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2 package com.trilead.ssh2.crypto.cipher;
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3
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4 import java.io.IOException;
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5 import java.io.OutputStream;
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6
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7 /**
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8 * CipherOutputStream.
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9 *
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10 * @author Christian Plattner, plattner@trilead.com
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11 * @version $Id: CipherOutputStream.java,v 1.1 2007/10/15 12:49:55 cplattne Exp $
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12 */
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13 public class CipherOutputStream {
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14 BlockCipher currentCipher;
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15 OutputStream bo;
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16 byte[] buffer;
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17 byte[] enc;
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18 int blockSize;
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19 int pos;
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20
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21 /*
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22 * We cannot use java.io.BufferedOutputStream, since that is not available
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23 * in J2ME. Everything could be improved here alot.
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24 */
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25
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26 final int BUFF_SIZE = 2048;
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27 byte[] out_buffer = new byte[BUFF_SIZE];
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28 int out_buffer_pos = 0;
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29
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30 public CipherOutputStream(BlockCipher tc, OutputStream bo) {
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31 this.bo = bo;
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32 changeCipher(tc);
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33 }
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34
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35 private void internal_write(byte[] src, int off, int len) throws IOException {
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36 while (len > 0) {
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37 int space = BUFF_SIZE - out_buffer_pos;
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38 int copy = (len > space) ? space : len;
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39 System.arraycopy(src, off, out_buffer, out_buffer_pos, copy);
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40 off += copy;
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41 out_buffer_pos += copy;
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42 len -= copy;
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43
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44 if (out_buffer_pos >= BUFF_SIZE) {
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45 bo.write(out_buffer, 0, BUFF_SIZE);
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46 out_buffer_pos = 0;
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47 }
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48 }
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49 }
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50
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51 private void internal_write(int b) throws IOException {
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52 out_buffer[out_buffer_pos++] = (byte) b;
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53
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54 if (out_buffer_pos >= BUFF_SIZE) {
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55 bo.write(out_buffer, 0, BUFF_SIZE);
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56 out_buffer_pos = 0;
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57 }
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58 }
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59
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60 public void flush() throws IOException {
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61 if (pos != 0)
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62 throw new IOException("FATAL: cannot flush since crypto buffer is not aligned.");
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63
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64 if (out_buffer_pos > 0) {
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65 bo.write(out_buffer, 0, out_buffer_pos);
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66 out_buffer_pos = 0;
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67 }
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68
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69 bo.flush();
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70 }
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71
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72 public void changeCipher(BlockCipher bc) {
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73 this.currentCipher = bc;
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74 blockSize = bc.getBlockSize();
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75 buffer = new byte[blockSize];
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76 enc = new byte[blockSize];
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77 pos = 0;
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78 }
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79
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80 private void writeBlock() throws IOException {
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81 try {
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82 currentCipher.transformBlock(buffer, 0, enc, 0);
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83 }
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84 catch (Exception e) {
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85 throw(IOException) new IOException("Error while decrypting block.").initCause(e);
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86 }
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87
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88 internal_write(enc, 0, blockSize);
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89 pos = 0;
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90 }
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91
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92 public void write(byte[] src, int off, int len) throws IOException {
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93 while (len > 0) {
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94 int avail = blockSize - pos;
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95 int copy = Math.min(avail, len);
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96 System.arraycopy(src, off, buffer, pos, copy);
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97 pos += copy;
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98 off += copy;
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99 len -= copy;
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100
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101 if (pos >= blockSize)
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102 writeBlock();
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103 }
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104 }
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105
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106 public void write(int b) throws IOException {
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107 buffer[pos++] = (byte) b;
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108
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109 if (pos >= blockSize)
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110 writeBlock();
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111 }
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112
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113 public void writePlain(int b) throws IOException {
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114 if (pos != 0)
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115 throw new IOException("Cannot write plain since crypto buffer is not aligned.");
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116
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117 internal_write(b);
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118 }
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119
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120 public void writePlain(byte[] b, int off, int len) throws IOException {
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121 if (pos != 0)
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122 throw new IOException("Cannot write plain since crypto buffer is not aligned.");
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123
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124 internal_write(b, off, len);
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125 }
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126 }
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