Free Cryptography libraries

Question

What are the most stable and useful Cryptography libraries, that they are:

• written with/for python, c++, c#, .net
• opensource, GNU, or other free license

Answer 1

Take a look at KeyCzar

Some features of Keyczar include:

• A simple API
• Key rotation and versioning
• Safe default algorithms, modes, and key lengths
• Automated generation of initialization vectors and ciphertext signatures
• Java, Python, and C++ implementations
• International support in Java (Python coming soon)

Doesn't seem to have C# support though.