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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.io.IOException;
import java.security.AccessController;
import java.security.AlgorithmParameters;
import java.security.GeneralSecurityException;
import java.security.PrivilegedAction;
import java.security.SecureRandom;

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;
import org.bouncycastle.util.Arrays;

/**
 * A basic wrapper for a JCE Cipher class to provide the needed AEAD cipher functionality for TLS.
 */
public class JceAEADCipherImpl
    implements TlsAEADCipherImpl
{
    @SuppressWarnings({ "rawtypes", "unchecked" })
    private static boolean checkForAEAD()
    {
        return (Boolean)AccessController.doPrivileged(new PrivilegedAction()
        {
            public Object 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 JcaTlsCrypto crypto;
    private final JcaJceHelper helper;
    private final int cipherMode;
    private final Cipher cipher;
    private final String algorithm;
    private final int keySize;
    private final String algorithmParamsName;

    private SecretKey key;
    private byte[]    nonce;
    private int       macSize;

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

    public void setKey(byte[] key, int keyOff, int keyLen)
    {
        if (keySize != keyLen)
        {
            throw new IllegalStateException();
        }

        this.key = new SecretKeySpec(key, keyOff, keyLen, algorithm);
    }

    public void init(byte[] nonce, int macSize)
    {
        // NOTE: Shouldn't need a SecureRandom, but this is cheaper if the provider would auto-create one
        SecureRandom random = crypto.getSecureRandom();

        try
        {
            if (canDoAEAD && algorithmParamsName != null)
            {
                AlgorithmParameters algParams = helper.createAlgorithmParameters(algorithmParamsName);

                // believe it or not but there are things out there that do not support the ASN.1 encoding...
                if (GCMUtil.isGCMParameterSpecAvailable())
                {
                    algParams.init(GCMUtil.createGCMParameterSpec(macSize * 8, nonce));
                }
                else
                {
                    // fortunately CCM and GCM parameters have the same ASN.1 structure
                    algParams.init(new GCMParameters(nonce, macSize).getEncoded());
                }

                cipher.init(cipherMode, key, algParams, random);
            }
            else
            {
                // Otherwise fall back to the BC-specific AEADParameterSpec
                cipher.init(cipherMode, key, new AEADParameterSpec(nonce, macSize * 8, null), random);
                this.nonce = Arrays.clone(nonce);
                this.macSize = macSize;
            }
        }
        catch (Exception e)
        {
            throw Exceptions.illegalStateException(e.getMessage(), e);
        }
    }

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

    public int doFinal(byte[] additionalData, byte[] input, int inputOffset, int inputLength, byte[] output, int outputOffset)
        throws IOException
    {
        if (!ArrayUtil.isNullOrEmpty(additionalData))
        {
            if (canDoAEAD)
            {
                cipher.updateAAD(additionalData);
            }
            else
            {
                try
                {
                    cipher.init(cipherMode, key, new AEADParameterSpec(nonce, macSize * 8, additionalData));
                }
                catch (Exception e)
                {
                    throw new IOException(e);
                }
            }
        }

        /*
         * NOTE: Some providers don't allow cipher update methods with AEAD decryption,
         * since they may return partial data that has not yet been authenticated. So we
         * make sure to use a single call for the whole record.
         */
        try
        {
            return cipher.doFinal(input, inputOffset, inputLength, output, outputOffset);
        }
        catch (GeneralSecurityException e)
        {
            throw Exceptions.illegalStateException("", e);
        }
    }
}