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package rsa;
import static rsa.BigNum.*;
import java.util.Arrays;
public class MontgomeryArray {
static void mont_prod_array(int length, int[] A, int B[], int M[], int[] s) {
if (A == s || B == s)
throw new IllegalArgumentException();
zero_array(length, s);
int[] qSub = new int[length];
int[] sMA = new int[length];
int[] sM = new int[length];
int[] sA = new int[length];
for (int wordIndex = length - 1; wordIndex >= 0; wordIndex--) {
for (int i = 0; i < 32; i++) {
sub_array(length, s, A, qSub); // int q = (s - b * A) & 1;
add_array(length, s, M, sM);
add_array(length, s, A, sA);
add_array(length, sM, A, sMA);
int b = (B[wordIndex] >>> i) & 1;
int[] qSelect = (b == 1) ? qSub : s;
int q = qSelect[length - 1] & 1; // int q = (s - b * A) & 1;
// s = (s + q*M + b*A) >>> 1;
if (q == 1 && b == 1) {
copy_array(length, sMA, s);
} else if (q == 1) {
copy_array(length, sM, s);
} else if (b == 1) {
copy_array(length, sA, s);
}
shift_right_1_array(length, s, s);
}
}
}
public static void m_residue(int length, int[] a, int[] modulus,
int[] residue) {
modulus_array(length, a, modulus, residue);
for (int i = 0; i < 32; i++) {
shift_left_1_array(length, residue, residue);
modulus_array(length, residue, modulus, residue);
}
}
static void modulus_array(int length, int[] a, int[] modulus, int[] reminder) {
// int[] tmp = new int[length];
// copy_array(length, a, reminder);
// copy_array(length, a, tmp);
//
// while((tmp[0] & 0x8000_0000) == 0) {
// System.out.printf("tmp: %s\n", Arrays.toString(tmp));
// System.out.printf("reminder: %s\n", Arrays.toString(reminder));
// copy_array(length, tmp, reminder);
// sub_array(length, tmp, modulus, tmp);
// }
int[] tmp = new int[length];
int[] tmp2 = new int[length];
copy_array(length, a, reminder);
while (!greater_than_array(length, modulus, reminder)) {
sub_array(length, reminder, tmp2, reminder);
copy_array(length, modulus, tmp);
zero_array(length, tmp2);
while (!greater_than_array(length, tmp, reminder)) {
copy_array(length, tmp, tmp2);
shift_left_1_array(length, tmp, tmp);
}
sub_array(length, reminder, tmp2, reminder);
}
}
public static void m_residue_2_2N_array(int length, int N, int[] M,
int[] temp, int[] Nr) {
zero_array(length, Nr);
Nr[length - 1] = 1; // Nr = 1 == 2**(2N-2N)
for (int i = 0; i < 2 * N ; i++) {
shift_left_1_array(length, Nr, Nr);
modulus_array(length, Nr, M, Nr);
}
}
static int findN(int length, int[] E) {
int n = -1;
for (int i = 0; i < 32 * length; i++) {
int ei_ = E[length - 1 - (i / 32)];
int ei = (ei_ >> (i % 32)) & 1;
if (ei == 1) {
n = i;
}
}
return n + 1;
}
public static void mont_exp_array(int length, int[] X, int[] E, int[] M,
int[] Nr, int[] P, int[] ONE, int[] temp, int[] Z) {
//debugArray("X ", length, X);
//debugArray("E ", length, E);
//debugArray("M ", length, M);
int n = 32 * length;
//System.out.println("N: " + n);
PerformanceClock.updateThen();
// 1. Nr := 2 ** 2N mod M
m_residue_2_2N_array(length, n, M, temp, Nr);
//debugArray("Nr", length, Nr);
PerformanceClock.debug("m_residue_2_2N_array");
// 2. Z0 := MontProd( 1, Nr, M )
zero_array(length, ONE);
ONE[length - 1] = 1;
mont_prod_array(length, ONE, Nr, M, Z);
//debugArray("Z0", length, Z);
PerformanceClock.debug("1*Nr mod M");
// 3. P0 := MontProd( X, Nr, M );
mont_prod_array(length, X, Nr, M, P);
//debugArray("P0", length, P);
PerformanceClock.debug("X*Nr mod M");
// 4. for i = 0 to n-1 loop
n = findN(length, E); //loop optimization
for (int i = 0; i < n; i++) {
int ei_ = E[length - 1 - (i / 32)];
int ei = (ei_ >> (i % 32)) & 1;
// 6. if (ei = 1) then Zi+1 := MontProd ( Zi, Pi, M) else Zi+1 := Zi
if (ei == 1) {
mont_prod_array(length, Z, P, M, temp);
copy_array(length, temp, Z);
//debugArray("Z ", length, Z);
}
// 5. Pi+1 := MontProd( Pi, Pi, M );
mont_prod_array(length, P, P, M, temp);
copy_array(length, temp, P);
//debugArray("P ", length, P);
} // 7. end for
PerformanceClock.debug("loop");
// 8. Zn := MontProd( 1, Zn, M );
mont_prod_array(length, ONE, Z, M, temp);
copy_array(length, temp, Z);
//debugArray("Z ", length, Z);
// 9. RETURN Zn
PerformanceClock.debug("1*Z mod M");
}
}
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