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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.sshd.common.signature;

import java.nio.charset.StandardCharsets;
import java.security.GeneralSecurityException;
import java.security.MessageDigest;
import java.security.PrivateKey;
import java.security.PublicKey;

import org.apache.sshd.common.config.keys.u2f.SecurityKeyPublicKey;
import org.apache.sshd.common.session.SessionContext;
import org.apache.sshd.common.util.buffer.ByteArrayBuffer;
import org.apache.sshd.common.util.security.SecurityUtils;

public abstract class AbstractSecurityKeySignature implements Signature {
    private static final int FLAG_USER_PRESENCE = 0x01;

    private final String keyType;
    private SecurityKeyPublicKey publicKey;
    private MessageDigest challengeDigest;

    protected AbstractSecurityKeySignature(String keyType) {
        this.keyType = keyType;
    }

    @Override
    public void initVerifier(SessionContext session, PublicKey key) throws GeneralSecurityException {
        if (!(key instanceof SecurityKeyPublicKey)) {
            throw new IllegalArgumentException("Only instances of SecurityKeyPublicKey can be used");
        }
        this.publicKey = (SecurityKeyPublicKey) key;
        this.challengeDigest = SecurityUtils.getMessageDigest("SHA-256");
    }

    @Override
    public void update(SessionContext session, byte[] hash, int off, int len) {
        if (challengeDigest == null) {
            throw new IllegalStateException("initVerifier must be called before update");
        }
        challengeDigest.update(hash, off, len);
    }

    protected abstract String getSignatureKeyType();

    protected abstract Signature getDelegateSignature();

    @Override
    public boolean verify(SessionContext session, byte[] sig) throws Exception {
        if (challengeDigest == null) {
            throw new IllegalStateException("initVerifier must be called before verify");
        }

        ByteArrayBuffer data = new ByteArrayBuffer(sig);
        String keyType = data.getString();
        if (!this.keyType.equals(keyType)) {
            return false;
        }
        byte[] rawSig = data.getBytes();
        byte flags = data.getByte();
        long counter = data.getUInt();

        // Return false if we don't understand the flags
        if ((flags & ~FLAG_USER_PRESENCE) != 0) {
            return false;
        }
        // Check user-presence flag is present if required by the public key
        if ((flags & FLAG_USER_PRESENCE) != FLAG_USER_PRESENCE && !publicKey.isNoTouchRequired()) {
            return false;
        }

        // Re-encode signature in a format to match the delegate
        ByteArrayBuffer encoded = new ByteArrayBuffer();
        encoded.putString(getSignatureKeyType());
        encoded.putBytes(rawSig);

        MessageDigest md = SecurityUtils.getMessageDigest("SHA-256");
        byte[] appNameDigest = md.digest(publicKey.getAppName().getBytes(StandardCharsets.UTF_8));
        byte[] challengeDigest = this.challengeDigest.digest();
        ByteArrayBuffer counterData = new ByteArrayBuffer(Integer.BYTES, false);
        counterData.putUInt(counter);

        Signature delegate = getDelegateSignature();
        delegate.initVerifier(session, publicKey.getDelegatePublicKey());
        delegate.update(session, appNameDigest);
        delegate.update(session, new byte[] { flags });
        delegate.update(session, counterData.getCompactData());
        delegate.update(session, challengeDigest);
        return delegate.verify(session, encoded.getCompactData());
    }

    @Override
    public void initSigner(SessionContext session, PrivateKey key) {
        throw new UnsupportedOperationException("Security key private key signatures are unsupported.");
    }

    @Override
    public byte[] sign(SessionContext session) {
        throw new UnsupportedOperationException("Security key private key signatures are unsupported.");
    }
}