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
|
/*
* Copyright (C) 2018 Denys Vlasenko
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
#include "tls.h"
typedef uint8_t byte;
typedef uint32_t word32;
#define XMEMSET memset
#define XMEMCPY memcpy
void FAST_FUNC xorbuf(void* buf, const void* mask, unsigned count)
{
word32 i;
byte* b = (byte*)buf;
const byte* m = (const byte*)mask;
for (i = 0; i < count; i++)
b[i] ^= m[i];
}
/* from wolfssl-3.15.3/wolfcrypt/src/aes.c */
static ALWAYS_INLINE void FlattenSzInBits(byte* buf, word32 sz)
{
/* Multiply the sz by 8 */
//bbox: these sizes are never even close to 2^32/8
// word32 szHi = (sz >> (8*sizeof(sz) - 3));
sz <<= 3;
/* copy over the words of the sz into the destination buffer */
// buf[0] = (szHi >> 24) & 0xff;
// buf[1] = (szHi >> 16) & 0xff;
// buf[2] = (szHi >> 8) & 0xff;
// buf[3] = szHi & 0xff;
*(uint32_t*)(buf + 0) = 0;
// buf[4] = (sz >> 24) & 0xff;
// buf[5] = (sz >> 16) & 0xff;
// buf[6] = (sz >> 8) & 0xff;
// buf[7] = sz & 0xff;
*(uint32_t*)(buf + 4) = SWAP_BE32(sz);
}
static void RIGHTSHIFTX(byte* x)
{
int i;
int carryOut = 0;
int carryIn = 0;
int borrow = x[15] & 0x01;
for (i = 0; i < AES_BLOCK_SIZE; i++) {
carryOut = x[i] & 0x01;
x[i] = (x[i] >> 1) | (carryIn ? 0x80 : 0);
carryIn = carryOut;
}
if (borrow) x[0] ^= 0xE1;
}
static void GMULT(byte* X, byte* Y)
{
byte Z[AES_BLOCK_SIZE];
byte V[AES_BLOCK_SIZE];
int i, j;
XMEMSET(Z, 0, AES_BLOCK_SIZE);
XMEMCPY(V, X, AES_BLOCK_SIZE);
for (i = 0; i < AES_BLOCK_SIZE; i++)
{
byte y = Y[i];
for (j = 0; j < 8; j++)
{
if (y & 0x80) {
xorbuf(Z, V, AES_BLOCK_SIZE);
}
RIGHTSHIFTX(V);
y = y << 1;
}
}
XMEMCPY(X, Z, AES_BLOCK_SIZE);
}
//bbox:
// for TLS AES-GCM, a (which as AAD) is always 13 bytes long, and bbox code provides
// extra 3 zeroed bytes, making it a[16], or a[AES_BLOCK_SIZE].
// Resulting auth tag in s is also always AES_BLOCK_SIZE bytes.
//
// This allows some simplifications.
#define aSz AES_BLOCK_SIZE
#define sSz AES_BLOCK_SIZE
void FAST_FUNC aesgcm_GHASH(byte* h,
const byte* a, //unsigned aSz,
const byte* c, unsigned cSz,
byte* s //, unsigned sSz
)
{
byte x[AES_BLOCK_SIZE] ALIGNED(4);
byte scratch[AES_BLOCK_SIZE] ALIGNED(4);
word32 blocks, partial;
//was: byte* h = aes->H;
//XMEMSET(x, 0, AES_BLOCK_SIZE);
/* Hash in A, the Additional Authentication Data */
// if (aSz != 0 && a != NULL) {
// blocks = aSz / AES_BLOCK_SIZE;
// partial = aSz % AES_BLOCK_SIZE;
// while (blocks--) {
//xorbuf(x, a, AES_BLOCK_SIZE);
XMEMCPY(x, a, AES_BLOCK_SIZE);// memcpy(x,a) = memset(x,0)+xorbuf(x,a)
GMULT(x, h);
// a += AES_BLOCK_SIZE;
// }
// if (partial != 0) {
// XMEMSET(scratch, 0, AES_BLOCK_SIZE);
// XMEMCPY(scratch, a, partial);
// xorbuf(x, scratch, AES_BLOCK_SIZE);
// GMULT(x, h);
// }
// }
/* Hash in C, the Ciphertext */
if (cSz != 0 /*&& c != NULL*/) {
blocks = cSz / AES_BLOCK_SIZE;
partial = cSz % AES_BLOCK_SIZE;
while (blocks--) {
xorbuf(x, c, AES_BLOCK_SIZE);
GMULT(x, h);
c += AES_BLOCK_SIZE;
}
if (partial != 0) {
XMEMSET(scratch, 0, AES_BLOCK_SIZE);
XMEMCPY(scratch, c, partial);
xorbuf(x, scratch, AES_BLOCK_SIZE);
GMULT(x, h);
}
}
/* Hash in the lengths of A and C in bits */
FlattenSzInBits(&scratch[0], aSz);
FlattenSzInBits(&scratch[8], cSz);
xorbuf(x, scratch, AES_BLOCK_SIZE);
GMULT(x, h);
/* Copy the result into s. */
XMEMCPY(s, x, sSz);
}
|
