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comparison src/com/trilead/ssh2/crypto/SimpleDERReader.java @ 0:0ce5cc452d02

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initial version
author Carl Byington <carl@five-ten-sg.com>
date Thu, 22 May 2014 10:41:19 -0700
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-1:000000000000 0:0ce5cc452d02
1 package com.trilead.ssh2.crypto;
2
3 import java.io.IOException;
4
5 import java.math.BigInteger;
6
7 /**
8 * SimpleDERReader.
9 *
10 * @author Christian Plattner, plattner@trilead.com
11 * @version $Id: SimpleDERReader.java,v 1.1 2007/10/15 12:49:56 cplattne Exp $
12 */
13 public class SimpleDERReader {
14 private static final int CONSTRUCTED = 0x20;
15
16 byte[] buffer;
17 int pos;
18 int count;
19
20 public SimpleDERReader(byte[] b) {
21 resetInput(b);
22 }
23
24 public SimpleDERReader(byte[] b, int off, int len) {
25 resetInput(b, off, len);
26 }
27
28 public void resetInput(byte[] b) {
29 resetInput(b, 0, b.length);
30 }
31
32 public void resetInput(byte[] b, int off, int len) {
33 buffer = b;
34 pos = off;
35 count = len;
36 }
37
38 private byte readByte() throws IOException {
39 if (count <= 0)
40 throw new IOException("DER byte array: out of data");
41
42 count--;
43 return buffer[pos++];
44 }
45
46 private byte[] readBytes(int len) throws IOException {
47 if (len > count)
48 throw new IOException("DER byte array: out of data");
49
50 byte[] b = new byte[len];
51 System.arraycopy(buffer, pos, b, 0, len);
52 pos += len;
53 count -= len;
54 return b;
55 }
56
57 public int available() {
58 return count;
59 }
60
61 private int readLength() throws IOException {
62 int len = readByte() & 0xff;
63
64 if ((len & 0x80) == 0)
65 return len;
66
67 int remain = len & 0x7F;
68
69 if (remain == 0)
70 return -1;
71
72 len = 0;
73
74 while (remain > 0) {
75 len = len << 8;
76 len = len | (readByte() & 0xff);
77 remain--;
78 }
79
80 return len;
81 }
82
83 public int ignoreNextObject() throws IOException {
84 int type = readByte() & 0xff;
85 int len = readLength();
86
87 if ((len < 0) || len > available())
88 throw new IOException("Illegal len in DER object (" + len + ")");
89
90 readBytes(len);
91 return type;
92 }
93
94 public BigInteger readInt() throws IOException {
95 int type = readByte() & 0xff;
96
97 if (type != 0x02)
98 throw new IOException("Expected DER Integer, but found type " + type);
99
100 int len = readLength();
101
102 if ((len < 0) || len > available())
103 throw new IOException("Illegal len in DER object (" + len + ")");
104
105 byte[] b = readBytes(len);
106 BigInteger bi = new BigInteger(b);
107 return bi;
108 }
109
110 public int readConstructedType() throws IOException {
111 int type = readByte() & 0xff;
112
113 if ((type & CONSTRUCTED) != CONSTRUCTED)
114 throw new IOException("Expected constructed type, but was " + type);
115
116 return type & 0x1f;
117 }
118
119 public SimpleDERReader readConstructed() throws IOException {
120 int len = readLength();
121
122 if ((len < 0) || len > available())
123 throw new IOException("Illegal len in DER object (" + len + ")");
124
125 SimpleDERReader cr = new SimpleDERReader(buffer, pos, len);
126 pos += len;
127 count -= len;
128 return cr;
129 }
130
131 public byte[] readSequenceAsByteArray() throws IOException {
132 int type = readByte() & 0xff;
133
134 if (type != 0x30)
135 throw new IOException("Expected DER Sequence, but found type " + type);
136
137 int len = readLength();
138
139 if ((len < 0) || len > available())
140 throw new IOException("Illegal len in DER object (" + len + ")");
141
142 byte[] b = readBytes(len);
143 return b;
144 }
145
146 public String readOid() throws IOException {
147 int type = readByte() & 0xff;
148
149 if (type != 0x06)
150 throw new IOException("Expected DER OID, but found type " + type);
151
152 int len = readLength();
153
154 if ((len < 1) || len > available())
155 throw new IOException("Illegal len in DER object (" + len + ")");
156
157 byte[] b = readBytes(len);
158 long value = 0;
159 StringBuilder sb = new StringBuilder(64);
160
161 switch (b[0] / 40) {
162 case 0:
163 sb.append('0');
164 break;
165
166 case 1:
167 sb.append('1');
168 b[0] -= 40;
169 break;
170
171 default:
172 sb.append('2');
173 b[0] -= 80;
174 break;
175 }
176
177 for (int i = 0; i < len; i++) {
178 value = (value << 7) + (b[i] & 0x7F);
179
180 if ((b[i] & 0x80) == 0) {
181 sb.append('.');
182 sb.append(value);
183 value = 0;
184 }
185 }
186
187 return sb.toString();
188 }
189
190 public byte[] readOctetString() throws IOException {
191 int type = readByte() & 0xff;
192
193 if (type != 0x04 && type != 0x03)
194 throw new IOException("Expected DER Octetstring, but found type " + type);
195
196 int len = readLength();
197
198 if ((len < 0) || len > available())
199 throw new IOException("Illegal len in DER object (" + len + ")");
200
201 byte[] b = readBytes(len);
202 return b;
203 }
204
205 }