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;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.bouncycastle.asn1.ASN1ObjectIdentifier;
import org.bouncycastle.asn1.nist.NISTObjectIdentifiers;
import org.bouncycastle.asn1.pkcs.PKCSObjectIdentifiers;
import org.bouncycastle.util.Integers;

final class PEMUtilities
{
    private static final Map KEYSIZES = new HashMap();
    private static final Set PKCS5_SCHEME_1 = new HashSet();
    private static final Set PKCS5_SCHEME_2 = new HashSet();

    static
    {
        PKCS5_SCHEME_1.add(PKCSObjectIdentifiers.pbeWithMD2AndDES_CBC);
        PKCS5_SCHEME_1.add(PKCSObjectIdentifiers.pbeWithMD2AndRC2_CBC);
        PKCS5_SCHEME_1.add(PKCSObjectIdentifiers.pbeWithMD5AndDES_CBC);
        PKCS5_SCHEME_1.add(PKCSObjectIdentifiers.pbeWithMD5AndRC2_CBC);
        PKCS5_SCHEME_1.add(PKCSObjectIdentifiers.pbeWithSHA1AndDES_CBC);
        PKCS5_SCHEME_1.add(PKCSObjectIdentifiers.pbeWithSHA1AndRC2_CBC);

        PKCS5_SCHEME_2.add(PKCSObjectIdentifiers.id_PBES2);
        PKCS5_SCHEME_2.add(PKCSObjectIdentifiers.des_EDE3_CBC);
        PKCS5_SCHEME_2.add(NISTObjectIdentifiers.id_aes128_CBC);
        PKCS5_SCHEME_2.add(NISTObjectIdentifiers.id_aes192_CBC);
        PKCS5_SCHEME_2.add(NISTObjectIdentifiers.id_aes256_CBC);

        KEYSIZES.put(PKCSObjectIdentifiers.des_EDE3_CBC.getId(), Integers.valueOf(192));
        KEYSIZES.put(NISTObjectIdentifiers.id_aes128_CBC.getId(), Integers.valueOf(128));
        KEYSIZES.put(NISTObjectIdentifiers.id_aes192_CBC.getId(), Integers.valueOf(192));
        KEYSIZES.put(NISTObjectIdentifiers.id_aes256_CBC.getId(), Integers.valueOf(256));
    }

    static int getKeySize(String algorithm)
    {
        if (!KEYSIZES.containsKey(algorithm))
        {
            throw new IllegalStateException("no key size for algorithm: " + algorithm);
        }
        
        return ((Integer)KEYSIZES.get(algorithm)).intValue();
    }

    static boolean isPKCS5Scheme1(ASN1ObjectIdentifier algOid)
    {
        return PKCS5_SCHEME_1.contains(algOid);
    }

    public static boolean isPKCS5Scheme2(ASN1ObjectIdentifier algOid)
    {
        return PKCS5_SCHEME_2.contains(algOid);
    }

    public static boolean isPKCS12(ASN1ObjectIdentifier algOid)
    {
        return algOid.getId().startsWith(PKCSObjectIdentifiers.pkcs_12PbeIds.getId());
    }
}