1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
/* $OpenBSD: cipher-ctr.c,v 1.10 2006/08/03 03:34:42 deraadt Exp $ */
/*
* Copyright (c) 2003 Markus Friedl <markus@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "includes.h"
#include <sys/types.h>
#include <stdarg.h>
#include <string.h>
#include <openssl/evp.h>
#include "xmalloc.h"
#include "log.h"
/* compatibility with old or broken OpenSSL versions */
#include "openbsd-compat/openssl-compat.h"
#ifndef USE_BUILTIN_RIJNDAEL
#include <openssl/aes.h>
#endif
const EVP_CIPHER *evp_aes_128_ctr(void);
void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
struct ssh_aes_ctr_ctx
{
AES_KEY aes_ctx;
u_char aes_counter[AES_BLOCK_SIZE];
};
/*
* increment counter 'ctr',
* the counter is of size 'len' bytes and stored in network-byte-order.
* (LSB at ctr[len-1], MSB at ctr[0])
*/
static void
ssh_ctr_inc(u_char *ctr, u_int len)
{
int i;
for (i = len - 1; i >= 0; i--)
if (++ctr[i]) /* continue on overflow */
return;
}
static int
ssh_aes_ctr(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
u_int len)
{
struct ssh_aes_ctr_ctx *c;
u_int n = 0;
u_char buf[AES_BLOCK_SIZE];
if (len == 0)
return (1);
if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL)
return (0);
while ((len--) > 0) {
if (n == 0) {
AES_encrypt(c->aes_counter, buf, &c->aes_ctx);
ssh_ctr_inc(c->aes_counter, AES_BLOCK_SIZE);
}
*(dest++) = *(src++) ^ buf[n];
n = (n + 1) % AES_BLOCK_SIZE;
}
return (1);
}
static int
ssh_aes_ctr_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
int enc)
{
struct ssh_aes_ctr_ctx *c;
if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
c = xmalloc(sizeof(*c));
EVP_CIPHER_CTX_set_app_data(ctx, c);
}
if (key != NULL)
AES_set_encrypt_key(key, EVP_CIPHER_CTX_key_length(ctx) * 8,
&c->aes_ctx);
if (iv != NULL)
memcpy(c->aes_counter, iv, AES_BLOCK_SIZE);
return (1);
}
static int
ssh_aes_ctr_cleanup(EVP_CIPHER_CTX *ctx)
{
struct ssh_aes_ctr_ctx *c;
if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
memset(c, 0, sizeof(*c));
xfree(c);
EVP_CIPHER_CTX_set_app_data(ctx, NULL);
}
return (1);
}
void
ssh_aes_ctr_iv(EVP_CIPHER_CTX *evp, int doset, u_char * iv, u_int len)
{
struct ssh_aes_ctr_ctx *c;
if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL)
fatal("ssh_aes_ctr_iv: no context");
if (doset)
memcpy(c->aes_counter, iv, len);
else
memcpy(iv, c->aes_counter, len);
}
const EVP_CIPHER *
evp_aes_128_ctr(void)
{
static EVP_CIPHER aes_ctr;
memset(&aes_ctr, 0, sizeof(EVP_CIPHER));
aes_ctr.nid = NID_undef;
aes_ctr.block_size = AES_BLOCK_SIZE;
aes_ctr.iv_len = AES_BLOCK_SIZE;
aes_ctr.key_len = 16;
aes_ctr.init = ssh_aes_ctr_init;
aes_ctr.cleanup = ssh_aes_ctr_cleanup;
aes_ctr.do_cipher = ssh_aes_ctr;
#ifndef SSH_OLD_EVP
aes_ctr.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CUSTOM_IV;
#endif
return (&aes_ctr);
}
|
