package org.spongycastle.crypto.macs;
import org.spongycastle.crypto.CipherParameters;
import org.spongycastle.crypto.DataLengthException;
import org.spongycastle.crypto.Mac;
import org.spongycastle.crypto.params.KeyParameter;
import org.spongycastle.crypto.params.ParametersWithSBox;
/**
* implementation of GOST 28147-89 MAC
*/
public class GOST28147Mac
implements Mac
{
private int blockSize = 8;
private int macSize = 4;
private int bufOff;
private byte[] buf;
private byte[] mac;
private boolean firstStep = true;
private int[] workingKey = null;
//
// This is default S-box - E_A.
private byte S[] = {
0x9,0x6,0x3,0x2,0x8,0xB,0x1,0x7,0xA,0x4,0xE,0xF,0xC,0x0,0xD,0x5,
0x3,0x7,0xE,0x9,0x8,0xA,0xF,0x0,0x5,0x2,0x6,0xC,0xB,0x4,0xD,0x1,
0xE,0x4,0x6,0x2,0xB,0x3,0xD,0x8,0xC,0xF,0x5,0xA,0x0,0x7,0x1,0x9,
0xE,0x7,0xA,0xC,0xD,0x1,0x3,0x9,0x0,0x2,0xB,0x4,0xF,0x8,0x5,0x6,
0xB,0x5,0x1,0x9,0x8,0xD,0xF,0x0,0xE,0x4,0x2,0x3,0xC,0x7,0xA,0x6,
0x3,0xA,0xD,0xC,0x1,0x2,0x0,0xB,0x7,0x5,0x9,0x4,0x8,0xF,0xE,0x6,
0x1,0xD,0x2,0x9,0x7,0xA,0x6,0x0,0x8,0xC,0x4,0x5,0xF,0x3,0xB,0xE,
0xB,0xA,0xF,0x5,0x0,0xC,0xE,0x8,0x6,0x2,0x3,0x9,0x1,0x7,0xD,0x4
};
public GOST28147Mac()
{
mac = new byte[blockSize];
buf = new byte[blockSize];
bufOff = 0;
}
private int[] generateWorkingKey(
byte[] userKey)
{
if (userKey.length != 32)
{
throw new IllegalArgumentException("Key length invalid. Key needs to be 32 byte - 256 bit!!!");
}
int key[] = new int[8];
for(int i=0; i!=8; i++)
{
key[i] = bytesToint(userKey,i*4);
}
return key;
}
public void init(
CipherParameters params)
throws IllegalArgumentException
{
reset();
buf = new byte[blockSize];
if (params instanceof ParametersWithSBox)
{
ParametersWithSBox param = (ParametersWithSBox)params;
//
// Set the S-Box
//
System.arraycopy(param.getSBox(), 0, this.S, 0, param.getSBox().length);
//
// set key if there is one
//
if (param.getParameters() != null)
{
workingKey = generateWorkingKey(((KeyParameter)param.getParameters()).getKey());
}
}
else if (params instanceof KeyParameter)
{
workingKey = generateWorkingKey(((KeyParameter)params).getKey());
}
else
{
throw new IllegalArgumentException("invalid parameter passed to GOST28147 init - " + params.getClass().getName());
}
}
public String getAlgorithmName()
{
return "GOST28147Mac";
}
public int getMacSize()
{
return macSize;
}
private int gost28147_mainStep(int n1, int key)
{
int cm = (key + n1); // CM1
// S-box replacing
int om = S[ 0 + ((cm >> (0 * 4)) & 0xF)] << (0 * 4);
om += S[ 16 + ((cm >> (1 * 4)) & 0xF)] << (1 * 4);
om += S[ 32 + ((cm >> (2 * 4)) & 0xF)] << (2 * 4);
om += S[ 48 + ((cm >> (3 * 4)) & 0xF)] << (3 * 4);
om += S[ 64 + ((cm >> (4 * 4)) & 0xF)] << (4 * 4);
om += S[ 80 + ((cm >> (5 * 4)) & 0xF)] << (5 * 4);
om += S[ 96 + ((cm >> (6 * 4)) & 0xF)] << (6 * 4);
om += S[112 + ((cm >> (7 * 4)) & 0xF)] << (7 * 4);
return om << 11 | om >>> (32-11); // 11-leftshift
}
private void gost28147MacFunc(
int[] workingKey,
byte[] in,
int inOff,
byte[] out,
int outOff)
{
int N1, N2, tmp; //tmp -> for saving N1
N1 = bytesToint(in, inOff);
N2 = bytesToint(in, inOff + 4);
for(int k = 0; k < 2; k++) // 1-16 steps
{
for(int j = 0; j < 8; j++)
{
tmp = N1;
N1 = N2 ^ gost28147_mainStep(N1, workingKey[j]); // CM2
N2 = tmp;
}
}
intTobytes(N1, out, outOff);
intTobytes(N2, out, outOff + 4);
}
//array of bytes to type int
private int bytesToint(
byte[] in,
int inOff)
{
return ((in[inOff + 3] << 24) & 0xff000000) + ((in[inOff + 2] << 16) & 0xff0000) +
((in[inOff + 1] << 8) & 0xff00) + (in[inOff] & 0xff);
}
//int to array of bytes
private void intTobytes(
int num,
byte[] out,
int outOff)
{
out[outOff + 3] = (byte)(num >>> 24);
out[outOff + 2] = (byte)(num >>> 16);
out[outOff + 1] = (byte)(num >>> 8);
out[outOff] = (byte)num;
}
private byte[] CM5func(byte[] buf, int bufOff, byte[] mac)
{
byte[] sum = new byte[buf.length - bufOff];
System.arraycopy(buf, bufOff, sum, 0, mac.length);
for (int i = 0; i != mac.length; i++)
{
sum[i] = (byte)(sum[i] ^ mac[i]);
}
return sum;
}
public void update(byte in)
throws IllegalStateException
{
if (bufOff == buf.length)
{
byte[] sumbuf = new byte[buf.length];
System.arraycopy(buf, 0, sumbuf, 0, mac.length);
if (firstStep)
{
firstStep = false;
}
else
{
sumbuf = CM5func(buf, 0, mac);
}
gost28147MacFunc(workingKey, sumbuf, 0, mac, 0);
bufOff = 0;
}
buf[bufOff++] = in;
}
public void update(byte[] in, int inOff, int len)
throws DataLengthException, IllegalStateException
{
if (len < 0)
{
throw new IllegalArgumentException("Can't have a negative input length!");
}
int gapLen = blockSize - bufOff;
if (len > gapLen)
{
System.arraycopy(in, inOff, buf, bufOff, gapLen);
byte[] sumbuf = new byte[buf.length];
System.arraycopy(buf, 0, sumbuf, 0, mac.length);
if (firstStep)
{
firstStep = false;
}
else
{
sumbuf = CM5func(buf, 0, mac);
}
gost28147MacFunc(workingKey, sumbuf, 0, mac, 0);
bufOff = 0;
len -= gapLen;
inOff += gapLen;
while (len > blockSize)
{
sumbuf = CM5func(in, inOff, mac);
gost28147MacFunc(workingKey, sumbuf, 0, mac, 0);
len -= blockSize;
inOff += blockSize;
}
}
System.arraycopy(in, inOff, buf, bufOff, len);
bufOff += len;
}
public int doFinal(byte[] out, int outOff)
throws DataLengthException, IllegalStateException
{
//padding with zero
while (bufOff < blockSize)
{
buf[bufOff] = 0;
bufOff++;
}
byte[] sumbuf = new byte[buf.length];
System.arraycopy(buf, 0, sumbuf, 0, mac.length);
if (firstStep)
{
firstStep = false;
}
else
{
sumbuf = CM5func(buf, 0, mac);
}
gost28147MacFunc(workingKey, sumbuf, 0, mac, 0);
System.arraycopy(mac, (mac.length/2)-macSize, out, outOff, macSize);
reset();
return macSize;
}
public void reset()
{
/*
* clean the buffer.
*/
for (int i = 0; i < buf.length; i++)
{
buf[i] = 0;
}
bufOff = 0;
firstStep = true;
}
}