SignatureDecoder (BlackBerry JDE 6.0.0 API Reference)

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net.rim.device.api.crypto.encoder
Class SignatureDecoder

java.lang.Object
  net.rim.device.api.crypto.encoder.SignatureDecoder

Direct Known Subclasses:: CMS_SignatureDecoder, WTLS_SignatureDecoder, X509_SignatureDecoder

public abstract class SignatureDecoder
extends Object
extends Object

Defines routines to decode signatures produced by the SignatureSigner classes. The details of creating and using the appropriate encoding algorithm are left to SignatureDecoder and are completely transparent to the developer.

Encoding Signatures

Encoding a signature involves calling the public static encode() method with a SignatureSigner object and a string that contains the requested encoding algorithm. For example, to encode an ECDSASignatureSigner using X509 encoding, code similar to the following would be used:

                    
      PrivateKey privateKey = ...;
      SignatureSigner signer = new ECDSASignatureSigner( privateKey );
      String message = "Buy 10000 shares of Jabroni Jeans";
      signer.update( message );
      EncodedSignature encodedSignature = SignatureEncoder.encode( signer, "X509" );

where signer is a valid ECDSASignatureSigner object that has been created with the appropriate parameters.

Decoding Signatures

Decoding a signature simply involves calling the public static decode() method in this class with an EncodedSignature object and the public key to use for verification. Decoding an ECDSA signature using the X509 encoding algorithm can be accomplished by using code similar to the following:

      PublicKey publicKey = ...;
      byte[] encodedSignatureData = ...;
      DecodedSignature decoded = SignatureDecoder.decode( encodedSignatureData, "X509" );
      SignatureVerifier verifier = decoded.getVerifier( publicKey );

Only the encoded signature and encoding algorithm into decode. The user gets back a SignatureDecoder which they can then pass a public key into to create a signature verifier. The user can also call the initialize function of the decoder in order to change the digest used by the signature verifier.

Supported Encoding Algorithms

Please see here for a list of the RIM supplied encoding algorithms. Currently, RIM provides the following signature encoding algorithms, which can be accessed with the specifed string:

X509 encoding use the encoding string "X509"
WTLS encoding use the encoding string "WTLS"
CMS encoding use the encoding string "CMS"

The X509 encoding is defined in RFC 2459. The WTLS encoding is found in WAP-199-WTLS from Feb 2000. Finally, the CMS encoding is defined in RFC 2630.

For algorithms not found in this list, a developer can implement additional signature encoding algorithms that can be integrated into the Crypto API. Please see the tutorial on Adding Encoders.

See Also:: DecodedSignature, SignatureEncoder, EncodedSignature
Category:: Signed: This element is only accessible by signed applications. If you intend to use this element, please visit http://www.blackberry.com/go/codesigning to obtain a set of code signing keys. Code signing is only required for applications running on BlackBerry smartphones; development on BlackBerry Smartphone Simulators can occur without code signing.
Since:: BlackBerry API 3.6.0

Constructor Summary
	`protected`	`SignatureDecoder()` Creates a new `SignatureDecoder` object.

Method Summary
	`static DecodedSignature`	`decode(byte[] encodedSignature, int offset, String encodingAlgorithm)` Decodes the specified encoded signature.
	`static DecodedSignature`	`decode(byte[] encodedSignature, int offset, String encodingAlgorithm, String signatureAlgorithm)` Decodes the specified encoded signature.
	`static DecodedSignature`	`decode(byte[] encodedSignature, String encodingAlgorithm)` Decodes the specified encoded signature.
	`static DecodedSignature`	`decode(InputStream encodedSignature, String encodingAlgorithm)` Decodes the specified encoded signature.
	`static DecodedSignature`	`decode(InputStream encodedSignature, String encodingAlgorithm, String signatureAlgorithm)` Decodes the specified encoded signature.
	`protected abstract DecodedSignature`	`decodeSignature(InputStream encodedSignature, String signatureAlgorithm, String digestAlgorithm)` Decodes the input stream.
	`protected static SignatureDecoder`	`getDecoder(String encodingAlgorithm, String signatureAlgorithm)` Returns the class associated with the encoding algorithm and the key algorithm.
	`protected abstract String`	`getEncodingAlgorithm()` Returns the encoding algorithm used, such as "X509".
	`protected abstract String[]`	`getSignatureAlgorithms()` Returns the signature algorithm used, such as ("DSA", "RSA_PKCS1_SHA1").
	`static boolean`	`register(SignatureDecoder decoder, SignatureDecoder baseDecoder)` Registers the class name, given the decoder and decoder scheme.

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

SignatureDecoder

protected SignatureDecoder()

Creates a new SignatureDecoder object.

This is the default constructor.

Category:: Signed: This element is only accessible by signed applications. If you intend to use this element, please visit http://www.blackberry.com/go/codesigning to obtain a set of code signing keys. Code signing is only required for applications running on BlackBerry smartphones; development on BlackBerry Smartphone Simulators can occur without code signing.
Since:: BlackBerry API 3.6.0

Method Detail