/*
 * Copyright 2003-2006 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * 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
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * 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).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package sun.security.pkcs11;

import java.math.BigInteger;

import java.security.*;
import java.security.spec.*;

import javax.crypto.spec.DHParameterSpec;

import sun.security.provider.ParameterCache;

import static sun.security.pkcs11.TemplateManager.*;
import sun.security.pkcs11.wrapper.*;
import static sun.security.pkcs11.wrapper.PKCS11Constants.*;

/**
 * KeyPairGenerator implementation class. This class currently supports
 * RSA, DSA, DH, and EC.
 *
 * Note that for DSA and DH we rely on the Sun and SunJCE providers to
 * obtain the parameters from.
 *
 * @author  Andreas Sterbenz
 * @since   1.5
 */
final class P11KeyPairGenerator extends KeyPairGeneratorSpi {

    // token instance
    private final Token token;

    // algorithm name
    private final String algorithm;

    // mechanism id
    private final long mechanism;

    // selected or default key size, always valid
    private int keySize;

    // parameters specified via init, if any
    private AlgorithmParameterSpec params;

    // for RSA, selected or default value of public exponent, always valid
    private BigInteger rsaPublicExponent;

    // SecureRandom instance, if specified in init
    private SecureRandom random;

    P11KeyPairGenerator(Token token, String algorithm, long mechanism)
            throws PKCS11Exception {
        super();
        this.token = token;
        this.algorithm = algorithm;
        this.mechanism = mechanism;
        if (algorithm.equals("EC")) {
            initialize(256, null);
        } else {
            initialize(1024, null);
        }
    }

    // see JCA spec
    public void initialize(int keySize, SecureRandom random) {
        token.ensureValid();
        try {
            checkKeySize(keySize);
        } catch (InvalidAlgorithmParameterException e) {
            throw new InvalidParameterException(e.getMessage());
        }
        this.keySize = keySize;
        this.params = null;
        this.random = random;
        this.rsaPublicExponent = RSAKeyGenParameterSpec.F4;
        if (algorithm.equals("EC")) {
            params = P11ECKeyFactory.getECParameterSpec(keySize);
            if (params == null) {
                throw new InvalidParameterException
                ("No EC parameters available for key size " + keySize + " bits");
            }
        }
    }

    // see JCA spec
    public void initialize(AlgorithmParameterSpec params, SecureRandom random)
            throws InvalidAlgorithmParameterException {
        token.ensureValid();
        if (algorithm.equals("DH")) {
            if (params instanceof DHParameterSpec == false) {
                throw new InvalidAlgorithmParameterException
                        ("DHParameterSpec required for Diffie-Hellman");
            }
            DHParameterSpec dhParams = (DHParameterSpec)params;
            this.keySize = dhParams.getP().bitLength();
            this.params = params;
            // XXX sanity check params
        } else if (algorithm.equals("RSA")) {
            if (params instanceof RSAKeyGenParameterSpec == false) {
                throw new InvalidAlgorithmParameterException
                        ("RSAKeyGenParameterSpec required for RSA");
            }
            RSAKeyGenParameterSpec rsaParams = (RSAKeyGenParameterSpec)params;
            this.keySize = rsaParams.getKeysize();
            this.params = null;
            this.rsaPublicExponent = rsaParams.getPublicExponent();
            // XXX sanity check params
        } else if (algorithm.equals("DSA")) {
            if (params instanceof DSAParameterSpec == false) {
                throw new InvalidAlgorithmParameterException
                        ("DSAParameterSpec required for DSA");
            }
            DSAParameterSpec dsaParams = (DSAParameterSpec)params;
            this.keySize = dsaParams.getP().bitLength();
            this.params = params;
            // XXX sanity check params
        } else if (algorithm.equals("EC")) {
            ECParameterSpec ecParams;
            if (params instanceof ECParameterSpec) {
                ecParams = P11ECKeyFactory.getECParameterSpec((ECParameterSpec)params);
                if (ecParams == null) {
                    throw new InvalidAlgorithmParameterException
                        ("Unsupported curve: " + params);
                }
            } else if (params instanceof ECGenParameterSpec) {
                String name = ((ECGenParameterSpec)params).getName();
                ecParams = P11ECKeyFactory.getECParameterSpec(name);
                if (ecParams == null) {
                    throw new InvalidAlgorithmParameterException
                        ("Unknown curve name: " + name);
                }
            } else {
                throw new InvalidAlgorithmParameterException
                    ("ECParameterSpec or ECGenParameterSpec required for EC");
            }
            this.keySize = ecParams.getCurve().getField().getFieldSize();
            this.params = ecParams;
        } else {
            throw new ProviderException("Unknown algorithm: " + algorithm);
        }
        this.random = random;
        checkKeySize(keySize);
    }

    private void checkKeySize(int keySize)
            throws InvalidAlgorithmParameterException {
        if (algorithm.equals("EC")) {
            if (keySize < 112) {
                throw new InvalidAlgorithmParameterException
                    ("Key size must be at least 112 bit");
            }
            if (keySize > 2048) {
                // sanity check, nobody really wants keys this large
                throw new InvalidAlgorithmParameterException
                    ("Key size must be at most 2048 bit");
            }
            return;
        }
        if (keySize < 512) {
            throw new InvalidAlgorithmParameterException
                ("Key size must be at least 512 bit");
        }
        if (algorithm.equals("RSA") ||
                (algorithm.equals("DH") && (params != null))) {
            // sanity check, nobody really wants keys this large
            if (keySize > 64 * 1024) {
                throw new InvalidAlgorithmParameterException
                    ("Key size must be at most 65536 bit");
            }
        } else {
            // this restriction is in the spec for DSA
            // since we currently use DSA parameters for DH as well,
            // it also applies to DH if no parameters are specified
            if ((keySize > 1024) || ((keySize & 0x3f) != 0)) {
                throw new InvalidAlgorithmParameterException
                    ("Key size must be a multiple of 64 and at most 1024 bit");
            }
        }
    }

    // see JCA spec
    public KeyPair generateKeyPair() {
        token.ensureValid();
        CK_ATTRIBUTE[] publicKeyTemplate;
        CK_ATTRIBUTE[] privateKeyTemplate;
        long keyType;
        if (algorithm.equals("RSA")) {
            keyType = CKK_RSA;
            publicKeyTemplate = new CK_ATTRIBUTE[] {
                new CK_ATTRIBUTE(CKA_MODULUS_BITS, keySize),
                new CK_ATTRIBUTE(CKA_PUBLIC_EXPONENT, rsaPublicExponent),
            };
            privateKeyTemplate = new CK_ATTRIBUTE[] {
                // empty
            };
        } else if (algorithm.equals("DSA")) {
            keyType = CKK_DSA;
            DSAParameterSpec dsaParams;
            if (params == null) {
                try {
                    dsaParams = ParameterCache.getDSAParameterSpec
                                                    (keySize, random);
                } catch (GeneralSecurityException e) {
                    throw new ProviderException
                            ("Could not generate DSA parameters", e);
                }
            } else {
                dsaParams = (DSAParameterSpec)params;
            }
            publicKeyTemplate = new CK_ATTRIBUTE[] {
                new CK_ATTRIBUTE(CKA_PRIME, dsaParams.getP()),
                new CK_ATTRIBUTE(CKA_SUBPRIME, dsaParams.getQ()),
                new CK_ATTRIBUTE(CKA_BASE, dsaParams.getG()),
            };
            privateKeyTemplate = new CK_ATTRIBUTE[] {
                // empty
            };
        } else if (algorithm.equals("DH")) {
            keyType = CKK_DH;
            DHParameterSpec dhParams;
            int privateBits;
            if (params == null) {
                try {
                    dhParams = ParameterCache.getDHParameterSpec
                                                    (keySize, random);
                } catch (GeneralSecurityException e) {
                    throw new ProviderException
                            ("Could not generate DH parameters", e);
                }
                privateBits = 0;
            } else {
                dhParams = (DHParameterSpec)params;
                privateBits = dhParams.getL();
            }
            if (privateBits <= 0) {
                // XXX find better defaults
                privateBits = (keySize >= 1024) ? 768 : 512;
            }
            publicKeyTemplate = new CK_ATTRIBUTE[] {
                new CK_ATTRIBUTE(CKA_PRIME, dhParams.getP()),
                new CK_ATTRIBUTE(CKA_BASE, dhParams.getG())
            };
            privateKeyTemplate = new CK_ATTRIBUTE[] {
                new CK_ATTRIBUTE(CKA_VALUE_BITS, privateBits),
            };
        } else if (algorithm.equals("EC")) {
            keyType = CKK_EC;
            byte[] encodedParams =
                    P11ECKeyFactory.encodeParameters((ECParameterSpec)params);
            publicKeyTemplate = new CK_ATTRIBUTE[] {
                new CK_ATTRIBUTE(CKA_EC_PARAMS, encodedParams),
            };
            privateKeyTemplate = new CK_ATTRIBUTE[] {
                // empty
            };
        } else {
            throw new ProviderException("Unknown algorithm: " + algorithm);
        }
        Session session = null;
        try {
            session = token.getObjSession();
            publicKeyTemplate = token.getAttributes
                (O_GENERATE, CKO_PUBLIC_KEY, keyType, publicKeyTemplate);
            privateKeyTemplate = token.getAttributes
                (O_GENERATE, CKO_PRIVATE_KEY, keyType, privateKeyTemplate);
            long[] keyIDs = token.p11.C_GenerateKeyPair
                (session.id(), new CK_MECHANISM(mechanism),
                publicKeyTemplate, privateKeyTemplate);
            PublicKey publicKey = P11Key.publicKey
                (session, keyIDs[0], algorithm, keySize, publicKeyTemplate);
            PrivateKey privateKey = P11Key.privateKey
                (session, keyIDs[1], algorithm, keySize, privateKeyTemplate);
            return new KeyPair(publicKey, privateKey);
        } catch (PKCS11Exception e) {
            throw new ProviderException(e);
        } finally {
            token.releaseSession(session);
        }
    }

}