title: Need to sign a string with RSASSA-PKCS1-v1_5 signature in c#
body: <p>I have a string with a message and a private key.  I need to write some C# code that can sign this string with a RSASSA-PKCS1-v1_5 signature.</p>
  
  <p>Do you have any hints or suggestions as to where I should start looking to accomplish this?  Are there existing APIs in .NET or in available libraries to do this?</p>