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package sun.security.pkcs11;

import java.math.BigInteger;

import java.security.*;

import java.security.spec.*;

import javax.crypto.*;

import javax.crypto.interfaces.*;

import javax.crypto.spec.*;

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

import sun.security.pkcs11.wrapper.*;

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

/**

 * KeyAgreement implementation class. This class currently supports

 * DH.

 *

 * @author  Andreas Sterbenz

 * @since   1.5

 */

final class P11KeyAgreement extends KeyAgreementSpi {

    // token instance

    private final Token token;

    // algorithm name

    private final String algorithm;

    // mechanism id

    private final long mechanism;

    // private key, if initialized

    private P11Key privateKey;

    // other sides public value ("y"), if doPhase() already called

    private BigInteger publicValue;

    // length of the secret to be derived

    private int secretLen;

    // KeyAgreement from SunJCE as fallback for > 2 party agreement

    private KeyAgreement multiPartyAgreement;

    P11KeyAgreement(Token token, String algorithm, long mechanism) {

        super();

        this.token = token;

        this.algorithm = algorithm;

        this.mechanism = mechanism;

    }

    // see JCE spec

    protected void engineInit(Key key, SecureRandom random)

            throws InvalidKeyException {

        if (key instanceof PrivateKey == false) {

            throw new InvalidKeyException

                        ("Key must be instance of PrivateKey");

        }

        privateKey = P11KeyFactory.convertKey(token, key, algorithm);

        publicValue = null;

        multiPartyAgreement = null;

    }

    // see JCE spec

    protected void engineInit(Key key, AlgorithmParameterSpec params,

            SecureRandom random) throws InvalidKeyException,

            InvalidAlgorithmParameterException {

        if (params != null) {

            throw new InvalidAlgorithmParameterException

                        ("Parameters not supported");

        }

        engineInit(key, random);

    }

    // see JCE spec

    protected Key engineDoPhase(Key key, boolean lastPhase)

            throws InvalidKeyException, IllegalStateException {

        if (privateKey == null) {

            throw new IllegalStateException("Not initialized");

        }

        if (publicValue != null) {

            throw new IllegalStateException("Phase already executed");

        }

        // PKCS#11 only allows key agreement between 2 parties

        // JCE allows >= 2 parties. To support that case (for compatibility

        // and to pass JCK), fall back to SunJCE in this case.

        // NOTE that we initialize using the P11Key, which will fail if it

        // is sensitive/unextractable. However, this is not an issue in the

        // compatibility configuration, which is all we are targeting here.

        if ((multiPartyAgreement != null) || (lastPhase == false)) {

            if (multiPartyAgreement == null) {

                try {

                    multiPartyAgreement = KeyAgreement.getInstance

                        ("DH", P11Util.getSunJceProvider());

                    multiPartyAgreement.init(privateKey);

                } catch (NoSuchAlgorithmException e) {

                    throw new InvalidKeyException

                        ("Could not initialize multi party agreement", e);

                }

            }

            return multiPartyAgreement.doPhase(key, lastPhase);

        }

        if ((key instanceof PublicKey == false)

                || (key.getAlgorithm().equals(algorithm) == false)) {

            throw new InvalidKeyException

                ("Key must be a PublicKey with algorithm DH");

        }

        BigInteger p, g, y;

        if (key instanceof DHPublicKey) {

            DHPublicKey dhKey = (DHPublicKey)key;

            y = dhKey.getY();

            DHParameterSpec params = dhKey.getParams();

            p = params.getP();

            g = params.getG();

        } else {

            // normally, DH PublicKeys will always implement DHPublicKey

            // just in case not, attempt conversion

            P11DHKeyFactory kf = new P11DHKeyFactory(token, "DH");

            try {

                y = spec.getY();

                p = spec.getP();

                g = spec.getG();

            } catch (InvalidKeySpecException e) {

                throw new InvalidKeyException("Could not obtain key values", e);

            }

        }

        // if parameters of private key are accessible, verify that

        // they match parameters of public key

        // XXX p and g should always be readable, even if the key is sensitive

        if (privateKey instanceof DHPrivateKey) {

            DHPrivateKey dhKey = (DHPrivateKey)privateKey;

            DHParameterSpec params = dhKey.getParams();

            if ((p.equals(params.getP()) == false)

                                || (g.equals(params.getG()) == false)) {

                throw new InvalidKeyException

                ("PublicKey DH parameters must match PrivateKey DH parameters");

            }

        }

        publicValue = y;

        // length of the secret is length of key

        secretLen = (p.bitLength() + 7) >> 3;

        return null;

    }

    // see JCE spec

    protected byte[] engineGenerateSecret() throws IllegalStateException {

        if (multiPartyAgreement != null) {

            byte[] val = multiPartyAgreement.generateSecret();

            multiPartyAgreement = null;

            return val;

        }

        if ((privateKey == null) || (publicValue == null)) {

            throw new IllegalStateException("Not initialized correctly");

        }

        Session session = null;

        try {

            session = token.getOpSession();

            CK_ATTRIBUTE[] attributes = new CK_ATTRIBUTE[] {

                new CK_ATTRIBUTE(CKA_CLASS, CKO_SECRET_KEY),

                new CK_ATTRIBUTE(CKA_KEY_TYPE, CKK_GENERIC_SECRET),

            };

            attributes = token.getAttributes

                (O_GENERATE, CKO_SECRET_KEY, CKK_GENERIC_SECRET, attributes);

            long keyID = token.p11.C_DeriveKey(session.id(),

                new CK_MECHANISM(mechanism, publicValue), privateKey.keyID,

                attributes);

            attributes = new CK_ATTRIBUTE[] {

                new CK_ATTRIBUTE(CKA_VALUE)

            };

            token.p11.C_GetAttributeValue(session.id(), keyID, attributes);

            byte[] secret = attributes[0].getByteArray();

            token.p11.C_DestroyObject(session.id(), keyID);

            // trim leading 0x00 bytes per JCE convention

            return P11Util.trimZeroes(secret);

        } catch (PKCS11Exception e) {

            throw new ProviderException("Could not derive key", e);

        } finally {

            publicValue = null;

            token.releaseSession(session);

        }

    }

    // see JCE spec

    protected int engineGenerateSecret(byte[] sharedSecret, int

            offset) throws IllegalStateException, ShortBufferException {

        if (multiPartyAgreement != null) {

            int n = multiPartyAgreement.generateSecret(sharedSecret, offset);

            multiPartyAgreement = null;

            return n;

        }

        if (offset + secretLen > sharedSecret.length) {

            throw new ShortBufferException("Need " + secretLen

                + " bytes, only " + (sharedSecret.length - offset) + " available");

        }

        byte[] secret = engineGenerateSecret();

        System.arraycopy(secret, 0, sharedSecret, offset, secret.length);

        return secret.length;

    }

    // see JCE spec

    protected SecretKey engineGenerateSecret(String algorithm)

            throws IllegalStateException, NoSuchAlgorithmException,

            InvalidKeyException {

        if (multiPartyAgreement != null) {

            SecretKey key = multiPartyAgreement.generateSecret(algorithm);

            multiPartyAgreement = null;

            return key;

        }

        if (algorithm == null) {

            throw new NoSuchAlgorithmException("Algorithm must not be null");

        }

        if (algorithm.equals("TlsPremasterSecret")) {

            // For now, only perform native derivation for TlsPremasterSecret

            // as that is required for FIPS compliance.

            // For other algorithms, there are unresolved issues regarding

            // how this should work in JCE plus a Solaris truncation bug.

            // (bug not yet filed).

            return nativeGenerateSecret(algorithm);

        }

        byte[] secret = engineGenerateSecret();

        // Maintain compatibility for SunJCE:

        // verify secret length is sensible for algorithm / truncate

        // return generated key itself if possible

        int keyLen;

        if (algorithm.equalsIgnoreCase("DES")) {

            keyLen = 8;

        } else if (algorithm.equalsIgnoreCase("DESede")) {

            keyLen = 24;

        } else if (algorithm.equalsIgnoreCase("Blowfish")) {

            keyLen = Math.min(56, secret.length);

        } else if (algorithm.equalsIgnoreCase("TlsPremasterSecret")) {

            keyLen = secret.length;

        } else {

            throw new NoSuchAlgorithmException

                ("Unknown algorithm " + algorithm);

        }

        if (secret.length < keyLen) {

            throw new InvalidKeyException("Secret too short");

        }

        if (algorithm.equalsIgnoreCase("DES") ||

            algorithm.equalsIgnoreCase("DESede")) {

                for (int i = 0; i < keyLen; i+=8) {

                    P11SecretKeyFactory.fixDESParity(secret, i);

                }

        }

        return new SecretKeySpec(secret, 0, keyLen, algorithm);

    }

    private SecretKey nativeGenerateSecret(String algorithm)

            throws IllegalStateException, NoSuchAlgorithmException,

            InvalidKeyException {

        if ((privateKey == null) || (publicValue == null)) {

            throw new IllegalStateException("Not initialized correctly");

        }

        long keyType = CKK_GENERIC_SECRET;

        Session session = null;

        try {

            session = token.getObjSession();

            CK_ATTRIBUTE[] attributes = new CK_ATTRIBUTE[] {

                new CK_ATTRIBUTE(CKA_CLASS, CKO_SECRET_KEY),

                new CK_ATTRIBUTE(CKA_KEY_TYPE, keyType),

            };

            attributes = token.getAttributes

                (O_GENERATE, CKO_SECRET_KEY, keyType, attributes);

            long keyID = token.p11.C_DeriveKey(session.id(),

                new CK_MECHANISM(mechanism, publicValue), privateKey.keyID,

                attributes);

            CK_ATTRIBUTE[] lenAttributes = new CK_ATTRIBUTE[] {

                new CK_ATTRIBUTE(CKA_VALUE_LEN),

            };

            token.p11.C_GetAttributeValue(session.id(), keyID, lenAttributes);

            int keyLen = (int)lenAttributes[0].getLong();

            SecretKey key = P11Key.secretKey

                        (session, keyID, algorithm, keyLen << 3, attributes);

            if ("RAW".equals(key.getFormat())) {

                // Workaround for Solaris bug 6318543.

                // Strip leading zeroes ourselves if possible (key not sensitive).

                // This should be removed once the Solaris fix is available

                // as here we always retrieve the CKA_VALUE even for tokens

                // that do not have that bug.

                byte[] keyBytes = key.getEncoded();

                byte[] newBytes = P11Util.trimZeroes(keyBytes);

                if (keyBytes != newBytes) {

                    key = new SecretKeySpec(newBytes, algorithm);

                }

            }

            return key;

        } catch (PKCS11Exception e) {

            throw new InvalidKeyException("Could not derive key", e);

        } finally {

            publicValue = null;

            token.releaseSession(session);

        }

    }

}