blob: e17078541c24181fde242740fe8e3b7b2ef34879 (
plain)
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
|
/**
* WinPR: Windows Portable Runtime
* RC4 implementation for RDP
*
* Copyright 2023 Armin Novak <anovak@thincast.com>
* Copyright 2023 Thincast Technologies GmbH
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <winpr/assert.h>
#include "rc4.h"
#define CTX_SIZE 256
struct winpr_int_rc4_ctx
{
size_t i;
size_t j;
BYTE s[CTX_SIZE];
BYTE t[CTX_SIZE];
};
static void swap(BYTE* p1, BYTE* p2)
{
BYTE t = *p1;
*p1 = *p2;
*p2 = t;
}
winpr_int_RC4_CTX* winpr_int_rc4_new(const BYTE* key, size_t keylength)
{
winpr_int_RC4_CTX* ctx = calloc(1, sizeof(winpr_int_RC4_CTX));
if (!ctx)
return NULL;
for (size_t i = 0; i < CTX_SIZE; i++)
{
ctx->s[i] = i;
ctx->t[i] = key[i % keylength];
}
size_t j = 0;
for (size_t i = 0; i < CTX_SIZE; i++)
{
j = (j + ctx->s[i] + ctx->t[i]) % CTX_SIZE;
swap(&ctx->s[i], &ctx->s[j]);
}
return ctx;
}
void winpr_int_rc4_free(winpr_int_RC4_CTX* ctx)
{
free(ctx);
}
BOOL winpr_int_rc4_update(winpr_int_RC4_CTX* ctx, size_t length, const BYTE* input, BYTE* output)
{
WINPR_ASSERT(ctx);
UINT32 t1 = ctx->i;
UINT32 t2 = ctx->j;
for (size_t i = 0; i < length; i++)
{
t1 = (t1 + 1) % CTX_SIZE;
t2 = (t2 + ctx->s[t1]) % CTX_SIZE;
swap(&ctx->s[t1], &ctx->s[t2]);
const size_t idx = ((size_t)ctx->s[t1] + ctx->s[t2]) % CTX_SIZE;
const BYTE val = ctx->s[idx];
const BYTE out = *input++ ^ val;
*output++ = out;
}
ctx->i = t1;
ctx->j = t2;
return TRUE;
}
|
