http://www.bouncycastle.org/java.html: The Bouncy Castle Java APIs for CMS, PKCS, EAC, TSP, CMP, CRMF, OCSP, and certificate generation. This jar contains APIs for JDK 1.5 to JDK 1.8. The APIs can be used in conjunction with a JCE/JCA provider such as the one provided with the Bouncy Castle Cryptography APIs.
  • The Legion of the Bouncy Castle Inc. 
package org.bouncycastle.openssl.bc;

import org.bouncycastle.openssl.PEMDecryptor;
import org.bouncycastle.openssl.PEMDecryptorProvider;
import org.bouncycastle.openssl.PEMException;
import org.bouncycastle.openssl.PasswordException;

public class BcPEMDecryptorProvider
    implements PEMDecryptorProvider
{
    private final char[] password;

    public BcPEMDecryptorProvider(char[] password)
    {
        this.password = password;
    }

    public PEMDecryptor get(final String dekAlgName)
    {
        return new PEMDecryptor()
        {
            public byte[] decrypt(byte[] keyBytes, byte[] iv)
                throws PEMException
            {
                if (password == null)
                {
                    throw new PasswordException("Password is null, but a password is required");
                }

                return PEMUtilities.crypt(false, keyBytes, password, dekAlgName, iv);
            }
        };
    }
}