edu.vt.middleware.crypt.io.PublicKeyCredentialReader.java Source code

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Here is the source code for edu.vt.middleware.crypt.io.PublicKeyCredentialReader.java

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/*
  $Id$
    
  Copyright (C) 2003-2013 Virginia Tech.
  All rights reserved.
    
  SEE LICENSE FOR MORE INFORMATION
    
  Author:  Middleware Services
  Email:   middleware@vt.edu
  Version: $Revision$
  Updated: $Date$
*/
package edu.vt.middleware.crypt.io;

import java.security.PublicKey;
import java.security.spec.X509EncodedKeySpec;
import edu.vt.middleware.crypt.CryptException;
import edu.vt.middleware.crypt.CryptProvider;
import org.bouncycastle.asn1.ASN1Object;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.DEREncodable;

/**
 * Reads encoded public keys in X.509 public key format. Both PEM and DER
 * encodings are supported.
 *
 * @author  Middleware Services
 * @version  $Revision$
 */
public class PublicKeyCredentialReader extends AbstractEncodedCredentialReader<PublicKey> {

    /** {@inheritDoc} */
    protected PublicKey decode(final byte[] encoded) throws CryptException {
        try {
            final ASN1Sequence seq = (ASN1Sequence) ASN1Object.fromByteArray(encoded);
            final ASN1Sequence innerSeq = (ASN1Sequence) seq.getObjectAt(0);
            final DEREncodable algId = innerSeq.getObjectAt(0);
            final String algorithm;
            if (RSA_ID.equals(algId)) {
                algorithm = "RSA";
            } else if (EC_ID.equals(algId)) {
                algorithm = "EC";
            } else if (DSA_ID.equals(algId)) {
                algorithm = "DSA";
            } else {
                throw new CryptException("Unsupported public key algorithm ID " + algId);
            }
            return CryptProvider.getKeyFactory(algorithm).generatePublic(new X509EncodedKeySpec(encoded));
        } catch (Exception e) {
            throw new CryptException("Invalid public key.", e);
        }
    }

}