org.bouncycastle.pqc.crypto.sphincs.Permute Maven / Gradle / Ivy
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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 1.4.
package org.bouncycastle.pqc.crypto.sphincs;
import org.bouncycastle.util.Pack;
class Permute
{
private static final int CHACHA_ROUNDS = 12;
protected static int rotl(int x, int y)
{
return (x << y) | (x >>> -y);
}
/**
* ChaCha core function
*/
public static void permute(int rounds, int[] x)
{
if (x.length != 16)
{
throw new IllegalArgumentException();
}
if (rounds % 2 != 0)
{
throw new IllegalArgumentException("Number of rounds must be even");
}
int x00 = x[ 0];
int x01 = x[ 1];
int x02 = x[ 2];
int x03 = x[ 3];
int x04 = x[ 4];
int x05 = x[ 5];
int x06 = x[ 6];
int x07 = x[ 7];
int x08 = x[ 8];
int x09 = x[ 9];
int x10 = x[10];
int x11 = x[11];
int x12 = x[12];
int x13 = x[13];
int x14 = x[14];
int x15 = x[15];
for (int i = rounds; i > 0; i -= 2)
{
x00 += x04; x12 = rotl(x12 ^ x00, 16);
x08 += x12; x04 = rotl(x04 ^ x08, 12);
x00 += x04; x12 = rotl(x12 ^ x00, 8);
x08 += x12; x04 = rotl(x04 ^ x08, 7);
x01 += x05; x13 = rotl(x13 ^ x01, 16);
x09 += x13; x05 = rotl(x05 ^ x09, 12);
x01 += x05; x13 = rotl(x13 ^ x01, 8);
x09 += x13; x05 = rotl(x05 ^ x09, 7);
x02 += x06; x14 = rotl(x14 ^ x02, 16);
x10 += x14; x06 = rotl(x06 ^ x10, 12);
x02 += x06; x14 = rotl(x14 ^ x02, 8);
x10 += x14; x06 = rotl(x06 ^ x10, 7);
x03 += x07; x15 = rotl(x15 ^ x03, 16);
x11 += x15; x07 = rotl(x07 ^ x11, 12);
x03 += x07; x15 = rotl(x15 ^ x03, 8);
x11 += x15; x07 = rotl(x07 ^ x11, 7);
x00 += x05; x15 = rotl(x15 ^ x00, 16);
x10 += x15; x05 = rotl(x05 ^ x10, 12);
x00 += x05; x15 = rotl(x15 ^ x00, 8);
x10 += x15; x05 = rotl(x05 ^ x10, 7);
x01 += x06; x12 = rotl(x12 ^ x01, 16);
x11 += x12; x06 = rotl(x06 ^ x11, 12);
x01 += x06; x12 = rotl(x12 ^ x01, 8);
x11 += x12; x06 = rotl(x06 ^ x11, 7);
x02 += x07; x13 = rotl(x13 ^ x02, 16);
x08 += x13; x07 = rotl(x07 ^ x08, 12);
x02 += x07; x13 = rotl(x13 ^ x02, 8);
x08 += x13; x07 = rotl(x07 ^ x08, 7);
x03 += x04; x14 = rotl(x14 ^ x03, 16);
x09 += x14; x04 = rotl(x04 ^ x09, 12);
x03 += x04; x14 = rotl(x14 ^ x03, 8);
x09 += x14; x04 = rotl(x04 ^ x09, 7);
}
x[ 0] = x00;
x[ 1] = x01;
x[ 2] = x02;
x[ 3] = x03;
x[ 4] = x04;
x[ 5] = x05;
x[ 6] = x06;
x[ 7] = x07;
x[ 8] = x08;
x[ 9] = x09;
x[10] = x10;
x[11] = x11;
x[12] = x12;
x[13] = x13;
x[14] = x14;
x[15] = x15;
}
void chacha_permute(byte[] out, byte[] in)
{
int i;
int[] x = new int[16];
for (i = 0; i < 16; i++)
{
x[i] = Pack.littleEndianToInt(in, 4 * i);
}
permute(CHACHA_ROUNDS, x);
// for (i = 0;i < 16;++i) x[i] = PLUS(x[i],input[i]); // XXX: Bad idea if we later xor the input to the state?
for (i = 0; i < 16; ++i)
{
Pack.intToLittleEndian(x[i], out, 4 * i);
}
}
}