C# TripleDES Provider without an Initialization Vector?

Question

I have a set of encrypted documents encoded with TripleDES coming from a remote system. I need to decode the data in C# and I have no control over the key or encoding algori

Answer 1

Trying to answer each point:

• The Initialization Vector is required in CBC mode. It is not required to be a secret (unlike the key) so it should be sent from the remote system.
• Since you need the IV, null is not the right thing to pass.
• Padding mode. You need to know which padding mode is used.
• TransformFinalBlock probably fails because the Padding mode is wrong.

Edit

The difference between ECB (Electronic Code Book) and CBC (Cipher Block Chaining) is illustrated below:

As you can see no IV is used in ECB mode. So even if you provide one it will be ignored.