Crypto.Net is a free and open cryptography library for C# and .Net. AES (Rijndeal), Twofish, Blowfish, RSA, Diffie-Hellman, SSL/TLS, X509-Certificate builder, stream cipher modes or a secure netowrk stream are only some features of this library.
Download
Binaries
The binaries contain the Crypto.Net library and some examples: