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
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
|
/*
* Copyright (c) 2021 Yubico AB. All rights reserved.
* Use of this source code is governed by a BSD-style
* license that can be found in the LICENSE file.
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "fido.h"
static int
aes256_cbc(const fido_blob_t *key, const u_char *iv, const fido_blob_t *in,
fido_blob_t *out, int encrypt)
{
EVP_CIPHER_CTX *ctx = NULL;
const EVP_CIPHER *cipher;
int ok = -1;
memset(out, 0, sizeof(*out));
if (key->len != 32) {
fido_log_debug("%s: invalid key len %zu", __func__, key->len);
goto fail;
}
if (in->len > UINT_MAX || in->len % 16 || in->len == 0) {
fido_log_debug("%s: invalid input len %zu", __func__, in->len);
goto fail;
}
out->len = in->len;
if ((out->ptr = calloc(1, out->len)) == NULL) {
fido_log_debug("%s: calloc", __func__);
goto fail;
}
if ((ctx = EVP_CIPHER_CTX_new()) == NULL ||
(cipher = EVP_aes_256_cbc()) == NULL) {
fido_log_debug("%s: EVP_CIPHER_CTX_new", __func__);
goto fail;
}
if (EVP_CipherInit(ctx, cipher, key->ptr, iv, encrypt) == 0 ||
EVP_Cipher(ctx, out->ptr, in->ptr, (u_int)out->len) < 0) {
fido_log_debug("%s: EVP_Cipher", __func__);
goto fail;
}
ok = 0;
fail:
if (ctx != NULL)
EVP_CIPHER_CTX_free(ctx);
if (ok < 0)
fido_blob_reset(out);
return ok;
}
static int
aes256_cbc_proto1(const fido_blob_t *key, const fido_blob_t *in,
fido_blob_t *out, int encrypt)
{
u_char iv[16];
memset(&iv, 0, sizeof(iv));
return aes256_cbc(key, iv, in, out, encrypt);
}
static int
aes256_cbc_fips(const fido_blob_t *secret, const fido_blob_t *in,
fido_blob_t *out, int encrypt)
{
fido_blob_t key, cin, cout;
u_char iv[16];
memset(out, 0, sizeof(*out));
if (secret->len != 64) {
fido_log_debug("%s: invalid secret len %zu", __func__,
secret->len);
return -1;
}
if (in->len < sizeof(iv)) {
fido_log_debug("%s: invalid input len %zu", __func__, in->len);
return -1;
}
if (encrypt) {
if (fido_get_random(iv, sizeof(iv)) < 0) {
fido_log_debug("%s: fido_get_random", __func__);
return -1;
}
cin = *in;
} else {
memcpy(iv, in->ptr, sizeof(iv));
cin.ptr = in->ptr + sizeof(iv);
cin.len = in->len - sizeof(iv);
}
key.ptr = secret->ptr + 32;
key.len = secret->len - 32;
if (aes256_cbc(&key, iv, &cin, &cout, encrypt) < 0)
return -1;
if (encrypt) {
if (cout.len > SIZE_MAX - sizeof(iv) ||
(out->ptr = calloc(1, sizeof(iv) + cout.len)) == NULL) {
fido_blob_reset(&cout);
return -1;
}
out->len = sizeof(iv) + cout.len;
memcpy(out->ptr, iv, sizeof(iv));
memcpy(out->ptr + sizeof(iv), cout.ptr, cout.len);
fido_blob_reset(&cout);
} else
*out = cout;
return 0;
}
static int
aes256_gcm(const fido_blob_t *key, const fido_blob_t *nonce,
const fido_blob_t *aad, const fido_blob_t *in, fido_blob_t *out,
int encrypt)
{
EVP_CIPHER_CTX *ctx = NULL;
const EVP_CIPHER *cipher;
size_t textlen;
int ok = -1;
memset(out, 0, sizeof(*out));
if (nonce->len != 12 || key->len != 32 || aad->len > UINT_MAX) {
fido_log_debug("%s: invalid params %zu, %zu, %zu", __func__,
nonce->len, key->len, aad->len);
goto fail;
}
if (in->len > UINT_MAX || in->len > SIZE_MAX - 16 || in->len < 16) {
fido_log_debug("%s: invalid input len %zu", __func__, in->len);
goto fail;
}
/* add tag to (on encrypt) or trim tag from the output (on decrypt) */
out->len = encrypt ? in->len + 16 : in->len - 16;
if ((out->ptr = calloc(1, out->len)) == NULL) {
fido_log_debug("%s: calloc", __func__);
goto fail;
}
if ((ctx = EVP_CIPHER_CTX_new()) == NULL ||
(cipher = EVP_aes_256_gcm()) == NULL) {
fido_log_debug("%s: EVP_CIPHER_CTX_new", __func__);
goto fail;
}
if (EVP_CipherInit(ctx, cipher, key->ptr, nonce->ptr, encrypt) == 0) {
fido_log_debug("%s: EVP_CipherInit", __func__);
goto fail;
}
if (encrypt)
textlen = in->len;
else {
textlen = in->len - 16;
/* point openssl at the mac tag */
if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, 16,
in->ptr + in->len - 16) == 0) {
fido_log_debug("%s: EVP_CIPHER_CTX_ctrl", __func__);
goto fail;
}
}
/* the last EVP_Cipher() will either compute or verify the mac tag */
if (EVP_Cipher(ctx, NULL, aad->ptr, (u_int)aad->len) < 0 ||
EVP_Cipher(ctx, out->ptr, in->ptr, (u_int)textlen) < 0 ||
EVP_Cipher(ctx, NULL, NULL, 0) < 0) {
fido_log_debug("%s: EVP_Cipher", __func__);
goto fail;
}
if (encrypt) {
/* append the mac tag */
if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, 16,
out->ptr + out->len - 16) == 0) {
fido_log_debug("%s: EVP_CIPHER_CTX_ctrl", __func__);
goto fail;
}
}
ok = 0;
fail:
if (ctx != NULL)
EVP_CIPHER_CTX_free(ctx);
if (ok < 0)
fido_blob_reset(out);
return ok;
}
int
aes256_cbc_enc(const fido_dev_t *dev, const fido_blob_t *secret,
const fido_blob_t *in, fido_blob_t *out)
{
return fido_dev_get_pin_protocol(dev) == 2 ? aes256_cbc_fips(secret,
in, out, 1) : aes256_cbc_proto1(secret, in, out, 1);
}
int
aes256_cbc_dec(const fido_dev_t *dev, const fido_blob_t *secret,
const fido_blob_t *in, fido_blob_t *out)
{
return fido_dev_get_pin_protocol(dev) == 2 ? aes256_cbc_fips(secret,
in, out, 0) : aes256_cbc_proto1(secret, in, out, 0);
}
int
aes256_gcm_enc(const fido_blob_t *key, const fido_blob_t *nonce,
const fido_blob_t *aad, const fido_blob_t *in, fido_blob_t *out)
{
return aes256_gcm(key, nonce, aad, in, out, 1);
}
int
aes256_gcm_dec(const fido_blob_t *key, const fido_blob_t *nonce,
const fido_blob_t *aad, const fido_blob_t *in, fido_blob_t *out)
{
return aes256_gcm(key, nonce, aad, in, out, 0);
}
|
