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
|
//
// TripleDESCryptoServiceProvider.cs: Default TripleDES implementation
//
// Author:
// Sebastien Pouliot <sebastien@ximian.com>
//
// (C) 2002 Motus Technologies Inc. (http://www.motus.com)
// Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System.Runtime.InteropServices;
using Mono.Security.Cryptography;
namespace System.Security.Cryptography {
// References:
// a. FIPS PUB 46-3: TripleDES
// http://csrc.nist.gov/publications/fips/fips46-3/fips46-3.pdf
// b. ANSI X9.52
// not free :-(
// http://webstore.ansi.org/ansidocstore/product.asp?sku=ANSI+X9%2E52%2D1998
// TripleDES is just DES-EDE
internal class TripleDESTransform : SymmetricTransform {
// for encryption
private DESTransform E1;
private DESTransform D2;
private DESTransform E3;
// for decryption
private DESTransform D1;
private DESTransform E2;
private DESTransform D3;
public TripleDESTransform (TripleDES algo, bool encryption, byte[] key, byte[] iv) : base (algo, encryption, iv)
{
if (key == null) {
key = GetStrongKey ();
}
// note: checking weak keys also checks valid key length
if (TripleDES.IsWeakKey (key)) {
string msg = Locale.GetText ("This is a known weak key.");
throw new CryptographicException (msg);
}
byte[] key1 = new byte [8];
byte[] key2 = new byte [8];
byte[] key3 = new byte [8];
DES des = DES.Create ();
Buffer.BlockCopy (key, 0, key1, 0, 8);
Buffer.BlockCopy (key, 8, key2, 0, 8);
if (key.Length == 16)
Buffer.BlockCopy (key, 0, key3, 0, 8);
else
Buffer.BlockCopy (key, 16, key3, 0, 8);
// note: some modes (like CFB) requires encryption when decrypting
if ((encryption) || (algo.Mode == CipherMode.CFB)) {
E1 = new DESTransform (des, true, key1, iv);
D2 = new DESTransform (des, false, key2, iv);
E3 = new DESTransform (des, true, key3, iv);
}
else {
D1 = new DESTransform (des, false, key3, iv);
E2 = new DESTransform (des, true, key2, iv);
D3 = new DESTransform (des, false, key1, iv);
}
}
// note: this method is garanteed to be called with a valid blocksize
// for both input and output
protected override void ECB (byte[] input, byte[] output)
{
DESTransform.Permutation (input, output, DESTransform.ipTab, false);
if (encrypt) {
E1.ProcessBlock (output, output);
D2.ProcessBlock (output, output);
E3.ProcessBlock (output, output);
}
else {
D1.ProcessBlock (output, output);
E2.ProcessBlock (output, output);
D3.ProcessBlock (output, output);
}
DESTransform.Permutation (output, output, DESTransform.fpTab, true);
}
static internal byte[] GetStrongKey ()
{
int size = DESTransform.BLOCK_BYTE_SIZE * 3;
byte[] key = KeyBuilder.Key (size);
while (TripleDES.IsWeakKey (key))
key = KeyBuilder.Key (size);
return key;
}
}
}
|
