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
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
|
/****************************************************************
* Licensed to the Apache Software Foundation (ASF) under one *
* or more contributor license agreements. See the NOTICE file *
* distributed with this work for additional information *
* regarding copyright ownership. The ASF licenses this file *
* to you 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. *
****************************************************************/
package org.apache.james.mime4j.storage;
import java.io.IOException;
import java.io.InputStream;
import java.security.GeneralSecurityException;
import java.security.NoSuchAlgorithmException;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import javax.crypto.spec.SecretKeySpec;
/**
* A {@link StorageProvider} that transparently scrambles and unscrambles the
* data stored by another <code>StorageProvider</code>.
*
* <p>
* Example usage:
*
* <pre>
* StorageProvider mistrusted = new TempFileStorageProvider();
* StorageProvider enciphered = new CipherStorageProvider(mistrusted);
* StorageProvider provider = new ThresholdStorageProvider(enciphered);
* DefaultStorageProvider.setInstance(provider);
* </pre>
*/
public class CipherStorageProvider extends AbstractStorageProvider {
private final StorageProvider backend;
private final String algorithm;
private final KeyGenerator keygen;
/**
* Creates a new <code>CipherStorageProvider</code> for the given back-end
* using the Blowfish cipher algorithm.
*
* @param backend
* back-end storage strategy to encrypt.
*/
public CipherStorageProvider(StorageProvider backend) {
this(backend, "Blowfish");
}
/**
* Creates a new <code>CipherStorageProvider</code> for the given back-end
* and cipher algorithm.
*
* @param backend
* back-end storage strategy to encrypt.
* @param algorithm
* the name of the symmetric block cipher algorithm such as
* "Blowfish", "AES" or "RC2".
*/
public CipherStorageProvider(StorageProvider backend, String algorithm) {
if (backend == null)
throw new IllegalArgumentException();
try {
this.backend = backend;
this.algorithm = algorithm;
this.keygen = KeyGenerator.getInstance(algorithm);
} catch (NoSuchAlgorithmException e) {
throw new IllegalArgumentException(e);
}
}
public StorageOutputStream createStorageOutputStream() throws IOException {
SecretKeySpec skeySpec = getSecretKeySpec();
return new CipherStorageOutputStream(backend
.createStorageOutputStream(), algorithm, skeySpec);
}
private SecretKeySpec getSecretKeySpec() {
byte[] raw = keygen.generateKey().getEncoded();
return new SecretKeySpec(raw, algorithm);
}
private static final class CipherStorageOutputStream extends
StorageOutputStream {
private final StorageOutputStream storageOut;
private final String algorithm;
private final SecretKeySpec skeySpec;
private final CipherOutputStream cipherOut;
public CipherStorageOutputStream(StorageOutputStream out,
String algorithm, SecretKeySpec skeySpec) throws IOException {
try {
this.storageOut = out;
this.algorithm = algorithm;
this.skeySpec = skeySpec;
Cipher cipher = Cipher.getInstance(algorithm);
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
this.cipherOut = new CipherOutputStream(out, cipher);
} catch (GeneralSecurityException e) {
throw (IOException) new IOException().initCause(e);
}
}
@Override
public void close() throws IOException {
super.close();
cipherOut.close();
}
@Override
protected void write0(byte[] buffer, int offset, int length)
throws IOException {
cipherOut.write(buffer, offset, length);
}
@Override
protected Storage toStorage0() throws IOException {
// cipherOut has already been closed because toStorage calls close
Storage encrypted = storageOut.toStorage();
return new CipherStorage(encrypted, algorithm, skeySpec);
}
}
private static final class CipherStorage implements Storage {
private Storage encrypted;
private final String algorithm;
private final SecretKeySpec skeySpec;
public CipherStorage(Storage encrypted, String algorithm,
SecretKeySpec skeySpec) {
this.encrypted = encrypted;
this.algorithm = algorithm;
this.skeySpec = skeySpec;
}
public void delete() {
if (encrypted != null) {
encrypted.delete();
encrypted = null;
}
}
public InputStream getInputStream() throws IOException {
if (encrypted == null)
throw new IllegalStateException("storage has been deleted");
try {
Cipher cipher = Cipher.getInstance(algorithm);
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
InputStream in = encrypted.getInputStream();
return new CipherInputStream(in, cipher);
} catch (GeneralSecurityException e) {
throw (IOException) new IOException().initCause(e);
}
}
}
}
|