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Topic: Encryption, MD5, RC4
Conf: (P-PDF) Developers, Msg: 53094
From: knewman
Date: 5/29/2002 04:56 PM

The PDF specification says encrypted files use the MD5 hashing algorithm and the RC4 encryption algorithm.

MD5 seems to be an RFC on the internet, so I don't think there are limitations to using it. Am I wrong? Is there a patent for MD5, or any licensing fees that you need to pay?

I know that RC4 is patented by RSA Security and you need to license it. There is a site ciphersaber.gurus.com that has the description of "ARC4" which is an algorithm that does the same thing as RC4 - but it isn't RC4. Would it be illegal to use this ARC4 without a license from RSA?

If you use an API to generate PDF files, and the API writers have a license from RSA for the RC4 encryption - do the end users need a license too, or just the API writers?

I'm a programmer - not a lawyer... but I don't want to do anything illegal!

Thanks,
Kevin

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