Windows Communication Foundation with x509 and Compact Framework 3.5 Max Keylength

Question

I am using Windows Communication Foundation with x509 message layer security to communicate with a windows compact framework 3.5 device.

I am using makecert to create the certificates.

Does anyone know what is the largest size of key length I can use in this situation? currently using 1024 but would like to move up 2048.

I know the default keylength for makecert is 1024 but cant find anymore information or if there is a limit on what the compact framework can handle...

Answer 1

The RSA implementation used by the .Net framework, RSACryptoServiceProvider, actually uses the underlying Windows CryptoAPI implementation. Most modern Microsoft OSes support 384 to 16384 bit key sizes (see RSACryptoServiceProvider.KeySize). You can call RSACryptoServiceProvider.LegalKeySizes to see the accepted values on the target platform, too.