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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.
package org.bouncycastle.crypto.modes.kgcm;
import org.bouncycastle.math.raw.Interleave;
/**
* Utilities for the GF(2^m) field with corresponding extension polynomial:
*
* GF (2^256) -> x^256 + x^10 + x^5 + x^2 + 1
*
* The representation is little-endian arrays of 64-bit words
*/
public class KGCMUtil_256
{
public static final int SIZE = 4;
public static void add(long[] x, long[] y, long[] z)
{
z[0] = x[0] ^ y[0];
z[1] = x[1] ^ y[1];
z[2] = x[2] ^ y[2];
z[3] = x[3] ^ y[3];
}
public static void copy(long[] x, long[] z)
{
z[0] = x[0];
z[1] = x[1];
z[2] = x[2];
z[3] = x[3];
}
public static boolean equal(long[] x, long[] y)
{
long d = 0L;
d |= x[0] ^ y[0];
d |= x[1] ^ y[1];
d |= x[2] ^ y[2];
d |= x[3] ^ y[3];
return d == 0L;
}
public static void multiply(long[] x, long[] y, long[] z)
{
long x0 = x[0], x1 = x[1], x2 = x[2], x3 = x[3];
long y0 = y[0], y1 = y[1], y2 = y[2], y3 = y[3];
long z0 = 0, z1 = 0, z2 = 0, z3 = 0, z4 = 0;
for (int j = 0; j < 64; ++j)
{
long m0 = -(x0 & 1L); x0 >>>= 1;
z0 ^= (y0 & m0);
z1 ^= (y1 & m0);
z2 ^= (y2 & m0);
z3 ^= (y3 & m0);
long m1 = -(x1 & 1L); x1 >>>= 1;
z1 ^= (y0 & m1);
z2 ^= (y1 & m1);
z3 ^= (y2 & m1);
z4 ^= (y3 & m1);
long c = y3 >> 63;
y3 = (y3 << 1) | (y2 >>> 63);
y2 = (y2 << 1) | (y1 >>> 63);
y1 = (y1 << 1) | (y0 >>> 63);
y0 = (y0 << 1) ^ (c & 0x425L);
}
long y4 = y3;
y3 = y2;
y2 = y1;
y1 = y0 ^ (y4 >>> 62) ^ (y4 >>> 59) ^ (y4 >>> 54);
y0 = y4 ^ (y4 << 2) ^ (y4 << 5) ^ (y4 << 10);
for (int j = 0; j < 64; ++j)
{
long m2 = -(x2 & 1L); x2 >>>= 1;
z0 ^= (y0 & m2);
z1 ^= (y1 & m2);
z2 ^= (y2 & m2);
z3 ^= (y3 & m2);
long m3 = -(x3 & 1L); x3 >>>= 1;
z1 ^= (y0 & m3);
z2 ^= (y1 & m3);
z3 ^= (y2 & m3);
z4 ^= (y3 & m3);
long c = y3 >> 63;
y3 = (y3 << 1) | (y2 >>> 63);
y2 = (y2 << 1) | (y1 >>> 63);
y1 = (y1 << 1) | (y0 >>> 63);
y0 = (y0 << 1) ^ (c & 0x425L);
}
z0 ^= z4 ^ (z4 << 2) ^ (z4 << 5) ^ (z4 << 10);
z1 ^= (z4 >>> 62) ^ (z4 >>> 59) ^ (z4 >>> 54);
z[0] = z0; z[1] = z1; z[2] = z2; z[3] = z3;
}
public static void multiplyX(long[] x, long[] z)
{
long x0 = x[0], x1 = x[1], x2 = x[2], x3 = x[3];
long m = x3 >> 63;
z[0] = (x0 << 1) ^ (m & 0x425L);
z[1] = (x1 << 1) | (x0 >>> 63);
z[2] = (x2 << 1) | (x1 >>> 63);
z[3] = (x3 << 1) | (x2 >>> 63);
}
public static void multiplyX8(long[] x, long[] z)
{
long x0 = x[0], x1 = x[1], x2 = x[2], x3 = x[3];
long c = x3 >>> 56;
z[0] = (x0 << 8) ^ c ^ (c << 2) ^ (c << 5) ^ (c << 10);
z[1] = (x1 << 8) | (x0 >>> 56);
z[2] = (x2 << 8) | (x1 >>> 56);
z[3] = (x3 << 8) | (x2 >>> 56);
}
public static void one(long[] z)
{
z[0] = 1;
z[1] = 0;
z[2] = 0;
z[3] = 0;
}
public static void square(long[] x, long[] z)
{
long[] t = new long[SIZE << 1];
for (int i = 0; i < SIZE; ++i)
{
Interleave.expand64To128(x[i], t, i << 1);
}
int j = SIZE << 1;
while (--j >= SIZE)
{
long n = t[j];
t[j - SIZE ] ^= n ^ (n << 2) ^ (n << 5) ^ (n << 10);
t[j - SIZE + 1] ^= (n >>> 62) ^ (n >>> 59) ^ (n >>> 54);
}
copy(t, z);
}
public static void x(long[] z)
{
z[0] = 2;
z[1] = 0;
z[2] = 0;
z[3] = 0;
}
public static void zero(long[] z)
{
z[0] = 0;
z[1] = 0;
z[2] = 0;
z[3] = 0;
}
}