96 lines
3.3 KiB
JavaScript
96 lines
3.3 KiB
JavaScript
const sha256 = function sha256(ascii) {
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function rightRotate(value, amount) {
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return (value >>> amount) | (value << (32 - amount));
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};
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const mathPow = Math.pow;
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const maxWord = mathPow(2, 32);
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const lengthProperty = 'length'
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let i, j; // Used as a counter across the whole file
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let result = ''
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let words = [];
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const asciiBitLength = ascii[lengthProperty] * 8;
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//* caching results is optional - remove/add slash from front of this line to toggle
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// Initial hash value: first 32 bits of the fractional parts of the square roots of the first 8 primes
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// (we actually calculate the first 64, but extra values are just ignored)
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let hash = sha256.h = sha256.h || [];
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// Round constants: first 32 bits of the fractional parts of the cube roots of the first 64 primes
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let k = sha256.k = sha256.k || [];
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let primeCounter = k[lengthProperty];
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/*/
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var hash = [], k = [];
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var primeCounter = 0;
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//*/
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let isComposite = {};
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for (let candidate = 2; primeCounter < 64; candidate++) {
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if (!isComposite[candidate]) {
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for (i = 0; i < 313; i += candidate) {
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isComposite[i] = candidate;
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}
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hash[primeCounter] = (mathPow(candidate, .5) * maxWord) | 0;
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k[primeCounter++] = (mathPow(candidate, 1 / 3) * maxWord) | 0;
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}
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}
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ascii += '\x80' // Append Ƈ' bit (plus zero padding)
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while (ascii[lengthProperty] % 64 - 56) ascii += '\x00' // More zero padding
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for (i = 0; i < ascii[lengthProperty]; i++) {
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j = ascii.charCodeAt(i);
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if (j >> 8) return; // ASCII check: only accept characters in range 0-255
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words[i >> 2] |= j << ((3 - i) % 4) * 8;
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}
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words[words[lengthProperty]] = ((asciiBitLength / maxWord) | 0);
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words[words[lengthProperty]] = (asciiBitLength)
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// process each chunk
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for (j = 0; j < words[lengthProperty];) {
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let w = words.slice(j, j += 16); // The message is expanded into 64 words as part of the iteration
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const oldHash = hash;
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// This is now the undefinedworking hash", often labelled as variables a...g
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// (we have to truncate as well, otherwise extra entries at the end accumulate
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hash = hash.slice(0, 8);
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for (i = 0; i < 64; i++) {
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const i2 = i + j;
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// Expand the message into 64 words
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// Used below if
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const w15 = w[i - 15], w2 = w[i - 2];
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// Iterate
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const a = hash[0], e = hash[4];
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const temp1 = hash[7]
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+ (rightRotate(e, 6) ^ rightRotate(e, 11) ^ rightRotate(e, 25)) // S1
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+ ((e & hash[5]) ^ ((~e) & hash[6])) // ch
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+ k[i]
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// Expand the message schedule if needed
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+ (w[i] = (i < 16) ? w[i] : (
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w[i - 16]
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+ (rightRotate(w15, 7) ^ rightRotate(w15, 18) ^ (w15 >>> 3)) // s0
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+ w[i - 7]
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+ (rightRotate(w2, 17) ^ rightRotate(w2, 19) ^ (w2 >>> 10)) // s1
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) | 0
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);
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// This is only used once, so *could* be moved below, but it only saves 4 bytes and makes things unreadble
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const temp2 = (rightRotate(a, 2) ^ rightRotate(a, 13) ^ rightRotate(a, 22)) // S0
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+ ((a & hash[1]) ^ (a & hash[2]) ^ (hash[1] & hash[2])); // maj
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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()
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hash[4] = (hash[4] + temp1) | 0;
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}
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for (i = 0; i < 8; i++) {
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hash[i] = (hash[i] + oldHash[i]) | 0;
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}
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}
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for (i = 0; i < 8; i++) {
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for (j = 3; j + 1; j--) {
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const b = (hash[i] >> (j * 8)) & 255;
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result += ((b < 16) ? 0 : '') + b.toString(16);
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}
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}
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return result;
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}; |