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comparison ed25519.c @ 1659:d32bcb5c557d

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Add Ed25519 support (#91) * Add support for Ed25519 as a public key type Ed25519 is a elliptic curve signature scheme that offers better security than ECDSA and DSA and good performance. It may be used for both user and host keys. OpenSSH key import and fuzzer are not supported yet. Initially inspired by Peter Szabo. * Add curve25519 and ed25519 fuzzers * Add import and export of Ed25519 keys
author Vladislav Grishenko <themiron@users.noreply.github.com>
date Wed, 11 Mar 2020 21:09:45 +0500
parents
children 41a0ff8d5a89
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1658:7402218141d4 1659:d32bcb5c557d
1 /*
2 * Dropbear - a SSH2 server
3 *
4 * Copyright (c) 2002,2003 Matt Johnston
5 * All rights reserved.
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23 * SOFTWARE. */
24
25 /* Perform Ed25519 operations on data, including reading keys, signing and
26 * verification. */
27
28 #include "includes.h"
29 #include "dbutil.h"
30 #include "buffer.h"
31 #include "ssh.h"
32 #include "curve25519.h"
33 #include "ed25519.h"
34
35 #if DROPBEAR_ED25519
36
37 /* Load a public ed25519 key from a buffer, initialising the values.
38 * The key will have the same format as buf_put_ed25519_key.
39 * These should be freed with ed25519_key_free.
40 * Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */
41 int buf_get_ed25519_pub_key(buffer *buf, dropbear_ed25519_key *key) {
42
43 unsigned int len;
44
45 TRACE(("enter buf_get_ed25519_pub_key"))
46 dropbear_assert(key != NULL);
47
48 buf_incrpos(buf, 4+SSH_SIGNKEY_ED25519_LEN); /* int + "ssh-ed25519" */
49
50 len = buf_getint(buf);
51 if (len != CURVE25519_LEN || buf->len - buf->pos < len) {
52 TRACE(("leave buf_get_ed25519_pub_key: failure"))
53 return DROPBEAR_FAILURE;
54 }
55
56 m_burn(key->priv, CURVE25519_LEN);
57 memcpy(key->pub, buf_getptr(buf, CURVE25519_LEN), CURVE25519_LEN);
58 buf_incrpos(buf, CURVE25519_LEN);
59
60 TRACE(("leave buf_get_ed25519_pub_key: success"))
61 return DROPBEAR_SUCCESS;
62 }
63
64 /* Same as buf_get_ed25519_pub_key, but reads private key at the end.
65 * Loads a public and private ed25519 key from a buffer
66 * Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */
67 int buf_get_ed25519_priv_key(buffer *buf, dropbear_ed25519_key *key) {
68
69 unsigned int len;
70
71 TRACE(("enter buf_get_ed25519_priv_key"))
72 dropbear_assert(key != NULL);
73
74 buf_incrpos(buf, 4+SSH_SIGNKEY_ED25519_LEN); /* int + "ssh-ed25519" */
75
76 len = buf_getint(buf);
77 if (len != CURVE25519_LEN*2 || buf->len - buf->pos < len) {
78 TRACE(("leave buf_get_ed25519_priv_key: failure"))
79 return DROPBEAR_FAILURE;
80 }
81
82 memcpy(key->priv, buf_getptr(buf, CURVE25519_LEN), CURVE25519_LEN);
83 buf_incrpos(buf, CURVE25519_LEN);
84 memcpy(key->pub, buf_getptr(buf, CURVE25519_LEN), CURVE25519_LEN);
85 buf_incrpos(buf, CURVE25519_LEN);
86
87 TRACE(("leave buf_get_ed25519_pub_key: success"))
88 return DROPBEAR_SUCCESS;
89 }
90
91 /* Clear and free the memory used by a public or private key */
92 void ed25519_key_free(dropbear_ed25519_key *key) {
93
94 TRACE2(("enter ed25519_key_free"))
95
96 if (key == NULL) {
97 TRACE2(("leave ed25519_key_free: key == NULL"))
98 return;
99 }
100 m_burn(key->priv, CURVE25519_LEN);
101 m_free(key);
102
103 TRACE2(("leave rsa_key_free"))
104 }
105
106 /* Put the public ed25519 key into the buffer in the required format */
107 void buf_put_ed25519_pub_key(buffer *buf, const dropbear_ed25519_key *key) {
108
109 TRACE(("enter buf_put_ed25519_pub_key"))
110 dropbear_assert(key != NULL);
111
112 buf_putstring(buf, SSH_SIGNKEY_ED25519, SSH_SIGNKEY_ED25519_LEN);
113 buf_putstring(buf, key->pub, CURVE25519_LEN);
114
115 TRACE(("leave buf_put_ed25519_pub_key"))
116 }
117
118 /* Put the public and private ed25519 key into the buffer in the required format */
119 void buf_put_ed25519_priv_key(buffer *buf, const dropbear_ed25519_key *key) {
120
121 TRACE(("enter buf_put_ed25519_priv_key"))
122 dropbear_assert(key != NULL);
123
124 buf_putstring(buf, SSH_SIGNKEY_ED25519, SSH_SIGNKEY_ED25519_LEN);
125 buf_putint(buf, CURVE25519_LEN*2);
126 buf_putbytes(buf, key->priv, CURVE25519_LEN);
127 buf_putbytes(buf, key->pub, CURVE25519_LEN);
128
129 TRACE(("leave buf_put_ed25519_priv_key"))
130 }
131
132 /* Sign the data presented with key, writing the signature contents
133 * to the buffer */
134 void buf_put_ed25519_sign(buffer* buf, const dropbear_ed25519_key *key, const buffer *data_buf) {
135
136 unsigned char s[64];
137 unsigned long slen = sizeof(s);
138
139 TRACE(("enter buf_put_ed25519_sign"))
140 dropbear_assert(key != NULL);
141
142 if (dropbear_ed25519_sign(data_buf->data, data_buf->len,
143 s, &slen, key->priv, key->pub) == 0) {
144 buf_putstring(buf, SSH_SIGNKEY_ED25519, SSH_SIGNKEY_ED25519_LEN);
145 buf_putstring(buf, s, slen);
146 }
147
148 TRACE(("leave buf_put_ed25519_sign"))
149 }
150
151 #if DROPBEAR_SIGNKEY_VERIFY
152 /* Verify a signature in buf, made on data by the key given.
153 * Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */
154 int buf_ed25519_verify(buffer *buf, const dropbear_ed25519_key *key, const buffer *data_buf) {
155
156 int ret = DROPBEAR_FAILURE;
157 unsigned char *s;
158 unsigned long slen;
159
160 TRACE(("enter buf_ed25519_verify"))
161 dropbear_assert(key != NULL);
162
163 slen = buf_getint(buf);
164 if (slen != 64 || buf->len - buf->pos < slen) {
165 TRACE(("bad size"))
166 goto out;
167 }
168 s = buf_getptr(buf, slen);
169
170 if (dropbear_ed25519_verify(data_buf->data, data_buf->len,
171 s, slen, key->pub) == 0) {
172 /* signature is valid */
173 TRACE(("success!"))
174 ret = DROPBEAR_SUCCESS;
175 }
176
177 out:
178 TRACE(("leave buf_ed25519_verify: ret %d", ret))
179 return ret;
180 }
181
182 #endif /* DROPBEAR_SIGNKEY_VERIFY */
183
184 #endif /* DROPBEAR_ED25519 */