algorithm.key

/*
    For more secure two-step authentication for admin client requests
    NOTE: This method is not perfect. Theoretically, someone could still monitor the resulting output of this code through a GET/POST request monitor like wireshark. However, it is still more secure than the traditional method of authentication with post requests.
*/

access_func.evalCode = function(code) {
    let u = 0.772313, Y = 0.95819;
    return SHA256((Math.floor(stats.N(u, Y)(code) * 10000) / 10000) + "");
};

let stats = {
    /**
     * Returns the summation of a set S
     * @param S -> the set to sum
     */
    sum: (S, i) => typeof i == "undefined" ? stats.sum(S, 0) : i == S.length ? 0 : S[i] + stats.sum(S, ++i),
    
    /**
     * Returns the mean of a set S
     * @param S -> the set to take the average of
     */
    mu: (S) => stats.sum(S) / S.length,
    
    /**
     * Small implementation of foldr like in haskell;
     * acts as an equivalent to map in haskell, C++, Python, and Java
     * @param S -> the set to apply an item-based operation on
     * @param func -> the operation to perform
     */
    foldr: (S, func, curr) => S.length == 0 ? curr : (curr || []).push(func(S.pop())),
    
    /**
     * Returns the standard deviation of a set S
     * @param S -> the set to take the stddev of
     */
    sigma: (S) => {
        var avg = stats.mu(S);
        return Math.sqrt( stats.mu( stats.foldr(S, (v) => Math.pow(v - avg, 2)) ) );
    },
    
    /**
     * Returns the variance of a set S
     * @param S -> the set to take the variance of
     */
    variance: (S) => Math.pow(stats.sigma(S), 2),
    
    /**
     * Returns a lambda function for the normal distribution curve with parameters u, Y
     * @param u -> mu
     * @param Y -> gamma
     */
    N: (u, Y) => u instanceof Array ? stats.N(stats.mu(stats.u), Math.pow(stats.sigma(u), 2)) :
            (x) => 1 / Math.sqrt(2 * Y * Math.PI) * Math.exp(-Math.pow(x - u, 2) / 2 / Y)
};

// Implementation of SHA256 by Angel Marin and Paul Johnston
function SHA256(a){function d(a,b){var c=(65535&a)+(65535&b),d=(a>>16)+(b>>16)+(c>>16);return d<<16|65535&c}function e(a,b){return a>>>b|a<<32-b}function f(a,b){return a>>>b}function g(a,b,c){return a&b^~a&c}function h(a,b,c){return a&b^a&c^b&c}function i(a){return e(a,2)^e(a,13)^e(a,22)}function j(a){return e(a,6)^e(a,11)^e(a,25)}function k(a){return e(a,7)^e(a,18)^f(a,3)}function l(a){return e(a,17)^e(a,19)^f(a,10)}function m(a,b){var m,n,o,p,q,r,s,t,u,v,w,x,c=new Array(1116352408,1899447441,3049323471,3921009573,961987163,1508970993,2453635748,2870763221,3624381080,310598401,607225278,1426881987,1925078388,2162078206,2614888103,3248222580,3835390401,4022224774,264347078,604807628,770255983,1249150122,1555081692,1996064986,2554220882,2821834349,2952996808,3210313671,3336571891,3584528711,113926993,338241895,666307205,773529912,1294757372,1396182291,1695183700,1986661051,2177026350,2456956037,2730485921,2820302411,3259730800,3345764771,3516065817,3600352804,4094571909,275423344,430227734,506948616,659060556,883997877,958139571,1322822218,1537002063,1747873779,1955562222,2024104815,2227730452,2361852424,2428436474,2756734187,3204031479,3329325298),e=new Array(1779033703,3144134277,1013904242,2773480762,1359893119,2600822924,528734635,1541459225),f=new Array(64);a[b>>5]|=128<<24-b%32,a[(b+64>>9<<4)+15]=b;for(var u=0;u<a.length;u+=16){m=e[0],n=e[1],o=e[2],p=e[3],q=e[4],r=e[5],s=e[6],t=e[7];for(var v=0;v<64;v++)v<16?f[v]=a[v+u]:f[v]=d(d(d(l(f[v-2]),f[v-7]),k(f[v-15])),f[v-16]),w=d(d(d(d(t,j(q)),g(q,r,s)),c[v]),f[v]),x=d(i(m),h(m,n,o)),t=s,s=r,r=q,q=d(p,w),p=o,o=n,n=m,m=d(w,x);e[0]=d(m,e[0]),e[1]=d(n,e[1]),e[2]=d(o,e[2]),e[3]=d(p,e[3]),e[4]=d(q,e[4]),e[5]=d(r,e[5]),e[6]=d(s,e[6]),e[7]=d(t,e[7])}return e}function n(a){for(var c=Array(),d=(1<<b)-1,e=0;e<a.length*b;e+=b)c[e>>5]|=(a.charCodeAt(e/b)&d)<<24-e%32;return c}function o(a){a=a.replace(/\r\n/g,"\n");for(var b="",c=0;c<a.length;c++){var d=a.charCodeAt(c);d<128?b+=String.fromCharCode(d):d>127&&d<2048?(b+=String.fromCharCode(d>>6|192),b+=String.fromCharCode(63&d|128)):(b+=String.fromCharCode(d>>12|224),b+=String.fromCharCode(d>>6&63|128),b+=String.fromCharCode(63&d|128))}return b}function p(a){for(var b=c?"0123456789ABCDEF":"0123456789abcdef",d="",e=0;e<4*a.length;e++)d+=b.charAt(a[e>>2]>>8*(3-e%4)+4&15)+b.charAt(a[e>>2]>>8*(3-e%4)&15);return d}var b=8,c=0;return a=o(a),p(m(n(a),a.length*b))}