sodium-javascript/crypto_scalarmult.js

83 lines
1.7 KiB
JavaScript
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2020-05-04 18:49:21 +00:00
module.exports = {
crypto_scalarmult,
crypto_scalarmult_base,
crypto_scalarmult_BYTES,
crypto_scalarmult_SCALARBYTES
}
function crypto_scalarmult(q, n, p) {
check(q, crypto_scalarmult_BYTES)
check(n, crypto_scalarmult_SCALARBYTES)
check(p, crypto_scalarmult_BYTES)
var z = new Uint8Array(32);
var x = new Float64Array(80), r, i;
var a = gf(), b = gf(), c = gf(),
d = gf(), e = gf(), f = gf();
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;
}
module.exports = {
crypto_scalarmult_base,
crypto_scalarmult_base,
crypto_scalarmult_BYTES,
crypto_scalarmult_SCALARBYTES
}
function crypto_scalarmult_base(q, n) {
return crypto_scalarmult(q, n, _9);
}
function check (buf, len) {
if (!buf || (len && buf.length < len)) throw new Error('Argument must be a buffer' + (len ? ' of length ' + len : ''))
}
var crypto_scalarmult_BYTES,
crypto_scalarmult_SCALARBYTES = 32,
crypto_scalarmult_BYTES,
crypto_scalarmult_SCALARBYTES = 32