2 // TripleDESCryptoServiceProvider.cs: Default TripleDES implementation
5 // Sebastien Pouliot <sebastien@ximian.com>
7 // (C) 2002 Motus Technologies Inc. (http://www.motus.com)
8 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
10 // Permission is hereby granted, free of charge, to any person obtaining
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12 // "Software"), to deal in the Software without restriction, including
13 // without limitation the rights to use, copy, modify, merge, publish,
14 // distribute, sublicense, and/or sell copies of the Software, and to
15 // permit persons to whom the Software is furnished to do so, subject to
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19 // included in all copies or substantial portions of the Software.
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30 using System.Runtime.InteropServices;
31 using Mono.Security.Cryptography;
33 namespace System.Security.Cryptography {
36 // a. FIPS PUB 46-3: TripleDES
37 // http://csrc.nist.gov/publications/fips/fips46-3/fips46-3.pdf
40 // http://webstore.ansi.org/ansidocstore/product.asp?sku=ANSI+X9%2E52%2D1998
45 public sealed class TripleDESCryptoServiceProvider : TripleDES {
47 public TripleDESCryptoServiceProvider ()
51 public override void GenerateIV ()
53 IVValue = KeyBuilder.IV (BlockSizeValue >> 3);
56 public override void GenerateKey ()
58 KeyValue = TripleDESTransform.GetStrongKey ();
61 public override ICryptoTransform CreateDecryptor (byte[] rgbKey, byte[] rgbIV)
63 return new TripleDESTransform (this, false, rgbKey, rgbIV);
66 public override ICryptoTransform CreateEncryptor (byte[] rgbKey, byte[] rgbIV)
68 return new TripleDESTransform (this, true, rgbKey, rgbIV);
72 // TripleDES is just DES-EDE
73 internal class TripleDESTransform : SymmetricTransform {
76 private DESTransform E1;
77 private DESTransform D2;
78 private DESTransform E3;
81 private DESTransform D1;
82 private DESTransform E2;
83 private DESTransform D3;
85 public TripleDESTransform (TripleDES algo, bool encryption, byte[] key, byte[] iv) : base (algo, encryption, iv)
89 key = GetStrongKey ();
92 // note: checking weak keys also checks valid key length
93 if (TripleDES.IsWeakKey (key)) {
94 string msg = Locale.GetText ("This is a known weak key.");
95 throw new CryptographicException (msg);
98 byte[] key1 = new byte [8];
99 byte[] key2 = new byte [8];
100 byte[] key3 = new byte [8];
101 DES des = DES.Create ();
102 Buffer.BlockCopy (key, 0, key1, 0, 8);
103 Buffer.BlockCopy (key, 8, key2, 0, 8);
104 if (key.Length == 16)
105 Buffer.BlockCopy (key, 0, key3, 0, 8);
107 Buffer.BlockCopy (key, 16, key3, 0, 8);
109 // note: some modes (like CFB) requires encryption when decrypting
110 if ((encryption) || (algo.Mode == CipherMode.CFB)) {
111 E1 = new DESTransform (des, true, key1, iv);
112 D2 = new DESTransform (des, false, key2, iv);
113 E3 = new DESTransform (des, true, key3, iv);
116 D1 = new DESTransform (des, false, key3, iv);
117 E2 = new DESTransform (des, true, key2, iv);
118 D3 = new DESTransform (des, false, key1, iv);
122 // note: this method is garanteed to be called with a valid blocksize
123 // for both input and output
124 protected override void ECB (byte[] input, byte[] output)
126 DESTransform.Permutation (input, output, DESTransform.ipTab, false);
128 E1.ProcessBlock (output, output);
129 D2.ProcessBlock (output, output);
130 E3.ProcessBlock (output, output);
133 D1.ProcessBlock (output, output);
134 E2.ProcessBlock (output, output);
135 D3.ProcessBlock (output, output);
137 DESTransform.Permutation (output, output, DESTransform.fpTab, true);
140 static internal byte[] GetStrongKey ()
142 int size = DESTransform.BLOCK_BYTE_SIZE * 3;
143 byte[] key = KeyBuilder.Key (size);
144 while (TripleDES.IsWeakKey (key))
145 key = KeyBuilder.Key (size);