tweetnacl-ts/es/scalarmult.js

Port of TweetNaCl cryptographic library to TypeScript (and ES6)

import { ByteArray, NumArray } from './array';
import { gf, _9, _121665, A, Z, M, S } from './core';
import { sel25519, inv25519, pack25519, unpack25519 } from './curve25519';
import { checkArrayTypes } from './check';
export function scalarMult(n, p) {
    checkArrayTypes(n, p);
    if (n.length !== 32 /* Scalar */)
        throw new Error('bad n size');
    if (p.length !== 32 /* GroupElement */)
        throw new Error('bad p size');
    var q = ByteArray(32 /* GroupElement */);
    _scalarMult(q, n, p);
    return q;
}
export function scalarMult_base(n) {
    checkArrayTypes(n);
    if (n.length !== 32 /* Scalar */)
        throw new Error('bad n size');
    var q = ByteArray(32 /* GroupElement */);
    _scalarMult_base(q, n);
    return q;
}
// low level
export function _scalarMult(q, n, p) {
    var z = ByteArray(32);
    var x = NumArray(80);
    var a = gf();
    var b = gf();
    var c = gf();
    var d = gf();
    var e = gf();
    var f = gf();
    var r, i;
    for (i = 0; i < 31; i++)
        z[i] = n[i];
    z[31] = (n[31] & 127) | 64;
    z[0] &= 248;
    unpack25519(x, p);
    for (i = 0; i < 16; i++) {
        b[i] = x[i];
        d[i] = a[i] = c[i] = 0;
    }
    a[0] = d[0] = 1;
    for (i = 254; i >= 0; --i) {
        r = (z[i >>> 3] >>> (i & 7)) & 1;
        sel25519(a, b, r);
        sel25519(c, d, r);
        A(e, a, c);
        Z(a, a, c);
        A(c, b, d);
        Z(b, b, d);
        S(d, e);
        S(f, a);
        M(a, c, a);
        M(c, b, e);
        A(e, a, c);
        Z(a, a, c);
        S(b, a);
        Z(c, d, f);
        M(a, c, _121665);
        A(a, a, d);
        M(c, c, a);
        M(a, d, f);
        M(d, b, x);
        S(b, e);
        sel25519(a, b, r);
        sel25519(c, d, r);
    }
    for (i = 0; i < 16; i++) {
        x[i + 16] = a[i];
        x[i + 32] = c[i];
        x[i + 48] = b[i];
        x[i + 64] = d[i];
    }
    var x32 = x.subarray(32);
    var x16 = x.subarray(16);
    inv25519(x32, x32);
    M(x16, x16, x32);
    pack25519(q, x16);
    return 0;
}
export function _scalarMult_base(q, n) {
    return _scalarMult(q, n, _9);
}
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