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1
2 package ch.ethz.ssh2.crypto.cipher;
3
4 import java.io.IOException  ;
5 import java.io.OutputStream ;
6
7
13 public class CipherOutputStream
14 {
15 BlockCipher currentCipher;
16 OutputStream bo;
17 byte[] buffer;
18 byte[] enc;
19 int blockSize;
20 int pos;
21
22
26
27 final int BUFF_SIZE = 2048;
28 byte[] out_buffer = new byte[BUFF_SIZE];
29 int out_buffer_pos = 0;
30
31 public CipherOutputStream(BlockCipher tc, OutputStream bo)
32 {
33 this.bo = bo;
34 changeCipher(tc);
35 }
36
37 private void internal_write(byte[] src, int off, int len) throws IOException
38 {
39 while (len > 0)
40 {
41 int space = BUFF_SIZE - out_buffer_pos;
42 int copy = (len > space) ? space : len;
43
44 System.arraycopy(src, off, out_buffer, out_buffer_pos, copy);
45
46 off += copy;
47 out_buffer_pos += copy;
48 len -= copy;
49
50 if (out_buffer_pos >= BUFF_SIZE)
51 {
52 bo.write(out_buffer, 0, BUFF_SIZE);
53 out_buffer_pos = 0;
54 }
55 }
56 }
57
58 private void internal_write(int b) throws IOException
59 {
60 out_buffer[out_buffer_pos++] = (byte) b;
61 if (out_buffer_pos >= BUFF_SIZE)
62 {
63 bo.write(out_buffer, 0, BUFF_SIZE);
64 out_buffer_pos = 0;
65 }
66 }
67
68 public void flush() throws IOException
69 {
70 if (pos != 0)
71 throw new IOException ("FATAL: cannot flush since crypto buffer is not aligned.");
72
73 if (out_buffer_pos > 0)
74 {
75 bo.write(out_buffer, 0, out_buffer_pos);
76 out_buffer_pos = 0;
77 }
78 bo.flush();
79 }
80
81 public void changeCipher(BlockCipher bc)
82 {
83 this.currentCipher = bc;
84 blockSize = bc.getBlockSize();
85 buffer = new byte[blockSize];
86 enc = new byte[blockSize];
87 pos = 0;
88 }
89
90 private void writeBlock() throws IOException
91 {
92 try
93 {
94 currentCipher.transformBlock(buffer, 0, enc, 0);
95 }
96 catch (Exception e)
97 {
98 throw (IOException ) new IOException ("Error while decrypting block.").initCause(e);
99 }
100
101 internal_write(enc, 0, blockSize);
102 pos = 0;
103 }
104
105 public void write(byte[] src, int off, int len) throws IOException
106 {
107 while (len > 0)
108 {
109 int avail = blockSize - pos;
110 int copy = Math.min(avail, len);
111
112 System.arraycopy(src, off, buffer, pos, copy);
113 pos += copy;
114 off += copy;
115 len -= copy;
116
117 if (pos >= blockSize)
118 writeBlock();
119 }
120 }
121
122 public void write(int b) throws IOException
123 {
124 buffer[pos++] = (byte) b;
125 if (pos >= blockSize)
126 writeBlock();
127 }
128
129 public void writePlain(int b) throws IOException
130 {
131 if (pos != 0)
132 throw new IOException ("Cannot write plain since crypto buffer is not aligned.");
133 internal_write(b);
134 }
135
136 public void writePlain(byte[] b, int off, int len) throws IOException
137 {
138 if (pos != 0)
139 throw new IOException ("Cannot write plain since crypto buffer is not aligned.");
140 internal_write(b, off, len);
141 }
142 }
143 |
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