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);
28 pkey->pkey = 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 return 0;
40 }
41
42 OPENSSL_memcpy(key->priv, in, 32);
43 X25519_public_from_private(key->pub, key->priv);
44 key->has_private = 1;
45
46 x25519_free(pkey);
47 pkey->pkey = key;
48 return 1;
49 }
50
x25519_set_pub_raw(EVP_PKEY * pkey,const uint8_t * in,size_t len)51 static int x25519_set_pub_raw(EVP_PKEY *pkey, const uint8_t *in, size_t len) {
52 if (len != 32) {
53 OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);
54 return 0;
55 }
56
57 X25519_KEY *key = OPENSSL_malloc(sizeof(X25519_KEY));
58 if (key == NULL) {
59 return 0;
60 }
61
62 OPENSSL_memcpy(key->pub, in, 32);
63 key->has_private = 0;
64
65 x25519_free(pkey);
66 pkey->pkey = key;
67 return 1;
68 }
69
x25519_get_priv_raw(const EVP_PKEY * pkey,uint8_t * out,size_t * out_len)70 static int x25519_get_priv_raw(const EVP_PKEY *pkey, uint8_t *out,
71 size_t *out_len) {
72 const X25519_KEY *key = pkey->pkey;
73 if (!key->has_private) {
74 OPENSSL_PUT_ERROR(EVP, EVP_R_NOT_A_PRIVATE_KEY);
75 return 0;
76 }
77
78 if (out == NULL) {
79 *out_len = 32;
80 return 1;
81 }
82
83 if (*out_len < 32) {
84 OPENSSL_PUT_ERROR(EVP, EVP_R_BUFFER_TOO_SMALL);
85 return 0;
86 }
87
88 OPENSSL_memcpy(out, key->priv, 32);
89 *out_len = 32;
90 return 1;
91 }
92
x25519_get_pub_raw(const EVP_PKEY * pkey,uint8_t * out,size_t * out_len)93 static int x25519_get_pub_raw(const EVP_PKEY *pkey, uint8_t *out,
94 size_t *out_len) {
95 const X25519_KEY *key = pkey->pkey;
96 if (out == NULL) {
97 *out_len = 32;
98 return 1;
99 }
100
101 if (*out_len < 32) {
102 OPENSSL_PUT_ERROR(EVP, EVP_R_BUFFER_TOO_SMALL);
103 return 0;
104 }
105
106 OPENSSL_memcpy(out, key->pub, 32);
107 *out_len = 32;
108 return 1;
109 }
110
x25519_set1_tls_encodedpoint(EVP_PKEY * pkey,const uint8_t * in,size_t len)111 static int x25519_set1_tls_encodedpoint(EVP_PKEY *pkey, const uint8_t *in,
112 size_t len) {
113 return x25519_set_pub_raw(pkey, in, len);
114 }
115
x25519_get1_tls_encodedpoint(const EVP_PKEY * pkey,uint8_t ** out_ptr)116 static size_t x25519_get1_tls_encodedpoint(const EVP_PKEY *pkey,
117 uint8_t **out_ptr) {
118 const X25519_KEY *key = pkey->pkey;
119 if (key == NULL) {
120 OPENSSL_PUT_ERROR(EVP, EVP_R_NO_KEY_SET);
121 return 0;
122 }
123
124 *out_ptr = OPENSSL_memdup(key->pub, 32);
125 return *out_ptr == NULL ? 0 : 32;
126 }
127
x25519_pub_decode(EVP_PKEY * out,CBS * params,CBS * key)128 static int x25519_pub_decode(EVP_PKEY *out, CBS *params, CBS *key) {
129 // See RFC 8410, section 4.
130
131 // The parameters must be omitted. Public keys have length 32.
132 if (CBS_len(params) != 0) {
133 OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);
134 return 0;
135 }
136
137 return x25519_set_pub_raw(out, CBS_data(key), CBS_len(key));
138 }
139
x25519_pub_encode(CBB * out,const EVP_PKEY * pkey)140 static int x25519_pub_encode(CBB *out, const EVP_PKEY *pkey) {
141 const X25519_KEY *key = pkey->pkey;
142
143 // See RFC 8410, section 4.
144 CBB spki, algorithm, oid, key_bitstring;
145 if (!CBB_add_asn1(out, &spki, CBS_ASN1_SEQUENCE) ||
146 !CBB_add_asn1(&spki, &algorithm, CBS_ASN1_SEQUENCE) ||
147 !CBB_add_asn1(&algorithm, &oid, CBS_ASN1_OBJECT) ||
148 !CBB_add_bytes(&oid, x25519_asn1_meth.oid, x25519_asn1_meth.oid_len) ||
149 !CBB_add_asn1(&spki, &key_bitstring, CBS_ASN1_BITSTRING) ||
150 !CBB_add_u8(&key_bitstring, 0 /* padding */) ||
151 !CBB_add_bytes(&key_bitstring, key->pub, 32) ||
152 !CBB_flush(out)) {
153 OPENSSL_PUT_ERROR(EVP, EVP_R_ENCODE_ERROR);
154 return 0;
155 }
156
157 return 1;
158 }
159
x25519_pub_cmp(const EVP_PKEY * a,const EVP_PKEY * b)160 static int x25519_pub_cmp(const EVP_PKEY *a, const EVP_PKEY *b) {
161 const X25519_KEY *a_key = a->pkey;
162 const X25519_KEY *b_key = b->pkey;
163 return OPENSSL_memcmp(a_key->pub, b_key->pub, 32) == 0;
164 }
165
x25519_priv_decode(EVP_PKEY * out,CBS * params,CBS * key)166 static int x25519_priv_decode(EVP_PKEY *out, CBS *params, CBS *key) {
167 // See RFC 8410, section 7.
168
169 // Parameters must be empty. The key is a 32-byte value wrapped in an extra
170 // OCTET STRING layer.
171 CBS inner;
172 if (CBS_len(params) != 0 ||
173 !CBS_get_asn1(key, &inner, CBS_ASN1_OCTETSTRING) ||
174 CBS_len(key) != 0) {
175 OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);
176 return 0;
177 }
178
179 return x25519_set_priv_raw(out, CBS_data(&inner), CBS_len(&inner));
180 }
181
x25519_priv_encode(CBB * out,const EVP_PKEY * pkey)182 static int x25519_priv_encode(CBB *out, const EVP_PKEY *pkey) {
183 const X25519_KEY *key = pkey->pkey;
184 if (!key->has_private) {
185 OPENSSL_PUT_ERROR(EVP, EVP_R_NOT_A_PRIVATE_KEY);
186 return 0;
187 }
188
189 // See RFC 8410, section 7.
190 CBB pkcs8, algorithm, oid, private_key, inner;
191 if (!CBB_add_asn1(out, &pkcs8, CBS_ASN1_SEQUENCE) ||
192 !CBB_add_asn1_uint64(&pkcs8, 0 /* version */) ||
193 !CBB_add_asn1(&pkcs8, &algorithm, CBS_ASN1_SEQUENCE) ||
194 !CBB_add_asn1(&algorithm, &oid, CBS_ASN1_OBJECT) ||
195 !CBB_add_bytes(&oid, x25519_asn1_meth.oid, x25519_asn1_meth.oid_len) ||
196 !CBB_add_asn1(&pkcs8, &private_key, CBS_ASN1_OCTETSTRING) ||
197 !CBB_add_asn1(&private_key, &inner, CBS_ASN1_OCTETSTRING) ||
198 // The PKCS#8 encoding stores only the 32-byte seed which is the first 32
199 // bytes of the private key.
200 !CBB_add_bytes(&inner, key->priv, 32) ||
201 !CBB_flush(out)) {
202 OPENSSL_PUT_ERROR(EVP, EVP_R_ENCODE_ERROR);
203 return 0;
204 }
205
206 return 1;
207 }
208
x25519_size(const EVP_PKEY * pkey)209 static int x25519_size(const EVP_PKEY *pkey) { return 32; }
210
x25519_bits(const EVP_PKEY * pkey)211 static int x25519_bits(const EVP_PKEY *pkey) { return 253; }
212
213 const EVP_PKEY_ASN1_METHOD x25519_asn1_meth = {
214 EVP_PKEY_X25519,
215 {0x2b, 0x65, 0x6e},
216 3,
217 &x25519_pkey_meth,
218 x25519_pub_decode,
219 x25519_pub_encode,
220 x25519_pub_cmp,
221 x25519_priv_decode,
222 x25519_priv_encode,
223 x25519_set_priv_raw,
224 x25519_set_pub_raw,
225 x25519_get_priv_raw,
226 x25519_get_pub_raw,
227 x25519_set1_tls_encodedpoint,
228 x25519_get1_tls_encodedpoint,
229 /*pkey_opaque=*/NULL,
230 x25519_size,
231 x25519_bits,
232 /*param_missing=*/NULL,
233 /*param_copy=*/NULL,
234 /*param_cmp=*/NULL,
235 x25519_free,
236 };
237