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Generate Serial-Key

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Hi, how can I generate a serial key (like "w9rt-we25-wbvt-344") from a string? What algorithms are used? bye, Chris

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I mean:
How do I generate a (fixed length, unique) serial key from a string like username.

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You can use a hash function like MD5, RIPEMD or SHA256.

You could also use a digital signature.

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The obvious way: a hashing function. Applying some mathematical hash mechanism to the username to output a number which is virtually unique to the input.

Algorithms like MD4/5, SHA-*, CRC, etc.

Recommend that you salt the value well, and employ multiple algorithms. Serial key generators are notoriously easy to create and exploit from programs.

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If you are worried about cracks and keygens, and are selling this, use multiple checks within the program, as well as multiple functions to calculate the serial, as well as just random calculations that have no effect on the output to throw off a keygener. Most you do the time its: Decompile->Find serial code -> rip to keygen, but you can add stuff in there that makes it just that much harder.

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Just a note from a more end user perspective: some companies ensure that their keys only consist of characters that are very easy to distinguish i.e. they never include I, 1, 7 o 0 etc in their keys

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Quote:
Original post by thesimon
Just a note from a more end user perspective: some companies ensure that their keys only consist of characters that are very easy to distinguish i.e. they never include I, 1, 7 o 0 etc in their keys


This is easy enough via most hashing algorithms since they return large numbers. Hex characters are difficult to mis-judge.

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