thedesk/app/js/common/sha256.js
2019-05-19 15:47:45 +09:00

96 lines
3.3 KiB
JavaScript

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;
};