I'm using TripleDESCryptoServiceProvider and MD5CryptoServiceProvider
in .NET Framework code. This requires 128-bit encryption. Some Windows
2000 platforms won't have 128-bit encryption and distribution of
Encpack_Win2000_EN.exe is complicated due to export law.

So...
Q1: What are the best classes to use if assuming 40-bit encryption?
Q2: Is there any other way of distributing 128-bit encryption or
assuring it is available?

Thanks.

Instead of using Crypto Service Providers that calls into CAPI you can use
managed implementaiton of corresponding crypto algorithms. There are several
open sources that you can check, starting from Mono crypto classes
http://www.go-mono.com/crypto.html and BouncyCastle C# port
http://www.bouncycastle.org/csharp/. (and btw. RijndaelManaged doesn't
require CAPI crypto service provider as well).

-Valery.
http://www.harper.no/valery

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This doesn't apply anymore. The export law changed (I believe it was on
January 1st, 2000) to allow the export of strong cryptography from the US to
any country that is not on its embargo list (Iran, North Korea, etc.).

Every .NET framework supports 128, 196 and 256 bit Rijndael encryptions,
regardless of the Windows version it's running on. Rijndael is the successor
of TripleDES, so you should consider using it.

Regards,
Pieter Philippaerts

P.S.: depending on your security requirements, you may want to consider
dropping MD5 in favor of another hash algorithm. MD5 has been recently
broken, so it shouldn't be used in new development anymore.

Thanks very much to both of you for your advice. In the end I used
RijndaelManaged and SHA256Managed for the hash, neither of which use
the CAPI.

In the process I came across
http://msdn.microsoft.com/msdnmag/issues/02/06/crypto/ which I found to
be a useful overview of cryptography in .NET.

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