org.smallmind.nutsnbolts.security.key.OpenSSHPubicKeyUtility Maven / Gradle / Ivy

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/*
 * Copyright (c) 2007 through 2024 David Berkman
 *
 * This file is part of the SmallMind Code Project.
 *
 * The SmallMind Code Project is free software, you can redistribute
 * it and/or modify it under either, at your discretion...
 *
 * 1) The terms of GNU Affero General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at
 * your option) any later version.
 *
 * ...or...
 *
 * 2) The terms of the Apache License, Version 2.0.
 *
 * The SmallMind Code Project 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 or Apache License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * and the Apache License along with the SmallMind Code Project. If not, see
 *  or .
 *
 * Additional permission under the GNU Affero GPL version 3 section 7
 * ------------------------------------------------------------------
 * If you modify this Program, or any covered work, by linking or
 * combining it with other code, such other code is not for that reason
 * alone subject to any of the requirements of the GNU Affero GPL
 * version 3.
 */
package org.smallmind.nutsnbolts.security.key;

import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.security.KeyFactory;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.RSAPublicKeySpec;
import org.smallmind.nutsnbolts.http.Base64Codec;

public class OpenSSHPubicKeyUtility {

  public static String convert (KeyFactors keyFactors)
    throws Exception {

    RSAPublicKey rsaPublicKey = (RSAPublicKey)KeyFactory.getInstance("RSA", "BC").generatePublic(new RSAPublicKeySpec(keyFactors.getModulus(), keyFactors.getExponent()));

    try (ByteArrayOutputStream buffer = new ByteArrayOutputStream()) {
      try (DataOutputStream output = new DataOutputStream(buffer)) {

        output.writeInt("ssh-rsa".getBytes().length);
        output.write("ssh-rsa".getBytes());
        output.writeInt(rsaPublicKey.getPublicExponent().toByteArray().length);
        output.write(rsaPublicKey.getPublicExponent().toByteArray());
        output.writeInt(rsaPublicKey.getModulus().toByteArray().length);
        output.write(rsaPublicKey.getModulus().toByteArray());

        return "ssh-rsa " + Base64Codec.encode(buffer.toByteArray());
      }
    }
  }
}