org.whispersystems.curve25519.java.scalarmult Maven / Gradle / Ivy
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Curve25519 library for Java
package org.whispersystems.curve25519.java;
public class scalarmult {
//CONVERT #include "crypto_scalarmult.h"
//CONVERT #include "fe.h"
public static int crypto_scalarmult(byte[] q,
byte[] n,
byte[] p)
{
byte[] e = new byte[32];
int i;
int[] x1 = new int[10];
int[] x2 = new int[10];
int[] z2 = new int[10];
int[] x3 = new int[10];
int[] z3 = new int[10];
int[] tmp0 = new int[10];
int[] tmp1 = new int[10];
int pos;
int swap;
int b;
for (i = 0;i < 32;++i) e[i] = n[i];
// e[0] &= 248;
// e[31] &= 127;
// e[31] |= 64;
fe_frombytes.fe_frombytes(x1,p);
fe_1.fe_1(x2);
fe_0.fe_0(z2);
fe_copy.fe_copy(x3,x1);
fe_1.fe_1(z3);
swap = 0;
for (pos = 254;pos >= 0;--pos) {
b = e[pos / 8] >>> (pos & 7);
b &= 1;
swap ^= b;
fe_cswap.fe_cswap(x2,x3,swap);
fe_cswap.fe_cswap(z2,z3,swap);
swap = b;
//CONVERT #include "montgomery.h"
/* qhasm: fe X2 */
/* qhasm: fe Z2 */
/* qhasm: fe X3 */
/* qhasm: fe Z3 */
/* qhasm: fe X4 */
/* qhasm: fe Z4 */
/* qhasm: fe X5 */
/* qhasm: fe Z5 */
/* qhasm: fe A */
/* qhasm: fe B */
/* qhasm: fe C */
/* qhasm: fe D */
/* qhasm: fe E */
/* qhasm: fe AA */
/* qhasm: fe BB */
/* qhasm: fe DA */
/* qhasm: fe CB */
/* qhasm: fe t0 */
/* qhasm: fe t1 */
/* qhasm: fe t2 */
/* qhasm: fe t3 */
/* qhasm: fe t4 */
/* qhasm: enter ladder */
/* qhasm: D = X3-Z3 */
/* asm 1: fe_sub.fe_sub(>D=fe#5,D=tmp0,B=fe#6,B=tmp1,A=fe#1,A=x2,C=fe#2,C=z2,DA=fe#4,DA=z3,CB=fe#2,CB=z2,BB=fe#5,BB=tmp0,AA=fe#6,AA=tmp1,t0=fe#3,t0=x3,t1=fe#2,t1=z2,X4=fe#1,X4=x2,E=fe#6,E=tmp1,t2=fe#2,t2=z2,t3=fe#4,t3=z3,X5=fe#3,X5=x3,t4=fe#5,t4=tmp0,Z5=fe#4,x1,Z5=z3,x1,Z4=fe#2,Z4=z2,