Can RSACryptoServiceProvider (.NET's RSA) use SHA256 for encryption (not signing) instead of SHA1?

Question

When encrypting, can RSACryptoServiceProvider (or any other RSA encryptor available from .NET) use SHA256 instead of SHA1?

SHA1 appears to be hard coded with no way

Answer 1

As of .NET 3.5 SP1 on any Windows Server 2003 and higher OS, yes, the RSACryptoServiceProvider does support RSA-SHA256 for signing, but not encrypting.

From the blog post Using RSACryptoServiceProvider for RSA-SHA256 signatures:

byte[] data = new byte[] { 0, 1, 2, 3, 4, 5 };
using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
{
    byte[] signature = rsa.SignData(data, "SHA256");

    if (rsa.VerifyData(data, "SHA256", signature))
    {
        Console.WriteLine("RSA-SHA256 signature verified");
    }
    else
    {
        Console.WriteLine("RSA-SHA256 signature failed to verify");
    }
}

You should read the original post though, as there are some gotcha's to be aware of.