org.whispersystems.curve25519.java.sc_reduce Maven / Gradle / Ivy
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Curve25519 library for Java
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package org.whispersystems.curve25519.java;
public class sc_reduce {
//CONVERT #include "sc.h"
//CONVERT #include "long.h"
//CONVERT #include "crypto_uint32.h"
//CONVERT #include "long.h"
public static long load_3(byte[] in, int index) {
long result;
result = ((long) in[index]) & 0xFF;
result |= (((long) in[index + 1]) << 8) & 0xFF00;
result |= (((long) in[index + 2]) << 16) & 0xFF0000;
return result;
}
public static long load_4(byte[] in, int index) {
long result;
result = (((long) in[index]) & 0xFF);
result |= ((((long) in[index + 1]) << 8) & 0xFF00);
result |= ((((long) in[index + 2]) << 16) & 0xFF0000);
result |= ((((long) in[index + 3]) << 24) & 0xFF000000L);
return result;
}
/*
Input:
s[0]+256*s[1]+...+256^63*s[63] = s
Output:
s[0]+256*s[1]+...+256^31*s[31] = s mod l
where l = 2^252 + 27742317777372353535851937790883648493.
Overwrites s in place.
*/
public static void sc_reduce(byte[] s) {
long s0 = 2097151 & load_3(s, 0);
long s1 = 2097151 & (load_4(s, 2) >>> 5);
long s2 = 2097151 & (load_3(s, 5) >>> 2);
long s3 = 2097151 & (load_4(s, 7) >>> 7);
long s4 = 2097151 & (load_4(s, 10) >>> 4);
long s5 = 2097151 & (load_3(s, 13) >>> 1);
long s6 = 2097151 & (load_4(s, 15) >>> 6);
long s7 = 2097151 & (load_3(s, 18) >>> 3);
long s8 = 2097151 & load_3(s, 21);
long s9 = 2097151 & (load_4(s, 23) >>> 5);
long s10 = 2097151 & (load_3(s, 26) >>> 2);
long s11 = 2097151 & (load_4(s, 28) >>> 7);
long s12 = 2097151 & (load_4(s, 31) >>> 4);
long s13 = 2097151 & (load_3(s, 34) >>> 1);
long s14 = 2097151 & (load_4(s, 36) >>> 6);
long s15 = 2097151 & (load_3(s, 39) >>> 3);
long s16 = 2097151 & load_3(s, 42);
long s17 = 2097151 & (load_4(s, 44) >>> 5);
long s18 = 2097151 & (load_3(s, 47) >>> 2);
long s19 = 2097151 & (load_4(s, 49) >>> 7);
long s20 = 2097151 & (load_4(s, 52) >>> 4);
long s21 = 2097151 & (load_3(s, 55) >>> 1);
long s22 = 2097151 & (load_4(s, 57) >>> 6);
long s23 = (load_4(s, 60) >>> 3);
long carry0;
long carry1;
long carry2;
long carry3;
long carry4;
long carry5;
long carry6;
long carry7;
long carry8;
long carry9;
long carry10;
long carry11;
long carry12;
long carry13;
long carry14;
long carry15;
long carry16;
s11 += s23 * 666643;
s12 += s23 * 470296;
s13 += s23 * 654183;
s14 -= s23 * 997805;
s15 += s23 * 136657;
s16 -= s23 * 683901;
s10 += s22 * 666643;
s11 += s22 * 470296;
s12 += s22 * 654183;
s13 -= s22 * 997805;
s14 += s22 * 136657;
s15 -= s22 * 683901;
s9 += s21 * 666643;
s10 += s21 * 470296;
s11 += s21 * 654183;
s12 -= s21 * 997805;
s13 += s21 * 136657;
s14 -= s21 * 683901;
s8 += s20 * 666643;
s9 += s20 * 470296;
s10 += s20 * 654183;
s11 -= s20 * 997805;
s12 += s20 * 136657;
s13 -= s20 * 683901;
s7 += s19 * 666643;
s8 += s19 * 470296;
s9 += s19 * 654183;
s10 -= s19 * 997805;
s11 += s19 * 136657;
s12 -= s19 * 683901;
s6 += s18 * 666643;
s7 += s18 * 470296;
s8 += s18 * 654183;
s9 -= s18 * 997805;
s10 += s18 * 136657;
s11 -= s18 * 683901;
carry6 = (s6 + (1 << 20)) >> 21;
s7 += carry6;
s6 -= carry6 << 21;
carry8 = (s8 + (1 << 20)) >> 21;
s9 += carry8;
s8 -= carry8 << 21;
carry10 = (s10 + (1 << 20)) >> 21;
s11 += carry10;
s10 -= carry10 << 21;
carry12 = (s12 + (1 << 20)) >> 21;
s13 += carry12;
s12 -= carry12 << 21;
carry14 = (s14 + (1 << 20)) >> 21;
s15 += carry14;
s14 -= carry14 << 21;
carry16 = (s16 + (1 << 20)) >> 21;
s17 += carry16;
s16 -= carry16 << 21;
carry7 = (s7 + (1 << 20)) >> 21;
s8 += carry7;
s7 -= carry7 << 21;
carry9 = (s9 + (1 << 20)) >> 21;
s10 += carry9;
s9 -= carry9 << 21;
carry11 = (s11 + (1 << 20)) >> 21;
s12 += carry11;
s11 -= carry11 << 21;
carry13 = (s13 + (1 << 20)) >> 21;
s14 += carry13;
s13 -= carry13 << 21;
carry15 = (s15 + (1 << 20)) >> 21;
s16 += carry15;
s15 -= carry15 << 21;
s5 += s17 * 666643;
s6 += s17 * 470296;
s7 += s17 * 654183;
s8 -= s17 * 997805;
s9 += s17 * 136657;
s10 -= s17 * 683901;
s4 += s16 * 666643;
s5 += s16 * 470296;
s6 += s16 * 654183;
s7 -= s16 * 997805;
s8 += s16 * 136657;
s9 -= s16 * 683901;
s3 += s15 * 666643;
s4 += s15 * 470296;
s5 += s15 * 654183;
s6 -= s15 * 997805;
s7 += s15 * 136657;
s8 -= s15 * 683901;
s2 += s14 * 666643;
s3 += s14 * 470296;
s4 += s14 * 654183;
s5 -= s14 * 997805;
s6 += s14 * 136657;
s7 -= s14 * 683901;
s1 += s13 * 666643;
s2 += s13 * 470296;
s3 += s13 * 654183;
s4 -= s13 * 997805;
s5 += s13 * 136657;
s6 -= s13 * 683901;
s0 += s12 * 666643;
s1 += s12 * 470296;
s2 += s12 * 654183;
s3 -= s12 * 997805;
s4 += s12 * 136657;
s5 -= s12 * 683901;
s12 = 0;
carry0 = (s0 + (1 << 20)) >> 21;
s1 += carry0;
s0 -= carry0 << 21;
carry2 = (s2 + (1 << 20)) >> 21;
s3 += carry2;
s2 -= carry2 << 21;
carry4 = (s4 + (1 << 20)) >> 21;
s5 += carry4;
s4 -= carry4 << 21;
carry6 = (s6 + (1 << 20)) >> 21;
s7 += carry6;
s6 -= carry6 << 21;
carry8 = (s8 + (1 << 20)) >> 21;
s9 += carry8;
s8 -= carry8 << 21;
carry10 = (s10 + (1 << 20)) >> 21;
s11 += carry10;
s10 -= carry10 << 21;
carry1 = (s1 + (1 << 20)) >> 21;
s2 += carry1;
s1 -= carry1 << 21;
carry3 = (s3 + (1 << 20)) >> 21;
s4 += carry3;
s3 -= carry3 << 21;
carry5 = (s5 + (1 << 20)) >> 21;
s6 += carry5;
s5 -= carry5 << 21;
carry7 = (s7 + (1 << 20)) >> 21;
s8 += carry7;
s7 -= carry7 << 21;
carry9 = (s9 + (1 << 20)) >> 21;
s10 += carry9;
s9 -= carry9 << 21;
carry11 = (s11 + (1 << 20)) >> 21;
s12 += carry11;
s11 -= carry11 << 21;
s0 += s12 * 666643;
s1 += s12 * 470296;
s2 += s12 * 654183;
s3 -= s12 * 997805;
s4 += s12 * 136657;
s5 -= s12 * 683901;
s12 = 0;
carry0 = s0 >> 21;
s1 += carry0;
s0 -= carry0 << 21;
carry1 = s1 >> 21;
s2 += carry1;
s1 -= carry1 << 21;
carry2 = s2 >> 21;
s3 += carry2;
s2 -= carry2 << 21;
carry3 = s3 >> 21;
s4 += carry3;
s3 -= carry3 << 21;
carry4 = s4 >> 21;
s5 += carry4;
s4 -= carry4 << 21;
carry5 = s5 >> 21;
s6 += carry5;
s5 -= carry5 << 21;
carry6 = s6 >> 21;
s7 += carry6;
s6 -= carry6 << 21;
carry7 = s7 >> 21;
s8 += carry7;
s7 -= carry7 << 21;
carry8 = s8 >> 21;
s9 += carry8;
s8 -= carry8 << 21;
carry9 = s9 >> 21;
s10 += carry9;
s9 -= carry9 << 21;
carry10 = s10 >> 21;
s11 += carry10;
s10 -= carry10 << 21;
carry11 = s11 >> 21;
s12 += carry11;
s11 -= carry11 << 21;
s0 += s12 * 666643;
s1 += s12 * 470296;
s2 += s12 * 654183;
s3 -= s12 * 997805;
s4 += s12 * 136657;
s5 -= s12 * 683901;
carry0 = s0 >> 21;
s1 += carry0;
s0 -= carry0 << 21;
carry1 = s1 >> 21;
s2 += carry1;
s1 -= carry1 << 21;
carry2 = s2 >> 21;
s3 += carry2;
s2 -= carry2 << 21;
carry3 = s3 >> 21;
s4 += carry3;
s3 -= carry3 << 21;
carry4 = s4 >> 21;
s5 += carry4;
s4 -= carry4 << 21;
carry5 = s5 >> 21;
s6 += carry5;
s5 -= carry5 << 21;
carry6 = s6 >> 21;
s7 += carry6;
s6 -= carry6 << 21;
carry7 = s7 >> 21;
s8 += carry7;
s7 -= carry7 << 21;
carry8 = s8 >> 21;
s9 += carry8;
s8 -= carry8 << 21;
carry9 = s9 >> 21;
s10 += carry9;
s9 -= carry9 << 21;
carry10 = s10 >> 21;
s11 += carry10;
s10 -= carry10 << 21;
s[0] = (byte) (s0);
s[1] = (byte) (s0 >> 8);
s[2] = (byte) ((s0 >> 16) | (s1 << 5));
s[3] = (byte) (s1 >> 3);
s[4] = (byte) (s1 >> 11);
s[5] = (byte) ((s1 >> 19) | (s2 << 2));
s[6] = (byte) (s2 >> 6);
s[7] = (byte) ((s2 >> 14) | (s3 << 7));
s[8] = (byte) (s3 >> 1);
s[9] = (byte) (s3 >> 9);
s[10] = (byte) ((s3 >> 17) | (s4 << 4));
s[11] = (byte) (s4 >> 4);
s[12] = (byte) (s4 >> 12);
s[13] = (byte) ((s4 >> 20) | (s5 << 1));
s[14] = (byte) (s5 >> 7);
s[15] = (byte) ((s5 >> 15) | (s6 << 6));
s[16] = (byte) (s6 >> 2);
s[17] = (byte) (s6 >> 10);
s[18] = (byte) ((s6 >> 18) | (s7 << 3));
s[19] = (byte) (s7 >> 5);
s[20] = (byte) (s7 >> 13);
s[21] = (byte) (s8);
s[22] = (byte) (s8 >> 8);
s[23] = (byte) ((s8 >> 16) | (s9 << 5));
s[24] = (byte) (s9 >> 3);
s[25] = (byte) (s9 >> 11);
s[26] = (byte) ((s9 >> 19) | (s10 << 2));
s[27] = (byte) (s10 >> 6);
s[28] = (byte) ((s10 >> 14) | (s11 << 7));
s[29] = (byte) (s11 >> 1);
s[30] = (byte) (s11 >> 9);
s[31] = (byte) (s11 >> 17);
}
}
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