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Java > Open Source Codes > com > quadcap > sql > file > EncryptedBlockStore


1 package com.quadcap.sql.file;
2
3 /*
4  * Copyright 1999 by Stan Bailes and Quadcap Software.
5  *
6  **/
7
8 import java.io.IOException JavaDoc;
9
10 import java.nio.ByteBuffer JavaDoc;
11
12 import com.quadcap.crypto.Digest;
13 import com.quadcap.crypto.Key;
14 import com.quadcap.crypto.KeyFactory;
15 import com.quadcap.crypto.SymmetricKey;
16
17 /**
18  *
19  *
20  * @author Stan Bailes
21  */
22 public class EncryptedBlockStore extends BlockStore {
23     SymmetricKey key;
24     Key encrypt;
25     Key decrypt;
26     byte[] buf0;
27     ByteBuffer JavaDoc b0;
28
29     /**
30      * Create a new EncryptedBlockStore object using the specified file and
31      * blocksize.
32      *
33      * @param file the underlying file.
34      * @param ra the randomly-accessible version of the file.
35      * @param blocksize the block size to use for accessing the file.
36      */
37     public EncryptedBlockStore() {
38     }
39
40     static final int oHASH_PASSWD_start = BlockFile.oHASH_PASSWD_start;
41     static final int oHASH_PASSWD_len = BlockFile.oHASH_PASSWD_len;
42
43     public void setKey(SymmetricKey key) throws IOException JavaDoc {
44         this.key = key;
45         this.encrypt = key.getEncryptionKey();
46         this.decrypt = key.getDecryptionKey();
47         this.buf0 = new byte[blockSize];
48         b0 = ByteBuffer.wrap(buf0);
49         byte[] digest = makeDigest(key.toString());
50         if (!isEncrypted()) {
51             synchronized (lock) {
52                 buf0[0] = 0x0e; // 4c -> ec! Encrypted.
53 fra.write(0, buf0, 0, 1);
54                 fra.write(oHASH_PASSWD_start, digest, 0, digest.length);
55             }
56         } else {
57             synchronized (lock) {
58                 fra.read(oHASH_PASSWD_start, buf0, 0, oHASH_PASSWD_len);
59                 for (int i = 0; i < digest.length; i++) {
60                     if (digest[i] != buf0[i]) {
61                         throw new IOException JavaDoc("Bad username/password");
62                     }
63                 }
64             }
65         }
66     }
67
68     byte[] makeDigest(String JavaDoc s) {
69         Digest d = KeyFactory.createDigest("SHA1");
70         for (int i = 0; i < s.length(); i++) {
71             char c = s.charAt(i);
72             d.update((byte)((c >> 8) & 0xff));
73             d.update((byte)(c & 0xff));
74         }
75         return d.digest();
76     }
77
78     /**
79      * Read a block into a buffer. If the specified block is beyond the
80      * current end of file, then grow the file
81      *
82      * @param blockNum the number of the block to read.
83      * @param buf the buffer into which the data is read.
84      */
85     public void read(long blockNum, byte[] buf)
86     throws IOException JavaDoc
87     {
88         synchronized (lock) {
89             if (blockNum != 0 && decrypt != null) {
90                 super.read(blockNum, buf0);
91                 b0.rewind();
92                 decrypt.f(b0, ByteBuffer.wrap(buf));
93             } else {
94                 super.read(blockNum, buf);
95             }
96         }
97     }
98
99     /**
100      * Write a block from a buffer into the file.
101      *
102      * @param blockNum the number of the block to write.
103      * @param buf the buffer from which the data is written.
104      * @exception IOException if an I/O error occurs.
105      */
106     public void write(long blockNum, byte[] buf)
107     throws IOException JavaDoc
108     {
109         synchronized (lock) {
110             if (blockNum != 0 && encrypt != null) {
111                 b0.clear();
112                 encrypt.f(ByteBuffer.wrap(buf), b0);
113                 super.write(blockNum, buf0);
114             } else {
115                 super.write(blockNum, buf);
116             }
117         }
118     }
119 }
120
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