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package org.spongycastle.pqc.crypto;
import org.spongycastle.crypto.CipherParameters;
import org.spongycastle.crypto.Digest;
import org.spongycastle.crypto.Signer;
import org.spongycastle.crypto.params.AsymmetricKeyParameter;
import org.spongycastle.crypto.params.ParametersWithRandom;
/**
* Implements the sign and verify functions for a Signature Scheme which can use a hash function.
*/
public class DigestingMessageSigner
implements Signer
{
private final Digest messDigest;
private final MessageSigner messSigner;
private boolean forSigning;
public DigestingMessageSigner(MessageSigner messSigner, Digest messDigest)
{
this.messSigner = messSigner;
this.messDigest = messDigest;
}
public void init(boolean forSigning,
CipherParameters param)
{
this.forSigning = forSigning;
AsymmetricKeyParameter k;
if (param instanceof ParametersWithRandom)
{
k = (AsymmetricKeyParameter)((ParametersWithRandom)param).getParameters();
}
else
{
k = (AsymmetricKeyParameter)param;
}
if (forSigning && !k.isPrivate())
{
throw new IllegalArgumentException("Signing Requires Private Key.");
}
if (!forSigning && k.isPrivate())
{
throw new IllegalArgumentException("Verification Requires Public Key.");
}
reset();
messSigner.init(forSigning, param);
}
/**
* This function signs the message that has been updated, making use of the
* private key.
*
* @return the signature of the message.
*/
public byte[] generateSignature()
{
if (!forSigning)
{
throw new IllegalStateException("RainbowDigestSigner not initialised for signature generation.");
}
byte[] hash = new byte[messDigest.getDigestSize()];
messDigest.doFinal(hash, 0);
return messSigner.generateSignature(hash);
}
/**
* This function verifies the signature of the message that has been
* updated, with the aid of the public key.
*
* @param signature the signature of the message is given as a byte array.
* @return true if the signature has been verified, false otherwise.
*/
public boolean verify(byte[] signature)
{
if (forSigning)
{
throw new IllegalStateException("RainbowDigestSigner not initialised for verification");
}
byte[] hash = new byte[messDigest.getDigestSize()];
messDigest.doFinal(hash, 0);
return messSigner.verifySignature(hash, signature);
}
public void update(byte b)
{
messDigest.update(b);
}
public void update(byte[] in, int off, int len)
{
messDigest.update(in, off, len);
}
public void reset()
{
messDigest.reset();
}
public boolean verifySignature(byte[] signature)
{
return this.verify(signature);
}
}
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