexToBIGNUM(const char * hex)35 static bssl::UniquePtr<BIGNUM> HexToBIGNUM(const char *hex) {
36   BIGNUM *bn = nullptr;
37   BN_hex2bn(&bn, hex);
38   return bssl::UniquePtr<BIGNUM>(bn);
39 }
40 
41 // Though we do not support secp160r1, it is reachable from the deprecated
42 // custom curve APIs and has some unique properties (n is larger than p with the
43 // difference crossing a word boundary on 32-bit), so test it explicitly.
NewSecp160r1Group()44 static bssl::UniquePtr<EC_GROUP> NewSecp160r1Group() {
45   static const char kP[] = "ffffffffffffffffffffffffffffffff7fffffff";
46   static const char kA[] = "ffffffffffffffffffffffffffffffff7ffffffc";
47   static const char kB[] = "1c97befc54bd7a8b65acf89f81d4d4adc565fa45";
48   static const char kX[] = "4a96b5688ef573284664698968c38bb913cbfc82";
49   static const char kY[] = "23a628553168947d59dcc912042351377ac5fb32";
50   static const char kN[] = "0100000000000000000001f4c8f927aed3ca752257";
51 
52   bssl::UniquePtr<BIGNUM> p = HexToBIGNUM(kP), a = HexToBIGNUM(kA),
53                           b = HexToBIGNUM(kB), x = HexToBIGNUM(kX),
54                           y = HexToBIGNUM(kY), n = HexToBIGNUM(kN);
55   if (!p || !a || !b || !x || !y || !n) {
56     return nullptr;
57   }
58 
59   bssl::UniquePtr<EC_GROUP> group(
60       EC_GROUP_new_curve_GFp(p.get(), a.get(), b.get(), nullptr));
61   if (!group) {
62     return nullptr;
63   }
64   bssl::UniquePtr<EC_POINT> g(EC_POINT_new(group.get()));
65   if (!g ||
66       !EC_POINT_set_affine_coordinates_GFp(group.get(), g.get(), x.get(),
67                                            y.get(), nullptr) ||
68       !EC_GROUP_set_generator(group.get(), g.get(), n.get(), BN_value_one())) {
69     return nullptr;
70   }
71   return group;
72 }
73 
74 enum API {
75   kEncodedAPI,
76   kRawAPI,
77 };
78 
79 // VerifyECDSASig checks that verifying |ecdsa_sig| gives |expected_result|.
VerifyECDSASig(API api,const uint8_t * digest,size_t digest_len,const ECDSA_SIG * ecdsa_sig,EC_KEY * eckey,int expected_result)80 static void VerifyECDSASig(API api, const uint8_t *digest, size_t digest_len,
81                            const ECDSA_SIG *ecdsa_sig, EC_KEY *eckey,
82                            int expected_result) {
83   switch (api) {
84     case kEncodedAPI: {
85       uint8_t *der;
86       size_t der_len;
87       ASSERT_TRUE(ECDSA_SIG_to_bytes(&der, &der_len, ecdsa_sig));
88       bssl::UniquePtr<uint8_t> delete_der(der);
89       EXPECT_EQ(expected_result,
90                 ECDSA_verify(0, digest, digest_len, der, der_len, eckey));
91       break;
92     }
93 
94     case kRawAPI:
95       EXPECT_EQ(expected_result,
96                 ECDSA_do_verify(digest, digest_len, ecdsa_sig, eckey));
97       break;
98 
99     default:
100       FAIL() << "Unknown API type.";
101   }
102 }
103 
104 // TestTamperedSig verifies that signature verification fails when a valid
105 // signature is tampered with. |ecdsa_sig| must be a valid signature, which will
106 // be modified.
TestTamperedSig(API api,const uint8_t * digest,size_t digest_len,ECDSA_SIG * ecdsa_sig,EC_KEY * eckey,const BIGNUM * order)107 static void TestTamperedSig(API api, const uint8_t *digest,
108                             size_t digest_len, ECDSA_SIG *ecdsa_sig,
109                             EC_KEY *eckey, const BIGNUM *order) {
110   SCOPED_TRACE(api);
111   // Modify a single byte of the signature: to ensure we don't
112   // garble the ASN1 structure, we read the raw signature and
113   // modify a byte in one of the bignums directly.
114 
115   // Store the two BIGNUMs in raw_buf.
116   size_t r_len = BN_num_bytes(ecdsa_sig->r);
117   size_t s_len = BN_num_bytes(ecdsa_sig->s);
118   size_t bn_len = BN_num_bytes(order);
119   ASSERT_LE(r_len, bn_len);
120   ASSERT_LE(s_len, bn_len);
121   size_t buf_len = 2 * bn_len;
122   std::vector<uint8_t> raw_buf(buf_len);
123   // Pad the bignums with leading zeroes.
124   ASSERT_TRUE(BN_bn2bin_padded(raw_buf.data(), bn_len, ecdsa_sig->r));
125   ASSERT_TRUE(BN_bn2bin_padded(raw_buf.data() + bn_len, bn_len, ecdsa_sig->s));
126 
127   // Modify a single byte in the buffer.
128   size_t offset = raw_buf[10] % buf_len;
129   uint8_t dirt = raw_buf[11] ? raw_buf[11] : 1;
130   raw_buf[offset] ^= dirt;
131   // Now read the BIGNUMs back in from raw_buf.
132   ASSERT_TRUE(BN_bin2bn(raw_buf.data(), bn_len, ecdsa_sig->r));
133   ASSERT_TRUE(BN_bin2bn(raw_buf.data() + bn_len, bn_len, ecdsa_sig->s));
134   VerifyECDSASig(api, digest, digest_len, ecdsa_sig, eckey, 0);
135 
136   // Sanity check: Undo the modification and verify signature.
137   raw_buf[offset] ^= dirt;
138   ASSERT_TRUE(BN_bin2bn(raw_buf.data(), bn_len, ecdsa_sig->r));
139   ASSERT_TRUE(BN_bin2bn(raw_buf.data() + bn_len, bn_len, ecdsa_sig->s));
140   VerifyECDSASig(api, digest, digest_len, ecdsa_sig, eckey, 1);
141 }
142 
TEST(ECDSATest,BuiltinCurves)143 TEST(ECDSATest, BuiltinCurves) {
144   // Fill digest values with some random data.
145   uint8_t digest[20], wrong_digest[20];
146   ASSERT_TRUE(RAND_bytes(digest, 20));
147   CONSTTIME_DECLASSIFY(digest, 20);
148   ASSERT_TRUE(RAND_bytes(wrong_digest, 20));
149   CONSTTIME_DECLASSIFY(wrong_digest, 20);
150 
151   static const struct {
152     int nid;
153     const char *name;
154   } kCurves[] = {
155       { NID_secp224r1, "secp224r1" },
156       { NID_X9_62_prime256v1, "secp256r1" },
157       { NID_secp384r1, "secp384r1" },
158       { NID_secp521r1, "secp521r1" },
159       { NID_secp160r1, "secp160r1" },
160   };
161 
162   for (const auto &curve : kCurves) {
163     SCOPED_TRACE(curve.name);
164 
165     bssl::UniquePtr<EC_GROUP> group;
166     if (curve.nid == NID_secp160r1) {
167       group = NewSecp160r1Group();
168     } else {
169       group.reset(EC_GROUP_new_by_curve_name(curve.nid));
170     }
171     ASSERT_TRUE(group);
172     const BIGNUM *order = EC_GROUP_get0_order(group.get());
173 
174     // Create a new ECDSA key.
175     bssl::UniquePtr<EC_KEY> eckey(EC_KEY_new());
176     ASSERT_TRUE(eckey);
177     ASSERT_TRUE(EC_KEY_set_group(eckey.get(), group.get()));
178     ASSERT_TRUE(EC_KEY_generate_key(eckey.get()));
179 
180     // Create a second key.
181     bssl::UniquePtr<EC_KEY> wrong_eckey(EC_KEY_new());
182     ASSERT_TRUE(wrong_eckey);
183     ASSERT_TRUE(EC_KEY_set_group(wrong_eckey.get(), group.get()));
184     ASSERT_TRUE(EC_KEY_generate_key(wrong_eckey.get()));
185 
186     // Check the key.
187     EXPECT_TRUE(EC_KEY_check_key(eckey.get()));
188 
189     // Test ASN.1-encoded signatures.
190     // Create a signature.
191     std::vector<uint8_t> signature(ECDSA_size(eckey.get()));
192     unsigned sig_len;
193     ASSERT_TRUE(
194         ECDSA_sign(0, digest, 20, signature.data(), &sig_len, eckey.get()));
195     signature.resize(sig_len);
196 
197     // ECDSA signing should be non-deterministic. This does not verify k is
198     // generated securely but at least checks it was randomized at all.
199     std::vector<uint8_t> signature2(ECDSA_size(eckey.get()));
200     ASSERT_TRUE(
201         ECDSA_sign(0, digest, 20, signature2.data(), &sig_len, eckey.get()));
202     signature2.resize(sig_len);
203     EXPECT_NE(Bytes(signature), Bytes(signature2));
204 
205     // Verify the signature.
206     EXPECT_TRUE(ECDSA_verify(0, digest, 20, signature.data(), signature.size(),
207                              eckey.get()));
208 
209     // Verify the signature with the wrong key.
210     EXPECT_FALSE(ECDSA_verify(0, digest, 20, signature.data(), signature.size(),
211                               wrong_eckey.get()));
212     ERR_clear_error();
213 
214     // Verify the signature using the wrong digest.
215     EXPECT_FALSE(ECDSA_verify(0, wrong_digest, 20, signature.data(),
216                               signature.size(), eckey.get()));
217     ERR_clear_error();
218 
219     // Verify a truncated signature.
220     EXPECT_FALSE(ECDSA_verify(0, digest, 20, signature.data(),
221                               signature.size() - 1, eckey.get()));
222     ERR_clear_error();
223 
224     // Verify a tampered signature.
225     bssl::UniquePtr<ECDSA_SIG> ecdsa_sig(
226         ECDSA_SIG_from_bytes(signature.data(), signature.size()));
227     ASSERT_TRUE(ecdsa_sig);
228     TestTamperedSig(kEncodedAPI, digest, 20, ecdsa_sig.get(), eckey.get(),
229                     order);
230 
231     // Test ECDSA_SIG signing and verification.
232     // Create a signature.
233     ecdsa_sig.reset(ECDSA_do_sign(digest, 20, eckey.get()));
234     ASSERT_TRUE(ecdsa_sig);
235 
236     // Verify the signature using the correct key.
237     EXPECT_TRUE(ECDSA_do_verify(digest, 20, ecdsa_sig.get(), eckey.get()));
238 
239     // Verify the signature with the wrong key.
240     EXPECT_FALSE(
241         ECDSA_do_verify(digest, 20, ecdsa_sig.get(), wrong_eckey.get()));
242     ERR_clear_error();
243 
244     // Verify the signature using the wrong digest.
245     EXPECT_FALSE(
246         ECDSA_do_verify(wrong_digest, 20, ecdsa_sig.get(), eckey.get()));
247     ERR_clear_error();
248 
249     // Verify a tampered signature.
250     TestTamperedSig(kRawAPI, digest, 20, ecdsa_sig.get(), eckey.get(), order);
251 
252     // Negative components should not be accepted.
253     BN_set_negative(ecdsa_sig->r, 1);
254     EXPECT_FALSE(ECDSA_do_verify(digest, 20, ecdsa_sig.get(), eckey.get()));
255     BN_set_negative(ecdsa_sig->r, 0);
256     BN_set_negative(ecdsa_sig->s, 1);
257     EXPECT_FALSE(ECDSA_do_verify(digest, 20, ecdsa_sig.get(), eckey.get()));
258     BN_set_negative(ecdsa_sig->s, 0);
259   }
260 }
261 
BitsToBytes(size_t bits)262 static size_t BitsToBytes(size_t bits) {
263   return (bits / 8) + (7 + (bits % 8)) / 8;
264 }
265 
TEST(ECDSATest,MaxSigLen)266 TEST(ECDSATest, MaxSigLen) {
267   static const size_t kBits[] = {224, 256, 384, 521, 10000};
268   for (size_t bits : kBits) {
269     SCOPED_TRACE(bits);
270     size_t order_len = BitsToBytes(bits);
271 
272     // Create the largest possible |ECDSA_SIG| of the given constraints.
273     bssl::UniquePtr<ECDSA_SIG> sig(ECDSA_SIG_new());
274     ASSERT_TRUE(sig);
275     std::vector<uint8_t> bytes(order_len, 0xff);
276     ASSERT_TRUE(BN_bin2bn(bytes.data(), bytes.size(), sig->r));
277     ASSERT_TRUE(BN_bin2bn(bytes.data(), bytes.size(), sig->s));
278     // Serialize it.
279     uint8_t *der;
280     size_t der_len;
281     ASSERT_TRUE(ECDSA_SIG_to_bytes(&der, &der_len, sig.get()));
282     OPENSSL_free(der);
283 
284     EXPECT_EQ(der_len, ECDSA_SIG_max_len(order_len));
285   }
286 }
287 
GetCurve(FileTest * t,const char * key)288 static bssl::UniquePtr<EC_GROUP> GetCurve(FileTest *t, const char *key) {
289   std::string curve_name;
290   if (!t->GetAttribute(&curve_name, key)) {
291     return nullptr;
292   }
293 
294   if (curve_name == "P-224") {
295     return bssl::UniquePtr<EC_GROUP>(const_cast<EC_GROUP *>(EC_group_p224()));
296   }
297   if (curve_name == "P-256") {
298     return bssl::UniquePtr<EC_GROUP>(const_cast<EC_GROUP *>(EC_group_p256()));
299   }
300   if (curve_name == "P-384") {
301     return bssl::UniquePtr<EC_GROUP>(const_cast<EC_GROUP *>(EC_group_p384()));
302   }
303   if (curve_name == "P-521") {
304     return bssl::UniquePtr<EC_GROUP>(const_cast<EC_GROUP *>(EC_group_p521()));
305   }
306   if (curve_name == "secp160r1") {
307     return NewSecp160r1Group();
308   }
309 
310   ADD_FAILURE() << "Unknown curve: " << curve_name;
311   return nullptr;
312 }
313 
MakeCustomClone(const EC_GROUP * group)314 static bssl::UniquePtr<EC_GROUP> MakeCustomClone(const EC_GROUP *group) {
315   bssl::UniquePtr<BN_CTX> ctx(BN_CTX_new());
316   bssl::UniquePtr<BIGNUM> p(BN_new()), a(BN_new()), b(BN_new()), x(BN_new()),
317       y(BN_new());
318   if (!ctx || !p || !a || !b || !x || !y ||
319       !EC_GROUP_get_curve_GFp(group, p.get(), a.get(), b.get(), ctx.get()) ||
320       !EC_POINT_get_affine_coordinates_GFp(
321           group, EC_GROUP_get0_generator(group), x.get(), y.get(), ctx.get())) {
322     return nullptr;
323   }
324   bssl::UniquePtr<EC_GROUP> ret(
325       EC_GROUP_new_curve_GFp(p.get(), a.get(), b.get(), ctx.get()));
326   if (!ret) {
327     return nullptr;
328   }
329   bssl::UniquePtr<EC_POINT> g(EC_POINT_new(ret.get()));
330   if (!g ||
331       !EC_POINT_set_affine_coordinates_GFp(ret.get(), g.get(), x.get(), y.get(),
332                                            ctx.get()) ||
333       !EC_GROUP_set_generator(ret.get(), g.get(), EC_GROUP_get0_order(group),
334                               BN_value_one())) {
335     return nullptr;
336   }
337   return ret;
338 }
339 
GetBIGNUM(FileTest * t,const char * key)340 static bssl::UniquePtr<BIGNUM> GetBIGNUM(FileTest *t, const char *key) {
341   std::vector<uint8_t> bytes;
342   if (!t->GetBytes(&bytes, key)) {
343     return nullptr;
344   }
345 
346   return bssl::UniquePtr<BIGNUM>(BN_bin2bn(bytes.data(), bytes.size(), nullptr));
347 }
348 
TEST(ECDSATest,VerifyTestVectors)349 TEST(ECDSATest, VerifyTestVectors) {
350   FileTestGTest("crypto/fipsmodule/ecdsa/ecdsa_verify_tests.txt",
351                 [](FileTest *t) {
352     for (bool custom_group : {false, true}) {
353       SCOPED_TRACE(custom_group);
354       bssl::UniquePtr<EC_GROUP> group = GetCurve(t, "Curve");
355       ASSERT_TRUE(group);
356       if (custom_group) {
357         group = MakeCustomClone(group.get());
358         ASSERT_TRUE(group);
359       }
360       bssl::UniquePtr<BIGNUM> x = GetBIGNUM(t, "X");
361       ASSERT_TRUE(x);
362       bssl::UniquePtr<BIGNUM> y = GetBIGNUM(t, "Y");
363       ASSERT_TRUE(y);
364       bssl::UniquePtr<BIGNUM> r = GetBIGNUM(t, "R");
365       ASSERT_TRUE(r);
366       bssl::UniquePtr<BIGNUM> s = GetBIGNUM(t, "S");
367       ASSERT_TRUE(s);
368       std::vector<uint8_t> digest;
369       ASSERT_TRUE(t->GetBytes(&digest, "Digest"));
370 
371       bssl::UniquePtr<EC_KEY> key(EC_KEY_new());
372       ASSERT_TRUE(key);
373       bssl::UniquePtr<EC_POINT> pub_key(EC_POINT_new(group.get()));
374       ASSERT_TRUE(pub_key);
375       bssl::UniquePtr<ECDSA_SIG> sig(ECDSA_SIG_new());
376       ASSERT_TRUE(sig);
377       ASSERT_TRUE(EC_KEY_set_group(key.get(), group.get()));
378       ASSERT_TRUE(EC_POINT_set_affine_coordinates_GFp(
379           group.get(), pub_key.get(), x.get(), y.get(), nullptr));
380       ASSERT_TRUE(EC_KEY_set_public_key(key.get(), pub_key.get()));
381       ASSERT_TRUE(BN_copy(sig->r, r.get()));
382       ASSERT_TRUE(BN_copy(sig->s, s.get()));
383 
384       EXPECT_EQ(
385           t->HasAttribute("Invalid") ? 0 : 1,
386           ECDSA_do_verify(digest.data(), digest.size(), sig.get(), key.get()));
387     }
388   });
389 }
390 
TEST(ECDSATest,SignTestVectors)391 TEST(ECDSATest, SignTestVectors) {
392   FileTestGTest("crypto/fipsmodule/ecdsa/ecdsa_sign_tests.txt",
393                 [](FileTest *t) {
394     for (bool custom_group : {false, true}) {
395       SCOPED_TRACE(custom_group);
396       bssl::UniquePtr<EC_GROUP> group = GetCurve(t, "Curve");
397       ASSERT_TRUE(group);
398       if (custom_group) {
399         group = MakeCustomClone(group.get());
400         ASSERT_TRUE(group);
401       }
402       bssl::UniquePtr<BIGNUM> priv_key = GetBIGNUM(t, "Private");
403       ASSERT_TRUE(priv_key);
404       bssl::UniquePtr<BIGNUM> x = GetBIGNUM(t, "X");
405       ASSERT_TRUE(x);
406       bssl::UniquePtr<BIGNUM> y = GetBIGNUM(t, "Y");
407       ASSERT_TRUE(y);
408       std::vector<uint8_t> k;
409       ASSERT_TRUE(t->GetBytes(&k, "K"));
410       bssl::UniquePtr<BIGNUM> r = GetBIGNUM(t, "R");
411       ASSERT_TRUE(r);
412       bssl::UniquePtr<BIGNUM> s = GetBIGNUM(t, "S");
413       ASSERT_TRUE(s);
414       std::vector<uint8_t> digest;
415       ASSERT_TRUE(t->GetBytes(&digest, "Digest"));
416 
417       bssl::UniquePtr<EC_KEY> key(EC_KEY_new());
418       ASSERT_TRUE(key);
419       bssl::UniquePtr<EC_POINT> pub_key(EC_POINT_new(group.get()));
420       ASSERT_TRUE(pub_key);
421       ASSERT_TRUE(EC_KEY_set_group(key.get(), group.get()));
422       ASSERT_TRUE(EC_KEY_set_private_key(key.get(), priv_key.get()));
423       ASSERT_TRUE(EC_POINT_set_affine_coordinates_GFp(
424           group.get(), pub_key.get(), x.get(), y.get(), nullptr));
425       ASSERT_TRUE(EC_KEY_set_public_key(key.get(), pub_key.get()));
426       ASSERT_TRUE(EC_KEY_check_key(key.get()));
427 
428       bssl::UniquePtr<ECDSA_SIG> sig(
429           ECDSA_sign_with_nonce_and_leak_private_key_for_testing(
430               digest.data(), digest.size(), key.get(), k.data(), k.size()));
431       ASSERT_TRUE(sig);
432 
433       EXPECT_EQ(0, BN_cmp(r.get(), sig->r));
434       EXPECT_EQ(0, BN_cmp(s.get(), sig->s));
435     }
436   });
437 }
438