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
|
/*
version 20140420
D. J. Bernstein
Public domain.
*/
#include "api.h"
#include "crypto_core_salsa208.h"
#include "utils.h"
typedef unsigned int uint32;
static const unsigned char sigma[16] = {
'e', 'x', 'p', 'a', 'n', 'd', ' ', '3', '2', '-', 'b', 'y', 't', 'e', ' ', 'k'
};
int crypto_stream_xor(
unsigned char *c,
const unsigned char *m,unsigned long long mlen,
const unsigned char *n,
const unsigned char *k
)
{
unsigned char in[16];
unsigned char block[64];
unsigned char kcopy[32];
unsigned int i;
unsigned int u;
if (!mlen) return 0;
for (i = 0;i < 32;++i) kcopy[i] = k[i];
for (i = 0;i < 8;++i) in[i] = n[i];
for (i = 8;i < 16;++i) in[i] = 0;
while (mlen >= 64) {
crypto_core_salsa208(block,in,kcopy,sigma);
for (i = 0;i < 64;++i) c[i] = m[i] ^ block[i];
u = 1;
for (i = 8;i < 16;++i) {
u += (unsigned int) in[i];
in[i] = u;
u >>= 8;
}
mlen -= 64;
c += 64;
m += 64;
}
if (mlen) {
crypto_core_salsa208(block,in,kcopy,sigma);
for (i = 0;i < (unsigned int) mlen;++i) c[i] = m[i] ^ block[i];
}
sodium_memzero(block, sizeof block);
sodium_memzero(kcopy, sizeof kcopy);
return 0;
}
|
