1 |
769 |
jeremybenn |
/* CALG.java --
|
2 |
|
|
Copyright (C) 2003, 2006 Free Software Foundation, Inc.
|
3 |
|
|
|
4 |
|
|
This file is a part of GNU Classpath.
|
5 |
|
|
|
6 |
|
|
GNU Classpath is free software; you can redistribute it and/or modify
|
7 |
|
|
it under the terms of the GNU General Public License as published by
|
8 |
|
|
the Free Software Foundation; either version 2 of the License, or (at
|
9 |
|
|
your option) any later version.
|
10 |
|
|
|
11 |
|
|
GNU Classpath is distributed in the hope that it will be useful, but
|
12 |
|
|
WITHOUT ANY WARRANTY; without even the implied warranty of
|
13 |
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
14 |
|
|
General Public License for more details.
|
15 |
|
|
|
16 |
|
|
You should have received a copy of the GNU General Public License
|
17 |
|
|
along with GNU Classpath; if not, write to the Free Software
|
18 |
|
|
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
|
19 |
|
|
USA
|
20 |
|
|
|
21 |
|
|
Linking this library statically or dynamically with other modules is
|
22 |
|
|
making a combined work based on this library. Thus, the terms and
|
23 |
|
|
conditions of the GNU General Public License cover the whole
|
24 |
|
|
combination.
|
25 |
|
|
|
26 |
|
|
As a special exception, the copyright holders of this library give you
|
27 |
|
|
permission to link this library with independent modules to produce an
|
28 |
|
|
executable, regardless of the license terms of these independent
|
29 |
|
|
modules, and to copy and distribute the resulting executable under
|
30 |
|
|
terms of your choice, provided that you also meet, for each linked
|
31 |
|
|
independent module, the terms and conditions of the license of that
|
32 |
|
|
module. An independent module is a module which is not derived from
|
33 |
|
|
or based on this library. If you modify this library, you may extend
|
34 |
|
|
this exception to your version of the library, but you are not
|
35 |
|
|
obligated to do so. If you do not wish to do so, delete this
|
36 |
|
|
exception statement from your version. */
|
37 |
|
|
|
38 |
|
|
|
39 |
|
|
package gnu.javax.crypto.sasl.srp;
|
40 |
|
|
|
41 |
|
|
import gnu.java.security.Registry;
|
42 |
|
|
import gnu.javax.crypto.assembly.Assembly;
|
43 |
|
|
import gnu.javax.crypto.assembly.Cascade;
|
44 |
|
|
import gnu.javax.crypto.assembly.Direction;
|
45 |
|
|
import gnu.javax.crypto.assembly.Stage;
|
46 |
|
|
import gnu.javax.crypto.assembly.Transformer;
|
47 |
|
|
import gnu.javax.crypto.assembly.TransformerException;
|
48 |
|
|
import gnu.javax.crypto.cipher.CipherFactory;
|
49 |
|
|
import gnu.javax.crypto.cipher.IBlockCipher;
|
50 |
|
|
import gnu.javax.crypto.mode.IMode;
|
51 |
|
|
import gnu.javax.crypto.mode.ModeFactory;
|
52 |
|
|
import gnu.javax.crypto.pad.IPad;
|
53 |
|
|
import gnu.javax.crypto.pad.PadFactory;
|
54 |
|
|
import gnu.javax.crypto.sasl.ConfidentialityException;
|
55 |
|
|
|
56 |
|
|
import java.util.HashMap;
|
57 |
|
|
|
58 |
|
|
import javax.security.sasl.SaslException;
|
59 |
|
|
|
60 |
|
|
/**
|
61 |
|
|
* A Factory class that returns CALG (Confidentiality Algorithm) instances that
|
62 |
|
|
* operate as described in the draft-burdis-cat-sasl-srp-08.
|
63 |
|
|
* <p>
|
64 |
|
|
* The designated CALG block cipher should be used in OFB (Output Feedback
|
65 |
|
|
* Block) mode in the ISO variant, as described in <i>The Handbook of Applied
|
66 |
|
|
* Cryptography</i>, algorithm 7.20.
|
67 |
|
|
* <p>
|
68 |
|
|
* Let <code>k</code> be the block size of the chosen symmetric key block
|
69 |
|
|
* cipher algorithm; e.g. for AES this is <code>128</code> bits or
|
70 |
|
|
* <code>16</code> octets. The OFB mode used shall be of length/size
|
71 |
|
|
* <code>k</code>.
|
72 |
|
|
* <p>
|
73 |
|
|
* It is recommended that block ciphers operating in OFB mode be used with an
|
74 |
|
|
* Initial Vector (the mode's IV). In such a mode of operation - OFB with key
|
75 |
|
|
* re-use - the IV need not be secret. For the mechanism in question the IVs
|
76 |
|
|
* shall be a random octet sequence of <code>k</code> bytes.
|
77 |
|
|
* <p>
|
78 |
|
|
* The input data to the confidentiality protection algorithm shall be a
|
79 |
|
|
* multiple of the symmetric cipher block size <code>k</code>. When the input
|
80 |
|
|
* length is not a multiple of <code>k</code> octets, the data shall be padded
|
81 |
|
|
* according to the following scheme:
|
82 |
|
|
* <p>
|
83 |
|
|
* Assuming the length of the input is <code>l</code> octets,
|
84 |
|
|
* <code>(k - (l mod k))</code> octets, all having the value
|
85 |
|
|
* <code>(k - (l mod k))</code>, shall be appended to the original data. In
|
86 |
|
|
* other words, the input is padded at the trailing end with one of the
|
87 |
|
|
* following sequences:
|
88 |
|
|
* <pre>
|
89 |
|
|
*
|
90 |
|
|
* 01 -- if l mod k = k-1
|
91 |
|
|
* 02 02 -- if l mod k = k-2
|
92 |
|
|
* ...
|
93 |
|
|
* ...
|
94 |
|
|
* ...
|
95 |
|
|
* k k ... k k -- if l mod k = 0
|
96 |
|
|
* </pre>
|
97 |
|
|
* <p>
|
98 |
|
|
* The padding can be removed unambiguously since all input is padded and no
|
99 |
|
|
* padding sequence is a suffix of another. This padding method is well-defined
|
100 |
|
|
* if and only if <code>k < 256</code> octets, which is the case with
|
101 |
|
|
* symmetric key block ciphers today, and in the forseeable future.
|
102 |
|
|
*/
|
103 |
|
|
public final class CALG
|
104 |
|
|
{
|
105 |
|
|
private Assembly assembly;
|
106 |
|
|
private Object modeNdx; // initialisation key of the cascade's attributes
|
107 |
|
|
private int blockSize; // the underlying cipher's blocksize == IV length
|
108 |
|
|
private int keySize; // the underlying cipher's key size (in bytes).
|
109 |
|
|
|
110 |
|
|
/** Private constructor to enforce instantiation through Factory method. */
|
111 |
|
|
private CALG(final int blockSize, final int keySize, final Object modeNdx,
|
112 |
|
|
final Assembly assembly)
|
113 |
|
|
{
|
114 |
|
|
super();
|
115 |
|
|
|
116 |
|
|
this.blockSize = blockSize;
|
117 |
|
|
this.keySize = keySize;
|
118 |
|
|
this.modeNdx = modeNdx;
|
119 |
|
|
this.assembly = assembly;
|
120 |
|
|
}
|
121 |
|
|
|
122 |
|
|
/**
|
123 |
|
|
* Returns an instance of a SASL-SRP CALG implementation.
|
124 |
|
|
*
|
125 |
|
|
* @param algorithm the name of the symmetric cipher algorithm.
|
126 |
|
|
* @return an instance of this object.
|
127 |
|
|
*/
|
128 |
|
|
static synchronized CALG getInstance(final String algorithm)
|
129 |
|
|
{
|
130 |
|
|
final IBlockCipher cipher = CipherFactory.getInstance(algorithm);
|
131 |
|
|
final int blockSize = cipher.defaultBlockSize();
|
132 |
|
|
final int keySize = cipher.defaultKeySize();
|
133 |
|
|
final Cascade ofbCipher = new Cascade();
|
134 |
|
|
IMode ofbMode = ModeFactory.getInstance(Registry.OFB_MODE,
|
135 |
|
|
cipher,
|
136 |
|
|
blockSize);
|
137 |
|
|
Stage modeStage = Stage.getInstance(ofbMode, Direction.FORWARD);
|
138 |
|
|
final Object modeNdx = ofbCipher.append(modeStage);
|
139 |
|
|
final IPad pkcs7 = PadFactory.getInstance(Registry.PKCS7_PAD);
|
140 |
|
|
final Assembly asm = new Assembly();
|
141 |
|
|
asm.addPreTransformer(Transformer.getCascadeTransformer(ofbCipher));
|
142 |
|
|
asm.addPreTransformer(Transformer.getPaddingTransformer(pkcs7));
|
143 |
|
|
return new CALG(blockSize, keySize, modeNdx, asm);
|
144 |
|
|
}
|
145 |
|
|
|
146 |
|
|
/**
|
147 |
|
|
* Initialises a SASL-SRP CALG implementation.
|
148 |
|
|
*
|
149 |
|
|
* @param kdf the key derivation function.
|
150 |
|
|
* @param iv the initial vector value to use.
|
151 |
|
|
* @param dir whether this CALG is used for encryption or decryption.
|
152 |
|
|
*/
|
153 |
|
|
public void init(final KDF kdf, final byte[] iv, final Direction dir)
|
154 |
|
|
throws SaslException
|
155 |
|
|
{
|
156 |
|
|
final byte[] realIV;
|
157 |
|
|
if (iv.length == blockSize)
|
158 |
|
|
realIV = iv;
|
159 |
|
|
else
|
160 |
|
|
{
|
161 |
|
|
realIV = new byte[blockSize];
|
162 |
|
|
if (iv.length > blockSize)
|
163 |
|
|
System.arraycopy(iv, 0, realIV, 0, blockSize);
|
164 |
|
|
else // shouldnt happen
|
165 |
|
|
System.arraycopy(iv, 0, realIV, 0, iv.length);
|
166 |
|
|
}
|
167 |
|
|
final HashMap modeAttributes = new HashMap();
|
168 |
|
|
final byte[] sk = kdf.derive(keySize);
|
169 |
|
|
modeAttributes.put(IBlockCipher.KEY_MATERIAL, sk);
|
170 |
|
|
modeAttributes.put(IMode.IV, realIV);
|
171 |
|
|
final HashMap attributes = new HashMap();
|
172 |
|
|
attributes.put(Assembly.DIRECTION, dir);
|
173 |
|
|
attributes.put(modeNdx, modeAttributes);
|
174 |
|
|
try
|
175 |
|
|
{
|
176 |
|
|
assembly.init(attributes);
|
177 |
|
|
}
|
178 |
|
|
catch (TransformerException x)
|
179 |
|
|
{
|
180 |
|
|
throw new SaslException("getInstance()", x);
|
181 |
|
|
}
|
182 |
|
|
}
|
183 |
|
|
|
184 |
|
|
/**
|
185 |
|
|
* Encrypts or decrypts, depending on the mode already set, a designated array
|
186 |
|
|
* of bytes and returns the result.
|
187 |
|
|
*
|
188 |
|
|
* @param data the data to encrypt/decrypt.
|
189 |
|
|
* @return the decrypted/encrypted result.
|
190 |
|
|
* @throws ConfidentialityException if an exception occurs duirng the process.
|
191 |
|
|
*/
|
192 |
|
|
public byte[] doFinal(final byte[] data) throws ConfidentialityException
|
193 |
|
|
{
|
194 |
|
|
return doFinal(data, 0, data.length);
|
195 |
|
|
}
|
196 |
|
|
|
197 |
|
|
/**
|
198 |
|
|
* Encrypts or decrypts, depending on the mode already set, a designated array
|
199 |
|
|
* of bytes and returns the result.
|
200 |
|
|
*
|
201 |
|
|
* @param data the data to encrypt/decrypt.
|
202 |
|
|
* @param offset where to start in <code>data</code>.
|
203 |
|
|
* @param length how many bytes to consider in <code>data</code>.
|
204 |
|
|
* @return the decrypted/encrypted result.
|
205 |
|
|
* @throws ConfidentialityException if an exception occurs duirng the process.
|
206 |
|
|
*/
|
207 |
|
|
public byte[] doFinal(final byte[] data, final int offset, final int length)
|
208 |
|
|
throws ConfidentialityException
|
209 |
|
|
{
|
210 |
|
|
final byte[] result;
|
211 |
|
|
try
|
212 |
|
|
{
|
213 |
|
|
result = assembly.lastUpdate(data, offset, length);
|
214 |
|
|
}
|
215 |
|
|
catch (TransformerException x)
|
216 |
|
|
{
|
217 |
|
|
throw new ConfidentialityException("doFinal()", x);
|
218 |
|
|
}
|
219 |
|
|
return result;
|
220 |
|
|
}
|
221 |
|
|
}
|