1 | // Unique ID creation requires a high quality random # generator. In the
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2 | // browser this is a little complicated due to unknown quality of Math.random()
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3 | // and inconsistent support for the `crypto` API. We do the best we can via
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4 | // feature-detection
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5 |
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6 | // getRandomValues needs to be invoked in a context where "this" is a Crypto implementation.
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7 | var getRandomValues = (typeof(crypto) != 'undefined' && crypto.getRandomValues.bind(crypto)) ||
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8 | (typeof(msCrypto) != 'undefined' && msCrypto.getRandomValues.bind(msCrypto));
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9 | if (getRandomValues) {
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10 | // WHATWG crypto RNG - http://wiki.whatwg.org/wiki/Crypto
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11 | var rnds8 = new Uint8Array(16); // eslint-disable-line no-undef
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12 |
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13 | module.exports = function whatwgRNG() {
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14 | getRandomValues(rnds8);
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15 | return rnds8;
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16 | };
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17 | } else {
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18 | // Math.random()-based (RNG)
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19 | //
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20 | // If all else fails, use Math.random(). It's fast, but is of unspecified
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21 | // quality.
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22 | var rnds = new Array(16);
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23 |
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24 | module.exports = function mathRNG() {
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25 | for (var i = 0, r; i < 16; i++) {
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26 | if ((i & 0x03) === 0) r = Math.random() * 0x100000000;
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27 | rnds[i] = r >>> ((i & 0x03) << 3) & 0xff;
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28 | }
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29 |
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30 | return rnds;
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31 | };
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32 | }
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