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
36 BSSL_NAMESPACE_BEGIN
37
38 namespace {
39
40 class ECKeyShare : public SSLKeyShare {
41 public:
ECKeyShare(int nid,uint16_t group_id)42 ECKeyShare(int nid, uint16_t group_id) : nid_(nid), group_id_(group_id) {}
43
GroupID() const44 uint16_t GroupID() const override { return group_id_; }
45
Offer(CBB * out)46 bool Offer(CBB *out) override {
47 assert(!private_key_);
48 // Set up a shared |BN_CTX| for all operations.
49 UniquePtr<BN_CTX> bn_ctx(BN_CTX_new());
50 if (!bn_ctx) {
51 return false;
52 }
53 BN_CTXScope scope(bn_ctx.get());
54
55 // Generate a private key.
56 UniquePtr<EC_GROUP> group(EC_GROUP_new_by_curve_name(nid_));
57 private_key_.reset(BN_new());
58 if (!group || !private_key_ ||
59 !BN_rand_range_ex(private_key_.get(), 1,
60 EC_GROUP_get0_order(group.get()))) {
61 return false;
62 }
63
64 // Compute the corresponding public key and serialize it.
65 UniquePtr<EC_POINT> public_key(EC_POINT_new(group.get()));
66 if (!public_key ||
67 !EC_POINT_mul(group.get(), public_key.get(), private_key_.get(), NULL,
68 NULL, bn_ctx.get()) ||
69 !EC_POINT_point2cbb(out, group.get(), public_key.get(),
70 POINT_CONVERSION_UNCOMPRESSED, bn_ctx.get())) {
71 return false;
72 }
73
74 return true;
75 }
76
Finish(Array<uint8_t> * out_secret,uint8_t * out_alert,Span<const uint8_t> peer_key)77 bool Finish(Array<uint8_t> *out_secret, uint8_t *out_alert,
78 Span<const uint8_t> peer_key) override {
79 assert(private_key_);
80 *out_alert = SSL_AD_INTERNAL_ERROR;
81
82 // Set up a shared |BN_CTX| for all operations.
83 UniquePtr<BN_CTX> bn_ctx(BN_CTX_new());
84 if (!bn_ctx) {
85 return false;
86 }
87 BN_CTXScope scope(bn_ctx.get());
88
89 UniquePtr<EC_GROUP> group(EC_GROUP_new_by_curve_name(nid_));
90 if (!group) {
91 return false;
92 }
93
94 UniquePtr<EC_POINT> peer_point(EC_POINT_new(group.get()));
95 UniquePtr<EC_POINT> result(EC_POINT_new(group.get()));
96 BIGNUM *x = BN_CTX_get(bn_ctx.get());
97 if (!peer_point || !result || !x) {
98 return false;
99 }
100
101 if (peer_key.empty() || peer_key[0] != POINT_CONVERSION_UNCOMPRESSED ||
102 !EC_POINT_oct2point(group.get(), peer_point.get(), peer_key.data(),
103 peer_key.size(), bn_ctx.get())) {
104 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_ECPOINT);
105 *out_alert = SSL_AD_DECODE_ERROR;
106 return false;
107 }
108
109 // Compute the x-coordinate of |peer_key| * |private_key_|.
110 if (!EC_POINT_mul(group.get(), result.get(), NULL, peer_point.get(),
111 private_key_.get(), bn_ctx.get()) ||
112 !EC_POINT_get_affine_coordinates_GFp(group.get(), result.get(), x, NULL,
113 bn_ctx.get())) {
114 return false;
115 }
116
117 // Encode the x-coordinate left-padded with zeros.
118 Array<uint8_t> secret;
119 if (!secret.Init((EC_GROUP_get_degree(group.get()) + 7) / 8) ||
120 !BN_bn2bin_padded(secret.data(), secret.size(), x)) {
121 return false;
122 }
123
124 *out_secret = std::move(secret);
125 return true;
126 }
127
Serialize(CBB * out)128 bool Serialize(CBB *out) override {
129 assert(private_key_);
130 CBB cbb;
131 UniquePtr<EC_GROUP> group(EC_GROUP_new_by_curve_name(nid_));
132 // Padding is added to avoid leaking the length.
133 size_t len = BN_num_bytes(EC_GROUP_get0_order(group.get()));
134 if (!CBB_add_asn1_uint64(out, group_id_) ||
135 !CBB_add_asn1(out, &cbb, CBS_ASN1_OCTETSTRING) ||
136 !BN_bn2cbb_padded(&cbb, len, private_key_.get()) ||
137 !CBB_flush(out)) {
138 return false;
139 }
140 return true;
141 }
142
Deserialize(CBS * in)143 bool Deserialize(CBS *in) override {
144 assert(!private_key_);
145 CBS private_key;
146 if (!CBS_get_asn1(in, &private_key, CBS_ASN1_OCTETSTRING)) {
147 return false;
148 }
149 private_key_.reset(BN_bin2bn(CBS_data(&private_key),
150 CBS_len(&private_key), nullptr));
151 return private_key_ != nullptr;
152 }
153
154 private:
155 UniquePtr<BIGNUM> private_key_;
156 int nid_;
157 uint16_t group_id_;
158 };
159
160 class X25519KeyShare : public SSLKeyShare {
161 public:
X25519KeyShare()162 X25519KeyShare() {}
163
GroupID() const164 uint16_t GroupID() const override { return SSL_CURVE_X25519; }
165
Offer(CBB * out)166 bool Offer(CBB *out) override {
167 uint8_t public_key[32];
168 X25519_keypair(public_key, private_key_);
169 return !!CBB_add_bytes(out, public_key, sizeof(public_key));
170 }
171
Finish(Array<uint8_t> * out_secret,uint8_t * out_alert,Span<const uint8_t> peer_key)172 bool Finish(Array<uint8_t> *out_secret, uint8_t *out_alert,
173 Span<const uint8_t> peer_key) override {
174 *out_alert = SSL_AD_INTERNAL_ERROR;
175
176 Array<uint8_t> secret;
177 if (!secret.Init(32)) {
178 OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
179 return false;
180 }
181
182 if (peer_key.size() != 32 ||
183 !X25519(secret.data(), private_key_, peer_key.data())) {
184 *out_alert = SSL_AD_DECODE_ERROR;
185 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_ECPOINT);
186 return false;
187 }
188
189 *out_secret = std::move(secret);
190 return true;
191 }
192
Serialize(CBB * out)193 bool Serialize(CBB *out) override {
194 return (CBB_add_asn1_uint64(out, GroupID()) &&
195 CBB_add_asn1_octet_string(out, private_key_, sizeof(private_key_)));
196 }
197
Deserialize(CBS * in)198 bool Deserialize(CBS *in) override {
199 CBS key;
200 if (!CBS_get_asn1(in, &key, CBS_ASN1_OCTETSTRING) ||
201 CBS_len(&key) != sizeof(private_key_) ||
202 !CBS_copy_bytes(&key, private_key_, sizeof(private_key_))) {
203 return false;
204 }
205 return true;
206 }
207
208 private:
209 uint8_t private_key_[32];
210 };
211
212 class CECPQ2KeyShare : public SSLKeyShare {
213 public:
CECPQ2KeyShare()214 CECPQ2KeyShare() {}
215
GroupID() const216 uint16_t GroupID() const override { return SSL_CURVE_CECPQ2; }
217
Offer(CBB * out)218 bool Offer(CBB *out) override {
219 uint8_t x25519_public_key[32];
220 X25519_keypair(x25519_public_key, x25519_private_key_);
221
222 uint8_t hrss_entropy[HRSS_GENERATE_KEY_BYTES];
223 HRSS_public_key hrss_public_key;
224 RAND_bytes(hrss_entropy, sizeof(hrss_entropy));
225 HRSS_generate_key(&hrss_public_key, &hrss_private_key_, hrss_entropy);
226
227 uint8_t hrss_public_key_bytes[HRSS_PUBLIC_KEY_BYTES];
228 HRSS_marshal_public_key(hrss_public_key_bytes, &hrss_public_key);
229
230 if (!CBB_add_bytes(out, x25519_public_key, sizeof(x25519_public_key)) ||
231 !CBB_add_bytes(out, hrss_public_key_bytes,
232 sizeof(hrss_public_key_bytes))) {
233 return false;
234 }
235
236 return true;
237 }
238
Accept(CBB * out_public_key,Array<uint8_t> * out_secret,uint8_t * out_alert,Span<const uint8_t> peer_key)239 bool Accept(CBB *out_public_key, Array<uint8_t> *out_secret,
240 uint8_t *out_alert, Span<const uint8_t> peer_key) override {
241 Array<uint8_t> secret;
242 if (!secret.Init(32 + HRSS_KEY_BYTES)) {
243 OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
244 return false;
245 }
246
247 uint8_t x25519_public_key[32];
248 X25519_keypair(x25519_public_key, x25519_private_key_);
249
250 HRSS_public_key peer_public_key;
251 if (peer_key.size() != 32 + HRSS_PUBLIC_KEY_BYTES ||
252 !HRSS_parse_public_key(&peer_public_key, peer_key.data() + 32) ||
253 !X25519(secret.data(), x25519_private_key_, peer_key.data())) {
254 *out_alert = SSL_AD_DECODE_ERROR;
255 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_ECPOINT);
256 return false;
257 }
258
259 uint8_t ciphertext[HRSS_CIPHERTEXT_BYTES];
260 uint8_t entropy[HRSS_ENCAP_BYTES];
261 RAND_bytes(entropy, sizeof(entropy));
262 HRSS_encap(ciphertext, secret.data() + 32, &peer_public_key, entropy);
263
264 if (!CBB_add_bytes(out_public_key, x25519_public_key,
265 sizeof(x25519_public_key)) ||
266 !CBB_add_bytes(out_public_key, ciphertext, sizeof(ciphertext))) {
267 return false;
268 }
269
270 *out_secret = std::move(secret);
271 return true;
272 }
273
Finish(Array<uint8_t> * out_secret,uint8_t * out_alert,Span<const uint8_t> peer_key)274 bool Finish(Array<uint8_t> *out_secret, uint8_t *out_alert,
275 Span<const uint8_t> peer_key) override {
276 *out_alert = SSL_AD_INTERNAL_ERROR;
277
278 Array<uint8_t> secret;
279 if (!secret.Init(32 + HRSS_KEY_BYTES)) {
280 OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
281 return false;
282 }
283
284 if (peer_key.size() != 32 + HRSS_CIPHERTEXT_BYTES ||
285 !X25519(secret.data(), x25519_private_key_, peer_key.data())) {
286 *out_alert = SSL_AD_DECODE_ERROR;
287 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_ECPOINT);
288 return false;
289 }
290
291 HRSS_decap(secret.data() + 32, &hrss_private_key_, peer_key.data() + 32,
292 peer_key.size() - 32);
293
294 *out_secret = std::move(secret);
295 return true;
296 }
297
298 private:
299 uint8_t x25519_private_key_[32];
300 HRSS_private_key hrss_private_key_;
301 };
302
303 CONSTEXPR_ARRAY NamedGroup kNamedGroups[] = {
304 {NID_secp224r1, SSL_CURVE_SECP224R1, "P-224", "secp224r1"},
305 {NID_X9_62_prime256v1, SSL_CURVE_SECP256R1, "P-256", "prime256v1"},
306 {NID_secp384r1, SSL_CURVE_SECP384R1, "P-384", "secp384r1"},
307 {NID_secp521r1, SSL_CURVE_SECP521R1, "P-521", "secp521r1"},
308 {NID_X25519, SSL_CURVE_X25519, "X25519", "x25519"},
309 {NID_CECPQ2, SSL_CURVE_CECPQ2, "CECPQ2", "CECPQ2"},
310 };
311
312 } // namespace
313
NamedGroups()314 Span<const NamedGroup> NamedGroups() {
315 return MakeConstSpan(kNamedGroups, OPENSSL_ARRAY_SIZE(kNamedGroups));
316 }
317
Create(uint16_t group_id)318 UniquePtr<SSLKeyShare> SSLKeyShare::Create(uint16_t group_id) {
319 switch (group_id) {
320 case SSL_CURVE_SECP224R1:
321 return UniquePtr<SSLKeyShare>(
322 New<ECKeyShare>(NID_secp224r1, SSL_CURVE_SECP224R1));
323 case SSL_CURVE_SECP256R1:
324 return UniquePtr<SSLKeyShare>(
325 New<ECKeyShare>(NID_X9_62_prime256v1, SSL_CURVE_SECP256R1));
326 case SSL_CURVE_SECP384R1:
327 return UniquePtr<SSLKeyShare>(
328 New<ECKeyShare>(NID_secp384r1, SSL_CURVE_SECP384R1));
329 case SSL_CURVE_SECP521R1:
330 return UniquePtr<SSLKeyShare>(
331 New<ECKeyShare>(NID_secp521r1, SSL_CURVE_SECP521R1));
332 case SSL_CURVE_X25519:
333 return UniquePtr<SSLKeyShare>(New<X25519KeyShare>());
334 case SSL_CURVE_CECPQ2:
335 return UniquePtr<SSLKeyShare>(New<CECPQ2KeyShare>());
336 default:
337 return nullptr;
338 }
339 }
340
Create(CBS * in)341 UniquePtr<SSLKeyShare> SSLKeyShare::Create(CBS *in) {
342 uint64_t group;
343 if (!CBS_get_asn1_uint64(in, &group) || group > 0xffff) {
344 return nullptr;
345 }
346 UniquePtr<SSLKeyShare> key_share = Create(static_cast<uint16_t>(group));
347 if (!key_share || !key_share->Deserialize(in)) {
348 return nullptr;
349 }
350 return key_share;
351 }
352
353
Accept(CBB * out_public_key,Array<uint8_t> * out_secret,uint8_t * out_alert,Span<const uint8_t> peer_key)354 bool SSLKeyShare::Accept(CBB *out_public_key, Array<uint8_t> *out_secret,
355 uint8_t *out_alert, Span<const uint8_t> peer_key) {
356 *out_alert = SSL_AD_INTERNAL_ERROR;
357 return Offer(out_public_key) &&
358 Finish(out_secret, out_alert, peer_key);
359 }
360
ssl_nid_to_group_id(uint16_t * out_group_id,int nid)361 bool ssl_nid_to_group_id(uint16_t *out_group_id, int nid) {
362 for (const auto &group : kNamedGroups) {
363 if (group.nid == nid) {
364 *out_group_id = group.group_id;
365 return true;
366 }
367 }
368 return false;
369 }
370
ssl_name_to_group_id(uint16_t * out_group_id,const char * name,size_t len)371 bool ssl_name_to_group_id(uint16_t *out_group_id, const char *name, size_t len) {
372 for (const auto &group : kNamedGroups) {
373 if (len == strlen(group.name) &&
374 !strncmp(group.name, name, len)) {
375 *out_group_id = group.group_id;
376 return true;
377 }
378 if (len == strlen(group.alias) &&
379 !strncmp(group.alias, name, len)) {
380 *out_group_id = group.group_id;
381 return true;
382 }
383 }
384 return false;
385 }
386
387 BSSL_NAMESPACE_END
388
389 using namespace bssl;
390
SSL_get_curve_name(uint16_t group_id)391 const char* SSL_get_curve_name(uint16_t group_id) {
392 for (const auto &group : kNamedGroups) {
393 if (group.group_id == group_id) {
394 return group.name;
395 }
396 }
397 return nullptr;
398 }
399