54 lines
1.6 KiB
JavaScript
54 lines
1.6 KiB
JavaScript
/*
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The current timestamp is sha1 hashed, then that hash value is converted
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into a number system represented by a 'legible' alphabet.
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This provides several enhancements over the default random keygen.
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1) Keys are unlikely to collide due to using timestamp as seed
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2) Keys will display more entropy due to sha1-hashing
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3) Similar-looking letters have been removed from alphabet
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*/
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var crypto = require('crypto');
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// the alphabet is separated this way so when we convert hex to this system,
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// we can have some manner of style, like upper case, followed by 2 lower case, etc.
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var code = ['ABCDEFGHJKMNPRSTWXYZ',
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'abcdefhkmnprstwxyz',
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/*'abcdefhkmnprstwxyz',
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'0123456789'*/];
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function sha1(str) {
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var hash = crypto.createHash('sha1');
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hash.update(str);
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return hash.digest('hex');
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}
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function convertNumberToLegible(n) {
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var legible = '';
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var codeIndex = 0;
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var alphabet = code[codeIndex];
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while (n > 0) {
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var c = n % alphabet.length;
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n = Math.floor(n / alphabet.length);
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legible += alphabet.charAt(c);
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codeIndex = (codeIndex+1) % code.length;
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alphabet = code[codeIndex];
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}
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return legible;
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}
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function createKey(keyLength) {
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// process.hrtime() gives more precision (nanoseconds?) than new Date().getTime() (milliseconds)
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var time = process.hrtime().join('');
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var sha1Hex= sha1(time).substring(0, 8);
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var key = convertNumberToLegible(parseInt(sha1Hex, 16));
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if (key.length > keyLength) {
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return key.substring(0, keyLength);
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}
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return key;
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};
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var UniqueRandomKeyGenerator = function() {};
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UniqueRandomKeyGenerator.prototype.createKey = createKey;
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module.exports = UniqueRandomKeyGenerator;
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