/* Source https://geraintluff.github.io/sha256/ Hosted version
    Version : 1.0
*/
var sha256 = function sha256(ascii) {
    function rightRotate(value, amount) {
	return (value>>>amount) | (value<<(32 - amount));
    };
    
    var mathPow = Math.pow;
    var maxWord = mathPow(2, 32);
    var lengthProperty = 'length'
    var i, j; // Used as a counter across the whole file
    var result = ''

    var words = [];
    var asciiBitLength = ascii[lengthProperty]*8;
    
    //* caching results is optional - remove/add slash from front of this line to toggle
    // Initial hash value: first 32 bits of the fractional parts of the square roots of the first 8 primes
    // (we actually calculate the first 64, but extra values are just ignored)
    var hash = sha256.h = sha256.h || [];
    // Round constants: first 32 bits of the fractional parts of the cube roots of the first 64 primes
    var k = sha256.k = sha256.k || [];
    var primeCounter = k[lengthProperty];
    /*/
      var hash = [], k = [];
      var primeCounter = 0;
    //*/

    var isComposite = {};
    for (var candidate = 2; primeCounter < 64; candidate++) {
	if (!isComposite[candidate]) {
	    for (i = 0; i < 313; i += candidate) {
		isComposite[i] = candidate;
	    }
	    hash[primeCounter] = (mathPow(candidate, .5)*maxWord)|0;
	    k[primeCounter++] = (mathPow(candidate, 1/3)*maxWord)|0;
	}
    }
    
    ascii += '\x80' // Append Ƈ' bit (plus zero padding)
    while (ascii[lengthProperty]%64 - 56) ascii += '\x00' // More zero padding
    for (i = 0; i < ascii[lengthProperty]; i++) {
	j = ascii.charCodeAt(i);
	if (j>>8) return; // ASCII check: only accept characters in range 0-255
	words[i>>2] |= j << ((3 - i)%4)*8;
    }
    words[words[lengthProperty]] = ((asciiBitLength/maxWord)|0);
    words[words[lengthProperty]] = (asciiBitLength)
    
    // process each chunk
    for (j = 0; j < words[lengthProperty];) {
	var w = words.slice(j, j += 16); // The message is expanded into 64 words as part of the iteration
	var oldHash = hash;
	// This is now the undefinedworking hash", often labelled as variables a...g
	// (we have to truncate as well, otherwise extra entries at the end accumulate
	hash = hash.slice(0, 8);
	
	for (i = 0; i < 64; i++) {
	    var i2 = i + j;
	    // Expand the message into 64 words
	    // Used below if 
	    var w15 = w[i - 15], w2 = w[i - 2];

	    // Iterate
	    var a = hash[0], e = hash[4];
	    var temp1 = hash[7]
		+ (rightRotate(e, 6) ^ rightRotate(e, 11) ^ rightRotate(e, 25)) // S1
		+ ((e&hash[5])^((~e)&hash[6])) // ch
		+ k[i]
	    // Expand the message schedule if needed
		+ (w[i] = (i < 16) ? w[i] : (
		    w[i - 16]
			+ (rightRotate(w15, 7) ^ rightRotate(w15, 18) ^ (w15>>>3)) // s0
			+ w[i - 7]
			+ (rightRotate(w2, 17) ^ rightRotate(w2, 19) ^ (w2>>>10)) // s1
		)|0
		  );
	    // This is only used once, so *could* be moved below, but it only saves 4 bytes and makes things unreadble
	    var temp2 = (rightRotate(a, 2) ^ rightRotate(a, 13) ^ rightRotate(a, 22)) // S0
		+ ((a&hash[1])^(a&hash[2])^(hash[1]&hash[2])); // maj
	    
	    hash = [(temp1 + temp2)|0].concat(hash); // We don't bother trimming off the extra ones, they're harmless as long as we're truncating when we do the slice()
	    hash[4] = (hash[4] + temp1)|0;
	}
	
	for (i = 0; i < 8; i++) {
	    hash[i] = (hash[i] + oldHash[i])|0;
	}
    }
    
    for (i = 0; i < 8; i++) {
	for (j = 3; j + 1; j--) {
	    var b = (hash[i]>>(j*8))&255;
	    result += ((b < 16) ? 0 : '') + b.toString(16);
	}
    }
    return result;
};
