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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.ntruprime;
import java.security.SecureRandom;
import org.bouncycastle.crypto.StreamCipher;
import org.bouncycastle.crypto.digests.SHA512Digest;
import org.bouncycastle.crypto.engines.AESEngine;
import org.bouncycastle.crypto.modes.SICBlockCipher;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.crypto.params.ParametersWithIV;
class Utils
{
protected static int getRandomUnsignedInteger(SecureRandom random)
{
byte[] c = new byte[4];
random.nextBytes(c);
return (bToUnsignedInt(c[0])
+ (bToUnsignedInt(c[1]) << 8)
+ (bToUnsignedInt(c[2]) << 16)
+ (bToUnsignedInt(c[3]) << 24));
}
protected static void getRandomSmallPolynomial(SecureRandom random, byte[] g)
{
for (int i = 0; i < g.length; i++)
g[i] = (byte)((((getRandomUnsignedInteger(random) & 0x3fffffff) * 3) >>> 30) - 1);
}
protected static int getModFreeze(int x, int n)
{
return getSignedDivMod((x + ((n - 1) / 2)), n)[1] - ((n - 1) / 2);
}
protected static boolean isInvertiblePolynomialInR3(byte[] g, byte[] ginv, int p)
{
byte[] f = new byte[p + 1];
byte[] h = new byte[p + 1];
byte[] r = new byte[p + 1];
byte[] v = new byte[p + 1];
int loop, delta, sign, swap, t, i;
r[0] = 1;
f[0] = 1;
f[p - 1] = -1;
f[p] = -1;
for (i = 0; i < p; i++)
h[p - 1 - i] = g[i];
h[p] = 0;
delta = 1;
for (loop = 0; loop < (2 * p) - 1; loop++)
{
System.arraycopy(v, 0, v, 1, p);
v[0] = 0;
sign = -h[0] * f[0];
swap = checkLessThanZero(-delta) & checkNotEqualToZero(h[0]);
delta ^= swap & (delta ^ -delta);
delta += 1;
for (i = 0; i < p + 1; i++)
{
t = swap & (f[i] ^ h[i]);
f[i] ^= t;
h[i] ^= t;
t = swap & (v[i] ^ r[i]);
v[i] ^= t;
r[i] ^= t;
}
for (i = 0; i < p + 1; i++)
h[i] = (byte)getModFreeze(h[i] + sign * f[i], 3);
for (i = 0; i < p + 1; i++)
r[i] = (byte)getModFreeze(r[i] + sign * v[i], 3);
for (i = 0; i < p; i++)
h[i] = h[i+1];
h[p] = 0;
}
sign = f[0];
for (i = 0; i < p; i++)
ginv[i] = (byte)(sign * v[p - 1 - i]);
return (delta == 0);
}
protected static void minmax(int[] L, int x, int y)
{
int xi = L[x];
int yi = L[y];
int xy = xi ^ yi;
int c = yi - xi;
c ^= xy & (c ^ yi ^ 0x80000000);
c = c >>> 31;
c = -c;
c &= xy;
L[x] = xi ^ c;
L[y] = yi ^ c;
}
protected static void cryptoSort(int[] L, int p)
{
int top, a, b, i;
if (p < 2)
return;
top = 1;
while (top < p - top)
top += top;
for (a = top; a > 0; a = a >>> 1)
{
for (i = 0; i < p - a; i++)
if ((i & a) == 0)
minmax(L, i, i + a);
for (b = top; b > a; b = b >>> 1)
for (i = 0; i < p - b; i++)
if ((i & a) == 0)
minmax(L, i + a, i + b);
}
}
protected static void sortGenerateShortPolynomial(byte[] f, int[] L, int p, int w)
{
for (int i = 0; i < w; i++)
L[i] = L[i] & -2;
for (int i = w; i < p; i++)
L[i] = (L[i] & -3) | 1;
cryptoSort(L, p);
for (int i = 0; i < p; i++)
f[i] = (byte)((L[i] & 3) - 1);
}
protected static void getRandomShortPolynomial(SecureRandom random, byte[] f, int p, int w)
{
int[] L = new int[p];
for (int i = 0; i < p; i++)
L[i] = getRandomUnsignedInteger(random);
sortGenerateShortPolynomial(f, L, p, w);
}
protected static int getInverseInRQ(int x, int q)
{
int ai = x;
for (int i = 1; i < q - 2; i++)
ai = getModFreeze(x * ai, q);
return ai;
}
protected static void getOneThirdInverseInRQ(short[] finv3, byte[] f, int p, int q)
{
short[] h = new short[p + 1];
short[] g = new short[p + 1];
short[] r = new short[p + 1];
short[] v = new short[p + 1];
int loop, delta, scale, swap, h0, g0, t, i;
r[0] = (short)getInverseInRQ(3, q);
h[0] = 1;
h[p - 1] = -1;
h[p] = -1;
for (i = 0; i < p; i++)
g[p - 1 - i] = f[i];
g[p] = 0;
delta = 1;
for (loop = 0; loop < (2 * p) - 1; loop++)
{
System.arraycopy(v, 0, v, 1, p);
v[0] = 0;
swap = checkLessThanZero(-delta) & checkNotEqualToZero(g[0]);
delta ^= swap & (delta ^ -delta);
delta += 1;
for (i = 0; i < p + 1; i++)
{
t = swap & (h[i] ^ g[i]);
h[i] ^= t;
g[i] ^= t;
t = swap & (v[i] ^ r[i]);
v[i] ^= t;
r[i] ^= t;
}
h0 = h[0];
g0 = g[0];
for (i = 0; i < p + 1; i++)
g[i] = (short)getModFreeze((h0 * g[i]) - (g0 * h[i]), q);
for (i = 0; i < p + 1; i++)
r[i] = (short)getModFreeze((h0 * r[i]) - (g0 * v[i]), q);
for (i = 0; i < p; i++)
g[i] = g[i+1];
g[p] = 0;
}
scale = getInverseInRQ(h[0], q);
for (i = 0; i < p; i++)
finv3[i] = (short)getModFreeze(scale * v[p - 1 - i], q);
}
protected static void multiplicationInRQ(short[] h, short[] finv3, byte[] g, int p, int q)
{
short[] fg = new short[p + p - 1];
short result;
int i, j;
for (i = 0; i < p; i++)
{
result = 0;
for (j = 0; j <= i; j++)
result = (short)getModFreeze(result + (finv3[j] * g[i - j]), q);
fg[i] = result;
}
for (i = p; i < p + p - 1; i++)
{
result = 0;
for (j = i - p + 1; j < p; j++)
result = (short)getModFreeze(result + (finv3[j] * g[i - j]), q);
fg[i] = result;
}
for (i = p + p - 2; i >= p; i--)
{
fg[i - p] = (short)getModFreeze(fg[i - p] + fg[i], q);
fg[i - p + 1] = (short)getModFreeze(fg[i - p + 1] + fg[i], q);
}
for (i = 0; i < p; i++)
h[i] = fg[i];
}
private static void encode(byte[] out, short[] R, short[] M, int len, int start)
{
if (len == 1)
{
short r = R[0];
short m = M[0];
while (m > 1)
{
out[start++] = (byte)r;
r = (short)(r >>> 8);
m = (short)((m + 255) >>> 8);
}
}
if (len > 1)
{
short[] R2 = new short[(len + 1) / 2];
short[] M2 = new short[(len + 1) / 2];
int i;
for (i = 0; i < len - 1; i += 2)
{
int m0 = M[i];
int r = R[i] + (R[i + 1] * m0);
int m = M[i + 1] * m0;
while (m >= 16384)
{
out[start++] = (byte)r;
r = r >>> 8;
m = (m + 255) >>> 8;
}
R2[i / 2] = (short)r;
M2[i / 2] = (short)m;
}
if (i < len)
{
R2[i / 2] = R[i];
M2[i / 2] = M[i];
}
encode(out, R2, M2,(len + 1) / 2, start);
}
}
protected static void getEncodedPolynomial(byte[] enc, short[] h, int p, int q)
{
short[] R = new short[p];
short[] M = new short[p];
for (int i = 0; i < p; i++)
R[i] = (short)(h[i] + ((q - 1) / 2));
for (int i = 0; i < p; i++)
M[i] = (short)q;
encode(enc, R, M, p, 0);
}
protected static void getEncodedSmallPolynomial(byte[] encSP, byte[] sp, int p)
{
byte x;
int spIndex = 0;
int encSPIndex = 0;
for (int i = 0; i < p / 4; i++)
{
x = (byte)(sp[spIndex++] + 1);
x += (byte)(sp[spIndex++] + 1) << 2;
x += (byte)(sp[spIndex++] + 1) << 4;
x += (byte)(sp[spIndex++] + 1) << 6;
encSP[encSPIndex++] = x;
}
encSP[encSPIndex] = (byte)(sp[spIndex] + 1);
}
private static void generateAES256CTRStream(byte[] in, byte[] out, byte[] nonce, byte[] key)
{
StreamCipher cipher = new SICBlockCipher(new AESEngine());
cipher.init(true, new ParametersWithIV(new KeyParameter(key), nonce));
cipher.processBytes(in, 0, out.length, out, 0);
}
protected static void expand(int[] L, byte[] k)
{
byte[] aesInput = new byte[L.length * 4];
byte[] aesOutput = new byte[L.length * 4];
byte[] nonce = new byte[16];
generateAES256CTRStream(aesInput, aesOutput, nonce, k);
for (int i = 0; i < L.length; i++)
L[i] = (bToUnsignedInt(aesOutput[i * 4])
+ (bToUnsignedInt(aesOutput[(i * 4) + 1]) << 8)
+ (bToUnsignedInt(aesOutput[(i * 4) + 2]) << 16)
+ (bToUnsignedInt(aesOutput[(i * 4) + 3]) << 24));
}
private static int getUnsignedMod(int x, int n)
{
return getUnsignedDivMod(x, n)[1];
}
protected static void generatePolynomialInRQFromSeed(short[] G, byte[] seed, int p, int q)
{
int[] L = new int[p];
expand(L, seed);
for (int i = 0; i < p; i++)
G[i] = (short)(getUnsignedMod(L[i], q) - ((q - 1) / 2));
}
protected static void roundPolynomial(short[] out, short[] in)
{
for (int i = 0; i < out.length; i++)
out[i] = (short)(in[i] - getModFreeze(in[i], 3));
}
protected static void getRoundedEncodedPolynomial(byte[] out, short[] in, int p, int q)
{
short[] R = new short[p];
short[] M = new short[p];
for (int i = 0; i < p; i++)
{
R[i] = (short)(((in[i] + ((q - 1) / 2)) * 10923) >>> 15);
M[i] = (short)((q + 2) / 3);
}
encode(out, R, M, p, 0);
}
protected static byte[] getHashWithPrefix(byte[] prefix, byte[] hashInput)
{
byte[] hash = new byte[64];
byte[] input = new byte[prefix.length + hashInput.length];
System.arraycopy(prefix, 0, input, 0, prefix.length);
System.arraycopy(hashInput, 0, input, prefix.length, hashInput.length);
SHA512Digest hashDigest = new SHA512Digest();
hashDigest.update(input, 0, input.length);
hashDigest.doFinal(hash, 0);
return hash;
}
private static void decode(short[] out, byte[] S, short[] M, int len, int start, int sIndex)
{
if (len == 1)
{
if (M[0] == 1)
out[start] = 0;
else if (M[0] <= 256)
out[start] = (short)getUnsignedMod(bToUnsignedInt(S[sIndex]), M[0]);
else
out[start] = (short)getUnsignedMod(bToUnsignedInt(S[sIndex]) + (S[sIndex + 1] << 8), M[0]);
}
if (len > 1)
{
short[] R2 = new short[(len + 1) / 2];
short[] M2 = new short[(len + 1) / 2];
short[] bottomr = new short[len / 2];
int[] bottomt = new int[len / 2];
int i;
for (i = 0; i < len - 1; i += 2)
{
int m = M[i] * (int)M[i+1];
if (m > (256 * 16383))
{
bottomt[i / 2] = 256 * 256;
bottomr[i / 2] = (short)(bToUnsignedInt(S[sIndex]) + (256 * bToUnsignedInt(S[sIndex + 1])));
sIndex += 2;
M2[i / 2] = (short)((((m + 255) >>> 8) + 255) >>> 8);
}
else if (m >= 16384)
{
bottomt[i / 2] = 256;
bottomr[i / 2] = (short)bToUnsignedInt(S[sIndex]);
sIndex += 1;
M2[i / 2] = (short)((m + 255) >>> 8);
}
else
{
bottomt[i / 2] = 1;
bottomr[i / 2] = 0;
M2[i / 2] = (short)m;
}
}
if (i < len)
M2[i / 2] = M[i];
decode(R2, S, M2,(len + 1) / 2, start, sIndex);
for (i = 0; i < len - 1; i += 2)
{
int r = sToUnsignedInt(bottomr[i / 2]);
r += bottomt[i / 2] * sToUnsignedInt(R2[i / 2]);
int[] r01 = getUnsignedDivMod(r, M[i]);
out[start++] = (short)r01[1];
out[start++] = (short)getUnsignedMod(r01[0], M[i + 1]);
}
if (i < len)
out[start] = R2[i / 2];
}
}
protected static void getDecodedPolynomial(short[] h, byte[] enc, int p, int q)
{
short[] R = new short[p];
short[] M = new short[p];
for (int i = 0; i < p; i++)
M[i] = (short)q;
decode(R, enc, M, p, 0, 0);
for (int i = 0; i < p; i++)
h[i] = (short)(R[i] - ((q - 1) / 2));
}
protected static void getRandomInputs(SecureRandom random, byte[] r)
{
byte[] seed = new byte[r.length / 8];
random.nextBytes(seed);
for (int i = 0; i < r.length; i++)
r[i] = (byte)(1 & (seed[i >>> 3] >>> (i & 7)));
}
protected static void getEncodedInputs(byte[] out, byte[] in)
{
for (int i = 0; i < in.length; i++)
out[i >>> 3] |= in[i] << (i & 7);
}
protected static void getRoundedDecodedPolynomial(short[] h, byte[] enc, int p, int q)
{
short[] R = new short[p];
short[] M = new short[p];
for (int i = 0; i < p; i++)
M[i] = (short)((q + 2) / 3);
decode(R, enc, M, p, 0, 0);
for (int i = 0; i < p; i++)
h[i] = (short)((R[i] * 3) - ((q - 1) / 2));
}
protected static void top(byte[] out, short[] bA, byte[] r, int q, int tau0, int tau1)
{
for (int i = 0; i < out.length; i++)
out[i] = (byte)((tau1 * (getModFreeze(bA[i] + r[i] * ((q - 1) / 2), q) + tau0) + 16384) >>> 15);
}
protected static void getTopEncodedPolynomial(byte[] out, byte[] in)
{
for (int i = 0; i < out.length; i++)
out[i] = (byte)(in[2 * i] + (in[(2 * i) + 1] << 4));
}
protected static void getDecodedSmallPolynomial(byte[] sp, byte[] encSP, int p)
{
byte x;
int spIndex = 0;
int encSPIndex = 0;
for (int i = 0; i < p / 4; i++)
{
x = encSP[encSPIndex++];
sp[spIndex++] = (byte)((bToUnsignedInt(x) & 3) - 1); x >>>= 2;
sp[spIndex++] = (byte)((bToUnsignedInt(x) & 3) - 1); x >>>= 2;
sp[spIndex++] = (byte)((bToUnsignedInt(x) & 3) - 1); x >>>= 2;
sp[spIndex++] = (byte)((bToUnsignedInt(x) & 3) - 1);
}
x = encSP[encSPIndex];
sp[spIndex] = (byte)((bToUnsignedInt(x) & 3) - 1);
}
protected static void scalarMultiplicationInRQ(short[] out, short[] in, int scalar, int q)
{
for (int i = 0; i < in.length; i++)
out[i] = (short)getModFreeze(scalar * in[i], q);
}
protected static void transformRQToR3(byte[] out, short[] in)
{
for (int i = 0; i < in.length; i++)
out[i] = (byte)getModFreeze(in[i], 3);
}
protected static void multiplicationInR3(byte[] h, byte[] finv3, byte[] g, int p)
{
byte[] fg = new byte[p + p - 1];
byte result;
int i, j;
for (i = 0; i < p; i++)
{
result = 0;
for (j = 0; j <= i; j++)
result = (byte) getModFreeze(result + (finv3[j] * g[i - j]), 3);
fg[i] = result;
}
for (i = p; i < p + p - 1; i++)
{
result = 0;
for (j = i - p + 1; j < p; j++)
result = (byte)getModFreeze(result + (finv3[j] * g[i - j]), 3);
fg[i] = result;
}
for (i = p + p - 2; i >= p; i--)
{
fg[i - p] = (byte)getModFreeze(fg[i - p] + fg[i], 3);
fg[i - p + 1] = (byte)getModFreeze(fg[i - p + 1] + fg[i], 3);
}
for (i = 0; i < p; i++)
h[i] = fg[i];
}
protected static void checkForSmallPolynomial(byte[] r, byte[] ev, int p, int w)
{
int weight = 0;
for (int i = 0; i != ev.length; i++)
{
weight += ev[i] & 1;
}
int mask = checkNotEqualToZero(weight - w);
for (int i = 0; i < w; i++)
r[i] = (byte)(((ev[i] ^ 1) & ~mask) ^ 1);
for (int i = w; i < p; i++)
r[i] = (byte)(ev[i] & ~mask);
}
protected static void updateDiffMask(byte[] encR, byte[] rho, int mask)
{
for (int i = 0; i < encR.length; i++)
encR[i] ^= mask & (encR[i] ^ rho[i]);
}
protected static void getTopDecodedPolynomial(byte[] out, byte[] in)
{
for (int i = 0; i < in.length; i++)
{
out[2 * i] = (byte)(in[i] & 15);
out[(2 * i) + 1] = (byte)(in[i] >>> 4);
}
}
protected static void right(byte[] out, short[] aB, byte[] T, int q, int w, int tau2, int tau3)
{
for (int i = 0; i < out.length; i++)
out[i] = (byte)(-checkLessThanZero(getModFreeze(getModFreeze((tau3 * T[i]) - tau2, q) - aB[i] + (4 * w) + 1, q)));
}
private static int[] getUnsignedDivMod(int dividend, int n)
{
long x = iToUnsignedLong(dividend);
long v = iToUnsignedLong(0x80000000);
long q, qpart, mask;
v /= n;
q = 0;
qpart = (x * v) >>> 31;
x -= qpart * n;
q += qpart;
qpart = (x * v) >>> 31;
x -= qpart * n;
q += qpart;
x -= n;
q += 1;
mask = -(x >>> 63);
x += mask & n;
q += mask;
return new int[]{toIntExact(q), toIntExact(x)};
}
private static int[] getSignedDivMod(int x, int n)
{
int q, r, mask;
int[] div1 = getUnsignedDivMod(toIntExact(0x80000000 + iToUnsignedLong(x)), n);
int[] div2 = getUnsignedDivMod(0x80000000, n);
q = toIntExact(iToUnsignedLong(div1[0]) - iToUnsignedLong(div2[0]));
r = toIntExact(iToUnsignedLong(div1[1]) - iToUnsignedLong(div2[1]));
mask = -(r >>> 31);
r += mask & n;
q += mask;
return new int[]{q, r};
}
private static int checkLessThanZero(int x)
{
return -(int)(x >>> 31);
}
private static int checkNotEqualToZero(int x)
{
long l = iToUnsignedLong(x);
l = -l;
return -(int)(l >>> 63);
}
static int bToUnsignedInt(byte b)
{
return b & 0xff;
}
static int sToUnsignedInt(short s)
{
return s & 0xffff;
}
static long iToUnsignedLong(int i)
{
return i & 0xffffffffL;
}
static int toIntExact(long l)
{
int i = (int)l;
if (i != l)
{
throw new IllegalStateException("value out of integer range");
}
return i;
}
}