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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.math.BigInteger;
import java.security.PublicKey;
import java.security.interfaces.RSAKey;
import java.util.Collections;
import java.util.Map;
import java.util.NavigableSet;
import java.util.TreeSet;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import org.apache.sshd.common.config.keys.KeyUtils;
import org.apache.sshd.common.keyprovider.KeyPairProvider;
import org.apache.sshd.common.session.SessionContext;
import org.apache.sshd.common.util.ValidateUtils;

/**
 * RSA Signature
 *
 * @author Apache MINA SSHD Project
 * @see    RFC4253 section 6.6
 */
public abstract class SignatureRSA extends AbstractSignature {
    public static final NavigableSet SUPPORTED_KEY_TYPES = Collections.unmodifiableNavigableSet(
            Stream.of(
                    KeyPairProvider.SSH_RSA,
                    KeyPairProvider.SSH_RSA_CERT,
                    KeyUtils.RSA_SHA256_KEY_TYPE_ALIAS,
                    KeyUtils.RSA_SHA512_KEY_TYPE_ALIAS,
                    KeyUtils.RSA_SHA256_CERT_TYPE_ALIAS,
                    KeyUtils.RSA_SHA512_CERT_TYPE_ALIAS)
                    .collect(Collectors.toCollection(() -> new TreeSet<>(String.CASE_INSENSITIVE_ORDER))));

    private int verifierSignatureSize = -1;

    private final String sshAlgorithmName;

    protected SignatureRSA(String algorithm, String sshAlgorithmName) {
        super(algorithm);
        this.sshAlgorithmName = ValidateUtils.checkNotNullAndNotEmpty(sshAlgorithmName,
                "Missing protocol name of the signature algorithm.");
    }

    @Override
    public String getSshAlgorithmName(String algo) {
        return sshAlgorithmName;
    }

    /**
     * @return The expected number of bytes in the signature - non-positive if not initialized or not intended to be
     *         used for verification
     */
    protected int getVerifierSignatureSize() {
        return verifierSignatureSize;
    }

    @Override
    public void initVerifier(SessionContext session, PublicKey key) throws Exception {
        super.initVerifier(session, key);
        RSAKey rsaKey = ValidateUtils.checkInstanceOf(key, RSAKey.class, "Not an RSA key");
        verifierSignatureSize = getVerifierSignatureSize(rsaKey);
    }

    public static int getVerifierSignatureSize(RSAKey key) {
        BigInteger modulus = key.getModulus();
        return (modulus.bitLength() + Byte.SIZE - 1) / Byte.SIZE;
    }

    @Override
    public boolean verify(SessionContext session, byte[] sig) throws Exception {
        byte[] data = sig;
        Map.Entry encoding = extractEncodedSignature(data, SUPPORTED_KEY_TYPES);
        if (encoding != null) {
            String keyType = encoding.getKey();
            /*
             * According to https://tools.ietf.org/html/rfc8332#section-3.2:
             *
             * OpenSSH 7.2 (but not 7.2p2) incorrectly encodes the algorithm in the signature as "ssh-rsa" when the
             * algorithm in SSH_MSG_USERAUTH_REQUEST is "rsa-sha2-256" or "rsa-sha2-512". In this case, the signature
             * does actually use either SHA-256 or SHA-512. A server MAY, but is not required to, accept this variant or
             * another variant that corresponds to a good-faith implementation and is considered safe to accept.
             */
            String canonicalName = KeyUtils.getCanonicalKeyType(keyType);
            ValidateUtils.checkTrue(SUPPORTED_KEY_TYPES.contains(canonicalName), "Mismatched key type: %s", keyType);
            data = encoding.getValue();
        }

        int expectedSize = getVerifierSignatureSize();
        ValidateUtils.checkTrue(expectedSize > 0, "Signature verification size has not been initialized");
        // Pad with zero if value is trimmed
        if (data.length < expectedSize) {
            byte[] pad = new byte[expectedSize];
            System.arraycopy(data, 0, pad, pad.length - data.length, data.length);
            data = pad;
        }

        return doVerify(data);
    }
}