ASN1Util


1   
2   package com.ca.commons.security.asn1;
3   
4   import com.ca.commons.cbutil.CBBase64;
5   
6   import java.io.*;
7   
8   /**
9    * This class provides some basic methods to convert ASN1Objects
10   * from/to byte arrays and files. The byte arrays can be base64 .
11   * encoded. The files can be in Privacy Enhanced Mail (PEM) format.
12   * They are all assumed not to be encrypted.
13   *
14   * @author who
15   */
16  public class ASN1Util implements java.io.Serializable  
17  {
18  
19      private static DERCoder derCoder = new DERCoder();
20  
21      /**
22       * Creates an ASN1Object from a byte array. The byte array can
23       * be base64 encoded or not.
24       * @exception   iss.security.asn1.ASN1Exception if creating the
25       * ASN1Obect from the byte array throws this exception.
26       */
27      public static ASN1Object fromByteArray(byte [] content)
28      throws ASN1Exception
29      {
30          if (content == null || content.length == 0)
31          {
32              return null;
33          }
34  
35          ASN1Object object = null;
36          byte [] byteArray;
37  
38          /* test whether base64 encoded */
39          byte [] base64Decoded = CBBase64.decode(content);
40          if (base64Decoded != null)
41          {
42              byteArray = base64Decoded;
43          }
44          else
45          {
46              byteArray = content;
47          }
48  
49          object = derCoder.decode(byteArray);
50          //  object.setByteArray(byteArray);
51          return object;
52      }
53  
54      /**
55       * Creates an ASN1Object from a file, while the file may be in binary
56       * form or in PEM format.
57       * @exception   iss.security.asn1.ASN1Exception if creating the
58       * ASN1Object from the file throws this exception.
59       */
60      public static ASN1Object fromFile(File f) throws IOException, ASN1Exception
61      {
62          BufferedReader reader = new BufferedReader(new FileReader(f));
63          byte [] buffer = new byte[(int) (f.length())];
64  
65          /* checks the PEM file beginning identifier */
66          String   s = null;
67          while ((s = reader.readLine()) != null
68                  && !(s.startsWith("-----BEGIN")))
69              ;
70  
71          /* file is in PEM format, need to do base64 decoding */
72          if (s != null)
73          {
74              s = reader.readLine();
75              int offset = 0;
76              byte [] temp;
77  
78              while (s != null)
79              {
80                  temp = s.getBytes();
81                  System.arraycopy(temp, 0, buffer, offset, temp.length);
82                  offset += temp.length;
83                  s = reader.readLine();
84                  if (s == null)
85                  {
86                      reader.close();
87                      return null;
88                  }
89  
90                  /* checks the PEM file ending identifier */
91                  if (s.startsWith("-----END"))
92                  {
93                      s = null;
94                  }
95              }
96              reader.close();
97              byte [] result = new byte[offset];
98              System.arraycopy(buffer, 0, result, 0, offset);
99              return fromByteArray(result);
100         }
101 
102         reader.close();
103 
104         /* file is in binary format, need not to do base64 decoding */
105         FileInputStream in = new FileInputStream(f);
106         in.read(buffer);
107         in.close();
108         return fromByteArray(buffer);
109     }
110 
111     /**
112      * Gets the DER encoded byte array of the given ASN1Object.
113      * @exception   iss.security.asn1.ASN1Exception if the DER encoding
114      * process throws the exception.
115      */
116     public static byte [] toByteArrayDER(ASN1Object o)
117     throws ASN1Exception
118     {
119         if (o.getByteArray() == null)
120         {
121             byte [] data = derCoder.encode(o);
122             o.setByteArray(data);
123             return data;
124         }
125         else
126         {
127             return o.getByteArray();
128         }
129     }
130 
131     /**
132      * Gets the PEM (DER and base64 encoded) byte array of the given
133      * ASN1Object.
134      * @exception   iss.security.asn1.ASN1Exception if the DER encoding
135      * process throws the exception.
136      */
137     public static byte [] toByteArrayPEM(ASN1Object o)
138     throws ASN1Exception
139     {
140         if (o.getByteArray() == null)
141         {
142             byte [] data = derCoder.encode(o);
143             o.setByteArray(data);
144             return CBBase64.encode(data);
145         }
146         else
147         {
148             return CBBase64.encode(o.getByteArray());
149         }
150     }
151 
152     /**
153      * Gets the DER encoded byte array of the given ASN1Object, and
154      * saves the byte array to a file.
155      * @exception   iss.security.asn1.ASN1Exception if the DER encoding
156      * process throws this exception.
157      */
158     public static void saveDER(ASN1Object o, File file)
159     throws IOException, ASN1Exception
160     {
161         byte [] data = toByteArrayDER(o);
162         FileOutputStream out = new FileOutputStream(file);
163         out.write(data);
164         out.close();
165     }
166 
167     /**
168      * Saves the given ASN1Object to a file in PEM format.
169      * @param   name the name/type of the ASN1Object.
170      * @exception   iss.security.asn1.ASN1Exception if the DER encoding
171      * process throws this exception.
172      */
173     public static void savePEM(ASN1Object o, File file, String   name)
174     throws IOException, ASN1Exception
175     {
176 
177         byte [] inPEM = toByteArrayPEM(o);
178         savePEM(inPEM, file, name);
179     }
180 
181     /**
182      * Saves the given Object ASN.1 encoding to a file in PEM format.
183      * @param   name - the name/type of the ASN1Object.
184      */
185     public static void savePEM(byte [] inPEM, File file, String   name)
186     throws IOException
187     {
188         PrintWriter writer = new PrintWriter(new FileWriter(file));
189 
190         /* write beginning line */
191         writer.print("-----BEGIN ");
192         writer.print(name);
193         writer.println("-----");
194 
195         /* write data */
196         int i;
197         for (i = 0; i < inPEM.length / 64; i++)
198         {
199             String   temp = new String  (inPEM, i*64, 64);
200             writer.println(temp);
201         }
202         if (inPEM.length != i * 64)
203         {
204             String   temp = new String  (inPEM, i*64, inPEM.length-i*64);
205             writer.println(temp);
206         }
207 
208         /* write ending line */
209         writer.print("-----END ");
210         writer.print(name);
211         writer.println("-----");
212         writer.close();
213     }
214 
215     /**
216      * Base64 encoding of the input byte array.
217     public static byte [] der2pem(byte [] data) {
218         return Base64Coder.encode(data);
219 }
220      */
221 
222     /**
223      * Base64 decoding of the input byte array.
224     public static byte [] pem2der(byte [] data) {
225         return Base64Coder.decode(data);
226 }
227      */
228 }
229
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