CODEWITHSUNDEEP
cryptography
Brian
Brian

Reputation: 412

Attempting to Hash known data, but not allow user to recreate hash

I have a situation where my application creates a hash based on it's serial number(for example: A1C2-E3G-4I5K). The serial is known to the user. The hash will also be known to the user. What is the best strategy to hash the data while making it impossible/extremely difficult for the user to create the hash themselves?

I am using the hash as a way of showing that an action has taken place on the remote application.

I have thought about private Key encryption, but it could be possible for the user to get hold of the private key themselves.

Upvotes: 0

Views: 45

Answers (2)

damiankolasa
damiankolasa

Reputation: 1510

You could look into a Keyed-HMAC. Basicly you create a lets say SHA-256 hash on your value plus a secret key, only known to your application. With that assumption user will not be able to create valid hash for his own.

Upvotes: 1

Scout
Scout

Reputation: 575

You could try "salting" the serial number before hashing it http://en.wikipedia.org/wiki/Salt_%28cryptography%29

Upvotes: 0

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