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package org.bouncycastle.crypto.tls;
import org.bouncycastle.crypto.AsymmetricBlockCipher;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.CryptoException;
import org.bouncycastle.crypto.Digest;
import org.bouncycastle.crypto.Signer;
import org.bouncycastle.crypto.encodings.PKCS1Encoding;
import org.bouncycastle.crypto.engines.RSABlindedEngine;
import org.bouncycastle.crypto.params.AsymmetricKeyParameter;
import org.bouncycastle.crypto.params.ParametersWithRandom;
import org.bouncycastle.crypto.params.RSAKeyParameters;
import org.bouncycastle.crypto.signers.GenericSigner;
import org.bouncycastle.crypto.signers.RSADigestSigner;
import org.bouncycastle.util.Arrays;
public class TlsRSASigner
extends AbstractTlsSigner
{
public byte[] generateRawSignature(AsymmetricKeyParameter privateKey, byte[] md5AndSha1)
throws CryptoException
{
AsymmetricBlockCipher engine = createRSAImpl();
engine.init(true, new ParametersWithRandom(privateKey, this.context.getSecureRandom()));
return engine.processBlock(md5AndSha1, 0, md5AndSha1.length);
}
public boolean verifyRawSignature(byte[] sigBytes, AsymmetricKeyParameter publicKey, byte[] md5AndSha1)
throws CryptoException
{
AsymmetricBlockCipher engine = createRSAImpl();
engine.init(false, publicKey);
byte[] signed = engine.processBlock(sigBytes, 0, sigBytes.length);
return Arrays.constantTimeAreEqual(signed, md5AndSha1);
}
public Signer createSigner(AsymmetricKeyParameter privateKey)
{
return makeSigner(new CombinedHash(), true,
new ParametersWithRandom(privateKey, this.context.getSecureRandom()));
}
public Signer createVerifyer(AsymmetricKeyParameter publicKey)
{
return makeSigner(new CombinedHash(), false, publicKey);
}
public boolean isValidPublicKey(AsymmetricKeyParameter publicKey)
{
return publicKey instanceof RSAKeyParameters && !publicKey.isPrivate();
}
protected Signer makeSigner(Digest d, boolean forSigning, CipherParameters cp)
{
Signer s;
if (ProtocolVersion.TLSv12.isEqualOrEarlierVersionOf(context.getServerVersion().getEquivalentTLSVersion()))
{
/*
* RFC 5246 4.7. In RSA signing, the opaque vector contains the signature generated
* using the RSASSA-PKCS1-v1_5 signature scheme defined in [PKCS1].
*/
s = new RSADigestSigner(d);
}
else
{
/*
* RFC 5246 4.7. Note that earlier versions of TLS used a different RSA signature scheme
* that did not include a DigestInfo encoding.
*/
s = new GenericSigner(createRSAImpl(), d);
}
s.init(forSigning, cp);
return s;
}
protected AsymmetricBlockCipher createRSAImpl()
{
/*
* RFC 5264 7.4.7.1. Implementation note: It is now known that remote timing-based attacks
* on TLS are possible, at least when the client and server are on the same LAN.
* Accordingly, implementations that use static RSA keys MUST use RSA blinding or some other
* anti-timing technique, as described in [TIMING].
*/
return new PKCS1Encoding(new RSABlindedEngine());
}
}
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