35 lines
1.3 KiB
JavaScript
35 lines
1.3 KiB
JavaScript
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// Unique ID creation requires a high quality random # generator. In the
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// browser this is a little complicated due to unknown quality of Math.random()
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// and inconsistent support for the `crypto` API. We do the best we can via
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// feature-detection
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// getRandomValues needs to be invoked in a context where "this" is a Crypto
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// implementation. Also, find the complete implementation of crypto on IE11.
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var getRandomValues = (typeof(crypto) != 'undefined' && crypto.getRandomValues && crypto.getRandomValues.bind(crypto)) ||
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(typeof(msCrypto) != 'undefined' && typeof window.msCrypto.getRandomValues == 'function' && msCrypto.getRandomValues.bind(msCrypto));
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if (getRandomValues) {
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// WHATWG crypto RNG - http://wiki.whatwg.org/wiki/Crypto
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var rnds8 = new Uint8Array(16); // eslint-disable-line no-undef
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module.exports = function whatwgRNG() {
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getRandomValues(rnds8);
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return rnds8;
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};
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} else {
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// Math.random()-based (RNG)
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//
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// If all else fails, use Math.random(). It's fast, but is of unspecified
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// quality.
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var rnds = new Array(16);
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module.exports = function mathRNG() {
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for (var i = 0, r; i < 16; i++) {
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if ((i & 0x03) === 0) r = Math.random() * 0x100000000;
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rnds[i] = r >>> ((i & 0x03) << 3) & 0xff;
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}
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return rnds;
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};
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}
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