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1
19
20 package com.maverick.crypto.asn1;
21
22 import java.io.ByteArrayOutputStream  ;
23 import java.io.IOException ;
24
25 public class DERBitString
26 extends DERObject
27 implements DERString
28 {
29 private static final char[] table = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
30
31 protected byte[] data;
32 protected int padBits;
33
34
38 static protected int getPadBits(
39 int bitString)
40 {
41 int val = 0;
42 for (int i = 3; i >= 0; i--)
43 {
44 if (i != 0)
49 {
50 if ((bitString >> (i * 8)) != 0)
51 {
52 val = (bitString >> (i * 8)) & 0xFF;
53 break;
54 }
55 }
56 else
57 {
58 if (bitString != 0)
59 {
60 val = bitString & 0xFF;
61 break;
62 }
63 }
64 }
65
66 if (val == 0)
67 {
68 return 7;
69 }
70
71
72 int bits = 1;
73
74 while (((val <<= 1) & 0xFF) != 0)
75 {
76 bits++;
77 }
78
79 return 8 - bits;
80 }
81
82
86 static protected byte[] getBytes(int bitString)
87 {
88 int bytes = 4;
89 for (int i = 3; i >= 1; i--)
90 {
91 if ((bitString & (0xFF << (i * 8))) != 0)
92 {
93 break;
94 }
95 bytes--;
96 }
97
98 byte[] result = new byte[bytes];
99 for (int i = 0; i < bytes; i++)
100 {
101 result[i] = (byte) ((bitString >> (i * 8)) & 0xFF);
102 }
103
104 return result;
105 }
106
107
112 public static DERBitString getInstance(
113 Object obj)
114 {
115 if (obj == null || obj instanceof DERBitString)
116 {
117 return (DERBitString)obj;
118 }
119
120 if (obj instanceof ASN1OctetString)
121 {
122 byte[] bytes = ((ASN1OctetString)obj).getOctets();
123 int padBits = bytes[0];
124 byte[] data = new byte[bytes.length - 1];
125
126 System.arraycopy(bytes, 1, data, 0, bytes.length - 1);
127
128 return new DERBitString(data, padBits);
129 }
130
131 if (obj instanceof ASN1TaggedObject)
132 {
133 return getInstance(((ASN1TaggedObject)obj).getObject());
134 }
135
136 throw new IllegalArgumentException ("illegal object in getInstance: " + obj.getClass().getName());
137 }
138
139
148 public static DERBitString getInstance(
149 ASN1TaggedObject obj,
150 boolean explicit)
151 {
152 return getInstance(obj.getObject());
153 }
154
155 protected DERBitString(
156 byte data,
157 int padBits)
158 {
159 this.data = new byte[1];
160 this.data[0] = data;
161 this.padBits = padBits;
162 }
163
164
168 public DERBitString(
169 byte[] data,
170 int padBits)
171 {
172 this.data = data;
173 this.padBits = padBits;
174 }
175
176 public DERBitString(
177 byte[] data)
178 {
179 this(data, 0);
180 }
181
182 public DERBitString(
183 DEREncodable obj)
184 {
185 try
186 {
187 ByteArrayOutputStream bOut = new ByteArrayOutputStream ();
188 DEROutputStream dOut = new DEROutputStream(bOut);
189
190 dOut.writeObject(obj);
191 dOut.close();
192
193 this.data = bOut.toByteArray();
194 this.padBits = 0;
195 }
196 catch (IOException e)
197 {
198 throw new IllegalArgumentException ("Error processing object : " + e.toString());
199 }
200 }
201
202 public byte[] getBytes()
203 {
204 return data;
205 }
206
207 public int getPadBits()
208 {
209 return padBits;
210 }
211
212 void encode(
213 DEROutputStream out)
214 throws IOException
215 {
216 byte[] bytes = new byte[getBytes().length + 1];
217
218 bytes[0] = (byte)getPadBits();
219 System.arraycopy(getBytes(), 0, bytes, 1, bytes.length - 1);
220
221 out.writeEncoded(BIT_STRING, bytes);
222 }
223
224 public int hashCode()
225 {
226 int value = 0;
227
228 for (int i = 0; i != data.length; i++)
229 {
230 value ^= (data[i] & 0xff) << (i % 4);
231 }
232
233 return value;
234 }
235
236 public boolean equals(
237 Object o)
238 {
239 if (o == null || !(o instanceof DERBitString))
240 {
241 return false;
242 }
243
244 DERBitString other = (DERBitString)o;
245
246 if (data.length != other.data.length)
247 {
248 return false;
249 }
250
251 for (int i = 0; i != data.length; i++)
252 {
253 if (data[i] != other.data[i])
254 {
255 return false;
256 }
257 }
258
259 return (padBits == other.padBits);
260 }
261
262 public String getString()
263 {
264 StringBuffer buf = new StringBuffer ("#");
265 ByteArrayOutputStream bOut = new ByteArrayOutputStream ();
266 ASN1OutputStream aOut = new ASN1OutputStream(bOut);
267
268 try
269 {
270 aOut.writeObject(this);
271 }
272 catch (IOException e)
273 {
274 throw new RuntimeException ("internal error encoding BitString");
275 }
276
277 byte[] string = bOut.toByteArray();
278
279 for (int i = 0; i != string.length; i++)
280 {
281 buf.append(table[(string[i] >>> 4) % 0xf]);
282 buf.append(table[string[i] & 0xf]);
283 }
284
285 return buf.toString();
286 }
287 }
288 |
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