http://www.bouncycastle.org/java.html: The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.8.
  • The Legion of the Bouncy Castle Inc. 
package org.bouncycastle.pqc.jcajce.provider.mceliece;

import org.bouncycastle.asn1.DERNull;
import org.bouncycastle.asn1.nist.NISTObjectIdentifiers;
import org.bouncycastle.asn1.oiw.OIWObjectIdentifiers;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.crypto.Digest;
import org.bouncycastle.crypto.util.DigestFactory;

class Utils
{
    static AlgorithmIdentifier getDigAlgId(String digestName)
    {
        if (digestName.equals("SHA-1"))
        {
            return new AlgorithmIdentifier(OIWObjectIdentifiers.idSHA1, DERNull.INSTANCE);
        }
        if (digestName.equals("SHA-224"))
        {
            return new AlgorithmIdentifier(NISTObjectIdentifiers.id_sha224, DERNull.INSTANCE);
        }
        if (digestName.equals("SHA-256"))
        {
            return new AlgorithmIdentifier(NISTObjectIdentifiers.id_sha256, DERNull.INSTANCE);
        }
        if (digestName.equals("SHA-384"))
        {
            return new AlgorithmIdentifier(NISTObjectIdentifiers.id_sha384, DERNull.INSTANCE);
        }
        if (digestName.equals("SHA-512"))
        {
            return new AlgorithmIdentifier(NISTObjectIdentifiers.id_sha512, DERNull.INSTANCE);
        }

        throw new IllegalArgumentException("unrecognised digest algorithm: " + digestName);
    }

    static Digest getDigest(AlgorithmIdentifier digest)
    {
        if (digest.getAlgorithm().equals(OIWObjectIdentifiers.idSHA1))
        {
            return DigestFactory.createSHA1();
        }
        if (digest.getAlgorithm().equals(NISTObjectIdentifiers.id_sha224))
        {
            return DigestFactory.createSHA224();
        }
        if (digest.getAlgorithm().equals(NISTObjectIdentifiers.id_sha256))
        {
            return DigestFactory.createSHA256();
        }
        if (digest.getAlgorithm().equals(NISTObjectIdentifiers.id_sha384))
        {
            return DigestFactory.createSHA384();
        }
        if (digest.getAlgorithm().equals(NISTObjectIdentifiers.id_sha512))
        {
            return DigestFactory.createSHA512();
        }
        throw new IllegalArgumentException("unrecognised OID in digest algorithm identifier: " + digest.getAlgorithm());
    }
}