DERObject


1   /*
2    * Title:        Oyster Project
3    * Description:  S/MIME email sending capabilities
4    * @Author       Vladimir Radisic
5    * @Version      2.1.5
6    */
7   
8   package  org.enhydra.oyster.der;
9   
10  import  org.enhydra.oyster.exception.SMIMEException;
11  import  org.enhydra.oyster.exception.ErrorStorage;
12  
13  /**
14   * Every element of data represented in ASN.1 notation should be encoded
15   * in the process of implementation. It can be done according to BER (Basic
16   * Encoding Rules) or according to DER (Distinguish Encoding Rules). DERObject
17   * class is the root class (super class) of all classes used in DER encodings
18   * of variety elements in data structures used by SMIME.<BR>
19   * <BR>
20   * DER encoding of elements can be performed in two forms: definite form and
21   * indefinite form. DERObject class represents definite form of encoding. Every
22   * encoded element, according to this rules, involves three parts: Identifier
23   * Octet (which represents Tag Type of the encoding data), Length Octets (one
24   * or more octets with the information about number of octets (bytes) in the
25   * content), and Content Octets (they represent data which have to be DER
26   * encoded). <BR>
27   * <BR>
28   * DERObject can be structured or primitive, which depends on his content.
29   */
30  public class DERObject {
31  
32  /**
33   * Identifier octet of DER encoding element. It must be in the range 0-255.
34   */
35    private int identifierOctet;
36  
37  /**
38   * Length Octets of DER encoding element.
39   */
40    private String   lengthOctets = "";
41  
42  /**
43   * Content Octets of DER encoding element.
44   */
45    private String   contentOctets = "";
46  
47  /**
48   * Type of element number (part of Identifier Octet). It must be in the
49   * range 0-30.
50   */
51    private int tagTypeNumber = 0;
52  
53  /**
54   * Class Type of element (part of Identifier Octet). It can have values:
55   * 0-Universal, 64-Application, 128-Context, 192-Private (Default 0)
56   */
57    private int tagClassType = 0;
58  
59  /**
60   * Complexity type of element. It can have values: 0-Primitive, 32-Structured
61   * (Default 0)
62   */
63    private int tagComplexity = 0;
64  
65  /**
66   * Total lenght (number of octets) of DER object (Default 0)
67   */
68    private int totalLength = 0;
69  
70  /**
71   * Creates DER Object with defined value for identifier octet.
72   * @param identifierOctet0 must be in the range 0-255 (whithouth 31)
73   * @exception SMIMEException in case of invalid identifierOctet0 parameter
74   */
75    public DERObject (int identifierOctet0) throws SMIMEException
76    {
77      if (identifierOctet0 < 0)
78        throw  new SMIMEException(this, 1000);
79      else if (identifierOctet0 > 255)
80        throw  new SMIMEException(this, 1001);
81      else if ((identifierOctet0 & 31) == 31)
82        throw  new SMIMEException(this, 1002);
83      identifierOctet = identifierOctet0;
84      tagClassType = identifierOctet0 & 192;
85      tagComplexity = identifierOctet0 & 32;
86      tagTypeNumber = identifierOctet0 & 31;
87      totalLength = 1;            // Current length of DER object (contain only Identifier octet)
88    }
89  
90  /**
91   * Creates DER Object with defined value for identifier octet and values of
92   * content octets
93   * @param identifierOctet0 must be in the range 0-255 (whithouth 31)
94   * @param content0 content of DER Object
95   * @exception SMIMEException in case of invalid identifierOctet0 parameter,
96   * or in case of adding content to DER object of type Null DER object
97   */
98    public DERObject (int identifierOctet0, byte[] content0) throws SMIMEException
99    {
100     this(identifierOctet0);
101     this.addContent(content0);
102   }
103 
104 /**
105  * Defines the Lenght Octets which is the part of DEROctet
106  * @param len0 number of octets in the content
107  * @return String representation of Length Octets that correspond to len0 number
108  * @exception SMIMEException caused by non SMIMEException which is:
109  * UnsupportedEncodingException.
110  */
111   private String   lengthDERPart (int len0) throws SMIMEException{
112     String   returnString = null;
113     if (len0 < 128) {
114       byte[] lenByte = new byte[1];
115       lenByte[0] = (byte)len0;
116       try {
117         returnString = new String  (lenByte, "ISO-8859-1");
118       }
119       catch(Exception   e) {
120         throw SMIMEException.getInstance(this, e, "lengthDERPart" );
121       }
122       return  returnString;
123     }
124     else {
125       int i = 1, a = 1;         // i: Number of required bits in length0 number
126       for (; (a*2) <= len0; i++)
127         a = a*2;
128       i = (int)Math.ceil((double)i/8);          // Number of required bytes for holding length data
129       byte[] lenByte = new byte[i + 1];         // + 1 for first byte in length string
130       lenByte[0] = (byte)(i);                   // First byte define number of following bytes used for holding length data
131       lenByte[0] = (byte)((int)lenByte[0] | 128);               // Indicate complex length octets with bit #8 set to 1
132       for (; i > 0; i--) {
133         a = 255 << ((lenByte.length - i - 1)*8);
134         lenByte[i] = (byte)((len0 & a) >> ((lenByte.length - i - 1)*8));
135       }
136       try {
137         returnString = new String  (lenByte, "ISO-8859-1");
138       }
139       catch(Exception   e) {
140         throw SMIMEException.getInstance(this, e, "lengthDERPart" );
141       }
142       return  returnString;
143     }
144   }
145 
146 /**
147  * Adds content to DER Object. Used only when the content isn't added earlier
148  * via second type of constructor in DERObject.
149  * @param content0 content octets for adding to DERObject
150  * @exception SMIMEException when adding content to DER object is of type
151  * Null DER object. Also, it can be caused by non SMIMEException which is:
152  * UnsupportedEncodingException.
153  */
154   void addContent (byte[] content0) throws SMIMEException {
155     if (identifierOctet == 5)
156       throw  new SMIMEException(this, 1003);
157     try {
158       contentOctets = contentOctets.concat(new String  (content0, "ISO-8859-1"));
159       lengthOctets = lengthDERPart(contentOctets.length());
160       totalLength = 1 + contentOctets.length() + lengthOctets.length();
161     }
162     catch(Exception   e) {
163       throw SMIMEException.getInstance(this, e, "addContent" );
164     }
165   }
166 
167 /**
168  * Returns DER encoded object
169  * @return DERObject as byte array
170  * @exception SMIMEException if content of DER object is absent. Also, it can be
171  * caused by non SMIMEException which is: UnsupportedEncodingException.
172  */
173   public byte[] getDEREncoded () throws SMIMEException {
174     if (totalLength == 1 && identifierOctet != 5)
175       throw  new SMIMEException(this, 1004);
176     byte[] returnByteArray = null;              // Variable for returning DER encoding object represented as byte array
177     try {
178       byte[] temp =  {
179         (byte)identifierOctet
180       };        // Import identifier octet in DER object string (first byte of string)
181       String   derOctet = new String  (temp, "ISO-8859-1");         // String with returning DER value
182       if (identifierOctet == 5)                 // Special DER format is for Null DER object
183       {
184         temp[0] = (byte)0x00;
185         contentOctets = contentOctets.concat(new String  (temp, "ISO-8859-1"));
186         derOctet = derOctet.concat(contentOctets);
187         totalLength = 2;
188         returnByteArray = derOctet.getBytes("ISO-8859-1");      // Null DER value
189       }
190       else {
191         derOctet = derOctet.concat(lengthOctets).concat(contentOctets);
192         totalLength = 1 + contentOctets.length() + lengthOctets.length();
193         returnByteArray = derOctet.getBytes("ISO-8859-1");
194       }
195     }
196     catch(Exception   e) {
197       throw SMIMEException.getInstance(this, e, "getDEREncoded" );
198     }
199     return  returnByteArray;
200   }
201 
202 /**
203  * Returns Identifier Octet
204  * @return Identifier Octet in the range 0-255
205  */
206   public int getIdentifierOctet () {
207     return  identifierOctet;
208   }
209 
210 /**
211  * Returns Tag Type
212  * @return Tag Type in the range 0-30
213  */
214   public int getTagTypeNumber () {
215     return  tagTypeNumber;
216   }
217 
218 /**
219  * Returns Class Type
220  * @return 0-Universal, 64-Application, 128-Context, 192-Private (Default 0)
221  */
222   public int getTagClassType () {
223     return  tagClassType;
224   }
225 
226 /**
227  * Returns Tag Complexity
228  * @return 0-primitive, 32-structured (Default 0)
229  */
230   public int getTagComplexity () {
231     return  tagComplexity;
232   }
233 
234 /**
235  * Returns size of content part in DER object (Number of content octets).
236  * @return Number of content octets in DER encoded object
237  */
238   public int getContentPartSize () {
239     return  contentOctets.length();
240   }
241 
242 /**
243  * Returns size of length part in DER object (Number of length octets).
244  * @return Number of length octets in DER encoded object
245  */
246   public int getLengthPartSize () {
247     return  lengthOctets.length();
248   }
249 
250 /**
251  * Return content octets part from DER object.
252  * @return Number of content octets in DER encoded object
253  * @exception SMIMEException caused by non SMIMEException which is:
254  * UnsupportedEncodingException .
255  */
256   public byte[] getContentOctets() throws SMIMEException {
257     byte[] returnByteArray = null;
258     try {
259       returnByteArray = contentOctets.getBytes("ISO-8859-1");
260     }
261     catch(Exception   e) {
262       throw SMIMEException.getInstance(this, e, "getContentOctets" );
263     }
264     return returnByteArray;
265   }
266 
267 /**
268  * Return length octets part from DER object.
269  * @return Number of length octets in DER encoded object
270  * @exception SMIMEException caused by non SMIMEException which is:
271  * UnsupportedEncodingException.
272  */
273   public byte[] getLengthOctets() throws SMIMEException {
274     byte[] returnByteArray = null;
275     try {
276       returnByteArray = lengthOctets.getBytes("ISO-8859-1");
277     }
278     catch(Exception   e) {
279       throw SMIMEException.getInstance(this, e, "getLengthOctets" );
280     }
281     return  returnByteArray;
282   }
283 
284 /**
285  * Returns total length of DER object
286  * @return Total length of DER Object (involves identifier octet, length
287  * octets and content octets)
288  */
289   public int getTotalSize () {
290     if (tagTypeNumber == 5)
291       return  totalLength + 1;
292     return  totalLength;
293   }
294 }
295 
296 
297 
298
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