package org.spongycastle.jcajce.provider.asymmetric.ec;
import java.math.BigInteger;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.spec.AlgorithmParameterSpec;
import java.util.Hashtable;
import javax.crypto.SecretKey;
import javax.crypto.ShortBufferException;
import javax.crypto.spec.SecretKeySpec;
import org.spongycastle.asn1.DERObjectIdentifier;
import org.spongycastle.asn1.nist.NISTObjectIdentifiers;
import org.spongycastle.asn1.pkcs.PKCSObjectIdentifiers;
import org.spongycastle.asn1.x9.X9IntegerConverter;
import org.spongycastle.crypto.BasicAgreement;
import org.spongycastle.crypto.CipherParameters;
import org.spongycastle.crypto.DerivationFunction;
import org.spongycastle.crypto.agreement.ECDHBasicAgreement;
import org.spongycastle.crypto.agreement.ECDHCBasicAgreement;
import org.spongycastle.crypto.agreement.ECMQVBasicAgreement;
import org.spongycastle.crypto.agreement.kdf.DHKDFParameters;
import org.spongycastle.crypto.agreement.kdf.ECDHKEKGenerator;
import org.spongycastle.crypto.digests.SHA1Digest;
import org.spongycastle.crypto.params.ECDomainParameters;
import org.spongycastle.crypto.params.ECPrivateKeyParameters;
import org.spongycastle.crypto.params.ECPublicKeyParameters;
import org.spongycastle.crypto.params.MQVPrivateParameters;
import org.spongycastle.crypto.params.MQVPublicParameters;
import org.spongycastle.jce.interfaces.ECPrivateKey;
import org.spongycastle.jce.interfaces.ECPublicKey;
import org.spongycastle.jce.interfaces.MQVPrivateKey;
import org.spongycastle.jce.interfaces.MQVPublicKey;
/**
* Diffie-Hellman key agreement using elliptic curve keys, ala IEEE P1363
* both the simple one, and the simple one with cofactors are supported.
*
* Also, MQV key agreement per SEC-1
*/
public class KeyAgreementSpi
extends javax.crypto.KeyAgreementSpi
{
private static final X9IntegerConverter converter = new X9IntegerConverter();
private static final Hashtable algorithms = new Hashtable();
static
{
Integer i128 = new Integer(128);
Integer i192 = new Integer(192);
Integer i256 = new Integer(256);
algorithms.put(NISTObjectIdentifiers.id_aes128_CBC.getId(), i128);
algorithms.put(NISTObjectIdentifiers.id_aes192_CBC.getId(), i192);
algorithms.put(NISTObjectIdentifiers.id_aes256_CBC.getId(), i256);
algorithms.put(NISTObjectIdentifiers.id_aes128_wrap.getId(), i128);
algorithms.put(NISTObjectIdentifiers.id_aes192_wrap.getId(), i192);
algorithms.put(NISTObjectIdentifiers.id_aes256_wrap.getId(), i256);
algorithms.put(PKCSObjectIdentifiers.id_alg_CMS3DESwrap.getId(), i192);
}
private String kaAlgorithm;
private BigInteger result;
private ECDomainParameters parameters;
private BasicAgreement agreement;
private DerivationFunction kdf;
private byte[] bigIntToBytes(
BigInteger r)
{
return converter.integerToBytes(r, converter.getByteLength(parameters.getG().getX()));
}
protected KeyAgreementSpi(
String kaAlgorithm,
BasicAgreement agreement,
DerivationFunction kdf)
{
this.kaAlgorithm = kaAlgorithm;
this.agreement = agreement;
this.kdf = kdf;
}
protected Key engineDoPhase(
Key key,
boolean lastPhase)
throws InvalidKeyException, IllegalStateException
{
if (parameters == null)
{
throw new IllegalStateException(kaAlgorithm + " not initialised.");
}
if (!lastPhase)
{
throw new IllegalStateException(kaAlgorithm + " can only be between two parties.");
}
CipherParameters pubKey;
if (agreement instanceof ECMQVBasicAgreement)
{
if (!(key instanceof MQVPublicKey))
{
throw new InvalidKeyException(kaAlgorithm + " key agreement requires "
+ getSimpleName(MQVPublicKey.class) + " for doPhase");
}
MQVPublicKey mqvPubKey = (MQVPublicKey)key;
ECPublicKeyParameters staticKey = (ECPublicKeyParameters)
ECUtil.generatePublicKeyParameter(mqvPubKey.getStaticKey());
ECPublicKeyParameters ephemKey = (ECPublicKeyParameters)
ECUtil.generatePublicKeyParameter(mqvPubKey.getEphemeralKey());
pubKey = new MQVPublicParameters(staticKey, ephemKey);
// TODO Validate that all the keys are using the same parameters?
}
else
{
if (!(key instanceof ECPublicKey))
{
throw new InvalidKeyException(kaAlgorithm + " key agreement requires "
+ getSimpleName(ECPublicKey.class) + " for doPhase");
}
pubKey = ECUtil.generatePublicKeyParameter((PublicKey)key);
// TODO Validate that all the keys are using the same parameters?
}
result = agreement.calculateAgreement(pubKey);
return null;
}
protected byte[] engineGenerateSecret()
throws IllegalStateException
{
if (kdf != null)
{
throw new UnsupportedOperationException(
"KDF can only be used when algorithm is known");
}
return bigIntToBytes(result);
}
protected int engineGenerateSecret(
byte[] sharedSecret,
int offset)
throws IllegalStateException, ShortBufferException
{
byte[] secret = engineGenerateSecret();
if (sharedSecret.length - offset < secret.length)
{
throw new ShortBufferException(kaAlgorithm + " key agreement: need " + secret.length + " bytes");
}
System.arraycopy(secret, 0, sharedSecret, offset, secret.length);
return secret.length;
}
protected SecretKey engineGenerateSecret(
String algorithm)
throws NoSuchAlgorithmException
{
byte[] secret = bigIntToBytes(result);
if (kdf != null)
{
if (!algorithms.containsKey(algorithm))
{
throw new NoSuchAlgorithmException("unknown algorithm encountered: " + algorithm);
}
int keySize = ((Integer)algorithms.get(algorithm)).intValue();
DHKDFParameters params = new DHKDFParameters(new DERObjectIdentifier(algorithm), keySize, secret);
byte[] keyBytes = new byte[keySize / 8];
kdf.init(params);
kdf.generateBytes(keyBytes, 0, keyBytes.length);
secret = keyBytes;
}
else
{
// TODO Should we be ensuring the key is the right length?
}
return new SecretKeySpec(secret, algorithm);
}
protected void engineInit(
Key key,
AlgorithmParameterSpec params,
SecureRandom random)
throws InvalidKeyException, InvalidAlgorithmParameterException
{
initFromKey(key);
}
protected void engineInit(
Key key,
SecureRandom random)
throws InvalidKeyException
{
initFromKey(key);
}
private void initFromKey(Key key)
throws InvalidKeyException
{
if (agreement instanceof ECMQVBasicAgreement)
{
if (!(key instanceof MQVPrivateKey))
{
throw new InvalidKeyException(kaAlgorithm + " key agreement requires "
+ getSimpleName(MQVPrivateKey.class) + " for initialisation");
}
MQVPrivateKey mqvPrivKey = (MQVPrivateKey)key;
ECPrivateKeyParameters staticPrivKey = (ECPrivateKeyParameters)
ECUtil.generatePrivateKeyParameter(mqvPrivKey.getStaticPrivateKey());
ECPrivateKeyParameters ephemPrivKey = (ECPrivateKeyParameters)
ECUtil.generatePrivateKeyParameter(mqvPrivKey.getEphemeralPrivateKey());
ECPublicKeyParameters ephemPubKey = null;
if (mqvPrivKey.getEphemeralPublicKey() != null)
{
ephemPubKey = (ECPublicKeyParameters)
ECUtil.generatePublicKeyParameter(mqvPrivKey.getEphemeralPublicKey());
}
MQVPrivateParameters localParams = new MQVPrivateParameters(staticPrivKey, ephemPrivKey, ephemPubKey);
this.parameters = staticPrivKey.getParameters();
// TODO Validate that all the keys are using the same parameters?
agreement.init(localParams);
}
else
{
if (!(key instanceof ECPrivateKey))
{
throw new InvalidKeyException(kaAlgorithm + " key agreement requires "
+ getSimpleName(ECPrivateKey.class) + " for initialisation");
}
ECPrivateKeyParameters privKey = (ECPrivateKeyParameters)ECUtil.generatePrivateKeyParameter((PrivateKey)key);
this.parameters = privKey.getParameters();
agreement.init(privKey);
}
}
private static String getSimpleName(Class clazz)
{
String fullName = clazz.getName();
return fullName.substring(fullName.lastIndexOf('.') + 1);
}
public static class DH
extends KeyAgreementSpi
{
public DH()
{
super("ECDH", new ECDHBasicAgreement(), null);
}
}
public static class DHC
extends KeyAgreementSpi
{
public DHC()
{
super("ECDHC", new ECDHCBasicAgreement(), null);
}
}
public static class MQV
extends KeyAgreementSpi
{
public MQV()
{
super("ECMQV", new ECMQVBasicAgreement(), null);
}
}
public static class DHwithSHA1KDF
extends KeyAgreementSpi
{
public DHwithSHA1KDF()
{
super("ECDHwithSHA1KDF", new ECDHBasicAgreement(), new ECDHKEKGenerator(new SHA1Digest()));
}
}
public static class MQVwithSHA1KDF
extends KeyAgreementSpi
{
public MQVwithSHA1KDF()
{
super("ECMQVwithSHA1KDF", new ECMQVBasicAgreement(), new ECDHKEKGenerator(new SHA1Digest()));
}
}
}