Implementing hashed license type

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Emilio

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Nov 29, 2011, 11:59:34 PM11/29/11
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Hi LicMax team!

I'm developing my first app for Blackberry devices and I'm thinking of
using hash license type; just offline verification.

When adding a new product instance you are asked about license
mechanism, in my case it would be Hashed.

Then I have to complete the "Hashed license key configuration" form.

First doubt about this:

1) Which Character set should I use?

2) If I select HEX key format the it doesn't matter wich Base Encoding/
Decoding I choose, since Hex keys aren't encoded, am I right?

3)Suppose I choose LAST(or START) for segment of hashed output and
let's say 10 as license key lenght; do I have to modify anything in
the LicValidHashedVerifier.java you provide in Reference
Implementation? I mean, the end user gets the 10 characters license
key(or 5 or 15), then the app ask for it and does the verification no
matter the lenght of the key?

Thanks for your help, and sorry for my english since my first language
is spanish.

Emilio Toncovich

licmax

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Nov 30, 2011, 5:12:20 PM11/30/11
to lic...@googlegroups.com
Dear Emilio,

Thanks for your interest in using the licmax system. Please see our answers below.


1) Which Character set should I use?

Here you want to use the same character set that you would use when constructing the key at the client side (your app running on the device). The character set "iso_8859_1" is most likely guaranteed to be available for all devices and platforms. The main thing is to make sure the same character set exists on the platform you want to deliver your program to.

2) If I select HEX key format the it doesn't matter wich Base Encoding/
Decoding I choose, since Hex keys aren't encoded, am I right?

Yes, you are right. Also, when in doubt, make an experiment.

3)Suppose I choose LAST(or START) for segment of hashed output and
let's say 10 as license key lenght; do I have to modify anything in
the LicValidHashedVerifier.java you provide in Reference
Implementation? I mean, the end user gets the 10 characters license
key(or 5 or 15), then the app ask for it and does the verification no
matter the lenght of the key?

Whatever you ask for from the licmax server for hashed license keys, you would need to do the exact same thing in your program at run time. For example, when you ask for the START 10 characters of the hashed license key generated by licmax, then you would have to take the START 10 characters of the key you generate at run time in your program too. The outcome should be exactly the same. Whichever segment of the long hashed license key generated you ask for, you would extract the same segment from the hashed key you generate in your program.

Should you need further help, please don't hesitate to call us too. We can guide you directly. Good luck with your product.

The English is just fine :)


Just for your reference, here is a blurb on Hashed License Key verification from our site: http://www.lichmax.com/developers.html#hashed_licensinghttp://www.lichmax.com/developers.html#hashed_licensing

Developers would code the application to apply the same hash algorithm they chose when adding their Product Instance. If you apply the same algorithm on the same secret key you chose at licmax™, you would end up with the same exact digest (license key). Compare the digest string you get from the algorithm your application applies when it runs on the device with the license key it has obtained from licmax. If they are the same, then the license key is valid. If they differ, then the license key is invalid.

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