io.gatling.recorder.internal.bouncycastle.pqc.crypto.crystals.kyber.CBD Maven / Gradle / Ivy
package io.gatling.recorder.internal.bouncycastle.pqc.crypto.crystals.kyber;
final class CBD
{
public static void kyberCBD(Poly r, byte[] bytes, int eta)
{
long t, d;
int a, b;
switch (eta)
{
case 3:
for (int i = 0; i < KyberEngine.KyberN / 4; i++)
{
t = convertByteTo24BitUnsignedInt(bytes, 3 * i);
d = t & 0x00249249;
d = d + ((t >> 1) & 0x00249249);
d = d + ((t >> 2) & 0x00249249);
for (int j = 0; j < 4; j++)
{
a = (short)((d >> (6 * j + 0)) & 0x7);
b = (short)((d >> (6 * j + 3)) & 0x7);
// System.out.printf("a = %d, b = %d\n", a, b);
r.setCoeffIndex(4 * i + j, (short)(a - b));
}
}
break;
default:
// Only for Kyber512 where eta = 2
for (int i = 0; i < KyberEngine.KyberN / 8; i++)
{
t = convertByteTo32BitUnsignedInt(bytes, 4 * i); // ? Problem
d = t & 0x55555555;
d = d + ((t >> 1) & 0x55555555);
for (int j = 0; j < 8; j++)
{
a = (short)((d >> (4 * j + 0)) & 0x3);
b = (short)((d >> (4 * j + eta)) & 0x3);
r.setCoeffIndex(8 * i + j, (short)(a - b));
}
}
}
}
/**
* Converts an Array of Bytes to a 32-bit Unsigned Integer
* Returns a 32-bit unsigned integer as a long
*
* @param x
* @return
*/
private static long convertByteTo32BitUnsignedInt(byte[] x, int offset)
{
// Convert first byte to an unsigned integer
// byte x & 0xFF allows us to grab the last 8 bits
long r = (long)(x[offset] & 0xFF);
// Perform the same operation then left bit shift to store the next 8 bits without
// altering the previous bits
r = r | (long)((long)(x[offset + 1] & 0xFF) << 8);
r = r | (long)((long)(x[offset + 2] & 0xFF) << 16);
r = r | (long)((long)(x[offset + 3] & 0xFF) << 24);
return r;
}
/**
* Converts an Array of Bytes to a 24-bit Unsigned Integer
* Returns a 24-bit unsigned integer as a long from byte x
*
* @param x
* @return
*/
private static long convertByteTo24BitUnsignedInt(byte[] x, int offset)
{
// Refer to convertByteTo32-BitUnsignedInt for explanation
long r = (long)(x[offset] & 0xFF);
r = r | (long)((long)(x[offset + 1] & 0xFF) << 8);
r = r | (long)((long)(x[offset + 2] & 0xFF) << 16);
return r;
}
}