Here is an excerpt from a JS encryption script that I am studying.
function permutationGenerator(nNumElements) {
this.nNumElements = nNumElements;
this.antranspositions = new Array;
var k = 0;
for (i = 0; i < nNumElements - 1; i++)
for (j = i + 1; j < nNumElements; j++)
this.antranspositions[ k++ ] = ( i << 8 ) | j;
// keep two positions as lo and hi byte!
this.nNumtranspositions = k;
this.fromCycle = permutationGenerator_fromCycle;
}
Can anyone explain the use of the double less than signs <<, as well as the single pipe | ?
Later in the script double greater than signs occur as well >>, also single ampersand & .
function permutationGenerator_fromCycle(anCycle) {
var anpermutation = new Array(this.nNumElements);
for (var i = 0; i < this.nNumElements; i++) anpermutation[i] = i;
for (var i = 0; i < anCycle.length; i++) {
var nT = this.antranspositions[anCycle[i]];
var n1 = nT & 255;
var n2 = (nT >> 8) & 255; // JC
nT = anpermutation[n1];
anpermutation[n1] = anpermutation[n2];
anpermutation[n2] = nT;
}
return anpermutation;
}
I am familiar with single < or > and of course logical && and logical || .
Thoughts?