# IT:AD:NET:HowTo:Licensing #



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* [http://www.softactivate.com/Purchase.aspx]
    * About 39Euros!
* [http://infralution.com/licensingpurchase.html](http://infralution.com/licensingpurchase.html)
    * About 170


<<
The library that I have successfully used for my licensing needs is SoftActivate Licensing SDK (from http://www.softactivate.com/ ). Unfortunately it is not completely free, but it is quite cheap compared to others which charge you an arm and a leg for the same functionality. This library generates digitally signed license keys using Eliptic Curve Cryptography (why ECC and not RSA ? Because with RSA, the generated license keys would be waay to long - like hunderds of characters long). What does this mean ? It means that there is one encryption key for license key generation and signing (which is NOT embedded in the application - it is only used at your company for generation), and a separate decryption key for digital signature verification of the license key (which is embedded in the application, but cannot be used to generate license keys, just to validate them). So even if a malicious party reverse engineers the application, they cannot generate license keys on your behalf.>>


## Resources ##

* [http://www.codeproject.com/Articles/398130/Software-Copy-Protection-for-Net-Applications-a-Tu](http://www.codeproject.com/Articles/398130/Software-Copy-Protection-for-Net-Applications-a-Tu)