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The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.4. Note: this package includes the NTRU encryption algorithms.
package org.bouncycastle.crypto.util;
import java.io.IOException;
import java.io.InputStream;
import java.math.BigInteger;
import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1InputStream;
import org.bouncycastle.asn1.ASN1Integer;
import org.bouncycastle.asn1.ASN1ObjectIdentifier;
import org.bouncycastle.asn1.ASN1OctetString;
import org.bouncycastle.asn1.ASN1Primitive;
import org.bouncycastle.asn1.DEROctetString;
import org.bouncycastle.asn1.oiw.ElGamalParameter;
import org.bouncycastle.asn1.oiw.OIWObjectIdentifiers;
import org.bouncycastle.asn1.pkcs.DHParameter;
import org.bouncycastle.asn1.pkcs.PKCSObjectIdentifiers;
import org.bouncycastle.asn1.pkcs.RSAPublicKey;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.asn1.x509.DSAParameter;
import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo;
import org.bouncycastle.asn1.x509.X509ObjectIdentifiers;
import org.bouncycastle.asn1.x9.DHPublicKey;
import org.bouncycastle.asn1.x9.DomainParameters;
import org.bouncycastle.asn1.x9.ECNamedCurveTable;
import org.bouncycastle.asn1.x9.ValidationParams;
import org.bouncycastle.asn1.x9.X962Parameters;
import org.bouncycastle.asn1.x9.X9ECParameters;
import org.bouncycastle.asn1.x9.X9ECPoint;
import org.bouncycastle.asn1.x9.X9ObjectIdentifiers;
import org.bouncycastle.crypto.ec.CustomNamedCurves;
import org.bouncycastle.crypto.params.AsymmetricKeyParameter;
import org.bouncycastle.crypto.params.DHParameters;
import org.bouncycastle.crypto.params.DHPublicKeyParameters;
import org.bouncycastle.crypto.params.DHValidationParameters;
import org.bouncycastle.crypto.params.DSAParameters;
import org.bouncycastle.crypto.params.DSAPublicKeyParameters;
import org.bouncycastle.crypto.params.ECDomainParameters;
import org.bouncycastle.crypto.params.ECNamedDomainParameters;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.crypto.params.ElGamalParameters;
import org.bouncycastle.crypto.params.ElGamalPublicKeyParameters;
import org.bouncycastle.crypto.params.RSAKeyParameters;
/**
* Factory to create asymmetric public key parameters for asymmetric ciphers from range of
* ASN.1 encoded SubjectPublicKeyInfo objects.
*/
public class PublicKeyFactory
{
/**
* Create a public key from a SubjectPublicKeyInfo encoding
*
* @param keyInfoData the SubjectPublicKeyInfo encoding
* @return the appropriate key parameter
* @throws IOException on an error decoding the key
*/
public static AsymmetricKeyParameter createKey(byte[] keyInfoData) throws IOException
{
return createKey(SubjectPublicKeyInfo.getInstance(ASN1Primitive.fromByteArray(keyInfoData)));
}
/**
* Create a public key from a SubjectPublicKeyInfo encoding read from a stream
*
* @param inStr the stream to read the SubjectPublicKeyInfo encoding from
* @return the appropriate key parameter
* @throws IOException on an error decoding the key
*/
public static AsymmetricKeyParameter createKey(InputStream inStr) throws IOException
{
return createKey(SubjectPublicKeyInfo.getInstance(new ASN1InputStream(inStr).readObject()));
}
/**
* Create a public key from the passed in SubjectPublicKeyInfo
*
* @param keyInfo the SubjectPublicKeyInfo containing the key data
* @return the appropriate key parameter
* @throws IOException on an error decoding the key
*/
public static AsymmetricKeyParameter createKey(SubjectPublicKeyInfo keyInfo) throws IOException
{
AlgorithmIdentifier algId = keyInfo.getAlgorithm();
if (algId.getAlgorithm().equals(PKCSObjectIdentifiers.rsaEncryption)
|| algId.getAlgorithm().equals(X509ObjectIdentifiers.id_ea_rsa))
{
RSAPublicKey pubKey = RSAPublicKey.getInstance(keyInfo.parsePublicKey());
return new RSAKeyParameters(false, pubKey.getModulus(), pubKey.getPublicExponent());
}
else if (algId.getAlgorithm().equals(X9ObjectIdentifiers.dhpublicnumber))
{
DHPublicKey dhPublicKey = DHPublicKey.getInstance(keyInfo.parsePublicKey());
BigInteger y = dhPublicKey.getY();
DomainParameters dhParams = DomainParameters.getInstance(algId.getParameters());
BigInteger p = dhParams.getP();
BigInteger g = dhParams.getG();
BigInteger q = dhParams.getQ();
BigInteger j = null;
if (dhParams.getJ() != null)
{
j = dhParams.getJ();
}
DHValidationParameters validation = null;
ValidationParams dhValidationParms = dhParams.getValidationParams();
if (dhValidationParms != null)
{
byte[] seed = dhValidationParms.getSeed();
BigInteger pgenCounter = dhValidationParms.getPgenCounter();
// TODO Check pgenCounter size?
validation = new DHValidationParameters(seed, pgenCounter.intValue());
}
return new DHPublicKeyParameters(y, new DHParameters(p, g, q, j, validation));
}
else if (algId.getAlgorithm().equals(PKCSObjectIdentifiers.dhKeyAgreement))
{
DHParameter params = DHParameter.getInstance(algId.getParameters());
ASN1Integer derY = (ASN1Integer)keyInfo.parsePublicKey();
BigInteger lVal = params.getL();
int l = lVal == null ? 0 : lVal.intValue();
DHParameters dhParams = new DHParameters(params.getP(), params.getG(), null, l);
return new DHPublicKeyParameters(derY.getValue(), dhParams);
}
else if (algId.getAlgorithm().equals(OIWObjectIdentifiers.elGamalAlgorithm))
{
ElGamalParameter params = ElGamalParameter.getInstance(algId.getParameters());
ASN1Integer derY = (ASN1Integer)keyInfo.parsePublicKey();
return new ElGamalPublicKeyParameters(derY.getValue(), new ElGamalParameters(
params.getP(), params.getG()));
}
else if (algId.getAlgorithm().equals(X9ObjectIdentifiers.id_dsa)
|| algId.getAlgorithm().equals(OIWObjectIdentifiers.dsaWithSHA1))
{
ASN1Integer derY = (ASN1Integer)keyInfo.parsePublicKey();
ASN1Encodable de = algId.getParameters();
DSAParameters parameters = null;
if (de != null)
{
DSAParameter params = DSAParameter.getInstance(de.toASN1Primitive());
parameters = new DSAParameters(params.getP(), params.getQ(), params.getG());
}
return new DSAPublicKeyParameters(derY.getValue(), parameters);
}
else if (algId.getAlgorithm().equals(X9ObjectIdentifiers.id_ecPublicKey))
{
X962Parameters params = X962Parameters.getInstance(algId.getParameters());
X9ECParameters x9;
ECDomainParameters dParams;
if (params.isNamedCurve())
{
ASN1ObjectIdentifier oid = (ASN1ObjectIdentifier)params.getParameters();
x9 = CustomNamedCurves.getByOID(oid);
if (x9 == null)
{
x9 = ECNamedCurveTable.getByOID(oid);
}
dParams = new ECNamedDomainParameters(
oid, x9.getCurve(), x9.getG(), x9.getN(), x9.getH(), x9.getSeed());
}
else
{
x9 = X9ECParameters.getInstance(params.getParameters());
dParams = new ECDomainParameters(
x9.getCurve(), x9.getG(), x9.getN(), x9.getH(), x9.getSeed());
}
ASN1OctetString key = new DEROctetString(keyInfo.getPublicKeyData().getBytes());
X9ECPoint derQ = new X9ECPoint(x9.getCurve(), key);
return new ECPublicKeyParameters(derQ.getPoint(), dParams);
}
else
{
throw new RuntimeException("algorithm identifier in key not recognised");
}
}
}