1 /* Copyright (c) 2015, Google Inc.
2 *
3 * Permission to use, copy, modify, and/or distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
6 *
7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
14
15 #include <openssl/ssl.h>
16
17 #include <assert.h>
18 #include <string.h>
19
20 #include <utility>
21
22 #include <openssl/bn.h>
23 #include <openssl/bytestring.h>
24 #include <openssl/curve25519.h>
25 #include <openssl/ec.h>
26 #include <openssl/err.h>
27 #include <openssl/hrss.h>
28 #include <openssl/mem.h>
29 #include <openssl/nid.h>
30 #include <openssl/rand.h>
31
32 #include "internal.h"
33 #include "../crypto/internal.h"
34
35 BSSL_NAMESPACE_BEGIN
36
37 namespace {
38
39 class ECKeyShare : public SSLKeyShare {
40 public:
ECKeyShare(int nid,uint16_t group_id)41 ECKeyShare(int nid, uint16_t group_id) : nid_(nid), group_id_(group_id) {}
42
GroupID() const43 uint16_t GroupID() const override { return group_id_; }
44
Offer(CBB * out)45 bool Offer(CBB *out) override {
46 assert(!private_key_);
47 // Set up a shared |BN_CTX| for all operations.
48 UniquePtr<BN_CTX> bn_ctx(BN_CTX_new());
49 if (!bn_ctx) {
50 return false;
51 }
52 BN_CTXScope scope(bn_ctx.get());
53
54 // Generate a private key.
55 UniquePtr<EC_GROUP> group(EC_GROUP_new_by_curve_name(nid_));
56 private_key_.reset(BN_new());
57 if (!group || !private_key_ ||
58 !BN_rand_range_ex(private_key_.get(), 1,
59 EC_GROUP_get0_order(group.get()))) {
60 return false;
61 }
62
63 // Compute the corresponding public key and serialize it.
64 UniquePtr<EC_POINT> public_key(EC_POINT_new(group.get()));
65 if (!public_key ||
66 !EC_POINT_mul(group.get(), public_key.get(), private_key_.get(), NULL,
67 NULL, bn_ctx.get()) ||
68 !EC_POINT_point2cbb(out, group.get(), public_key.get(),
69 POINT_CONVERSION_UNCOMPRESSED, bn_ctx.get())) {
70 return false;
71 }
72
73 return true;
74 }
75
Finish(Array<uint8_t> * out_secret,uint8_t * out_alert,Span<const uint8_t> peer_key)76 bool Finish(Array<uint8_t> *out_secret, uint8_t *out_alert,
77 Span<const uint8_t> peer_key) override {
78 assert(private_key_);
79 *out_alert = SSL_AD_INTERNAL_ERROR;
80
81 // Set up a shared |BN_CTX| for all operations.
82 UniquePtr<BN_CTX> bn_ctx(BN_CTX_new());
83 if (!bn_ctx) {
84 return false;
85 }
86 BN_CTXScope scope(bn_ctx.get());
87
88 UniquePtr<EC_GROUP> group(EC_GROUP_new_by_curve_name(nid_));
89 if (!group) {
90 return false;
91 }
92
93 UniquePtr<EC_POINT> peer_point(EC_POINT_new(group.get()));
94 UniquePtr<EC_POINT> result(EC_POINT_new(group.get()));
95 BIGNUM *x = BN_CTX_get(bn_ctx.get());
96 if (!peer_point || !result || !x) {
97 return false;
98 }
99
100 if (peer_key.empty() || peer_key[0] != POINT_CONVERSION_UNCOMPRESSED ||
101 !EC_POINT_oct2point(group.get(), peer_point.get(), peer_key.data(),
102 peer_key.size(), bn_ctx.get())) {
103 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_ECPOINT);
104 *out_alert = SSL_AD_DECODE_ERROR;
105 return false;
106 }
107
108 // Compute the x-coordinate of |peer_key| * |private_key_|.
109 if (!EC_POINT_mul(group.get(), result.get(), NULL, peer_point.get(),
110 private_key_.get(), bn_ctx.get()) ||
111 !EC_POINT_get_affine_coordinates_GFp(group.get(), result.get(), x, NULL,
112 bn_ctx.get())) {
113 return false;
114 }
115
116 // Encode the x-coordinate left-padded with zeros.
117 Array<uint8_t> secret;
118 if (!secret.Init((EC_GROUP_get_degree(group.get()) + 7) / 8) ||
119 !BN_bn2bin_padded(secret.data(), secret.size(), x)) {
120 return false;
121 }
122
123 *out_secret = std::move(secret);
124 return true;
125 }
126
Serialize(CBB * out)127 bool Serialize(CBB *out) override {
128 assert(private_key_);
129 CBB cbb;
130 UniquePtr<EC_GROUP> group(EC_GROUP_new_by_curve_name(nid_));
131 // Padding is added to avoid leaking the length.
132 size_t len = BN_num_bytes(EC_GROUP_get0_order(group.get()));
133 if (!CBB_add_asn1_uint64(out, group_id_) ||
134 !CBB_add_asn1(out, &cbb, CBS_ASN1_OCTETSTRING) ||
135 !BN_bn2cbb_padded(&cbb, len, private_key_.get()) ||
136 !CBB_flush(out)) {
137 return false;
138 }
139 return true;
140 }
141
Deserialize(CBS * in)142 bool Deserialize(CBS *in) override {
143 assert(!private_key_);
144 CBS private_key;
145 if (!CBS_get_asn1(in, &private_key, CBS_ASN1_OCTETSTRING)) {
146 return false;
147 }
148 private_key_.reset(BN_bin2bn(CBS_data(&private_key),
149 CBS_len(&private_key), nullptr));
150 return private_key_ != nullptr;
151 }
152
153 private:
154 UniquePtr<BIGNUM> private_key_;
155 int nid_;
156 uint16_t group_id_;
157 };
158
159 class X25519KeyShare : public SSLKeyShare {
160 public:
X25519KeyShare()161 X25519KeyShare() {}
162
GroupID() const163 uint16_t GroupID() const override { return SSL_CURVE_X25519; }
164
Offer(CBB * out)165 bool Offer(CBB *out) override {
166 uint8_t public_key[32];
167 X25519_keypair(public_key, private_key_);
168 return !!CBB_add_bytes(out, public_key, sizeof(public_key));
169 }
170
Finish(Array<uint8_t> * out_secret,uint8_t * out_alert,Span<const uint8_t> peer_key)171 bool Finish(Array<uint8_t> *out_secret, uint8_t *out_alert,
172 Span<const uint8_t> peer_key) override {
173 *out_alert = SSL_AD_INTERNAL_ERROR;
174
175 Array<uint8_t> secret;
176 if (!secret.Init(32)) {
177 OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
178 return false;
179 }
180
181 if (peer_key.size() != 32 ||
182 !X25519(secret.data(), private_key_, peer_key.data())) {
183 *out_alert = SSL_AD_DECODE_ERROR;
184 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_ECPOINT);
185 return false;
186 }
187
188 *out_secret = std::move(secret);
189 return true;
190 }
191
Serialize(CBB * out)192 bool Serialize(CBB *out) override {
193 return (CBB_add_asn1_uint64(out, GroupID()) &&
194 CBB_add_asn1_octet_string(out, private_key_, sizeof(private_key_)));
195 }
196
Deserialize(CBS * in)197 bool Deserialize(CBS *in) override {
198 CBS key;
199 if (!CBS_get_asn1(in, &key, CBS_ASN1_OCTETSTRING) ||
200 CBS_len(&key) != sizeof(private_key_) ||
201 !CBS_copy_bytes(&key, private_key_, sizeof(private_key_))) {
202 return false;
203 }
204 return true;
205 }
206
207 private:
208 uint8_t private_key_[32];
209 };
210
211 class CECPQ2KeyShare : public SSLKeyShare {
212 public:
CECPQ2KeyShare()213 CECPQ2KeyShare() {}
214
GroupID() const215 uint16_t GroupID() const override { return SSL_CURVE_CECPQ2; }
216
Offer(CBB * out)217 bool Offer(CBB *out) override {
218 uint8_t x25519_public_key[32];
219 X25519_keypair(x25519_public_key, x25519_private_key_);
220
221 uint8_t hrss_entropy[HRSS_GENERATE_KEY_BYTES];
222 HRSS_public_key hrss_public_key;
223 RAND_bytes(hrss_entropy, sizeof(hrss_entropy));
224 HRSS_generate_key(&hrss_public_key, &hrss_private_key_, hrss_entropy);
225
226 uint8_t hrss_public_key_bytes[HRSS_PUBLIC_KEY_BYTES];
227 HRSS_marshal_public_key(hrss_public_key_bytes, &hrss_public_key);
228
229 if (!CBB_add_bytes(out, x25519_public_key, sizeof(x25519_public_key)) ||
230 !CBB_add_bytes(out, hrss_public_key_bytes,
231 sizeof(hrss_public_key_bytes))) {
232 return false;
233 }
234
235 return true;
236 }
237
Accept(CBB * out_public_key,Array<uint8_t> * out_secret,uint8_t * out_alert,Span<const uint8_t> peer_key)238 bool Accept(CBB *out_public_key, Array<uint8_t> *out_secret,
239 uint8_t *out_alert, Span<const uint8_t> peer_key) override {
240 Array<uint8_t> secret;
241 if (!secret.Init(32 + HRSS_KEY_BYTES)) {
242 OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
243 return false;
244 }
245
246 uint8_t x25519_public_key[32];
247 X25519_keypair(x25519_public_key, x25519_private_key_);
248
249 HRSS_public_key peer_public_key;
250 if (peer_key.size() != 32 + HRSS_PUBLIC_KEY_BYTES ||
251 !HRSS_parse_public_key(&peer_public_key, peer_key.data() + 32) ||
252 !X25519(secret.data(), x25519_private_key_, peer_key.data())) {
253 *out_alert = SSL_AD_DECODE_ERROR;
254 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_ECPOINT);
255 return false;
256 }
257
258 uint8_t ciphertext[HRSS_CIPHERTEXT_BYTES];
259 uint8_t entropy[HRSS_ENCAP_BYTES];
260 RAND_bytes(entropy, sizeof(entropy));
261 HRSS_encap(ciphertext, secret.data() + 32, &peer_public_key, entropy);
262
263 if (!CBB_add_bytes(out_public_key, x25519_public_key,
264 sizeof(x25519_public_key)) ||
265 !CBB_add_bytes(out_public_key, ciphertext, sizeof(ciphertext))) {
266 return false;
267 }
268
269 *out_secret = std::move(secret);
270 return true;
271 }
272
Finish(Array<uint8_t> * out_secret,uint8_t * out_alert,Span<const uint8_t> peer_key)273 bool Finish(Array<uint8_t> *out_secret, uint8_t *out_alert,
274 Span<const uint8_t> peer_key) override {
275 *out_alert = SSL_AD_INTERNAL_ERROR;
276
277 Array<uint8_t> secret;
278 if (!secret.Init(32 + HRSS_KEY_BYTES)) {
279 OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
280 return false;
281 }
282
283 if (peer_key.size() != 32 + HRSS_CIPHERTEXT_BYTES ||
284 !X25519(secret.data(), x25519_private_key_, peer_key.data())) {
285 *out_alert = SSL_AD_DECODE_ERROR;
286 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_ECPOINT);
287 return false;
288 }
289
290 HRSS_decap(secret.data() + 32, &hrss_private_key_, peer_key.data() + 32,
291 peer_key.size() - 32);
292
293 *out_secret = std::move(secret);
294 return true;
295 }
296
297 private:
298 uint8_t x25519_private_key_[32];
299 HRSS_private_key hrss_private_key_;
300 };
301
302 CONSTEXPR_ARRAY NamedGroup kNamedGroups[] = {
303 {NID_secp224r1, SSL_CURVE_SECP224R1, "P-224", "secp224r1"},
304 {NID_X9_62_prime256v1, SSL_CURVE_SECP256R1, "P-256", "prime256v1"},
305 {NID_secp384r1, SSL_CURVE_SECP384R1, "P-384", "secp384r1"},
306 {NID_secp521r1, SSL_CURVE_SECP521R1, "P-521", "secp521r1"},
307 {NID_X25519, SSL_CURVE_X25519, "X25519", "x25519"},
308 {NID_CECPQ2, SSL_CURVE_CECPQ2, "CECPQ2", "CECPQ2"},
309 };
310
311 } // namespace
312
NamedGroups()313 Span<const NamedGroup> NamedGroups() {
314 return MakeConstSpan(kNamedGroups, OPENSSL_ARRAY_SIZE(kNamedGroups));
315 }
316
Create(uint16_t group_id)317 UniquePtr<SSLKeyShare> SSLKeyShare::Create(uint16_t group_id) {
318 switch (group_id) {
319 case SSL_CURVE_SECP224R1:
320 return UniquePtr<SSLKeyShare>(
321 New<ECKeyShare>(NID_secp224r1, SSL_CURVE_SECP224R1));
322 case SSL_CURVE_SECP256R1:
323 return UniquePtr<SSLKeyShare>(
324 New<ECKeyShare>(NID_X9_62_prime256v1, SSL_CURVE_SECP256R1));
325 case SSL_CURVE_SECP384R1:
326 return UniquePtr<SSLKeyShare>(
327 New<ECKeyShare>(NID_secp384r1, SSL_CURVE_SECP384R1));
328 case SSL_CURVE_SECP521R1:
329 return UniquePtr<SSLKeyShare>(
330 New<ECKeyShare>(NID_secp521r1, SSL_CURVE_SECP521R1));
331 case SSL_CURVE_X25519:
332 return UniquePtr<SSLKeyShare>(New<X25519KeyShare>());
333 case SSL_CURVE_CECPQ2:
334 return UniquePtr<SSLKeyShare>(New<CECPQ2KeyShare>());
335 default:
336 return nullptr;
337 }
338 }
339
Create(CBS * in)340 UniquePtr<SSLKeyShare> SSLKeyShare::Create(CBS *in) {
341 uint64_t group;
342 if (!CBS_get_asn1_uint64(in, &group) || group > 0xffff) {
343 return nullptr;
344 }
345 UniquePtr<SSLKeyShare> key_share = Create(static_cast<uint16_t>(group));
346 if (!key_share || !key_share->Deserialize(in)) {
347 return nullptr;
348 }
349 return key_share;
350 }
351
352
Accept(CBB * out_public_key,Array<uint8_t> * out_secret,uint8_t * out_alert,Span<const uint8_t> peer_key)353 bool SSLKeyShare::Accept(CBB *out_public_key, Array<uint8_t> *out_secret,
354 uint8_t *out_alert, Span<const uint8_t> peer_key) {
355 *out_alert = SSL_AD_INTERNAL_ERROR;
356 return Offer(out_public_key) &&
357 Finish(out_secret, out_alert, peer_key);
358 }
359
ssl_nid_to_group_id(uint16_t * out_group_id,int nid)360 bool ssl_nid_to_group_id(uint16_t *out_group_id, int nid) {
361 for (const auto &group : kNamedGroups) {
362 if (group.nid == nid) {
363 *out_group_id = group.group_id;
364 return true;
365 }
366 }
367 return false;
368 }
369
ssl_name_to_group_id(uint16_t * out_group_id,const char * name,size_t len)370 bool ssl_name_to_group_id(uint16_t *out_group_id, const char *name, size_t len) {
371 for (const auto &group : kNamedGroups) {
372 if (len == strlen(group.name) &&
373 !strncmp(group.name, name, len)) {
374 *out_group_id = group.group_id;
375 return true;
376 }
377 if (len == strlen(group.alias) &&
378 !strncmp(group.alias, name, len)) {
379 *out_group_id = group.group_id;
380 return true;
381 }
382 }
383 return false;
384 }
385
386 BSSL_NAMESPACE_END
387
388 using namespace bssl;
389
SSL_get_curve_name(uint16_t group_id)390 const char* SSL_get_curve_name(uint16_t group_id) {
391 for (const auto &group : kNamedGroups) {
392 if (group.group_id == group_id) {
393 return group.name;
394 }
395 }
396 return nullptr;
397 }
398