StringBuffer buf;
String octet;
ASN1IA5String newAsn1Object;
ByteArrayInputStream in;
DERDecoder decoder;
ASN1Type asn1Type;
/* Create ASN.1 object.
*/
asn1Object = new ASN1IA5String("Hello World !");
/* Print the ASN.1 object to the standard output.
*/
System.out.println("ASN.1 object: ");
System.out.println(asn1Object.toString());
System.out.println();
/* Encoding process.
*/
/* Initialize an output stream to which the encoded data will be
* written.
*/
out = new ByteArrayOutputStream();
/* Initialize encoder instance with this output stream.
*/
encoder = new DEREncoder(out);
/* Byte array to store the encoded data.
*/
encodedAsn1Object = null;
try
{
/* Encoder reads the data stored in the variable asn1Object and
* encodes it writing the output to the output stream.
*/
asn1Object.encode(encoder);
/* Store the data in the output stream in a byte array. This array
* will be decoded later.
*/
encodedAsn1Object = out.toByteArray();
/* Close the stream.
*/
encoder.close();
}
catch (ASN1Exception e)
{
System.out.println("Error during encoding.");
e.printStackTrace();
}
catch (IOException e)
{
System.out.println("Error during encoding.");
e.printStackTrace();
}
/* Print the encoded data to the standard output in hexadecimal
* representation.
*/
buf = new StringBuffer();
for (int i = 0; i < encodedAsn1Object.length; i++)
{
octet = Integer.toHexString(encodedAsn1Object[i] & 0xff);
buf.append(" 0x");
if (octet.length() == 1)
{
buf.append('0');
}
buf.append(octet);
}
System.out.println("Encoded ASN.1 object:");
System.out.println(buf.toString());
System.out.println();
/* Decoding process.
*/
/* Create new empty object of the expected class. This object will
* store the decoded values.
*/
newAsn1Object = new ASN1IA5String();
/* Initialize input stream containing the encoded data.
*/
in = new ByteArrayInputStream(encodedAsn1Object);
/* Initialize decoder instance with this input stream.
*/
decoder = new DERDecoder(in);
try
{
/* Decode the data in the input stream and stored it in
* newAsn1Object.
*/
newAsn1Object.decode(decoder);
/* Close the stream.
*/
decoder.close();
}
catch (ASN1Exception e)
{
System.out.println("Error during decoding.");
e.printStackTrace();
}
catch (IOException e)
{
System.out.println("Error during decoding.");
e.printStackTrace();
}
/* Print the new ASN.1 object to the standard output.
*/
System.out.println(
"New ASN.1 object got by decoding the previous bytes:");
System.out.println(newAsn1Object.toString());
System.out.println();
/* Alternative decoding procedure without assuming to know the ASN.1
* type to be decoded.
*/
System.out.println("Alternative decoding procedure:");
/* Variable to store the data that will be decoded. Its type is not
* determined.
*/
asn1Type = null;
/* Input stream containing the encoded data.
*/
in = new ByteArrayInputStream(encodedAsn1Object);
/* Initialize decoder instance with this input stream.
*/
decoder = new DERDecoder(in);
try
{
/* Decoder returns a Java object of the corresponding CODEC class
* and already containing the decoded data.
*/
asn1Type = decoder.readType();
decoder.close();
}
catch (ASN1Exception e)
{
System.out.println("Error during decoding.");
e.printStackTrace();
}
catch (IOException e)
{
System.out.println("Error during decoding.");
e.printStackTrace();
}
/* Print the new ASN.1 object to the standard output.
*/
System.out.println(
"New ASN.1 object got by decoding the previous bytes:");
System.out.println(asn1Type.toString());
System.out.println();
}