Need a function to create a smaller hash from a larger hash

Question

Basically I have 24 digit hexadecimal id values. I need a function that can take one of these ids and turn it into a 10 digit decimal value. It does not need to be cryptographically secure. I just need to ensure that the same input will always get the same output, and that the resulting value has as low of a chance as possible to be the same with different inputs.

Without knowing something about the distribution of those hexadecimal ID values, we can't suggest anything with a lower chance of duplicates than just converting from hex to decimal and taking the last ten digits. — ruakh, Mar 24 '17 at 18:37
See also: [smaller hash from a standard hash](http://stackoverflow.com/a/32913069/3789665). — greybeard, Mar 25 '17 at 00:41

score 2 · Accepted Answer · answered Mar 24 '17 at 18:36

2

Something like this should work as you are asking -

shorterHash := MD5(hexId) # 16 byte
return shortedHash.substring(0, 10) # this is still non-colliding enough

I hope there are many standard implementations of MD5 on your language on internet.

answered Mar 24 '17 at 18:36

Kaidul

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Glad to help! Please accept the answer if it's working. – Kaidul Mar 24 '17 at 18:41
I will, can't for 5 more minutes. – chrispytoes Mar 24 '17 at 18:42
1

... which is 10 bytes and thus by far greater than 10 decimal digits. – stefan Mar 24 '17 at 19:05
Do you have any idea to store a digit in less than 1 byte? – Kaidul Mar 24 '17 at 19:07

Need a function to create a smaller hash from a larger hash

1 Answers1