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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
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*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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package sun.security.ec;
import java.security.*;
import java.security.interfaces.*;
import java.security.spec.*;
import javax.crypto.*;
import javax.crypto.spec.*;
/**
* KeyAgreement implementation for ECDH.
*
* @since 1.7
*/
public final class ECDHKeyAgreement extends KeyAgreementSpi {
// private key, if initialized
private ECPrivateKey privateKey;
// encoded public point, non-null between doPhase() & generateSecret() only
private byte[] publicValue;
// length of the secret to be derived
private int secretLen;
/**
* Constructs a new ECDHKeyAgreement.
*/
public ECDHKeyAgreement() {
}
// see JCE spec
@Override
protected void engineInit(Key key, SecureRandom random)
throws InvalidKeyException {
if (!(key instanceof PrivateKey)) {
throw new InvalidKeyException
("Key must be instance of PrivateKey");
}
privateKey = (ECPrivateKey) ECKeyFactory.toECKey(key);
publicValue = null;
}
// see JCE spec
@Override
protected void engineInit(Key key, AlgorithmParameterSpec params,
SecureRandom random) throws InvalidKeyException,
InvalidAlgorithmParameterException {
if (params != null) {
throw new InvalidAlgorithmParameterException
("Parameters not supported");
}
engineInit(key, random);
}
// see JCE spec
@Override
protected Key engineDoPhase(Key key, boolean lastPhase)
throws InvalidKeyException, IllegalStateException {
if (privateKey == null) {
throw new IllegalStateException("Not initialized");
}
if (publicValue != null) {
throw new IllegalStateException("Phase already executed");
}
if (!lastPhase) {
throw new IllegalStateException
("Only two party agreement supported, lastPhase must be true");
}
if (!(key instanceof ECPublicKey)) {
throw new InvalidKeyException
("Key must be a PublicKey with algorithm EC");
}
ECPublicKey ecKey = (ECPublicKey)key;
ECParameterSpec params = ecKey.getParams();
if (ecKey instanceof ECPublicKeyImpl) {
publicValue = ((ECPublicKeyImpl)ecKey).getEncodedPublicValue();
} else { // instanceof ECPublicKey
publicValue =
ECParameters.encodePoint(ecKey.getW(), params.getCurve());
}
int keyLenBits = params.getCurve().getField().getFieldSize();
secretLen = (keyLenBits + 7) >> 3;
return null;
}
// see JCE spec
@Override
protected byte[] engineGenerateSecret() throws IllegalStateException {
if ((privateKey == null) || (publicValue == null)) {
throw new IllegalStateException("Not initialized correctly");
}
byte[] s = privateKey.getS().toByteArray();
byte[] encodedParams =
ECParameters.encodeParameters(privateKey.getParams()); // DER OID
try {
return deriveKey(s, publicValue, encodedParams);
} catch (GeneralSecurityException e) {
throw new ProviderException("Could not derive key", e);
}
}
// see JCE spec
@Override
protected int engineGenerateSecret(byte[] sharedSecret, int
offset) throws IllegalStateException, ShortBufferException {
if (offset + secretLen > sharedSecret.length) {
throw new ShortBufferException("Need " + secretLen
+ " bytes, only " + (sharedSecret.length - offset) + " available");
}
byte[] secret = engineGenerateSecret();
System.arraycopy(secret, 0, sharedSecret, offset, secret.length);
return secret.length;
}
// see JCE spec
@Override
protected SecretKey engineGenerateSecret(String algorithm)
throws IllegalStateException, NoSuchAlgorithmException,
InvalidKeyException {
if (algorithm == null) {
throw new NoSuchAlgorithmException("Algorithm must not be null");
}
if (!(algorithm.equals("TlsPremasterSecret"))) {
throw new NoSuchAlgorithmException
("Only supported for algorithm TlsPremasterSecret");
}
return new SecretKeySpec(engineGenerateSecret(), "TlsPremasterSecret");
}
/**
* Generates a secret key using the public and private keys.
*
* @param s the private key's S value.
* @param w the public key's W point (in uncompressed form).
* @param encodedParams the curve's DER encoded object identifier.
*
* @return byte[] the secret key.
*/
private static native byte[] deriveKey(byte[] s, byte[] w,
byte[] encodedParams) throws GeneralSecurityException;
}