iaik.smime
Interface Canonicalizer

All Known Implementing Classes:
BinaryCanonicalizer, DefaultCanonicalizer

public interface Canonicalizer

Interface to be implemented for providing a special canonicalization scheme.

IAIK-S/MIME itself implements this interface with the DefaultCanonicalizer only ensuring that <CR> and <LF> always occurs together as <CR><LF> except when binary content transfer encoding is used. An application having or wishing to use a more specific canonicalization scheme may implement this interface and register its new Canonicalizer by calling the static setCanonicalizer method of the SMimeParameters class. Note that for outging messages the Canonicalizer only is visited when modelling body parts and multiparts by classes SMimeBodyPart and SMimeMultipart classes or when supplying a text message by means of method setText for a multipart/signed SignedContent object. When parsing an ingoing message the canonicalizer only is utilized for the contents part of a multipart/signed message.

See Also:
DefaultCanonicalizer

Method Summary
 java.io.InputStream canonicalizeInputStream(LineInputStream is, java.lang.String boundary)
          Wraps an canonicalizing input stream around the given input stream This method may be implemented for applying a special canonicalization scheme to the MIME entity read from the given input stream.
 java.io.OutputStream canonicalizeOutputStream(java.io.OutputStream os, java.lang.String contentType, java.lang.String contentTransferEncoding)
          Wraps an canonicalizing output stream around the given output stream.
 

Method Detail

canonicalizeOutputStream

java.io.OutputStream canonicalizeOutputStream(java.io.OutputStream os,
                                              java.lang.String contentType,
                                              java.lang.String contentTransferEncoding)
                                              throws java.io.IOException
Wraps an canonicalizing output stream around the given output stream. This method may be implemented for applying a special canonicalization scheme to a MIME body part written to the given output stream.

Parameters:
os - the (buffered) output stream where the MIME body part shall be written.
contentType - the MIME content type of the body part to be written
contentTransferEncoding - the content transfer encoding of the body part to be written.
Returns:
the canonicalizing output stream
Throws:
java.io.IOException - if an error has to be thrown when setting the canonicalizing wrapping stream

canonicalizeInputStream

java.io.InputStream canonicalizeInputStream(LineInputStream is,
                                            java.lang.String boundary)
                                            throws java.io.IOException
Wraps an canonicalizing input stream around the given input stream This method may be implemented for applying a special canonicalization scheme to the MIME entity read from the given input stream.

The input stream is an iaik.utils.LineInputStream allowing to use method readLine for parsing the MIME entity line by line from the given stream. The boundary parameter indicates the boundary line belonging to the MIME entity read from the stream. When implementing this method for canonicalizing the MIME entity the stream shall be read only until it reaches the given boundary line, e.g.:

 public class MyCanonicalizeInputStream extends FilterInputStream {
   private String boundary;
   ...
   // constructor:
   public MyCanonicalizeInputStream(LineInputStream in, String boundary) {
     super(in);
     this.boundary = "--" + boundary;
   }
   ...
   public int read(byte b[], int off, int len) throws IOException {
     ...
     String line = ((LineInputStream)in).readLine();
     if( (line == null) || line.equals(boundary) ) {
        // stop processing
        return -1;
     }
   }
   ...
 }

 // And now implement the Canonicalizer:
 public class MyCanonicalizer implements Canonicalizer {
   ...
   public OutputStream canonicalizeOutputStream(OutputStream os, String contentType, String contentTransferEncoding) {
      ...
   }

   public InputStream canonicalizeInputStream(LineInputStream is, String boundary) {
     return new MyCanonicalizeInputStream(is, boundary);
   }
 }
 

Parameters:
is - the input stream representing the MIME entity to be canonicalized
boundary - the boundary line indicating the end of the MIME entity
Returns:
the canonicalizing input stream
Throws:
java.io.IOException - if an error has to be thrown when setting the canonicalizing wrapping stream

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IAIK-CMS 5.1, (c) 2002 IAIK, (c) 2003 - 2010 SIC