1/* Copyright (c) 2017, 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
26static void ed25519_free(EVP_PKEY *pkey) {
27 OPENSSL_free(pkey->pkey.ptr);
28 pkey->pkey.ptr = NULL;
29}
30
31static int ed25519_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 ED25519_KEY *key = OPENSSL_malloc(sizeof(ED25519_KEY));
38 if (key == NULL) {
39 OPENSSL_PUT_ERROR(EVP, ERR_R_MALLOC_FAILURE);
40 return 0;
41 }
42
43 // The RFC 8032 encoding stores only the 32-byte seed, so we must recover the
44 // full representation which we use from it.
45 uint8_t pubkey_unused[32];
46 ED25519_keypair_from_seed(pubkey_unused, key->key.priv, in);
47 key->has_private = 1;
48
49 ed25519_free(pkey);
50 pkey->pkey.ptr = key;
51 return 1;
52}
53
54static int ed25519_set_pub_raw(EVP_PKEY *pkey, const uint8_t *in, size_t len) {
55 if (len != 32) {
56 OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);
57 return 0;
58 }
59
60 ED25519_KEY *key = OPENSSL_malloc(sizeof(ED25519_KEY));
61 if (key == NULL) {
62 OPENSSL_PUT_ERROR(EVP, ERR_R_MALLOC_FAILURE);
63 return 0;
64 }
65
66 OPENSSL_memcpy(key->key.pub.value, in, 32);
67 key->has_private = 0;
68
69 ed25519_free(pkey);
70 pkey->pkey.ptr = key;
71 return 1;
72}
73
74static int ed25519_get_priv_raw(const EVP_PKEY *pkey, uint8_t *out,
75 size_t *out_len) {
76 const ED25519_KEY *key = pkey->pkey.ptr;
77 if (!key->has_private) {
78 OPENSSL_PUT_ERROR(EVP, EVP_R_NOT_A_PRIVATE_KEY);
79 return 0;
80 }
81
82 if (out == NULL) {
83 *out_len = 32;
84 return 1;
85 }
86
87 if (*out_len < 32) {
88 OPENSSL_PUT_ERROR(EVP, EVP_R_BUFFER_TOO_SMALL);
89 return 0;
90 }
91
92 // The raw private key format is the first 32 bytes of the private key.
93 OPENSSL_memcpy(out, key->key.priv, 32);
94 *out_len = 32;
95 return 1;
96}
97
98static int ed25519_get_pub_raw(const EVP_PKEY *pkey, uint8_t *out,
99 size_t *out_len) {
100 const ED25519_KEY *key = pkey->pkey.ptr;
101 if (out == NULL) {
102 *out_len = 32;
103 return 1;
104 }
105
106 if (*out_len < 32) {
107 OPENSSL_PUT_ERROR(EVP, EVP_R_BUFFER_TOO_SMALL);
108 return 0;
109 }
110
111 OPENSSL_memcpy(out, key->key.pub.value, 32);
112 *out_len = 32;
113 return 1;
114}
115
116static int ed25519_pub_decode(EVP_PKEY *out, CBS *params, CBS *key) {
117 // See RFC 8410, section 4.
118
119 // The parameters must be omitted. Public keys have length 32.
120 if (CBS_len(params) != 0) {
121 OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);
122 return 0;
123 }
124
125 return ed25519_set_pub_raw(out, CBS_data(key), CBS_len(key));
126}
127
128static int ed25519_pub_encode(CBB *out, const EVP_PKEY *pkey) {
129 const ED25519_KEY *key = pkey->pkey.ptr;
130
131 // See RFC 8410, section 4.
132 CBB spki, algorithm, oid, key_bitstring;
133 if (!CBB_add_asn1(out, &spki, CBS_ASN1_SEQUENCE) ||
134 !CBB_add_asn1(&spki, &algorithm, CBS_ASN1_SEQUENCE) ||
135 !CBB_add_asn1(&algorithm, &oid, CBS_ASN1_OBJECT) ||
136 !CBB_add_bytes(&oid, ed25519_asn1_meth.oid, ed25519_asn1_meth.oid_len) ||
137 !CBB_add_asn1(&spki, &key_bitstring, CBS_ASN1_BITSTRING) ||
138 !CBB_add_u8(&key_bitstring, 0 /* padding */) ||
139 !CBB_add_bytes(&key_bitstring, key->key.pub.value, 32) ||
140 !CBB_flush(out)) {
141 OPENSSL_PUT_ERROR(EVP, EVP_R_ENCODE_ERROR);
142 return 0;
143 }
144
145 return 1;
146}
147
148static int ed25519_pub_cmp(const EVP_PKEY *a, const EVP_PKEY *b) {
149 const ED25519_KEY *a_key = a->pkey.ptr;
150 const ED25519_KEY *b_key = b->pkey.ptr;
151 return OPENSSL_memcmp(a_key->key.pub.value, b_key->key.pub.value, 32) == 0;
152}
153
154static int ed25519_priv_decode(EVP_PKEY *out, CBS *params, CBS *key) {
155 // See RFC 8410, section 7.
156
157 // Parameters must be empty. The key is a 32-byte value wrapped in an extra
158 // OCTET STRING layer.
159 CBS inner;
160 if (CBS_len(params) != 0 ||
161 !CBS_get_asn1(key, &inner, CBS_ASN1_OCTETSTRING) ||
162 CBS_len(key) != 0) {
163 OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);
164 return 0;
165 }
166
167 return ed25519_set_priv_raw(out, CBS_data(&inner), CBS_len(&inner));
168}
169
170static int ed25519_priv_encode(CBB *out, const EVP_PKEY *pkey) {
171 ED25519_KEY *key = pkey->pkey.ptr;
172 if (!key->has_private) {
173 OPENSSL_PUT_ERROR(EVP, EVP_R_NOT_A_PRIVATE_KEY);
174 return 0;
175 }
176
177 // See RFC 8410, section 7.
178 CBB pkcs8, algorithm, oid, private_key, inner;
179 if (!CBB_add_asn1(out, &pkcs8, CBS_ASN1_SEQUENCE) ||
180 !CBB_add_asn1_uint64(&pkcs8, 0 /* version */) ||
181 !CBB_add_asn1(&pkcs8, &algorithm, CBS_ASN1_SEQUENCE) ||
182 !CBB_add_asn1(&algorithm, &oid, CBS_ASN1_OBJECT) ||
183 !CBB_add_bytes(&oid, ed25519_asn1_meth.oid, ed25519_asn1_meth.oid_len) ||
184 !CBB_add_asn1(&pkcs8, &private_key, CBS_ASN1_OCTETSTRING) ||
185 !CBB_add_asn1(&private_key, &inner, CBS_ASN1_OCTETSTRING) ||
186 // The PKCS#8 encoding stores only the 32-byte seed which is the first 32
187 // bytes of the private key.
188 !CBB_add_bytes(&inner, key->key.priv, 32) ||
189 !CBB_flush(out)) {
190 OPENSSL_PUT_ERROR(EVP, EVP_R_ENCODE_ERROR);
191 return 0;
192 }
193
194 return 1;
195}
196
197static int ed25519_size(const EVP_PKEY *pkey) { return 64; }
198
199static int ed25519_bits(const EVP_PKEY *pkey) { return 256; }
200
201const EVP_PKEY_ASN1_METHOD ed25519_asn1_meth = {
202 EVP_PKEY_ED25519,
203 {0x2b, 0x65, 0x70},
204 3,
205 ed25519_pub_decode,
206 ed25519_pub_encode,
207 ed25519_pub_cmp,
208 ed25519_priv_decode,
209 ed25519_priv_encode,
210 ed25519_set_priv_raw,
211 ed25519_set_pub_raw,
212 ed25519_get_priv_raw,
213 ed25519_get_pub_raw,
214 NULL /* pkey_opaque */,
215 ed25519_size,
216 ed25519_bits,
217 NULL /* param_missing */,
218 NULL /* param_copy */,
219 NULL /* param_cmp */,
220 ed25519_free,
221};
222