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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     OPENSSL_PUT_ERROR(EVP, ERR_R_MALLOC_FAILURE);
31     return 0;
32   }
33 
34   if (!EVP_PKEY_set_type(pkey, EVP_PKEY_X25519)) {
35     OPENSSL_free(key);
36     return 0;
37   }
38 
39   X25519_keypair(key->pub, key->priv);
40   key->has_private = 1;
41 
42   OPENSSL_free(pkey->pkey.ptr);
43   pkey->pkey.ptr = key;
44   return 1;
45 }
46 
pkey_x25519_derive(EVP_PKEY_CTX * ctx,uint8_t * out,size_t * out_len)47 static int pkey_x25519_derive(EVP_PKEY_CTX *ctx, uint8_t *out,
48                               size_t *out_len) {
49   if (ctx->pkey == NULL || ctx->peerkey == NULL) {
50     OPENSSL_PUT_ERROR(EVP, EVP_R_KEYS_NOT_SET);
51     return 0;
52   }
53 
54   const X25519_KEY *our_key = ctx->pkey->pkey.ptr;
55   const X25519_KEY *peer_key = ctx->peerkey->pkey.ptr;
56   if (our_key == NULL || peer_key == NULL) {
57     OPENSSL_PUT_ERROR(EVP, EVP_R_KEYS_NOT_SET);
58     return 0;
59   }
60 
61   if (!our_key->has_private) {
62     OPENSSL_PUT_ERROR(EVP, EVP_R_NOT_A_PRIVATE_KEY);
63     return 0;
64   }
65 
66   if (out != NULL) {
67     if (*out_len < 32) {
68       OPENSSL_PUT_ERROR(EVP, EVP_R_BUFFER_TOO_SMALL);
69       return 0;
70     }
71     if (!X25519(out, our_key->priv, peer_key->pub)) {
72       OPENSSL_PUT_ERROR(EVP, EVP_R_INVALID_PEER_KEY);
73       return 0;
74     }
75   }
76 
77   *out_len = 32;
78   return 1;
79 }
80 
pkey_x25519_ctrl(EVP_PKEY_CTX * ctx,int type,int p1,void * p2)81 static int pkey_x25519_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2) {
82   switch (type) {
83     case EVP_PKEY_CTRL_PEER_KEY:
84       // |EVP_PKEY_derive_set_peer| requires the key implement this command,
85       // even if it is a no-op.
86       return 1;
87 
88     default:
89       OPENSSL_PUT_ERROR(EVP, EVP_R_COMMAND_NOT_SUPPORTED);
90       return 0;
91   }
92 }
93 
94 const EVP_PKEY_METHOD x25519_pkey_meth = {
95     EVP_PKEY_X25519,
96     NULL /* init */,
97     pkey_x25519_copy,
98     NULL /* cleanup */,
99     pkey_x25519_keygen,
100     NULL /* sign */,
101     NULL /* sign_message */,
102     NULL /* verify */,
103     NULL /* verify_message */,
104     NULL /* verify_recover */,
105     NULL /* encrypt */,
106     NULL /* decrypt */,
107     pkey_x25519_derive,
108     NULL /* paramgen */,
109     pkey_x25519_ctrl,
110 };
111