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The Bouncy Castle Java APIs for the TLS, including a JSSE provider. The APIs are designed primarily to be used in conjunction with the BC FIPS provider. The APIs may also be used with other providers although if being used in a FIPS context it is the responsibility of the user to ensure that any other providers used are FIPS certified and used appropriately.

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package org.bouncycastle.tls.crypto.impl.jcajce;

import java.security.AccessController;
import java.security.AlgorithmParameters;
import java.security.GeneralSecurityException;
import java.security.PrivilegedAction;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import org.bouncycastle.asn1.cms.GCMParameters;
import org.bouncycastle.jcajce.spec.AEADParameterSpec;
import org.bouncycastle.jcajce.util.JcaJceHelper;
import org.bouncycastle.tls.crypto.impl.TlsAEADCipherImpl;

/**
 * A basic wrapper for a JCE Cipher class to provide the needed AEAD cipher functionality for TLS.
 */
public class JceAEADCipherImpl
    implements TlsAEADCipherImpl
{
    private static boolean checkForAEAD()
    {
        return AccessController.doPrivileged(new PrivilegedAction()
        {
            @Override
            public Boolean run()
            {
                try
                {
                    return Cipher.class.getMethod("updateAAD", byte[].class) != null;
                }
                catch (Exception ignore)
                {
                    // TODO[logging] Log the fact that we are falling back to BC-specific class
                    return Boolean.FALSE;
                }
            }
        });
    }

    private static final boolean canDoAEAD = checkForAEAD();

    private static String getAlgParamsName(JcaJceHelper helper, String cipherName)
    {
        try
        {
            String algName = cipherName.contains("CCM") ? "CCM" : "GCM";
            helper.createAlgorithmParameters(algName);
            return algName;
        }
        catch (Exception e)
        {
            return null;
        }
    }

    private final JcaJceHelper helper;
    private final int cipherMode;
    private final Cipher cipher;
    private final String algorithm;
    private final String algorithmParamsName;

    private SecretKey key;

    public JceAEADCipherImpl(JcaJceHelper helper, String cipherName, String algorithm, boolean isEncrypting)
        throws GeneralSecurityException
    {
        this.helper = helper;
        this.cipher = helper.createCipher(cipherName);
        this.algorithm = algorithm;
        this.cipherMode = (isEncrypting) ? Cipher.ENCRYPT_MODE : Cipher.DECRYPT_MODE;
        this.algorithmParamsName = getAlgParamsName(helper, cipherName);
    }

    public void setKey(byte[] key, int keyOff, int keyLen)
    {
        this.key = new SecretKeySpec(key, keyOff, keyLen, algorithm);
    }

    public void init(byte[] nonce, int macSize, byte[] additionalData)
    {
        try
        {
            if (canDoAEAD && algorithmParamsName != null)
            {
                AlgorithmParameters algParams = helper.createAlgorithmParameters(algorithmParamsName);

                // fortunately CCM and GCM parameters have the same ASN.1 structure
                algParams.init(new GCMParameters(nonce, macSize).getEncoded());

                cipher.init(cipherMode, key, algParams);

                if (additionalData != null && additionalData.length > 0)
                {
                    cipher.updateAAD(additionalData);
                }
            }
            else
            {
                // Otherwise fall back to the BC-specific AEADParameterSpec
                cipher.init(cipherMode, key, new AEADParameterSpec(nonce, macSize * 8, additionalData));
            }
        }
        catch (Exception e)
        {
            throw new IllegalStateException(e.getMessage(), e);
        }
    }

    public int getOutputSize(int inputLength)
    {
        return cipher.getOutputSize(inputLength);
    }

    public int doFinal(byte[] input, int inputOffset, int inputLength, byte[] output, int outputOffset)
    {
        try
        {
            return cipher.doFinal(input, inputOffset, inputLength, output, outputOffset);
        }
        catch (GeneralSecurityException e)
        {
            throw new IllegalStateException(e);
        }
    }
}