RE: RSACryptoServiceProvider error with message "Illegal key size for this algorithm"

From: Shawn Farkas (shawnfa_at_online.microsoft.com)
Date: 04/23/04 

Date: Thu, 22 Apr 2004 23:44:09 GMT

Hi Johan,

        The RSACryptoServiceProvider class is actually a pretty thin wrapper around Windows' CAPI implementation of RSA. Since CAPI
delegates its work to various crytpo service providers, the RSACryptoServiceProvider can provide no stronger protection than the CSP installed
on your machine. Check to see if you've got the enhanced CSP installed on the Win9x machine, by checking to see if rsaenh.dll is on your system.
You can also check the IE help->about dialog box to check to see what the encryption strength is on your machine.

I've also written a blog posting on how to detect which CSP you have installed:
http://blogs.msdn.com/shawnfa/archive/2004/03/08/86233.aspx

Mitch Gallant has a utility that can do the same:
http://www.jensign.com/JavaScience/ListAlgs/

-Shawn
http://blogs.msdn.com/shawnfa 

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--------------------
>From: JohanG@pronet.com.au (joewu)
>Newsgroups: microsoft.public.dotnet.security
>Subject: RSACryptoServiceProvider error with message "Illegal key size for this algorithm"
>Date: 21 Apr 2004 22:49:03 -0700
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>Hi,
>   I have use RSACryptoServiceProvider in my application program, it
>works fine in Windows 2000 and XP. But when I tried it out in windows
>98, it throws an exception "Illegal key size for this algorithm". I
>have search the Internet for this exception, but it does not appear to
>be a solution for it. I am using IE version 6 SP 1 in windows 98.
>Please help.
>
>TIA.
>Johan
>

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