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annotate app/src/main/java/ch/ethz/ssh2/crypto/cipher/CipherInputStream.java @ 526:9a8862b87f6e stable-1.9.4-8
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author | Carl Byington <carl@five-ten-sg.com> |
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date | Sat, 01 Jun 2024 10:27:22 -0600 |
parents | d29cce60f393 |
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1 /* |
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2 * Copyright (c) 2006-2011 Christian Plattner. All rights reserved. |
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3 * Please refer to the LICENSE.txt for licensing details. |
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4 */ |
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5 package ch.ethz.ssh2.crypto.cipher; |
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6 |
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7 import java.io.IOException; |
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8 import java.io.InputStream; |
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9 |
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10 /** |
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11 * CipherInputStream. |
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12 * |
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13 * @author Christian Plattner |
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14 * @version $Id: CipherInputStream.java 11 2011-05-27 14:14:06Z dkocher@sudo.ch $ |
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15 */ |
307 | 16 public class CipherInputStream { |
17 BlockCipher currentCipher; | |
18 InputStream bi; | |
19 byte[] buffer; | |
20 byte[] enc; | |
21 int blockSize; | |
22 int pos; | |
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23 |
307 | 24 /* |
25 * We cannot use java.io.BufferedInputStream, since that is not available in | |
26 * J2ME. Everything could be improved alot here. | |
27 */ | |
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28 |
307 | 29 private static final int BUFF_SIZE = 8192; |
30 byte[] input_buffer = new byte[BUFF_SIZE]; | |
31 int input_buffer_pos = 0; | |
32 int input_buffer_size = 0; | |
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33 |
307 | 34 public CipherInputStream(BlockCipher tc, InputStream bi) { |
35 this.bi = bi; | |
36 changeCipher(tc); | |
37 } | |
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38 |
307 | 39 private int fill_buffer() throws IOException { |
40 input_buffer_pos = 0; | |
41 input_buffer_size = 0; | |
42 input_buffer_size = bi.read(input_buffer, 0, BUFF_SIZE); | |
43 return input_buffer_size; | |
44 } | |
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45 |
307 | 46 private int internal_read(byte[] b, int off, int len) throws IOException { |
47 if (input_buffer_size < 0) { | |
48 return -1; | |
49 } | |
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50 |
307 | 51 if (input_buffer_pos >= input_buffer_size) { |
52 if (fill_buffer() <= 0) { | |
53 return -1; | |
54 } | |
55 } | |
56 | |
57 int avail = input_buffer_size - input_buffer_pos; | |
58 int thiscopy = (len > avail) ? avail : len; | |
59 System.arraycopy(input_buffer, input_buffer_pos, b, off, thiscopy); | |
60 input_buffer_pos += thiscopy; | |
61 return thiscopy; | |
62 } | |
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63 |
307 | 64 public void changeCipher(BlockCipher bc) { |
65 this.currentCipher = bc; | |
66 blockSize = bc.getBlockSize(); | |
67 buffer = new byte[blockSize]; | |
68 enc = new byte[blockSize]; | |
69 pos = blockSize; | |
70 } | |
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71 |
307 | 72 private void getBlock() throws IOException { |
73 int n = 0; | |
74 | |
75 while (n < blockSize) { | |
76 int len = internal_read(enc, n, blockSize - n); | |
77 | |
78 if (len < 0) { | |
79 throw new IOException("Cannot read full block, EOF reached."); | |
80 } | |
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81 |
307 | 82 n += len; |
83 } | |
84 | |
85 try { | |
86 currentCipher.transformBlock(enc, 0, buffer, 0); | |
87 } | |
88 catch (Exception e) { | |
89 throw new IOException("Error while decrypting block."); | |
90 } | |
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91 |
307 | 92 pos = 0; |
93 } | |
94 | |
95 public int read(byte[] dst) throws IOException { | |
96 return read(dst, 0, dst.length); | |
97 } | |
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98 |
307 | 99 public int read(byte[] dst, int off, int len) throws IOException { |
100 int count = 0; | |
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101 |
307 | 102 while (len > 0) { |
103 if (pos >= blockSize) { | |
104 getBlock(); | |
105 } | |
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106 |
307 | 107 int avail = blockSize - pos; |
108 int copy = Math.min(avail, len); | |
109 System.arraycopy(buffer, pos, dst, off, copy); | |
110 pos += copy; | |
111 off += copy; | |
112 len -= copy; | |
113 count += copy; | |
114 } | |
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115 |
307 | 116 return count; |
117 } | |
118 | |
119 public int read() throws IOException { | |
120 if (pos >= blockSize) { | |
121 getBlock(); | |
122 } | |
123 | |
124 return buffer[pos++] & 0xff; | |
125 } | |
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126 |
307 | 127 public int readPlain(byte[] b, int off, int len) throws IOException { |
128 if (pos != blockSize) { | |
129 throw new IOException("Cannot read plain since crypto buffer is not aligned."); | |
130 } | |
131 | |
132 int n = 0; | |
133 | |
134 while (n < len) { | |
135 int cnt = internal_read(b, off + n, len - n); | |
136 | |
137 if (cnt < 0) { | |
138 throw new IOException("Cannot fill buffer, EOF reached."); | |
139 } | |
140 | |
141 n += cnt; | |
142 } | |
143 | |
144 return n; | |
145 } | |
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146 } |