lib.js

/*************************

Use: 'hello'.encrypt(13).decrypt(13)

*************************/
// SHA256 Lib

String.prototype.sha256 = function() {
	let s = this;

    const chrsz = 8;
    const hexcase = 0;

    function safe_add(x, y) {
        const lsw = (x & 0xFFFF) + (y & 0xFFFF);
        const msw = (x >> 16) + (y >> 16) + (lsw >> 16);
        return (msw << 16) | (lsw & 0xFFFF);
    }

    function S(X, n) {
        return (X >>> n) | (X << (32 - n));
    }

    function R(X, n) {
        return (X >>> n);
    }

    function Ch(x, y, z) {
        return ((x & y) ^ ((~x) & z));
    }

    function Maj(x, y, z) {
        return ((x & y) ^ (x & z) ^ (y & z));
    }

    function Sigma0256(x) {
        return (S(x, 2) ^ S(x, 13) ^ S(x, 22));
    }

    function Sigma1256(x) {
        return (S(x, 6) ^ S(x, 11) ^ S(x, 25));
    }

    function Gamma0256(x) {
        return (S(x, 7) ^ S(x, 18) ^ R(x, 3));
    }

    function Gamma1256(x) {
        return (S(x, 17) ^ S(x, 19) ^ R(x, 10));
    }

    function core_sha256(m, l) {
        const K = new Array(0x428A2F98, 0x71374491, 0xB5C0FBCF, 0xE9B5DBA5, 0x3956C25B, 0x59F111F1, 0x923F82A4, 0xAB1C5ED5, 0xD807AA98, 0x12835B01, 0x243185BE, 0x550C7DC3, 0x72BE5D74, 0x80DEB1FE, 0x9BDC06A7, 0xC19BF174, 0xE49B69C1, 0xEFBE4786, 0xFC19DC6, 0x240CA1CC, 0x2DE92C6F, 0x4A7484AA, 0x5CB0A9DC, 0x76F988DA, 0x983E5152, 0xA831C66D, 0xB00327C8, 0xBF597FC7, 0xC6E00BF3, 0xD5A79147, 0x6CA6351, 0x14292967, 0x27B70A85, 0x2E1B2138, 0x4D2C6DFC, 0x53380D13, 0x650A7354, 0x766A0ABB, 0x81C2C92E, 0x92722C85, 0xA2BFE8A1, 0xA81A664B, 0xC24B8B70, 0xC76C51A3, 0xD192E819, 0xD6990624, 0xF40E3585, 0x106AA070, 0x19A4C116, 0x1E376C08, 0x2748774C, 0x34B0BCB5, 0x391C0CB3, 0x4ED8AA4A, 0x5B9CCA4F, 0x682E6FF3, 0x748F82EE, 0x78A5636F, 0x84C87814, 0x8CC70208, 0x90BEFFFA, 0xA4506CEB, 0xBEF9A3F7, 0xC67178F2);
        const HASH = new Array(0x6A09E667, 0xBB67AE85, 0x3C6EF372, 0xA54FF53A, 0x510E527F, 0x9B05688C, 0x1F83D9AB, 0x5BE0CD19);
        const W = new Array(64);
        let a;
        let b;
        let c;
        let d;
        let e;
        let f;
        let g;
        let h;
        var i;
        var j;
        let T1;
        let T2;
        m[l >> 5] |= 0x80 << (24 - l % 32);
        m[((l + 64 >> 9) << 4) + 15] = l;
        for (var i = 0; i < m.length; i += 16) {
            a = HASH[0];

            b = HASH[1];

            c = HASH[2];

            d = HASH[3];

            e = HASH[4];

            f = HASH[5];

            g = HASH[6];

            h = HASH[7];
            for (var j = 0; j < 64; j++) {
                if (j < 16) W[j] = m[j + i];
                else W[j] = safe_add(safe_add(safe_add(Gamma1256(W[j - 2]), W[j - 7]), Gamma0256(W[j - 15])), W[j - 16]);

                T1 = safe_add(safe_add(safe_add(safe_add(h, Sigma1256(e)), Ch(e, f, g)), K[j]), W[j]);
                T2 = safe_add(Sigma0256(a), Maj(a, b, c));
                h = g;
                g = f;
                f = e;
                e = safe_add(d, T1);
                d = c;
                c = b;
                b = a;
                a = safe_add(T1, T2);
            }
            HASH[0] = safe_add(a, HASH[0]);

            HASH[1] = safe_add(b, HASH[1]);

            HASH[2] = safe_add(c, HASH[2]);

            HASH[3] = safe_add(d, HASH[3]);

            HASH[4] = safe_add(e, HASH[4]);

            HASH[5] = safe_add(f, HASH[5]);

            HASH[6] = safe_add(g, HASH[6]);

            HASH[7] = safe_add(h, HASH[7]);

        }
        return HASH;
    }

    function str2binb(str) {
        const bin = Array();

        const mask = (1 << chrsz) - 1;

        for (let i = 0; i < str.length * chrsz; i += chrsz) {

            bin[i >> 5] |= (str.charCodeAt(i / chrsz) & mask) << (24 - i % 32);

        }

        return bin;

    }


    function Utf8Encode(string) {

        string = string.replace(/\r\n/g, "\n");

        let utftext = "";
        for (let n = 0; n < string.length; n++) {
            const c = string.charCodeAt(n);
            if (c < 128) {

                utftext += String.fromCharCode(c);

            } else if ((c > 127) && (c < 2048)) {

                utftext += String.fromCharCode((c >> 6) | 192);

                utftext += String.fromCharCode((c & 63) | 128);

            } else {

                utftext += String.fromCharCode((c >> 12) | 224);

                utftext += String.fromCharCode(((c >> 6) & 63) | 128);

                utftext += String.fromCharCode((c & 63) | 128);

            }
        }
        return utftext;

    }

    function binb2hex(binarray) {

        const hex_tab = hexcase ? "0123456789ABCDEF" : "0123456789abcdef";

        let str = "";

        for (let i = 0; i < binarray.length * 4; i++) {

            str += hex_tab.charAt((binarray[i >> 2] >> ((3 - i % 4) * 8 + 4)) & 0xF) +

                hex_tab.charAt((binarray[i >> 2] >> ((3 - i % 4) * 8)) & 0xF);

        }

        return str;

    }
    s = Utf8Encode(s);

    return binb2hex(core_sha256(str2binb(s), s.length * chrsz));
}

function* rand(seed) {
	let s = seed
	while (true) {
		const hash = s.toString().sha256().slice(0, 10)
		const n = parseInt(hash, 16)
		let r = (n >> 13 * s) % 99371
		s = (r ^ n << 2 + n) % 70937
		yield Math.abs(r) / 99371
	}
}

Number.prototype.genKey = function (c) {
	const alphabet = "abcdefghijklmnopqrstuvwxyz".split("")
	let out = ""
	let gen = rand(this)
	for (var i = 0; i < c; i++) {
		out += alphabet[Math.floor(gen.next().value * alphabet.length)]
	}
	return out;
};

String.prototype.encrypt = function (c) {
	const key = c.genKey(this.length)
	const alphabet = "abcdefghijklmnopqrstuvwxyz".split("")
	let nText = []
	let kText = []
	for (let i of this) {
		nText.push(alphabet.indexOf(i.toLowerCase()))
	}
	for (let i of key) {
		kText.push(alphabet.indexOf(i.toLowerCase()))
	}
	let out = ""
	for (let i in nText) {
		out += alphabet[(nText[i] + kText[i]) % 26]
	}
	return out;
}
String.prototype.decrypt = function (c) {
	const key = c.genKey(this.length)
	const alphabet = "abcdefghijklmnopqrstuvwxyz".split("")
	let nText = []
	let kText = []
	for (let i of this) {
		nText.push(alphabet.indexOf(i.toLowerCase()))
	}
	for (let i of key) {
		kText.push(alphabet.indexOf(i.toLowerCase()))
	}
	let out = ""
	for (let i in nText) {
		out += alphabet[(nText[i] - kText[i]) < 0 ? 26 + (nText[i] - kText[i]) : (nText[i] - kText[i]) % 26]
	}
	return out;
}

module.exports = {
	encrypt: (str, key) => str.encrypt(key),
	decrypt: (str, key) => str.decrypt(key)
}