/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* @author Alexander Y. Kleymenov
* @version $Revision$
*/
package org.apache.harmony.security.x509;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;
import java.security.spec.X509EncodedKeySpec;
import org.apache.harmony.security.asn1.ASN1BitString;
import org.apache.harmony.security.asn1.ASN1Sequence;
import org.apache.harmony.security.asn1.ASN1Type;
import org.apache.harmony.security.asn1.BerInputStream;
import org.apache.harmony.security.asn1.BitString;
/**
* The class encapsulates the ASN.1 DER encoding/decoding work
* with the following structure which is a part of X.509 certificate
* (as specified in RFC 3280 -
* Internet X.509 Public Key Infrastructure.
* Certificate and Certificate Revocation List (CRL) Profile.
* http://www.ietf.org/rfc/rfc3280.txt):
*
* <pre>
* SubjectPublicKeyInfo ::= SEQUENCE {
* algorithm AlgorithmIdentifier,
* subjectPublicKey BIT STRING
* }
* </pre>
*/
public final class SubjectPublicKeyInfo {
/** the value of algorithmID field of the structure */
private AlgorithmIdentifier algorithmID;
/** the value of subjectPublicKey field of the structure */
private byte[] subjectPublicKey;
/** the public key corresponding to this SubjectPublicKeyInfo */
private PublicKey publicKey;
/** the value of unusedBits field of the structure */
private int unusedBits;
/** the ASN.1 encoded form of SubjectPublicKeyInfo */
private byte[] encoding;
public SubjectPublicKeyInfo(AlgorithmIdentifier algID, byte[] subjectPublicKey) {
this(algID, subjectPublicKey, 0);
}
public SubjectPublicKeyInfo(AlgorithmIdentifier algID, byte[] subjectPublicKey, int unused) {
this(algID, subjectPublicKey, 0, null);
}
private SubjectPublicKeyInfo(AlgorithmIdentifier algID,
byte[] subjectPublicKey, int unused,
byte[] encoding) {
this.algorithmID = algID;
this.subjectPublicKey = subjectPublicKey;
this.unusedBits = unused;
this.encoding = encoding;
}
/**
* Returns the value of algorithmIdentifier field of the structure.
*/
public AlgorithmIdentifier getAlgorithmIdentifier() {
return algorithmID;
}
/**
* Returns the value of subjectPublicKey field of the structure.
*/
public byte[] getSubjectPublicKey() {
return subjectPublicKey;
}
/**
* Returns ASN.1 encoded form of this X.509 SubjectPublicKeyInfo value.
*/
public byte[] getEncoded() {
if (encoding == null) {
encoding = ASN1.encode(this);
}
return encoding;
}
/**
* Returns the PublicKey corresponding to this SubjectPublicKeyInfo
* instance.
*/
public PublicKey getPublicKey() {
if (publicKey == null) {
final byte[] encoded = getEncoded();
final KeySpec keySpec = new X509EncodedKeySpec(encoded);
/* Try using the algorithm name first. */
final String algName = algorithmID.getAlgorithmName();
publicKey = generateKeyForAlgorithm(keySpec, algName);
/*
* Fall back to using the algorithm OID if it's not the same as the
* algorithm name.
*/
final String algOid = algorithmID.getAlgorithm();
if (publicKey == null && !algOid.equals(algName)) {
publicKey = generateKeyForAlgorithm(keySpec, algOid);
}
/*
* Encode this as an X.509 public key since we didn't have any
* KeyFactory that could handle this algorithm name or OID. Perhaps
* the thing that's using this can decode it.
*/
if (publicKey == null) {
publicKey = new X509PublicKey(algOid, encoded, subjectPublicKey);
}
}
return publicKey;
}
/**
* Try to generate a PublicKey for a given {@code keySpec} and
* {@code algorithm} identifier. If there a problem generating the key like
* a missing {@code KeyFactory} or invalid {@code KeySpec}, it will return
* {@code null}.
*/
private static PublicKey generateKeyForAlgorithm(KeySpec keySpec, String algorithm) {
try {
return KeyFactory.getInstance(algorithm).generatePublic(keySpec);
} catch (InvalidKeySpecException ignored) {
} catch (NoSuchAlgorithmException ignored) {
}
return null;
}
public static final ASN1Sequence ASN1 = new ASN1Sequence(new ASN1Type[] {
AlgorithmIdentifier.ASN1, ASN1BitString.getInstance() }) {
@Override protected Object getDecodedObject(BerInputStream in) {
Object[] values = (Object[]) in.content;
return new SubjectPublicKeyInfo(
(AlgorithmIdentifier) values[0],
((BitString) values[1]).bytes,
((BitString) values[1]).unusedBits,
in.getEncoded());
}
@Override protected void getValues(Object object, Object[] values) {
SubjectPublicKeyInfo spki = (SubjectPublicKeyInfo) object;
values[0] = spki.algorithmID;
values[1] = new BitString(spki.subjectPublicKey, spki.unusedBits);
}
};
}