Class DSASigner

java.lang.Object

org.gudy.bouncycastle.crypto.signers.DSASigner

All Implemented Interfaces:

DSA

public class DSASigner
extends Object
implements DSA

The Digital Signature Algorithm - as described in "Handbook of Applied Cryptography", pages 452 - 453.

Field Summary

Fields

Modifier and Type	Field	Description
(package private) DSAKeyParameters	key
(package private) SecureRandom	random

Constructor Summary

Constructors

Constructor	Description
DSASigner()

Method Summary

Modifier and Type	Method	Description
private BigInteger	calculateE(BigInteger n, byte[] message)
BigInteger[]	generateSignature(byte[] message)	generate a signature for the given message using the key we were initialised with.
void	init(boolean forSigning, CipherParameters param)	initialise the signer for signature generation or signature verification.
boolean	verifySignature(byte[] message, BigInteger r, BigInteger s)	return true if the value r and s represent a DSA signature for the passed in message for standard DSA the message should be a SHA-1 hash of the real message to be verified.

Methods inherited from class Object

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

Field Details

key

DSAKeyParameters key

random

SecureRandom random

Constructor Details

DSASigner

public DSASigner()

Method Details

init

public void init(boolean forSigning,
 CipherParameters param)

Description copied from interface: DSA

initialise the signer for signature generation or signature verification.

Specified by:

init in interface DSA

Parameters:

forSigning - true if we are generating a signature, false otherwise.

param - key parameters for signature generation.

generateSignature

public BigInteger[] generateSignature(byte[] message)

generate a signature for the given message using the key we were initialised with. For conventional DSA the message should be a SHA-1 hash of the message of interest.

Specified by:

generateSignature in interface DSA

Parameters:

message - the message that will be verified later.

Returns:

two big integers representing the r and s values respectively.

verifySignature

public boolean verifySignature(byte[] message,
 BigInteger r,
 BigInteger s)

return true if the value r and s represent a DSA signature for the passed in message for standard DSA the message should be a SHA-1 hash of the real message to be verified.

Specified by:

verifySignature in interface DSA

Parameters:

message - the message that was supposed to have been signed.

r - the r signature value.

s - the s signature value.

calculateE

private BigInteger calculateE(BigInteger n,
 byte[] message)