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/curve25519.h>
18 #include <openssl/err.h>
19 #include <openssl/mem.h>
20
21 #include "internal.h"
22
23
24 // X25519 has no parameters to copy.
pkey_x25519_copy(EVP_PKEY_CTX * dst,EVP_PKEY_CTX * src)25 static int pkey_x25519_copy(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src) { return 1; }
26
pkey_x25519_keygen(EVP_PKEY_CTX * ctx,EVP_PKEY * pkey)27 static int pkey_x25519_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey) {
28 X25519_KEY *key = OPENSSL_malloc(sizeof(X25519_KEY));
29 if (key == NULL) {
30 return 0;
31 }
32
33 evp_pkey_set_method(pkey, &x25519_asn1_meth);
34
35 X25519_keypair(key->pub, key->priv);
36 key->has_private = 1;
37
38 OPENSSL_free(pkey->pkey);
39 pkey->pkey = key;
40 return 1;
41 }
42
pkey_x25519_derive(EVP_PKEY_CTX * ctx,uint8_t * out,size_t * out_len)43 static int pkey_x25519_derive(EVP_PKEY_CTX *ctx, uint8_t *out,
44 size_t *out_len) {
45 if (ctx->pkey == NULL || ctx->peerkey == NULL) {
46 OPENSSL_PUT_ERROR(EVP, EVP_R_KEYS_NOT_SET);
47 return 0;
48 }
49
50 const X25519_KEY *our_key = ctx->pkey->pkey;
51 const X25519_KEY *peer_key = ctx->peerkey->pkey;
52 if (our_key == NULL || peer_key == NULL) {
53 OPENSSL_PUT_ERROR(EVP, EVP_R_KEYS_NOT_SET);
54 return 0;
55 }
56
57 if (!our_key->has_private) {
58 OPENSSL_PUT_ERROR(EVP, EVP_R_NOT_A_PRIVATE_KEY);
59 return 0;
60 }
61
62 if (out != NULL) {
63 if (*out_len < 32) {
64 OPENSSL_PUT_ERROR(EVP, EVP_R_BUFFER_TOO_SMALL);
65 return 0;
66 }
67 if (!X25519(out, our_key->priv, peer_key->pub)) {
68 OPENSSL_PUT_ERROR(EVP, EVP_R_INVALID_PEER_KEY);
69 return 0;
70 }
71 }
72
73 *out_len = 32;
74 return 1;
75 }
76
pkey_x25519_ctrl(EVP_PKEY_CTX * ctx,int type,int p1,void * p2)77 static int pkey_x25519_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2) {
78 switch (type) {
79 case EVP_PKEY_CTRL_PEER_KEY:
80 // |EVP_PKEY_derive_set_peer| requires the key implement this command,
81 // even if it is a no-op.
82 return 1;
83
84 default:
85 OPENSSL_PUT_ERROR(EVP, EVP_R_COMMAND_NOT_SUPPORTED);
86 return 0;
87 }
88 }
89
90 const EVP_PKEY_METHOD x25519_pkey_meth = {
91 EVP_PKEY_X25519,
92 NULL /* init */,
93 pkey_x25519_copy,
94 NULL /* cleanup */,
95 pkey_x25519_keygen,
96 NULL /* sign */,
97 NULL /* sign_message */,
98 NULL /* verify */,
99 NULL /* verify_message */,
100 NULL /* verify_recover */,
101 NULL /* encrypt */,
102 NULL /* decrypt */,
103 pkey_x25519_derive,
104 NULL /* paramgen */,
105 pkey_x25519_ctrl,
106 };
107