1 /* Copyright (c) 2019, 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/evp.h>
16
17 #include <openssl/bytestring.h>
18 #include <openssl/curve25519.h>
19 #include <openssl/err.h>
20 #include <openssl/mem.h>
21
22 #include "internal.h"
23 #include "../internal.h"
24
25
x25519_free(EVP_PKEY * pkey)26 static void x25519_free(EVP_PKEY *pkey) {
27 OPENSSL_free(pkey->pkey.ptr);
28 pkey->pkey.ptr = NULL;
29 }
30
x25519_set_priv_raw(EVP_PKEY * pkey,const uint8_t * in,size_t len)31 static int x25519_set_priv_raw(EVP_PKEY *pkey, const uint8_t *in, size_t len) {
32 if (len != 32) {
33 OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);
34 return 0;
35 }
36
37 X25519_KEY *key = OPENSSL_malloc(sizeof(X25519_KEY));
38 if (key == NULL) {
39 OPENSSL_PUT_ERROR(EVP, ERR_R_MALLOC_FAILURE);
40 return 0;
41 }
42
43 OPENSSL_memcpy(key->priv, in, 32);
44 X25519_public_from_private(key->pub, key->priv);
45 key->has_private = 1;
46
47 x25519_free(pkey);
48 pkey->pkey.ptr = key;
49 return 1;
50 }
51
x25519_set_pub_raw(EVP_PKEY * pkey,const uint8_t * in,size_t len)52 static int x25519_set_pub_raw(EVP_PKEY *pkey, const uint8_t *in, size_t len) {
53 if (len != 32) {
54 OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);
55 return 0;
56 }
57
58 X25519_KEY *key = OPENSSL_malloc(sizeof(X25519_KEY));
59 if (key == NULL) {
60 OPENSSL_PUT_ERROR(EVP, ERR_R_MALLOC_FAILURE);
61 return 0;
62 }
63
64 OPENSSL_memcpy(key->pub, in, 32);
65 key->has_private = 0;
66
67 x25519_free(pkey);
68 pkey->pkey.ptr = key;
69 return 1;
70 }
71
x25519_get_priv_raw(const EVP_PKEY * pkey,uint8_t * out,size_t * out_len)72 static int x25519_get_priv_raw(const EVP_PKEY *pkey, uint8_t *out,
73 size_t *out_len) {
74 const X25519_KEY *key = pkey->pkey.ptr;
75 if (!key->has_private) {
76 OPENSSL_PUT_ERROR(EVP, EVP_R_NOT_A_PRIVATE_KEY);
77 return 0;
78 }
79
80 if (out == NULL) {
81 *out_len = 32;
82 return 1;
83 }
84
85 if (*out_len < 32) {
86 OPENSSL_PUT_ERROR(EVP, EVP_R_BUFFER_TOO_SMALL);
87 return 0;
88 }
89
90 OPENSSL_memcpy(out, key->priv, 32);
91 *out_len = 32;
92 return 1;
93 }
94
x25519_get_pub_raw(const EVP_PKEY * pkey,uint8_t * out,size_t * out_len)95 static int x25519_get_pub_raw(const EVP_PKEY *pkey, uint8_t *out,
96 size_t *out_len) {
97 const X25519_KEY *key = pkey->pkey.ptr;
98 if (out == NULL) {
99 *out_len = 32;
100 return 1;
101 }
102
103 if (*out_len < 32) {
104 OPENSSL_PUT_ERROR(EVP, EVP_R_BUFFER_TOO_SMALL);
105 return 0;
106 }
107
108 OPENSSL_memcpy(out, key->pub, 32);
109 *out_len = 32;
110 return 1;
111 }
112
x25519_pub_decode(EVP_PKEY * out,CBS * params,CBS * key)113 static int x25519_pub_decode(EVP_PKEY *out, CBS *params, CBS *key) {
114 // See RFC 8410, section 4.
115
116 // The parameters must be omitted. Public keys have length 32.
117 if (CBS_len(params) != 0) {
118 OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);
119 return 0;
120 }
121
122 return x25519_set_pub_raw(out, CBS_data(key), CBS_len(key));
123 }
124
x25519_pub_encode(CBB * out,const EVP_PKEY * pkey)125 static int x25519_pub_encode(CBB *out, const EVP_PKEY *pkey) {
126 const X25519_KEY *key = pkey->pkey.ptr;
127
128 // See RFC 8410, section 4.
129 CBB spki, algorithm, oid, key_bitstring;
130 if (!CBB_add_asn1(out, &spki, CBS_ASN1_SEQUENCE) ||
131 !CBB_add_asn1(&spki, &algorithm, CBS_ASN1_SEQUENCE) ||
132 !CBB_add_asn1(&algorithm, &oid, CBS_ASN1_OBJECT) ||
133 !CBB_add_bytes(&oid, x25519_asn1_meth.oid, x25519_asn1_meth.oid_len) ||
134 !CBB_add_asn1(&spki, &key_bitstring, CBS_ASN1_BITSTRING) ||
135 !CBB_add_u8(&key_bitstring, 0 /* padding */) ||
136 !CBB_add_bytes(&key_bitstring, key->pub, 32) ||
137 !CBB_flush(out)) {
138 OPENSSL_PUT_ERROR(EVP, EVP_R_ENCODE_ERROR);
139 return 0;
140 }
141
142 return 1;
143 }
144
x25519_pub_cmp(const EVP_PKEY * a,const EVP_PKEY * b)145 static int x25519_pub_cmp(const EVP_PKEY *a, const EVP_PKEY *b) {
146 const X25519_KEY *a_key = a->pkey.ptr;
147 const X25519_KEY *b_key = b->pkey.ptr;
148 return OPENSSL_memcmp(a_key->pub, b_key->pub, 32) == 0;
149 }
150
x25519_priv_decode(EVP_PKEY * out,CBS * params,CBS * key)151 static int x25519_priv_decode(EVP_PKEY *out, CBS *params, CBS *key) {
152 // See RFC 8410, section 7.
153
154 // Parameters must be empty. The key is a 32-byte value wrapped in an extra
155 // OCTET STRING layer.
156 CBS inner;
157 if (CBS_len(params) != 0 ||
158 !CBS_get_asn1(key, &inner, CBS_ASN1_OCTETSTRING) ||
159 CBS_len(key) != 0) {
160 OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);
161 return 0;
162 }
163
164 return x25519_set_priv_raw(out, CBS_data(&inner), CBS_len(&inner));
165 }
166
x25519_priv_encode(CBB * out,const EVP_PKEY * pkey)167 static int x25519_priv_encode(CBB *out, const EVP_PKEY *pkey) {
168 X25519_KEY *key = pkey->pkey.ptr;
169 if (!key->has_private) {
170 OPENSSL_PUT_ERROR(EVP, EVP_R_NOT_A_PRIVATE_KEY);
171 return 0;
172 }
173
174 // See RFC 8410, section 7.
175 CBB pkcs8, algorithm, oid, private_key, inner;
176 if (!CBB_add_asn1(out, &pkcs8, CBS_ASN1_SEQUENCE) ||
177 !CBB_add_asn1_uint64(&pkcs8, 0 /* version */) ||
178 !CBB_add_asn1(&pkcs8, &algorithm, CBS_ASN1_SEQUENCE) ||
179 !CBB_add_asn1(&algorithm, &oid, CBS_ASN1_OBJECT) ||
180 !CBB_add_bytes(&oid, x25519_asn1_meth.oid, x25519_asn1_meth.oid_len) ||
181 !CBB_add_asn1(&pkcs8, &private_key, CBS_ASN1_OCTETSTRING) ||
182 !CBB_add_asn1(&private_key, &inner, CBS_ASN1_OCTETSTRING) ||
183 // The PKCS#8 encoding stores only the 32-byte seed which is the first 32
184 // bytes of the private key.
185 !CBB_add_bytes(&inner, key->priv, 32) ||
186 !CBB_flush(out)) {
187 OPENSSL_PUT_ERROR(EVP, EVP_R_ENCODE_ERROR);
188 return 0;
189 }
190
191 return 1;
192 }
193
x25519_size(const EVP_PKEY * pkey)194 static int x25519_size(const EVP_PKEY *pkey) { return 32; }
195
x25519_bits(const EVP_PKEY * pkey)196 static int x25519_bits(const EVP_PKEY *pkey) { return 253; }
197
198 const EVP_PKEY_ASN1_METHOD x25519_asn1_meth = {
199 EVP_PKEY_X25519,
200 {0x2b, 0x65, 0x6e},
201 3,
202 x25519_pub_decode,
203 x25519_pub_encode,
204 x25519_pub_cmp,
205 x25519_priv_decode,
206 x25519_priv_encode,
207 x25519_set_priv_raw,
208 x25519_set_pub_raw,
209 x25519_get_priv_raw,
210 x25519_get_pub_raw,
211 NULL /* pkey_opaque */,
212 x25519_size,
213 x25519_bits,
214 NULL /* param_missing */,
215 NULL /* param_copy */,
216 NULL /* param_cmp */,
217 x25519_free,
218 };
219
EVP_PKEY_set1_tls_encodedpoint(EVP_PKEY * pkey,const uint8_t * in,size_t len)220 int EVP_PKEY_set1_tls_encodedpoint(EVP_PKEY *pkey, const uint8_t *in,
221 size_t len) {
222 // TODO(davidben): In OpenSSL, this function also works for |EVP_PKEY_EC|
223 // keys. Add support if it ever comes up.
224 if (pkey->type != EVP_PKEY_X25519) {
225 OPENSSL_PUT_ERROR(EVP, EVP_R_UNSUPPORTED_PUBLIC_KEY_TYPE);
226 return 0;
227 }
228
229 return x25519_set_pub_raw(pkey, in, len);
230 }
231
EVP_PKEY_get1_tls_encodedpoint(const EVP_PKEY * pkey,uint8_t ** out_ptr)232 size_t EVP_PKEY_get1_tls_encodedpoint(const EVP_PKEY *pkey, uint8_t **out_ptr) {
233 // TODO(davidben): In OpenSSL, this function also works for |EVP_PKEY_EC|
234 // keys. Add support if it ever comes up.
235 if (pkey->type != EVP_PKEY_X25519) {
236 OPENSSL_PUT_ERROR(EVP, EVP_R_UNSUPPORTED_PUBLIC_KEY_TYPE);
237 return 0;
238 }
239
240 const X25519_KEY *key = pkey->pkey.ptr;
241 if (key == NULL) {
242 OPENSSL_PUT_ERROR(EVP, EVP_R_NO_KEY_SET);
243 return 0;
244 }
245
246 *out_ptr = OPENSSL_memdup(key->pub, 32);
247 return *out_ptr == NULL ? 0 : 32;
248 }
249