content: /*
   * 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 com.aliyun.oss.crypto;
  
  import com.aliyun.oss.common.utils.BinaryUtil;
  
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.math.BigInteger;
  import java.security.Provider;
  import java.security.Security;
  import java.security.spec.RSAPrivateKeySpec;
  
  public class CryptoRuntime {
      static final String BOUNCY_CASTLE_PROVIDER = "BC";
      private static final String BC_PROVIDER_FQCN = "org.bouncycastle.jce.provider.BouncyCastleProvider";
  
      /**
       * Checks if the crypto mode is supported by the runtime.
       *
       * @throws UnsupportedOperationException if the necessary security provider
       *                                       cannot be found
       */
      public static void enableBouncyCastle() {
          if (!isBouncyCastleAvailable()) {
              addBouncyCastleProvider();
              if (!isBouncyCastleAvailable()) {
                  throw new UnsupportedOperationException("The Bouncy castle library is not found.");
              }
          }
      }
  
      public static RSAPrivateKeySpec convertPemPKCS1ToPrivateKey(byte[] buffer)
      {
          try {
              Class<?> clz = Class.forName("org.bouncycastle.asn1.pkcs.RSAPrivateKey");
              Method method = clz.getMethod("getInstance", new Class[] { Object.class});
              Object obj = method.invoke(null, new Object[] {buffer});
  
              clz = Class.forName("org.bouncycastle.asn1.pkcs.RSAPrivateKey");
              method = clz.getMethod("getModulus", null);
              BigInteger modulus = (BigInteger) method.invoke(obj, null);
  
              method = clz.getMethod("getPrivateExponent", null);
              BigInteger exponent = (BigInteger) method.invoke(obj, null);
  
              return new RSAPrivateKeySpec(modulus,exponent);
  
          } catch (Exception e) {
              throw new UnsupportedOperationException("convertPemPKCS1ToPrivateKey fail.");
          }
      }
  
      private static synchronized boolean isBouncyCastleAvailable() {
          return Security.getProvider(BOUNCY_CASTLE_PROVIDER) != null;
      }
  
      private static synchronized void addBouncyCastleProvider() {
          if (isBouncyCastleAvailable()) {
              return;
          }
          try {
              @SuppressWarnings("unchecked")
              Class<Provider> c = (Class<Provider>) Class.forName(BC_PROVIDER_FQCN);
              Provider provider = c.newInstance();
              Security.addProvider(provider);
          } catch (Exception e) {
          }
      }
  }
  