我目前正在开发一个产品(用c#开发的)，可以免费下载和安装，但版本非常有限。要获得所有功能，用户必须支付许可费并获得密钥。然后，该密钥将被输入应用程序以“解锁”完整版本。
像这样使用许可密钥是很常见的，我想知道:
这个问题通常是怎么解决的? 如何生成密钥以及应用程序如何验证密钥? 我怎样才能避免一个密钥被发布在互联网上，并被其他没有支付许可证的人使用(一个基本上不是“他们的”密钥)。
我想我还应该以某种方式将密钥绑定到应用程序的版本，这样就有可能在功能版本中对新密钥收费。
在这种情况下，还有什么需要考虑的吗?
当前回答
我以前用过Crypkey。这是许多可用的之一。
使用任何许可方案，您只能在一定程度上保护软件。
其他回答
我们用来生成许可证密钥的c# / .NET引擎现在是开源的:
https://github.com/appsoftware/.NET-Licence-Key-Generator。
它基于“部分密钥验证”系统，这意味着只有用于生成密钥的密钥子集必须编译到您的分布式文件中。您自己创建密钥，因此许可证实现对于您的软件是惟一的。
如上所述，如果您的代码可以反编译，那么绕过大多数许可系统就相对容易。
要做到你所要求的一切，唯一的方法就是要求互联网接入和服务器验证。应用程序需要使用密钥登录到服务器，然后需要存储会话详细信息，如IP地址。这将防止密钥在多台不同的机器上使用。这通常不太受应用程序用户的欢迎，除非这是一个非常昂贵和复杂的应用程序，否则不值得这样做。
您可以只拥有应用程序的许可密钥，然后检查客户端密钥是否有效，但是很容易将此密钥分发给其他用户，并且可以使用反编译器生成新密钥。
你可以使用免费的第三方解决方案来解决这个问题，比如Quantum-Key。Net它是免费的，通过paypal为你创建的网络销售页面处理支付，通过电子邮件发放钥匙，并将钥匙锁定到特定的计算机以防止盗版。
你还应该注意混淆/加密你的代码，或者它可以很容易地使用De4dot和. netreflector等软件进行逆向工程。ConfuserEx是一个很好的免费代码混淆器，它使用起来快速简单，比昂贵的替代品更有效。
你应该通过De4Dot和. netreflector运行你完成的软件来逆向工程它，看看黑客会看到什么，如果他们做同样的事情，并确保你没有留下任何重要的代码暴露或未伪装。
你的软件仍然是可以被破解的，但对于那些偶然的破解者来说，这可能足以让他们望而却步，这些简单的步骤也可以防止你的代码被提取和重用。
https://quantum-key.net
如何使用ConfuserEx?
https://github.com/0xd4d/de4dot
https://www.red-gate.com/dynamic/products/dotnet-development/reflector/download
生成许可密钥的方法有很多，但真正安全的方法很少。这很遗憾，因为对于公司来说，许可证密钥的价值几乎与真正的现金相同。
理想情况下，您希望您的许可密钥具有以下属性:
Only your company should be able to generate license keys for your products, even if someone completely reverse engineers your products (which WILL happen, I speak from experience). Obfuscating the algorithm or hiding an encryption key within your software is really out of the question if you are serious about controlling licensing. If your product is successful, someone will make a key generator in a matter of days from release. A license key should be useable on only one computer (or at least you should be able to control this very tightly) A license key should be short and easy to type or dictate over the phone. You don't want every customer calling the technical support because they don't understand if the key contains a "l" or a "1". Your support department would thank you for this, and you will have lower costs in this area.
那么如何解决这些挑战呢?
The answer is simple but technically challenging: digital signatures using public key cryptography. Your license keys should be in fact signed "documents", containing some useful data, signed with your company's private key. The signatures should be part of the license key. The product should validate the license keys with the corresponding public key. This way, even if someone has full access to your product's logic, they cannot generate license keys because they don't have the private key. A license key would look like this: BASE32(CONCAT(DATA, PRIVATE_KEY_ENCRYPTED(HASH(DATA)))) The biggest challenge here is that the classical public key algorithms have large signature sizes. RSA512 has an 1024-bit signature. You don't want your license keys to have hundreds of characters. One of the most powerful approaches is to use elliptic curve cryptography (with careful implementations to avoid the existing patents). ECC keys are like 6 times shorter than RSA keys, for the same strength. You can further reduce the signature sizes using algorithms like the Schnorr digital signature algorithm (patent expired in 2008 - good :) ) This is achievable by product activation (Windows is a good example). Basically, for a customer with a valid license key, you need to generate some "activation data" which is a signed message embedding the computer's hardware id as the signed data. This is usually done over the internet, but only ONCE: the product sends the license key and the computer hardware id to an activation server, and the activation server sends back the signed message (which can also be made short and easy to dictate over the phone). From that moment on, the product does not check the license key at startup, but the activation data, which needs the computer to be the same in order to validate (otherwise, the DATA would be different and the digital signature would not validate). Note that the activation data checking do not require verification over the Internet: it is sufficient to verify the digital signature of the activation data with the public key already embedded in the product. Well, just eliminate redundant characters like "1", "l", "0", "o" from your keys. Split the license key string into groups of characters.
简单的答案-无论你使用什么方案都可以被破解。
不要用一个旨在防止黑客的系统来惩罚诚实的客户，因为黑客无论如何都会破解它。
一个简单的散列代码绑定到他们的电子邮件或类似的可能就足够了。当人们需要重新安装或更新硬件时，基于硬件的id总是会成为一个问题。
关于这个问题的好帖子: http://discuss.joelonsoftware.com/default.asp?biz.5.82298.34
