edu.vt.middleware.crypt.signature
Class DSASignature

java.lang.Object
  edu.vt.middleware.crypt.AbstractAlgorithm
      edu.vt.middleware.crypt.signature.SignatureAlgorithm
          edu.vt.middleware.crypt.signature.DSASignature

All Implemented Interfaces:

Algorithm

public class DSASignature
extends SignatureAlgorithm

Implements the DSA signature algorithm.

Version:

$Revision: 3 $

Author:

Middleware Services

Field Summary

Fields inherited from class edu.vt.middleware.crypt.signature.SignatureAlgorithm

digest, signKey, verifyKey

Fields inherited from class edu.vt.middleware.crypt.AbstractAlgorithm

algorithm, logger, randomByteSize, randomProvider

Constructor Summary

DSASignature()
Creates a new DSA signature class that uses a SHA-1 for message digest computation.

DSASignature(DigestAlgorithm d)
Creates a new DSA signature class that uses the given digest algorithm for message digest computation.

Method Summary

protected BigInteger[]	decode(byte[] in) Produces the r,s integer pair of a DSA signature from a DER-encoded byte representation.
protected byte[]	encode(BigInteger r, BigInteger s) Produces DER-encoded byte array output from the raw DSA signature output parameters, r and s.
protected void	init(boolean forSigning, org.bouncycastle.crypto.CipherParameters params) Initialize the signer.
void	initSign() Initialize the signature for the SignatureAlgorithm.sign(byte[]) operation.
void	initVerify() Initialize the signature for the SignatureAlgorithm.verify(byte[], byte[]) operation.
void	setSignKey(PrivateKey key) Sets the private key used for signing.
void	setVerifyKey(PublicKey key) Sets the public key used for verification.
byte[]	sign(byte[] data) Signs the given data and returns the signature as a byte array.
byte[]	sign(InputStream in) Computes the signature of the data in the given input stream by processing in chunks.
boolean	verify(byte[] data, byte[] signature) Verifies the signature of the given data matches the given signature.
boolean	verify(InputStream in, byte[] signature) Verifies the signature of the given data matches the given signature.

Methods inherited from class edu.vt.middleware.crypt.signature.SignatureAlgorithm

newInstance, newInstance, sign, sign, verify, verify

Methods inherited from class edu.vt.middleware.crypt.AbstractAlgorithm

getAlgorithm, getRandomData, setRandomProvider, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

DSASignature

public DSASignature()

Creates a new DSA signature class that uses a SHA-1 for message digest computation. This is the conventional DSA signature configuration.

DSASignature

public DSASignature(DigestAlgorithm d)

Creates a new DSA signature class that uses the given digest algorithm for message digest computation.

Parameters:

d - Message digest algorithm.

Method Detail

setSignKey

public void setSignKey(PrivateKey key)

Sets the private key used for signing.

Overrides:

setSignKey in class SignatureAlgorithm

Parameters:

key - Private key.

setVerifyKey

public void setVerifyKey(PublicKey key)

Sets the public key used for verification.

Overrides:

setVerifyKey in class SignatureAlgorithm

Parameters:

key - Public key.

initSign

public void initSign()

Initialize the signature for the SignatureAlgorithm.sign(byte[]) operation.

Overrides:

initSign in class SignatureAlgorithm

initVerify

public void initVerify()

Initialize the signature for the SignatureAlgorithm.verify(byte[], byte[]) operation.

Overrides:

initVerify in class SignatureAlgorithm

sign

public byte[] sign(byte[] data)
            throws CryptException

Signs the given data and returns the signature as a byte array.

Overrides:

sign in class SignatureAlgorithm

Parameters:

data - Data to be signed.

Returns:

Signature of given data as byte array.

Throws:

CryptException - On signature failure.

sign

public byte[] sign(InputStream in)
            throws CryptException,
                   IOException

Computes the signature of the data in the given input stream by processing in chunks.

Overrides:

sign in class SignatureAlgorithm

Parameters:

in - Input stream containing data to be signed.

Returns:

Signature of given data as byte array.

Throws:

CryptException - On signature failure.

IOException - On input stream read errors.

verify

public boolean verify(byte[] data,
                      byte[] signature)
               throws CryptException

Verifies the signature of the given data matches the given signature.

Overrides:

verify in class SignatureAlgorithm

Parameters:

data - Data to be verified.

signature - Signature to be used for comparison.

Returns:

True if the signed data matches the given signature, false otherwise.

Throws:

CryptException - On verification failure.

verify

public boolean verify(InputStream in,
                      byte[] signature)
               throws CryptException,
                      IOException

Verifies the signature of the given data matches the given signature.

Overrides:

verify in class SignatureAlgorithm

Parameters:

in - Input stream containing data to be verified.

signature - Signature to be used for comparison.

Returns:

True if the signed data matches the given signature, false otherwise.

Throws:

CryptException - On verification failure.

IOException - On input stream read errors.

init

protected void init(boolean forSigning,
                    org.bouncycastle.crypto.CipherParameters params)

Initialize the signer.

Parameters:

forSigning - Whether to initialize signer for the sign operation.

params - BC cipher parameters.

encode

protected byte[] encode(BigInteger r,
                        BigInteger s)
                 throws CryptException

Produces DER-encoded byte array output from the raw DSA signature output parameters, r and s.

Parameters:

r - DSA signature output integer r.

s - DSA signature output integer s.

Returns:

DER-encoded concatenation of byte representations of r and s.

Throws:

CryptException - On cryptographic errors.

decode

protected BigInteger[] decode(byte[] in)
                       throws CryptException

Produces the r,s integer pair of a DSA signature from a DER-encoded byte representation.

Parameters:

in - DER-encoded concatenation of byte representation of r and s.

Returns:

DSA signature output parameters (r,s).

Throws:

CryptException - On cryptographic errors.