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
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
|
/*
* AES-256-GCM for HyBBX (NIST SP 800-38D) using bundled tiny-AES-c.
*/
#include "aes256gcm.h"
#include "aes.h"
#include <stdint.h>
#include <string.h>
typedef struct {
uint64_t hi;
uint64_t lo;
} u128;
static u128 u128_from_be(const uint8_t in[16])
{
u128 v;
int i;
v.hi = 0;
v.lo = 0;
for (i = 0; i < 8; i++) {
v.hi = (v.hi << 8) | in[i];
v.lo = (v.lo << 8) | in[8 + i];
}
return v;
}
static void u128_to_be(u128 v, uint8_t out[16])
{
int i;
for (i = 7; i >= 0; i--) {
out[i] = (uint8_t)(v.hi & 0xff);
v.hi >>= 8;
}
for (i = 15; i >= 8; i--) {
out[i] = (uint8_t)(v.lo & 0xff);
v.lo >>= 8;
}
}
static void u128_xor(u128 *a, const u128 *b)
{
a->hi ^= b->hi;
a->lo ^= b->lo;
}
static void u128_shr1(u128 *v)
{
int lsb = (int)(v->lo & 1);
v->lo = (v->hi << 63) | (v->lo >> 1);
v->hi >>= 1;
if (lsb) {
v->hi ^= 0xe100000000000000ULL;
}
}
static void gcm_gmult(uint8_t x[16], const uint8_t y[16])
{
u128 V = u128_from_be(y);
u128 Z = { 0, 0 };
int i;
for (i = 0; i < 128; i++) {
if (x[i / 8] & (0x80u >> (i % 8))) {
u128_xor(&Z, &V);
}
if (i == 127) {
break;
}
u128_shr1(&V);
}
u128_to_be(Z, x);
}
static void xor_block(uint8_t dst[16], const uint8_t a[16], const uint8_t b[16])
{
int i;
for (i = 0; i < 16; i++) {
dst[i] = (uint8_t)(a[i] ^ b[i]);
}
}
static void aes_ecb_encrypt_block(const struct AES_ctx *ctx,
const uint8_t in[16], uint8_t out[16])
{
uint8_t buf[16];
memcpy(buf, in, 16);
AES_ECB_encrypt((struct AES_ctx *)ctx, buf);
memcpy(out, buf, 16);
}
static void ghash(const uint8_t h[16], const uint8_t *aad, size_t aad_len,
const uint8_t *cipher, size_t cipher_len, uint8_t out[16])
{
uint8_t y[16] = { 0 };
uint8_t block[16];
size_t i;
for (i = 0; i + 16 <= aad_len; i += 16) {
xor_block(y, y, aad + i);
gcm_gmult(y, h);
}
if (i < aad_len) {
memset(block, 0, sizeof(block));
memcpy(block, aad + i, aad_len - i);
xor_block(y, y, block);
gcm_gmult(y, h);
}
for (i = 0; i + 16 <= cipher_len; i += 16) {
xor_block(y, y, cipher + i);
gcm_gmult(y, h);
}
if (i < cipher_len) {
memset(block, 0, sizeof(block));
memcpy(block, cipher + i, cipher_len - i);
xor_block(y, y, block);
gcm_gmult(y, h);
}
memset(block, 0, sizeof(block));
for (i = 0; i < 8; i++) {
block[7 - i] = (uint8_t)((aad_len * 8) >> (i * 8));
block[15 - i] = (uint8_t)((cipher_len * 8) >> (i * 8));
}
xor_block(y, y, block);
gcm_gmult(y, h);
memcpy(out, y, 16);
}
static void gctr(struct AES_ctx *ctx, const uint8_t icb[16], uint8_t *data,
size_t len)
{
uint8_t counter[16];
uint8_t stream[16];
size_t i;
memcpy(counter, icb, 16);
for (i = 0; i < len; i += 16) {
size_t j;
aes_ecb_encrypt_block(ctx, counter, stream);
for (j = 0; j < 16 && i + j < len; j++) {
data[i + j] ^= stream[j];
}
{
int k;
for (k = 15; k >= 12; k--) {
counter[k] = (uint8_t)(counter[k] + 1);
if (counter[k] != 0) {
break;
}
}
}
}
}
static void inc32(uint8_t block[16])
{
int i;
for (i = 15; i >= 12; i--) {
block[i] = (uint8_t)(block[i] + 1);
if (block[i] != 0) {
break;
}
}
}
static int aes256gcm_crypt(int encrypt, const uint8_t key[32],
const uint8_t nonce[12], const uint8_t *aad,
size_t aad_len, const uint8_t *in, size_t in_len,
uint8_t *out, const uint8_t tag_in[16],
uint8_t tag_out[16])
{
struct AES_ctx ctx;
uint8_t h[16] = { 0 };
uint8_t j0[16];
uint8_t s[16];
uint8_t expected[16];
int diff = 0;
size_t i;
if (key == NULL || nonce == NULL) {
return -1;
}
if (in_len > 0 && (in == NULL || out == NULL)) {
return -1;
}
AES_init_ctx(&ctx, key);
aes_ecb_encrypt_block(&ctx, h, h);
memset(j0, 0, sizeof(j0));
memcpy(j0, nonce, 12);
j0[15] = 1;
if (in_len > 0) {
memcpy(out, in, in_len);
if (encrypt) {
memcpy(expected, j0, 16);
inc32(expected);
gctr(&ctx, expected, out, in_len);
}
}
ghash(h, aad, aad_len, out, in_len, s);
memcpy(expected, j0, 16);
gctr(&ctx, expected, s, 16);
if (encrypt) {
if (tag_out != NULL) {
memcpy(tag_out, s, 16);
}
return 0;
}
if (tag_in == NULL) {
return -1;
}
for (i = 0; i < 16; i++) {
diff |= (int)(s[i] ^ tag_in[i]);
}
if (diff != 0) {
return -1;
}
if (in_len > 0) {
memcpy(expected, j0, 16);
inc32(expected);
memcpy(out, in, in_len);
gctr(&ctx, expected, out, in_len);
}
return 0;
}
int hybbx_aes256gcm_encrypt(const uint8_t key[HYBBX_AES256GCM_KEY_SIZE],
const uint8_t nonce[HYBBX_AES256GCM_NONCE_SIZE],
const uint8_t *aad, size_t aad_len,
const uint8_t *plaintext, size_t plaintext_len,
uint8_t *ciphertext,
uint8_t tag[HYBBX_AES256GCM_TAG_SIZE])
{
return aes256gcm_crypt(1, key, nonce, aad, aad_len, plaintext,
plaintext_len, ciphertext, NULL, tag);
}
int hybbx_aes256gcm_decrypt(const uint8_t key[HYBBX_AES256GCM_KEY_SIZE],
const uint8_t nonce[HYBBX_AES256GCM_NONCE_SIZE],
const uint8_t *aad, size_t aad_len,
const uint8_t *ciphertext, size_t ciphertext_len,
uint8_t *plaintext,
const uint8_t tag[HYBBX_AES256GCM_TAG_SIZE])
{
return aes256gcm_crypt(0, key, nonce, aad, aad_len, ciphertext,
ciphertext_len, plaintext, tag, NULL);
}
|
