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POObsfucate a 5 digit number
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  1. POObsfucate a 5 digit number
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    copied!<p>I wish to obfuscate a 5 digit number </p> <p>Properties of the obfuscated number that I care about:</p> <ul> <li>it's impossible (or as a fall back, extremely unlikely) to collide with other obfuscated numbers</li> <li>it's also a 5 digit number (no alpha characters please)</li> <li>it's not easily determinable by a regular human without computational assistance (e.g. it's not something obvious like "multiply by 2 and subtract 5" </li> <li>it's an algorithm ... as opposed to storing a look up table of all possible 5 digit numbers to their corresponding hash or some other "brute force" technique</li> </ul> <p>Properties of the obfuscated number that I don't care about:</p> <ul> <li>whether it's repeatable or not i.e. if "12345" always results in "73624", I okay</li> <li>whether it's cryptographically secure or not</li> </ul> <p>Thus far I haven't found anything that fits my requirements... but am hoping this is due to poor memory, incomplete education or dubious lifestyle choices rather than no "nice" solution being present.</p> <p>An example that can be easily translated into C# would be a bonus.</p> <p><strong>Update:</strong></p> <p>I'm investigating using the idea of doing a simple bit mapping for the moment.</p> <pre><code> static List&lt;int&gt; bitMapping = new List&lt;int&gt;() { 8, 6, 9, 3, 7, 5, ... etc... }; private static int Obfuscate(int number) { var bits = new bool[bitMapping.Count]; foreach (var ordinal in bitMapping) { var mask = (int)Math.Pow(2, ordinal); var bit = (mask &amp; number) == mask; var mappedOrdinal = bitMapping[ordinal]; bits[mappedOrdinal] = bit; } var obfuscatedNumber = 0; for (var ordinal = 0; ordinal &lt; bits.Length; ordinal++) { if (bits[ordinal]) { obfuscatedNumber += (int)Math.Pow(2, ordinal); } } return obfuscatedNumber; </code></pre> <p>It seems to meet most of my requirements thus far.</p>
 

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