org.bouncycastle.tls.crypto.impl.jcajce.JceBlockCipherWithCBCImplicitIVImpl Maven / Gradle / Ivy

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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.GeneralSecurityException;
import java.security.SecureRandom;

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

import org.bouncycastle.tls.TlsUtils;
import org.bouncycastle.tls.crypto.impl.TlsBlockCipherImpl;

/**
 * A basic wrapper for a JCE Cipher class to provide the needed block cipher functionality for TLS where the
 * cipher requires the IV to be continued between calls.
 */
public class JceBlockCipherWithCBCImplicitIVImpl
    implements TlsBlockCipherImpl
{
    private static final int BUF_SIZE = 32 * 1024;

    private final JcaTlsCrypto crypto;
    private final Cipher cipher;
    private final String algorithm;
    private final int cipherMode;

    private SecretKey key;
    private byte[] nextIV;

    public JceBlockCipherWithCBCImplicitIVImpl(JcaTlsCrypto crypto, Cipher cipher, String algorithm,
        boolean isEncrypting)
        throws GeneralSecurityException
    {
        this.crypto = crypto;
        this.cipher = cipher;
        this.algorithm = algorithm;
        this.cipherMode = isEncrypting ? Cipher.ENCRYPT_MODE : Cipher.DECRYPT_MODE;
    }

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

    public void init(byte[] iv, int ivOff, int ivLen)
    {
        if (nextIV != null)
        {
            throw new IllegalStateException("unexpected reinitialization of an implicit-IV cipher");
        }

        nextIV = TlsUtils.copyOfRangeExact(iv, ivOff, ivOff + ivLen);
    }

    public int doFinal(byte[] input, int inputOffset, int inputLength, byte[] output, int outputOffset)
    {
        // NOTE: Shouldn't need a SecureRandom, but this is cheaper if the provider would auto-create one
        SecureRandom random = crypto.getSecureRandom();
        
        try
        {
            cipher.init(cipherMode, key, new IvParameterSpec(nextIV), random);

            nextIV = null;

            if (Cipher.ENCRYPT_MODE != cipherMode)
            {
                nextIV = TlsUtils.copyOfRangeExact(input, inputOffset + inputLength - cipher.getBlockSize(), inputOffset + inputLength);
            }

            // to avoid performance issue in FIPS jar  1.0.0-1.0.2
            int totLen = 0;
            while (inputLength > BUF_SIZE)
            {
                totLen += cipher.update(input, inputOffset, BUF_SIZE, output, outputOffset + totLen);

                inputOffset += BUF_SIZE;
                inputLength -= BUF_SIZE;
            }

            totLen += cipher.update(input, inputOffset, inputLength, output, outputOffset + totLen);
            totLen += cipher.doFinal(output, outputOffset + totLen);

            if (Cipher.ENCRYPT_MODE == cipherMode)
            {
                nextIV = TlsUtils.copyOfRangeExact(output, outputOffset + totLen - cipher.getBlockSize(), outputOffset + totLen);
            }

            return totLen;
        }
        catch (GeneralSecurityException e)
        {
            throw Exceptions.illegalStateException(e.getMessage(), e);
        }
    }

    public int getBlockSize()
    {
        return cipher.getBlockSize();
    }
}