Cryptography Stack Exchange
Cryptography Stack Exchange

Questions tagged [copy-protection]

Copy protection or content protection covers various mechanism, such as DRM and software license keys, used to restrict the unauthorized copying or use of software or digital media.

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Advanced Access Content System (AACS) and Subset Difference techniques for Broadcast Encryption

I'm trying to get a grasp on AACS and Subset Difference (archived version with images) for a project I'm working on and am having a hard time coming up with a technically valid layman explanation, let alone implementation. Is it fair to say that the…
makerofthings7
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Cryptographically secure product keys

I am looking for a scheme to generate and validate cryptographically secure product keys. My requirements are: Unforgeable. It must be impossible (or at least very hard) for users to forge a product key. Short. Users may enter product keys by…
Bill Zissimopoulos
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Is a RSA-signature of some identifying data a safe way to implement a license key?

I have this idea of implementing a license key: After the user downloads the program, he connects to a website and sends his Windows product ID. The website, then, sends this back to him with a signature using a private RSA key. The program, then,…
ispiro
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Cipher for Product Registration?

I'd like to implement a "Product Registration" scheme into my software where upon initial use, the User must enter a key to unlock it. The key they enter is compared to their encrypted Username. They would have to acquire the key from myself if…
Anti Earth
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Can I use SHA1 as license key?

I have recently started looking into creating secure, while not validating against an external server, software product keys. The idea I have had is to create a key consisting of two parts firstly a section that contains some (but not all) details…
MindStormer
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How does PUF hardware help in software activation?

I have read that one of the PUF's application is software licensing, but do not know how. I have been reading different articles and forums (such as here), but still not clear for me. One vague point for me is that PUF is a hardware and I do not…
Shannon
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A situation where security by obscurity might be the best solution - or am I wrong?

Imagine the following situation. There is an application for a microcontroller-driven system. The profits are made from manufacturing and selling the device itself. However, it is expected, that the users can later download software-updates from a…
vsz
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One-time token to decrypt a local file

I am trying to achieve the following: Encrypted files are stored on users filesystem. The user uses my client to authenticate against a server. Once he is authenticated successfully he gets a token to decrypt the files. Things I want to ensure: the…
esskar
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Is AES secure for java application licensing?

I have to license a java application and want to code a quick implementation, the scheme I came up with is: The Application calculates a string X which we assume to be the md5 sum of the computer's mac address, the current date and some other…
dendini
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Activation keys and asymmetric encryption

To me it seems that a quite safe way of creating activation keys is by using asymmetric encryption, so that the end-user could only reverse-engineer the validation method. This way the company keeps the generation algorithm (and key) safe. Assume…
Fabi
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Short software license keys with asymmetric verification

Would it be possible to implement a modern version of the old software license key scheme that uses an asymmetric signing approach, while keeping the length of the key short, say 40 chars of base64? The purpose is to use license keys to unlock…
Larsp
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AES-CBC pre-determined IV vs. null IV

Is there any security advantage to using a pre-determined IV in CBC mode over a null IV? I'm implementing a license key system similar to this article on CodeProject, but I'm confused by the authors use of a pre-determined IV embedded in the client…
Neil
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What is the proper approach to software licensing system?

I am willing to create a server side licensing system for my commercial softwares but not really sure what cryptography method I should be using for best possible security per the standard of modern cryptography and how should I implement the…
Farukh
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Strategies for securing public key storage on software

I´m kind of new in this so I apologize in advance for any noob mistakes (feel free to point it out) We are developing a licensing mechanism on our software, and I would like some advice. The software is installed on premises on the client, good…
Fedaykin
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How to make a document truly read only

How is it possibile to cryptographically make a document truly read only? As in read only I imply that the user can obviously view it which can be achieved by coding which pixels have which colors. But how is it done in the industry? and what's more…
Samuel Allan
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