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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
 * under the terms of the GNU General Public License version 2 only, as
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 * 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
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 * 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 javax.crypto;

import java.io.*;
import java.security.*;
import java.security.spec.*;
import sun.security.x509.AlgorithmId;
import sun.security.util.DerValue;
import sun.security.util.DerInputStream;
import sun.security.util.DerOutputStream;

/**
 * This class implements the <code>EncryptedPrivateKeyInfo</code> type
 * as defined in PKCS #8.
 * <p>Its ASN.1 definition is as follows:
 *
 * <pre>
 * EncryptedPrivateKeyInfo ::=  SEQUENCE {
 *     encryptionAlgorithm   AlgorithmIdentifier,
 *     encryptedData   OCTET STRING }
 *
 * AlgorithmIdentifier  ::=  SEQUENCE  {
 *     algorithm              OBJECT IDENTIFIER,
 *     parameters             ANY DEFINED BY algorithm OPTIONAL  }
 * </pre>
 *
 * @author Valerie Peng
 *
 * @see java.security.spec.PKCS8EncodedKeySpec
 *
 * @since 1.4
 */

public class EncryptedPrivateKeyInfo {

    // the "encryptionAlgorithm" field
    private AlgorithmId algid;

    // the algorithm name of the encrypted private key
    private String keyAlg;

    // the "encryptedData" field
    private byte[] encryptedData;

    // the ASN.1 encoded contents of this class
    private byte[] encoded = null;

    /**
     * Constructs (i.e., parses) an <code>EncryptedPrivateKeyInfo</code> from
     * its ASN.1 encoding.
     * @param encoded the ASN.1 encoding of this object. The contents of
     * the array are copied to protect against subsequent modification.
     * @exception NullPointerException if the <code>encoded</code> is null.
     * @exception IOException if error occurs when parsing the ASN.1 encoding.
     */
    public EncryptedPrivateKeyInfo(byte[] encoded) throws IOException {
        if (encoded == null) {
            throw new NullPointerException("the encoded parameter " +
                "must be non-null");
        }

        this.encoded = encoded.clone();
        DerValue val = DerValue.wrap(this.encoded);
        if (val.tag != DerValue.tag_Sequence) {
            throw new IOException("DER header error: no SEQ tag");
        }

        DerValue[] seq = new DerValue[2];

        seq[0] = val.data.getDerValue();
        seq[1] = val.data.getDerValue();

        if (val.data.available() != 0) {
            throw new IOException("overrun, bytes = " + val.data.available());
        }

        this.algid = AlgorithmId.parse(seq[0]);
        if (seq[0].data.available() != 0) {
            throw new IOException("encryptionAlgorithm field overrun");
        }

        this.encryptedData = seq[1].getOctetString();
        if (seq[1].data.available() != 0) {
            throw new IOException("encryptedData field overrun");
        }
    }

    /**
     * Constructs an <code>EncryptedPrivateKeyInfo</code> from the
     * encryption algorithm name and the encrypted data.
     *
     * <p>Note: This constructor will use null as the value of the
     * algorithm parameters. If the encryption algorithm has
     * parameters whose value is not null, a different constructor,
     * e.g. EncryptedPrivateKeyInfo(AlgorithmParameters, byte[]),
     * should be used.
     *
     * @param algName encryption algorithm name. See the
     * <a href="{@docRoot}/../specs/security/standard-names.html">
     * Java Security Standard Algorithm Names</a> document
     * for information about standard Cipher algorithm names.
     * @param encryptedData encrypted data. The contents of
     * <code>encrypedData</code> are copied to protect against subsequent
     * modification when constructing this object.
     * @exception NullPointerException if <code>algName</code> or
     * <code>encryptedData</code> is null.
     * @exception IllegalArgumentException if <code>encryptedData</code>
     * is empty, i.e. 0-length.
     * @exception NoSuchAlgorithmException if the specified algName is
     * not supported.
     */
    public EncryptedPrivateKeyInfo(String algName, byte[] encryptedData)
        throws NoSuchAlgorithmException {

        if (algName == null)
                throw new NullPointerException("the algName parameter " +
                                               "must be non-null");
        this.algid = AlgorithmId.get(algName);

        if (encryptedData == null) {
            throw new NullPointerException("the encryptedData " +
                                           "parameter must be non-null");
        } else if (encryptedData.length == 0) {
            throw new IllegalArgumentException("the encryptedData " +
                                                "parameter must not be empty");
        } else {
            this.encryptedData = encryptedData.clone();
        }
        // delay the generation of ASN.1 encoding until
        // getEncoded() is called
        this.encoded = null;
    }

    /**
     * Constructs an <code>EncryptedPrivateKeyInfo</code> from the
     * encryption algorithm parameters and the encrypted data.
     *
     * @param algParams the algorithm parameters for the encryption
     * algorithm. <code>algParams.getEncoded()</code> should return
     * the ASN.1 encoded bytes of the <code>parameters</code> field
     * of the <code>AlgorithmIdentifer</code> component of the
     * <code>EncryptedPrivateKeyInfo</code> type.
     * @param encryptedData encrypted data. The contents of
     * <code>encrypedData</code> are copied to protect against
     * subsequent modification when constructing this object.
     * @exception NullPointerException if <code>algParams</code> or
     * <code>encryptedData</code> is null.
     * @exception IllegalArgumentException if <code>encryptedData</code>
     * is empty, i.e. 0-length.
     * @exception NoSuchAlgorithmException if the specified algName of
     * the specified <code>algParams</code> parameter is not supported.
     */
    public EncryptedPrivateKeyInfo(AlgorithmParameters algParams,
        byte[] encryptedData) throws NoSuchAlgorithmException {

        if (algParams == null) {
            throw new NullPointerException("algParams must be non-null");
        }
        this.algid = AlgorithmId.get(algParams);

        if (encryptedData == null) {
            throw new NullPointerException("encryptedData must be non-null");
        } else if (encryptedData.length == 0) {
            throw new IllegalArgumentException("the encryptedData " +
                                                "parameter must not be empty");
        } else {
            this.encryptedData = encryptedData.clone();
        }

        // delay the generation of ASN.1 encoding until
        // getEncoded() is called
        this.encoded = null;
    }


    /**
     * Returns the encryption algorithm.
     * <p>Note: Standard name is returned instead of the specified one
     * in the constructor when such mapping is available.
     * See the <a href="{@docRoot}/../specs/security/standard-names.html">
     * Java Security Standard Algorithm Names</a> document
     * for information about standard Cipher algorithm names.
     *
     * @return the encryption algorithm name.
     */
    public String getAlgName() {
        return this.algid.getName();
    }

    /**
     * Returns the algorithm parameters used by the encryption algorithm.
     * @return the algorithm parameters.
     */
    public AlgorithmParameters getAlgParameters() {
        return this.algid.getParameters();
    }

    /**
     * Returns the encrypted data.
     * @return the encrypted data. Returns a new array
     * each time this method is called.
     */
    public byte[] getEncryptedData() {
        return this.encryptedData.clone();
    }

    /**
     * Extract the enclosed PKCS8EncodedKeySpec object from the
     * encrypted data and return it.
     * <br>Note: In order to successfully retrieve the enclosed
     * PKCS8EncodedKeySpec object, <code>cipher</code> needs
     * to be initialized to either Cipher.DECRYPT_MODE or
     * Cipher.UNWRAP_MODE, with the same key and parameters used
     * for generating the encrypted data.
     *
     * @param cipher the initialized cipher object which will be
     * used for decrypting the encrypted data.
     * @return the PKCS8EncodedKeySpec object.
     * @exception NullPointerException if <code>cipher</code>
     * is null.
     * @exception InvalidKeySpecException if the given cipher is
     * inappropriate for the encrypted data or the encrypted
     * data is corrupted and cannot be decrypted.
     */
    public PKCS8EncodedKeySpec getKeySpec(Cipher cipher)
        throws InvalidKeySpecException {
        byte[] encoded = null;
        try {
            encoded = cipher.doFinal(encryptedData);
            checkPKCS8Encoding(encoded);
        } catch (GeneralSecurityException |
                 IOException |
                 IllegalStateException ex) {
            throw new InvalidKeySpecException(
                    "Cannot retrieve the PKCS8EncodedKeySpec", ex);
        }
        return new PKCS8EncodedKeySpec(encoded, keyAlg);
    }

    private PKCS8EncodedKeySpec getKeySpecImpl(Key decryptKey,
        Provider provider) throws NoSuchAlgorithmException,
        InvalidKeyException {
        byte[] encoded = null;
        Cipher c;
        try {
            if (provider == null) {
                // use the most preferred one
                c = Cipher.getInstance(algid.getName());
            } else {
                c = Cipher.getInstance(algid.getName(), provider);
            }
            c.init(Cipher.DECRYPT_MODE, decryptKey, algid.getParameters());
            encoded = c.doFinal(encryptedData);
            checkPKCS8Encoding(encoded);
        } catch (NoSuchAlgorithmException nsae) {
            // rethrow
            throw nsae;
        } catch (GeneralSecurityException | IOException ex) {
            throw new InvalidKeyException(
                    "Cannot retrieve the PKCS8EncodedKeySpec", ex);
        }
        return new PKCS8EncodedKeySpec(encoded, keyAlg);
    }

    /**
     * Extract the enclosed PKCS8EncodedKeySpec object from the
     * encrypted data and return it.
     * @param decryptKey key used for decrypting the encrypted data.
     * @return the PKCS8EncodedKeySpec object.
     * @exception NullPointerException if <code>decryptKey</code>
     * is null.
     * @exception NoSuchAlgorithmException if cannot find appropriate
     * cipher to decrypt the encrypted data.
     * @exception InvalidKeyException if <code>decryptKey</code>
     * cannot be used to decrypt the encrypted data or the decryption
     * result is not a valid PKCS8KeySpec.
     *
     * @since 1.5
     */
    public PKCS8EncodedKeySpec getKeySpec(Key decryptKey)
        throws NoSuchAlgorithmException, InvalidKeyException {
        if (decryptKey == null) {
            throw new NullPointerException("decryptKey is null");
        }
        return getKeySpecImpl(decryptKey, null);
    }

    /**
     * Extract the enclosed PKCS8EncodedKeySpec object from the
     * encrypted data and return it.
     * @param decryptKey key used for decrypting the encrypted data.
     * @param providerName the name of provider whose Cipher
     * implementation will be used.
     * @return the PKCS8EncodedKeySpec object.
     * @exception NullPointerException if <code>decryptKey</code>
     * or <code>providerName</code> is null.
     * @exception NoSuchProviderException if no provider
     * <code>providerName</code> is registered.
     * @exception NoSuchAlgorithmException if cannot find appropriate
     * cipher to decrypt the encrypted data.
     * @exception InvalidKeyException if <code>decryptKey</code>
     * cannot be used to decrypt the encrypted data or the decryption
     * result is not a valid PKCS8KeySpec.
     *
     * @since 1.5
     */
    public PKCS8EncodedKeySpec getKeySpec(Key decryptKey,
        String providerName) throws NoSuchProviderException,
        NoSuchAlgorithmException, InvalidKeyException {
        if (decryptKey == null) {
            throw new NullPointerException("decryptKey is null");
        }
        if (providerName == null) {
            throw new NullPointerException("provider is null");
        }
        Provider provider = Security.getProvider(providerName);
        if (provider == null) {
            throw new NoSuchProviderException("provider " +
                providerName + " not found");
        }
        return getKeySpecImpl(decryptKey, provider);
    }

    /**
     * Extract the enclosed PKCS8EncodedKeySpec object from the
     * encrypted data and return it.
     * @param decryptKey key used for decrypting the encrypted data.
     * @param provider the name of provider whose Cipher implementation
     * will be used.
     * @return the PKCS8EncodedKeySpec object.
     * @exception NullPointerException if <code>decryptKey</code>
     * or <code>provider</code> is null.
     * @exception NoSuchAlgorithmException if cannot find appropriate
     * cipher to decrypt the encrypted data in <code>provider</code>.
     * @exception InvalidKeyException if <code>decryptKey</code>
     * cannot be used to decrypt the encrypted data or the decryption
     * result is not a valid PKCS8KeySpec.
     *
     * @since 1.5
     */
    public PKCS8EncodedKeySpec getKeySpec(Key decryptKey,
        Provider provider) throws NoSuchAlgorithmException,
        InvalidKeyException {
        if (decryptKey == null) {
            throw new NullPointerException("decryptKey is null");
        }
        if (provider == null) {
            throw new NullPointerException("provider is null");
        }
        return getKeySpecImpl(decryptKey, provider);
    }

    /**
     * Returns the ASN.1 encoding of this object.
     * @return the ASN.1 encoding. Returns a new array
     * each time this method is called.
     * @exception IOException if error occurs when constructing its
     * ASN.1 encoding.
     */
    public byte[] getEncoded() throws IOException {
        if (this.encoded == null) {
            DerOutputStream out = new DerOutputStream();
            DerOutputStream tmp = new DerOutputStream();

            // encode encryption algorithm
            algid.encode(tmp);

            // encode encrypted data
            tmp.putOctetString(encryptedData);

            // wrap everything into a SEQUENCE
            out.write(DerValue.tag_Sequence, tmp);
            this.encoded = out.toByteArray();
        }
        return this.encoded.clone();
    }

    private static void checkTag(DerValue val, byte tag, String valName)
        throws IOException {
        if (val.getTag() != tag) {
            throw new IOException("invalid key encoding - wrong tag for " +
                                  valName);
        }
    }

    @SuppressWarnings("fallthrough")
    private void checkPKCS8Encoding(byte[] encodedKey)
        throws IOException {
        DerInputStream in = new DerInputStream(encodedKey);
        DerValue[] values = in.getSequence(3);

        switch (values.length) {
        case 4:
            checkTag(values[3], DerValue.TAG_CONTEXT, "attributes");
            /* fall through */
        case 3:
            checkTag(values[0], DerValue.tag_Integer, "version");
            keyAlg = AlgorithmId.parse(values[1]).getName();
            checkTag(values[2], DerValue.tag_OctetString, "privateKey");
            break;
        default:
            throw new IOException("invalid key encoding");
        }
    }
}
