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/buf.h>
18 #include <openssl/bytestring.h>
19 #include <openssl/curve25519.h>
20 #include <openssl/err.h>
21 #include <openssl/mem.h>
22
23 #include "internal.h"
24 #include "../internal.h"
25
26
x25519_free(EVP_PKEY * pkey)27 static void x25519_free(EVP_PKEY *pkey) {
28 OPENSSL_free(pkey->pkey.ptr);
29 pkey->pkey.ptr = NULL;
30 }
31
x25519_set_priv_raw(EVP_PKEY * pkey,const uint8_t * in,size_t len)32 static int x25519_set_priv_raw(EVP_PKEY *pkey, const uint8_t *in, size_t len) {
33 if (len != 32) {
34 OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);
35 return 0;
36 }
37
38 X25519_KEY *key = OPENSSL_malloc(sizeof(X25519_KEY));
39 if (key == NULL) {
40 OPENSSL_PUT_ERROR(EVP, ERR_R_MALLOC_FAILURE);
41 return 0;
42 }
43
44 OPENSSL_memcpy(key->priv, in, 32);
45 X25519_public_from_private(key->pub, key->priv);
46 key->has_private = 1;
47
48 x25519_free(pkey);
49 pkey->pkey.ptr = key;
50 return 1;
51 }
52
x25519_set_pub_raw(EVP_PKEY * pkey,const uint8_t * in,size_t len)53 static int x25519_set_pub_raw(EVP_PKEY *pkey, const uint8_t *in, size_t len) {
54 if (len != 32) {
55 OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);
56 return 0;
57 }
58
59 X25519_KEY *key = OPENSSL_malloc(sizeof(X25519_KEY));
60 if (key == NULL) {
61 OPENSSL_PUT_ERROR(EVP, ERR_R_MALLOC_FAILURE);
62 return 0;
63 }
64
65 OPENSSL_memcpy(key->pub, in, 32);
66 key->has_private = 0;
67
68 x25519_free(pkey);
69 pkey->pkey.ptr = key;
70 return 1;
71 }
72
x25519_get_priv_raw(const EVP_PKEY * pkey,uint8_t * out,size_t * out_len)73 static int x25519_get_priv_raw(const EVP_PKEY *pkey, uint8_t *out,
74 size_t *out_len) {
75 const X25519_KEY *key = pkey->pkey.ptr;
76 if (!key->has_private) {
77 OPENSSL_PUT_ERROR(EVP, EVP_R_NOT_A_PRIVATE_KEY);
78 return 0;
79 }
80
81 if (out == NULL) {
82 *out_len = 32;
83 return 1;
84 }
85
86 if (*out_len < 32) {
87 OPENSSL_PUT_ERROR(EVP, EVP_R_BUFFER_TOO_SMALL);
88 return 0;
89 }
90
91 OPENSSL_memcpy(out, key->priv, 32);
92 *out_len = 32;
93 return 1;
94 }
95
x25519_get_pub_raw(const EVP_PKEY * pkey,uint8_t * out,size_t * out_len)96 static int x25519_get_pub_raw(const EVP_PKEY *pkey, uint8_t *out,
97 size_t *out_len) {
98 const X25519_KEY *key = pkey->pkey.ptr;
99 if (out == NULL) {
100 *out_len = 32;
101 return 1;
102 }
103
104 if (*out_len < 32) {
105 OPENSSL_PUT_ERROR(EVP, EVP_R_BUFFER_TOO_SMALL);
106 return 0;
107 }
108
109 OPENSSL_memcpy(out, key->pub, 32);
110 *out_len = 32;
111 return 1;
112 }
113
x25519_pub_decode(EVP_PKEY * out,CBS * params,CBS * key)114 static int x25519_pub_decode(EVP_PKEY *out, CBS *params, CBS *key) {
115 // See RFC 8410, section 4.
116
117 // The parameters must be omitted. Public keys have length 32.
118 if (CBS_len(params) != 0) {
119 OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);
120 return 0;
121 }
122
123 return x25519_set_pub_raw(out, CBS_data(key), CBS_len(key));
124 }
125
x25519_pub_encode(CBB * out,const EVP_PKEY * pkey)126 static int x25519_pub_encode(CBB *out, const EVP_PKEY *pkey) {
127 const X25519_KEY *key = pkey->pkey.ptr;
128
129 // See RFC 8410, section 4.
130 CBB spki, algorithm, oid, key_bitstring;
131 if (!CBB_add_asn1(out, &spki, CBS_ASN1_SEQUENCE) ||
132 !CBB_add_asn1(&spki, &algorithm, CBS_ASN1_SEQUENCE) ||
133 !CBB_add_asn1(&algorithm, &oid, CBS_ASN1_OBJECT) ||
134 !CBB_add_bytes(&oid, x25519_asn1_meth.oid, x25519_asn1_meth.oid_len) ||
135 !CBB_add_asn1(&spki, &key_bitstring, CBS_ASN1_BITSTRING) ||
136 !CBB_add_u8(&key_bitstring, 0 /* padding */) ||
137 !CBB_add_bytes(&key_bitstring, key->pub, 32) ||
138 !CBB_flush(out)) {
139 OPENSSL_PUT_ERROR(EVP, EVP_R_ENCODE_ERROR);
140 return 0;
141 }
142
143 return 1;
144 }
145
x25519_pub_cmp(const EVP_PKEY * a,const EVP_PKEY * b)146 static int x25519_pub_cmp(const EVP_PKEY *a, const EVP_PKEY *b) {
147 const X25519_KEY *a_key = a->pkey.ptr;
148 const X25519_KEY *b_key = b->pkey.ptr;
149 return OPENSSL_memcmp(a_key->pub, b_key->pub, 32) == 0;
150 }
151
x25519_priv_decode(EVP_PKEY * out,CBS * params,CBS * key)152 static int x25519_priv_decode(EVP_PKEY *out, CBS *params, CBS *key) {
153 // See RFC 8410, section 7.
154
155 // Parameters must be empty. The key is a 32-byte value wrapped in an extra
156 // OCTET STRING layer.
157 CBS inner;
158 if (CBS_len(params) != 0 ||
159 !CBS_get_asn1(key, &inner, CBS_ASN1_OCTETSTRING) ||
160 CBS_len(key) != 0) {
161 OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);
162 return 0;
163 }
164
165 return x25519_set_priv_raw(out, CBS_data(&inner), CBS_len(&inner));
166 }
167
x25519_priv_encode(CBB * out,const EVP_PKEY * pkey)168 static int x25519_priv_encode(CBB *out, const EVP_PKEY *pkey) {
169 X25519_KEY *key = pkey->pkey.ptr;
170 if (!key->has_private) {
171 OPENSSL_PUT_ERROR(EVP, EVP_R_NOT_A_PRIVATE_KEY);
172 return 0;
173 }
174
175 // See RFC 8410, section 7.
176 CBB pkcs8, algorithm, oid, private_key, inner;
177 if (!CBB_add_asn1(out, &pkcs8, CBS_ASN1_SEQUENCE) ||
178 !CBB_add_asn1_uint64(&pkcs8, 0 /* version */) ||
179 !CBB_add_asn1(&pkcs8, &algorithm, CBS_ASN1_SEQUENCE) ||
180 !CBB_add_asn1(&algorithm, &oid, CBS_ASN1_OBJECT) ||
181 !CBB_add_bytes(&oid, x25519_asn1_meth.oid, x25519_asn1_meth.oid_len) ||
182 !CBB_add_asn1(&pkcs8, &private_key, CBS_ASN1_OCTETSTRING) ||
183 !CBB_add_asn1(&private_key, &inner, CBS_ASN1_OCTETSTRING) ||
184 // The PKCS#8 encoding stores only the 32-byte seed which is the first 32
185 // bytes of the private key.
186 !CBB_add_bytes(&inner, key->priv, 32) ||
187 !CBB_flush(out)) {
188 OPENSSL_PUT_ERROR(EVP, EVP_R_ENCODE_ERROR);
189 return 0;
190 }
191
192 return 1;
193 }
194
x25519_size(const EVP_PKEY * pkey)195 static int x25519_size(const EVP_PKEY *pkey) { return 32; }
196
x25519_bits(const EVP_PKEY * pkey)197 static int x25519_bits(const EVP_PKEY *pkey) { return 253; }
198
199 const EVP_PKEY_ASN1_METHOD x25519_asn1_meth = {
200 EVP_PKEY_X25519,
201 {0x2b, 0x65, 0x6e},
202 3,
203 x25519_pub_decode,
204 x25519_pub_encode,
205 x25519_pub_cmp,
206 x25519_priv_decode,
207 x25519_priv_encode,
208 x25519_set_priv_raw,
209 x25519_set_pub_raw,
210 x25519_get_priv_raw,
211 x25519_get_pub_raw,
212 NULL /* pkey_opaque */,
213 x25519_size,
214 x25519_bits,
215 NULL /* param_missing */,
216 NULL /* param_copy */,
217 NULL /* param_cmp */,
218 x25519_free,
219 };
220
EVP_PKEY_set1_tls_encodedpoint(EVP_PKEY * pkey,const uint8_t * in,size_t len)221 int EVP_PKEY_set1_tls_encodedpoint(EVP_PKEY *pkey, const uint8_t *in,
222 size_t len) {
223 // TODO(davidben): In OpenSSL, this function also works for |EVP_PKEY_EC|
224 // keys. Add support if it ever comes up.
225 if (pkey->type != EVP_PKEY_X25519) {
226 OPENSSL_PUT_ERROR(EVP, EVP_R_UNSUPPORTED_PUBLIC_KEY_TYPE);
227 return 0;
228 }
229
230 return x25519_set_pub_raw(pkey, in, len);
231 }
232
EVP_PKEY_get1_tls_encodedpoint(const EVP_PKEY * pkey,uint8_t ** out_ptr)233 size_t EVP_PKEY_get1_tls_encodedpoint(const EVP_PKEY *pkey, uint8_t **out_ptr) {
234 // TODO(davidben): In OpenSSL, this function also works for |EVP_PKEY_EC|
235 // keys. Add support if it ever comes up.
236 if (pkey->type != EVP_PKEY_X25519) {
237 OPENSSL_PUT_ERROR(EVP, EVP_R_UNSUPPORTED_PUBLIC_KEY_TYPE);
238 return 0;
239 }
240
241 const X25519_KEY *key = pkey->pkey.ptr;
242 if (key == NULL) {
243 OPENSSL_PUT_ERROR(EVP, EVP_R_NO_KEY_SET);
244 return 0;
245 }
246
247 *out_ptr = BUF_memdup(key->pub, 32);
248 return *out_ptr == NULL ? 0 : 32;
249 }
250