ConstructKeys.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
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 * 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,
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package com.sun.crypto.provider;

import java.security.Key;
import java.security.PublicKey;
import java.security.PrivateKey;
import java.security.KeyFactory;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.security.spec.InvalidKeySpecException;
import java.util.Arrays;
import javax.crypto.SecretKey;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

/**
 * This class is a helper class which construct key objects
 * from encoded keys.
 *
 * @author Sharon Liu
 *
 */

final class ConstructKeys {
    /**
     * Construct a public key from its encoding.
     *
     * @param encodedKey the encoding of a public key.
     *
     * @param encodedKeyAlgorithm the algorithm the encodedKey is for.
     *
     * @return a public key constructed from the encodedKey.
     */
    private static final PublicKey constructPublicKey(byte[] encodedKey,
            String encodedKeyAlgorithm)
            throws InvalidKeyException, NoSuchAlgorithmException {
        PublicKey key = null;
        try {
            KeyFactory keyFactory =
                KeyFactory.getInstance(encodedKeyAlgorithm,
                    SunJCE.getInstance());
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(encodedKey);
            key = keyFactory.generatePublic(keySpec);
        } catch (NoSuchAlgorithmException nsae) {
            // Try to see whether there is another
            // provider which supports this algorithm
            try {
                KeyFactory keyFactory =
                    KeyFactory.getInstance(encodedKeyAlgorithm);
                X509EncodedKeySpec keySpec =
                    new X509EncodedKeySpec(encodedKey);
                key = keyFactory.generatePublic(keySpec);
            } catch (NoSuchAlgorithmException nsae2) {
                throw new NoSuchAlgorithmException("No installed providers " +
                                                   "can create keys for the " +
                                                   encodedKeyAlgorithm +
                                                   "algorithm");
            } catch (InvalidKeySpecException ikse2) {
                InvalidKeyException ike =
                    new InvalidKeyException("Cannot construct public key");
                ike.initCause(ikse2);
                throw ike;
            }
        } catch (InvalidKeySpecException ikse) {
            InvalidKeyException ike =
                new InvalidKeyException("Cannot construct public key");
            ike.initCause(ikse);
            throw ike;
        }

        return key;
    }

    /**
     * Construct a private key from its encoding.
     *
     * @param encodedKey the encoding of a private key.
     *
     * @param encodedKeyAlgorithm the algorithm the wrapped key is for.
     *
     * @return a private key constructed from the encodedKey.
     */
    private static final PrivateKey constructPrivateKey(byte[] encodedKey,
            String encodedKeyAlgorithm)
            throws InvalidKeyException, NoSuchAlgorithmException {
        PrivateKey key = null;

        try {
            KeyFactory keyFactory =
                KeyFactory.getInstance(encodedKeyAlgorithm,
                    SunJCE.getInstance());
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(encodedKey);
            return keyFactory.generatePrivate(keySpec);
        } catch (NoSuchAlgorithmException nsae) {
            // Try to see whether there is another
            // provider which supports this algorithm
            try {
                KeyFactory keyFactory =
                    KeyFactory.getInstance(encodedKeyAlgorithm);
                PKCS8EncodedKeySpec keySpec =
                    new PKCS8EncodedKeySpec(encodedKey);
                key = keyFactory.generatePrivate(keySpec);
            } catch (NoSuchAlgorithmException nsae2) {
                throw new NoSuchAlgorithmException("No installed providers " +
                                                   "can create keys for the " +
                                                   encodedKeyAlgorithm +
                                                   "algorithm");
            } catch (InvalidKeySpecException ikse2) {
                InvalidKeyException ike =
                    new InvalidKeyException("Cannot construct private key");
                ike.initCause(ikse2);
                throw ike;
            }
        } catch (InvalidKeySpecException ikse) {
            InvalidKeyException ike =
                new InvalidKeyException("Cannot construct private key");
            ike.initCause(ikse);
            throw ike;
        }

        return key;
    }

    /**
     * Construct a secret key from its encoding.
     *
     * @param encodedKey the encoding of a secret key.
     *
     * @param encodedKeyAlgorithm the algorithm the secret key is for.
     *
     * @return a secret key constructed from the encodedKey.
     */
    private static final SecretKey constructSecretKey(byte[] encodedKey,
            int ofs, int len, String encodedKeyAlgorithm) {
        return (new SecretKeySpec(encodedKey, ofs, len, encodedKeyAlgorithm));
    }

    static final Key constructKey(byte[] encoding, String keyAlgorithm,
            int keyType) throws InvalidKeyException, NoSuchAlgorithmException {
        return constructKey(encoding, 0, encoding.length, keyAlgorithm,
                keyType);
    }

    static final Key constructKey(byte[] encoding, int ofs, int len,
            String keyAlgorithm, int keyType)
            throws InvalidKeyException, NoSuchAlgorithmException {
        switch (keyType) {
        case Cipher.SECRET_KEY:
            try {
                return ConstructKeys.constructSecretKey(encoding, ofs, len,
                        keyAlgorithm);
            } finally {
                Arrays.fill(encoding, ofs, len, (byte)0);
            }
        case Cipher.PRIVATE_KEY:
            byte[] encoding2 = encoding;
            try {
                if (ofs != 0 || len != encoding.length) {
                    encoding2 = Arrays.copyOfRange(encoding, ofs, ofs + len);
                }
                return ConstructKeys.constructPrivateKey(encoding2,
                        keyAlgorithm);
            } finally {
                Arrays.fill(encoding, ofs, len, (byte)0);
                if (encoding2 != encoding) {
                    Arrays.fill(encoding2, (byte)0);
                }
            }
        case Cipher.PUBLIC_KEY:
            if (ofs != 0 || len != encoding.length) {
                encoding = Arrays.copyOfRange(encoding, ofs, ofs + len);
            }
            return ConstructKeys.constructPublicKey(encoding, keyAlgorithm);
        default:
            throw new NoSuchAlgorithmException("Unsupported key type");
        }
    }
}