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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;

import java.io.IOException;

import org.bouncycastle.tls.AlertDescription;
import org.bouncycastle.tls.TlsFatalAlert;
import org.bouncycastle.tls.TlsUtils;
import org.bouncycastle.tls.crypto.TlsCipher;
import org.bouncycastle.tls.crypto.TlsCryptoParameters;
import org.bouncycastle.util.Arrays;

/**
 * A generic TLS 1.2 AEAD cipher.
 */
public class TlsAEADCipher
    implements TlsCipher
{
    // TODO[draft-zauner-tls-aes-ocb-04] Apply data volume limit described in section 8.4

    public static final int NONCE_RFC5288 = 1;
    public static final int NONCE_RFC7905 = 2;
    
    public static final byte[] EPOCH_1 = {0x00, 0x01};

    private static Class fipsNonceGeneratorClass = lookup("org.bouncycastle.crypto.fips.FipsNonceGenerator");

    protected final TlsCryptoParameters cryptoParams;
    protected final int macSize;
    // TODO SecurityParameters.record_iv_length
    protected final int record_iv_length;

    protected final TlsAEADCipherImpl decryptCipher, encryptCipher;

    protected final byte[] encryptImplicitNonce, decryptImplicitNonce;

    protected final int nonceMode;
    protected final AEADNonceGenerator encryptNonceGenerator;

    public TlsAEADCipher(TlsCryptoParameters cryptoParams, TlsAEADCipherImpl encryptCipher, TlsAEADCipherImpl decryptCipher,
                         int cipherKeySize, int macSize)
        throws IOException
    {
        this(cryptoParams, encryptCipher, decryptCipher, cipherKeySize, macSize, NONCE_RFC5288);
    }

    public TlsAEADCipher(TlsCryptoParameters cryptoParams, TlsAEADCipherImpl encryptCipher, TlsAEADCipherImpl decryptCipher,
                         int cipherKeySize, int macSize, int nonceMode)
        throws IOException
    {
        if (!TlsImplUtils.isTLSv12(cryptoParams))
        {
            throw new TlsFatalAlert(AlertDescription.internal_error);
        }

        this.nonceMode = nonceMode;

        // TODO SecurityParameters.fixed_iv_length
        int fixed_iv_length;

        switch (nonceMode)
        {
        case NONCE_RFC5288:
            fixed_iv_length = 4;
            this.record_iv_length = 8;
            break;
        case NONCE_RFC7905:
            fixed_iv_length = 12;
            this.record_iv_length = 0;
            break;
        default:
            throw new TlsFatalAlert(AlertDescription.internal_error);
        }

        this.cryptoParams = cryptoParams;
        this.macSize = macSize;

        this.encryptCipher = encryptCipher;
        this.decryptCipher = decryptCipher;

        TlsAEADCipherImpl clientCipher, serverCipher;
        if (cryptoParams.isServer())
        {
            clientCipher = decryptCipher;
            serverCipher = encryptCipher;
        }
        else
        {
            clientCipher = encryptCipher;
            serverCipher = decryptCipher;
        }

        int key_block_size = (2 * cipherKeySize) + (2 * fixed_iv_length);

        byte[] key_block = TlsImplUtils.calculateKeyBlock(cryptoParams, key_block_size);

        int offset = 0;

        clientCipher.setKey(key_block, offset, cipherKeySize);
        offset += cipherKeySize;
        serverCipher.setKey(key_block, offset, cipherKeySize);
        offset += cipherKeySize;

        byte[] client_write_IV = Arrays.copyOfRange(key_block, offset, offset + fixed_iv_length);
        offset += fixed_iv_length;
        byte[] server_write_IV = Arrays.copyOfRange(key_block, offset, offset + fixed_iv_length);
        offset += fixed_iv_length;

        if (offset != key_block_size)
        {
            throw new TlsFatalAlert(AlertDescription.internal_error);
        }

        if (cryptoParams.isServer())
        {
            this.encryptImplicitNonce = server_write_IV;
            this.decryptImplicitNonce = client_write_IV;
        }
        else
        {
            this.encryptImplicitNonce = client_write_IV;
            this.decryptImplicitNonce = server_write_IV;
        }

        byte[] dummyNonce = new byte[fixed_iv_length + record_iv_length];

        this.encryptCipher.init(dummyNonce, macSize, null);
        this.decryptCipher.init(dummyNonce, macSize, null);

        if (fipsNonceGeneratorClass != null)
        {
            if (cryptoParams.getServerVersion().isDTLS())
            {
                this.encryptNonceGenerator = new BCFipsAEADNonceGenerator(Arrays.clone(EPOCH_1), 48);
            }
            else
            {
                this.encryptNonceGenerator = new BCFipsAEADNonceGenerator(64);
            }
        }
        else
        {
            this.encryptNonceGenerator = null;
        }
    }

    public int getCiphertextLimit(int plaintextLimit)
    {
        return plaintextLimit + macSize + record_iv_length;
    }

    public int getPlaintextLimit(int ciphertextLimit)
    {
        // TODO We ought to be able to ask the decryptCipher (independently of it's current state!)
        return ciphertextLimit - macSize - record_iv_length;
    }

    public byte[] encodePlaintext(long seqNo, short type, byte[] plaintext, int offset, int len)
        throws IOException
    {
        byte[] nonce = new byte[encryptImplicitNonce.length + record_iv_length];

        switch (nonceMode)
        {
        case NONCE_RFC5288:

            System.arraycopy(encryptImplicitNonce, 0, nonce, 0, encryptImplicitNonce.length);

            if (encryptNonceGenerator != null)
            {
                encryptNonceGenerator.generateNonce(nonce, encryptImplicitNonce.length);
            }
            else
            {
                // RFC 5288/6655: The nonce_explicit MAY be the 64-bit sequence number.
                TlsUtils.writeUint64(seqNo, nonce, encryptImplicitNonce.length);
            }

            break;
        case NONCE_RFC7905:
            TlsUtils.writeUint64(seqNo, nonce, nonce.length - 8);
            for (int i = 0; i < encryptImplicitNonce.length; ++i)
            {
                nonce[i] ^= encryptImplicitNonce[i];
            }
            break;
        default:
            throw new TlsFatalAlert(AlertDescription.internal_error);
        }

        int plaintextOffset = offset;
        int plaintextLength = len;
        int ciphertextLength = encryptCipher.getOutputSize(plaintextLength);

        byte[] output = new byte[record_iv_length + ciphertextLength];
        if (record_iv_length != 0)
        {
            System.arraycopy(nonce, nonce.length - record_iv_length, output, 0, record_iv_length);
        }
        int outputPos = record_iv_length;

        byte[] additionalData = getAdditionalData(seqNo, type, plaintextLength);

        try
        {
            encryptCipher.init(nonce, macSize, additionalData);
            outputPos += encryptCipher.doFinal(plaintext, plaintextOffset, plaintextLength, output, outputPos);
        }
        catch (Exception e)
        {
            throw new TlsFatalAlert(AlertDescription.internal_error, e);
        }

        if (outputPos != output.length)
        {
            // NOTE: Existing AEAD cipher implementations all give exact output lengths
            throw new TlsFatalAlert(AlertDescription.internal_error);
        }

        return output;
    }

    public byte[] decodeCiphertext(long seqNo, short type, byte[] ciphertext, int offset, int len)
        throws IOException
    {
        if (getPlaintextLimit(len) < 0)
        {
            throw new TlsFatalAlert(AlertDescription.decode_error);
        }

        byte[] nonce = new byte[decryptImplicitNonce.length + record_iv_length];

        switch (nonceMode)
        {
        case NONCE_RFC5288:
            System.arraycopy(decryptImplicitNonce, 0, nonce, 0, decryptImplicitNonce.length);
            System.arraycopy(ciphertext, offset, nonce, nonce.length - record_iv_length, record_iv_length);
            break;
        case NONCE_RFC7905:
            TlsUtils.writeUint64(seqNo, nonce, nonce.length - 8);
            for (int i = 0; i < decryptImplicitNonce.length; ++i)
            {
                nonce[i] ^= decryptImplicitNonce[i];
            }
            break;
        default:
            throw new TlsFatalAlert(AlertDescription.internal_error);
        }

        int ciphertextOffset = offset + record_iv_length;
        int ciphertextLength = len - record_iv_length;
        int plaintextLength = decryptCipher.getOutputSize(ciphertextLength);

        byte[] output = new byte[plaintextLength];
        int outputPos = 0;

        byte[] additionalData = getAdditionalData(seqNo, type, plaintextLength);

        try
        {
            decryptCipher.init(nonce, macSize, additionalData);
            outputPos += decryptCipher.doFinal(ciphertext, ciphertextOffset, ciphertextLength, output, outputPos);
        }
        catch (Exception e)
        {
            throw new TlsFatalAlert(AlertDescription.bad_record_mac, e);
        }

        if (outputPos != output.length)
        {
            // NOTE: Existing AEAD cipher implementations all give exact output lengths
            throw new TlsFatalAlert(AlertDescription.internal_error);
        }

        return output;
    }

    protected byte[] getAdditionalData(long seqNo, short type, int len)
        throws IOException
    {
        /*
         * additional_data = seq_num + TLSCompressed.type + TLSCompressed.version +
         * TLSCompressed.length
         */

        byte[] additional_data = new byte[13];
        TlsUtils.writeUint64(seqNo, additional_data, 0);
        TlsUtils.writeUint8(type, additional_data, 8);
        TlsUtils.writeVersion(cryptoParams.getServerVersion(), additional_data, 9);
        TlsUtils.writeUint16(len, additional_data, 11);

        return additional_data;
    }

    private static Class lookup(String className)
    {
        try
        {
            Class def = TlsAEADCipher.class.getClassLoader().loadClass(className);

            return def;
        }
        catch (Exception e)
        {
            return null;
        }
    }
}