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The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.8.
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package org.bouncycastle.crypto.engines;
import java.io.ByteArrayOutputStream;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.CryptoServicesRegistrar;
import org.bouncycastle.crypto.DataLengthException;
import org.bouncycastle.crypto.InvalidCipherTextException;
import org.bouncycastle.crypto.OutputLengthException;
import org.bouncycastle.crypto.constraints.DefaultServiceProperties;
import org.bouncycastle.crypto.modes.AEADCipher;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.crypto.params.ParametersWithIV;
import org.bouncycastle.util.Pack;
/**
* Grain-128 AEAD, based on the current round 3 submission, https://grain-128aead.github.io/
*/
public class Grain128AEADEngine
implements AEADCipher
{
/**
* Constants
*/
private static final int STATE_SIZE = 4;
/**
* Variables to hold the state of the engine during encryption and
* decryption
*/
private byte[] workingKey;
private byte[] workingIV;
private int[] lfsr;
private int[] nfsr;
private int[] authAcc;
private int[] authSr;
private boolean initialised = false;
private boolean aadFinished = false;
private ErasableOutputStream aadData = new ErasableOutputStream();
private byte[] mac;
public String getAlgorithmName()
{
return "Grain-128AEAD";
}
/**
* Initialize a Grain-128AEAD cipher.
*
* @param forEncryption Whether or not we are for encryption.
* @param params The parameters required to set up the cipher.
* @throws IllegalArgumentException If the params argument is inappropriate.
*/
public void init(boolean forEncryption, CipherParameters params)
throws IllegalArgumentException
{
/*
* Grain encryption and decryption is completely symmetrical, so the
* 'forEncryption' is irrelevant.
*/
if (!(params instanceof ParametersWithIV))
{
throw new IllegalArgumentException(
"Grain-128AEAD init parameters must include an IV");
}
ParametersWithIV ivParams = (ParametersWithIV)params;
byte[] iv = ivParams.getIV();
if (iv == null || iv.length != 12)
{
throw new IllegalArgumentException(
"Grain-128AEAD requires exactly 12 bytes of IV");
}
if (!(ivParams.getParameters() instanceof KeyParameter))
{
throw new IllegalArgumentException(
"Grain-128AEAD init parameters must include a key");
}
KeyParameter key = (KeyParameter)ivParams.getParameters();
byte[] keyBytes = key.getKey();
if (keyBytes.length != 16)
{
throw new IllegalArgumentException(
"Grain-128AEAD key must be 128 bits long");
}
CryptoServicesRegistrar.checkConstraints(new DefaultServiceProperties(
this.getAlgorithmName(), 128, params, Utils.getPurpose(forEncryption)));
/*
* Initialize variables.
*/
workingIV = new byte[16];
workingKey = new byte[16];
lfsr = new int[STATE_SIZE];
nfsr = new int[STATE_SIZE];
authAcc = new int[2];
authSr = new int[2];
System.arraycopy(iv, 0, workingIV, 0, iv.length);
System.arraycopy(keyBytes, 0, workingKey, 0, keyBytes.length);
reset();
}
/**
* 320 clocks initialization phase.
*/
private void initGrain()
{
for (int i = 0; i < 320; ++i)
{
int output = getOutput();
nfsr = shift(nfsr, (getOutputNFSR() ^ lfsr[0] ^ output) & 1);
lfsr = shift(lfsr, (getOutputLFSR() ^ output) & 1);
}
for (int quotient = 0; quotient < 8; ++quotient)
{
for (int remainder = 0; remainder < 8; ++remainder)
{
int output = getOutput();
nfsr = shift(nfsr, (getOutputNFSR() ^ lfsr[0] ^ output ^ ((workingKey[quotient]) >> remainder)) & 1);
lfsr = shift(lfsr, (getOutputLFSR() ^ output ^ ((workingKey[quotient + 8]) >> remainder)) & 1);
}
}
for (int quotient = 0; quotient < 2; ++quotient)
{
for (int remainder = 0; remainder < 32; ++remainder)
{
int output = getOutput();
nfsr = shift(nfsr, (getOutputNFSR() ^ lfsr[0]) & 1);
lfsr = shift(lfsr, (getOutputLFSR()) & 1);
authAcc[quotient] |= output << remainder;
}
}
for (int quotient = 0; quotient < 2; ++quotient)
{
for (int remainder = 0; remainder < 32; ++remainder)
{
int output = getOutput();
nfsr = shift(nfsr, (getOutputNFSR() ^ lfsr[0]) & 1);
lfsr = shift(lfsr, (getOutputLFSR()) & 1);
authSr[quotient] |= output << remainder;
}
}
initialised = true;
}
/**
* Get output from non-linear function g(x).
*
* @return Output from NFSR.
*/
private int getOutputNFSR()
{
int b0 = nfsr[0];
int b3 = nfsr[0] >>> 3;
int b11 = nfsr[0] >>> 11;
int b13 = nfsr[0] >>> 13;
int b17 = nfsr[0] >>> 17;
int b18 = nfsr[0] >>> 18;
int b22 = nfsr[0] >>> 22;
int b24 = nfsr[0] >>> 24;
int b25 = nfsr[0] >>> 25;
int b26 = nfsr[0] >>> 26;
int b27 = nfsr[0] >>> 27;
int b40 = nfsr[1] >>> 8;
int b48 = nfsr[1] >>> 16;
int b56 = nfsr[1] >>> 24;
int b59 = nfsr[1] >>> 27;
int b61 = nfsr[1] >>> 29;
int b65 = nfsr[2] >>> 1;
int b67 = nfsr[2] >>> 3;
int b68 = nfsr[2] >>> 4;
int b70 = nfsr[2] >>> 6;
int b78 = nfsr[2] >>> 14;
int b82 = nfsr[2] >>> 18;
int b84 = nfsr[2] >>> 20;
int b88 = nfsr[2] >>> 24;
int b91 = nfsr[2] >>> 27;
int b92 = nfsr[2] >>> 28;
int b93 = nfsr[2] >>> 29;
int b95 = nfsr[2] >>> 31;
int b96 = nfsr[3];
return (b0 ^ b26 ^ b56 ^ b91 ^ b96 ^ b3 & b67 ^ b11 & b13 ^ b17 & b18
^ b27 & b59 ^ b40 & b48 ^ b61 & b65 ^ b68 & b84 ^ b22 & b24 & b25 ^ b70 & b78 & b82 ^ b88 & b92 & b93 & b95) & 1;
}
/**
* Get output from linear function f(x).
*
* @return Output from LFSR.
*/
private int getOutputLFSR()
{
int s0 = lfsr[0];
int s7 = lfsr[0] >>> 7;
int s38 = lfsr[1] >>> 6;
int s70 = lfsr[2] >>> 6;
int s81 = lfsr[2] >>> 17;
int s96 = lfsr[3];
return (s0 ^ s7 ^ s38 ^ s70 ^ s81 ^ s96) & 1;
}
/**
* Get output from output function h(x).
*
* @return y_t.
*/
private int getOutput()
{
int b2 = nfsr[0] >>> 2;
int b12 = nfsr[0] >>> 12;
int b15 = nfsr[0] >>> 15;
int b36 = nfsr[1] >>> 4;
int b45 = nfsr[1] >>> 13;
int b64 = nfsr[2];
int b73 = nfsr[2] >>> 9;
int b89 = nfsr[2] >>> 25;
int b95 = nfsr[2] >>> 31;
int s8 = lfsr[0] >>> 8;
int s13 = lfsr[0] >>> 13;
int s20 = lfsr[0] >>> 20;
int s42 = lfsr[1] >>> 10;
int s60 = lfsr[1] >>> 28;
int s79 = lfsr[2] >>> 15;
int s93 = lfsr[2] >>> 29;
int s94 = lfsr[2] >>> 30;
return ((b12 & s8) ^ (s13 & s20) ^ (b95 & s42) ^ (s60 & s79) ^ (b12 & b95 & s94) ^ s93
^ b2 ^ b15 ^ b36 ^ b45 ^ b64 ^ b73 ^ b89) & 1;
}
/**
* Shift array 1 bit and add val to index.length - 1.
*
* @param array The array to shift.
* @param val The value to shift in.
* @return The shifted array with val added to index.length - 1.
*/
private int[] shift(int[] array, int val)
{
array[0] = (array[0] >>> 1) | (array[1] << 31);
array[1] = (array[1] >>> 1) | (array[2] << 31);
array[2] = (array[2] >>> 1) | (array[3] << 31);
array[3] = (array[3] >>> 1) | (val << 31);
return array;
}
/**
* Set keys, reset cipher.
*
* @param keyBytes The key.
* @param ivBytes The IV.
*/
private void setKey(byte[] keyBytes, byte[] ivBytes)
{
ivBytes[12] = (byte)0xFF;
ivBytes[13] = (byte)0xFF;
ivBytes[14] = (byte)0xFF;
ivBytes[15] = (byte)0x7F;
workingKey = keyBytes;
workingIV = ivBytes;
/*
* Load NFSR and LFSR
*/
Pack.littleEndianToInt(workingKey, 0, nfsr);
Pack.littleEndianToInt(workingIV, 0, lfsr);
}
public int processBytes(byte[] input, int inOff, int len, byte[] output, int outOff)
throws DataLengthException
{
if (!initialised)
{
throw new IllegalStateException(getAlgorithmName() + " not initialised");
}
if (!aadFinished)
{
doProcessAADBytes(aadData.getBuf(), 0, aadData.size());
aadFinished = true;
}
if ((inOff + len) > input.length)
{
throw new DataLengthException("input buffer too short");
}
if ((outOff + len) > output.length)
{
throw new OutputLengthException("output buffer too short");
}
getKeyStream(input, inOff, len, output, outOff);
return len;
}
public void reset()
{
reset(true);
}
private void reset(boolean clearMac)
{
if (clearMac)
{
this.mac = null;
}
this.aadData.reset();
this.aadFinished = false;
setKey(workingKey, workingIV);
initGrain();
}
private byte[] getKeyStream(byte[] input, int inOff, int len, byte[] ciphertext, int outOff)
{
for (int i = 0; i < len; ++i)
{
byte cc = 0, input_i = input[inOff + i];
for (int j = 0; j < 8; ++j)
{
int output = getOutput();
nfsr = shift(nfsr, (getOutputNFSR() ^ lfsr[0]) & 1);
lfsr = shift(lfsr, (getOutputLFSR()) & 1);
int input_i_j = (input_i >> j) & 1;
cc |= (input_i_j ^ output) << j;
// if (input_i_j != 0)
// {
// accumulate();
// }
int mask = -input_i_j;
authAcc[0] ^= authSr[0] & mask;
authAcc[1] ^= authSr[1] & mask;
authShift(getOutput());
nfsr = shift(nfsr, (getOutputNFSR() ^ lfsr[0]) & 1);
lfsr = shift(lfsr, (getOutputLFSR()) & 1);
}
ciphertext[outOff + i] = cc;
}
return ciphertext;
}
public void processAADByte(byte in)
{
if (aadFinished)
{
throw new IllegalStateException("associated data must be added before plaintext/ciphertext");
}
aadData.write(in);
}
public void processAADBytes(byte[] input, int inOff, int len)
{
if (aadFinished)
{
throw new IllegalStateException("associated data must be added before plaintext/ciphertext");
}
aadData.write(input, inOff, len);
}
private void doProcessAADBytes(byte[] input, int inOff, int len)
{
byte[] ader;
int aderlen;
//encodeDer
if (len < 128)
{
ader = new byte[1 + len];
ader[0] = (byte)len;
aderlen = 0;
}
else
{
// aderlen is the highest bit position divided by 8
aderlen = len_length(len);
ader = new byte[1 + aderlen + len];
ader[0] = (byte)(0x80 | aderlen);
int tmp = len;
for (int i = 0; i < aderlen; ++i)
{
ader[1 + i] = (byte)tmp;
tmp >>>= 8;
}
}
for (int i = 0; i < len; ++i)
{
ader[1 + aderlen + i] = input[inOff + i];
}
for (int i = 0; i < ader.length; ++i)
{
byte ader_i = ader[i];
for (int j = 0; j < 8; ++j)
{
nfsr = shift(nfsr, (getOutputNFSR() ^ lfsr[0]) & 1);
lfsr = shift(lfsr, (getOutputLFSR()) & 1);
int ader_i_j = (ader_i >> j) & 1;
// if (ader_i_j != 0)
// {
// accumulate();
// }
int mask = -ader_i_j;
authAcc[0] ^= authSr[0] & mask;
authAcc[1] ^= authSr[1] & mask;
authShift(getOutput());
nfsr = shift(nfsr, (getOutputNFSR() ^ lfsr[0]) & 1);
lfsr = shift(lfsr, (getOutputLFSR()) & 1);
}
}
}
private void accumulate()
{
authAcc[0] ^= authSr[0];
authAcc[1] ^= authSr[1];
}
private void authShift(int val)
{
authSr[0] = (authSr[0] >>> 1) | (authSr[1] << 31);
authSr[1] = (authSr[1] >>> 1) | (val << 31);
}
public int processByte(byte input, byte[] output, int outOff)
throws DataLengthException
{
return processBytes(new byte[]{input}, 0, 1, output, outOff);
}
public int doFinal(byte[] out, int outOff)
throws IllegalStateException, InvalidCipherTextException
{
if (!aadFinished)
{
doProcessAADBytes(aadData.getBuf(), 0, aadData.size());
aadFinished = true;
}
accumulate();
this.mac = Pack.intToLittleEndian(authAcc);
System.arraycopy(mac, 0, out, outOff, mac.length);
reset(false);
return mac.length;
}
public byte[] getMac()
{
return mac;
}
public int getUpdateOutputSize(int len)
{
return len;
}
public int getOutputSize(int len)
{
//the last 8 bytes are from AD
return len + 8;
}
private static int len_length(int v)
{
if ((v & 0xff) == v)
{
return 1;
}
if ((v & 0xffff) == v)
{
return 2;
}
if ((v & 0xffffff) == v)
{
return 3;
}
return 4;
}
private static final class ErasableOutputStream
extends ByteArrayOutputStream
{
public ErasableOutputStream()
{
}
public byte[] getBuf()
{
return buf;
}
// public void erase()
// {
// Arrays.fill(this.buf, (byte)0);
// // this for JVM compatibility
// this.reset();
// }
}
}
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