org.bouncycastle.cms.jcajce.JceCMSMacCalculatorBuilder Maven / Gradle / Ivy

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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.

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package org.bouncycastle.cms.jcajce;

import java.io.OutputStream;
import java.security.AlgorithmParameterGenerator;
import java.security.AlgorithmParameters;
import java.security.GeneralSecurityException;
import java.security.Provider;
import java.security.SecureRandom;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.KeyGenerator;
import javax.crypto.Mac;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.RC2ParameterSpec;

import org.bouncycastle.asn1.ASN1ObjectIdentifier;
import org.bouncycastle.asn1.pkcs.PKCSObjectIdentifiers;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.cms.CMSException;
import org.bouncycastle.jcajce.io.MacOutputStream;
import org.bouncycastle.operator.GenericKey;
import org.bouncycastle.operator.MacCalculator;
import org.bouncycastle.operator.jcajce.JceGenericKey;

public class JceCMSMacCalculatorBuilder
{
    private final ASN1ObjectIdentifier macOID;
    private final int                  keySize;

    private EnvelopedDataHelper helper = new EnvelopedDataHelper(new DefaultJcaJceExtHelper());
    private SecureRandom random;

    public JceCMSMacCalculatorBuilder(ASN1ObjectIdentifier macOID)
    {
        this(macOID, -1);
    }

    public JceCMSMacCalculatorBuilder(ASN1ObjectIdentifier macOID, int keySize)
    {
        this.macOID = macOID;
        this.keySize = keySize;
    }

    public JceCMSMacCalculatorBuilder setProvider(Provider provider)
    {
        this.helper = new EnvelopedDataHelper(new ProviderJcaJceExtHelper(provider));

        return this;
    }

    public JceCMSMacCalculatorBuilder setProvider(String providerName)
    {
        this.helper = new EnvelopedDataHelper(new NamedJcaJceExtHelper(providerName));

        return this;
    }

    public JceCMSMacCalculatorBuilder setSecureRandom(SecureRandom random)
    {
        this.random = random;

        return this;
    }

    public MacCalculator build()
        throws CMSException
    {
        return new CMSMacCalculator(macOID, keySize, random);
    }

    private class CMSMacCalculator
        implements MacCalculator
    {
        private SecretKey encKey;
        private AlgorithmIdentifier algorithmIdentifier;
        private Mac mac;
        private SecureRandom random;

        CMSMacCalculator(ASN1ObjectIdentifier macOID, int keySize, SecureRandom random)
            throws CMSException
        {
            KeyGenerator keyGen = helper.createKeyGenerator(macOID);

            if (random == null)
            {
                random = new SecureRandom();
            }

            this.random = random;

            if (keySize < 0)
            {
                keyGen.init(random);
            }
            else
            {
                keyGen.init(keySize, random);
            }

            encKey = keyGen.generateKey();

            AlgorithmParameterSpec paramSpec = generateParameterSpec(macOID, encKey);

            algorithmIdentifier = helper.getAlgorithmIdentifier(macOID, paramSpec);
            mac = helper.createContentMac(encKey, algorithmIdentifier);
        }

        public AlgorithmIdentifier getAlgorithmIdentifier()
        {
            return algorithmIdentifier;
        }

        public OutputStream getOutputStream()
        {
            return new MacOutputStream(mac);
        }

        public byte[] getMac()
        {
            return mac.doFinal();
        }

        public GenericKey getKey()
        {
            return new JceGenericKey(algorithmIdentifier, encKey);
        }

        protected AlgorithmParameterSpec generateParameterSpec(ASN1ObjectIdentifier macOID, SecretKey encKey)
            throws CMSException
        {
            try
            {
                if (macOID.equals(PKCSObjectIdentifiers.RC2_CBC))
                {
                    byte[] iv = new byte[8];

                    random.nextBytes(iv);

                    return new RC2ParameterSpec(encKey.getEncoded().length * 8, iv);
                }

                AlgorithmParameterGenerator pGen = helper.createAlgorithmParameterGenerator(macOID);

                AlgorithmParameters p = pGen.generateParameters();

                return p.getParameterSpec(IvParameterSpec.class);
            }
            catch (GeneralSecurityException e)
            {
                return null;
            }
        }
    }
}