need to encrypt and decrypt using a shared secret key, not password

[quickbeam]

I have code on another device and I'm trying to send encrypted data to it. I can store a key there and decrypt data, but I don't see how store the same key in AutoIt.

Yes, Diffie-Hellman Key Exchange might be a better solution, but I don't see how to do that in the other device.

To use _Crypt_EncryptData, I need a handle from_Crypt_DeriveKey(). That wants a password as an input, and then it will derive a session key, but I just want to store a known binary value. Is there a way to do that?

[RTFC]

Diffie-Hellman is definitely the way to go; don't bother with _Crypt_*. I use this C++ library myself, but @jchd has provided this AutoIt implementation.

[quickbeam]

Unfortunately my other device (an embedded device) doesn't support Diffie-Hellman. I was just hoping for a simple way to use AES with a given key, not a password.

[TheXman]

 

28 minutes ago, quickbeam said:

I was just hoping for a simple way to use AES with a given key, not a password.

 

This may help.

 

 

Taken from the CryptoNG Purpose statement:

Quote

... In addition the Crypt.au3 UDF lib, as it is currently written, has a very limited ability to decrypt AES data that was not encrypted using Crypt.au3 functions.  That is because Crypt.au3 functions do not allow you to specify an actual key or initialization vector (IV).  It only lets you specify data to be used to derive a key and uses a static IV. ...

 

Edited July 2 by TheXman

[quickbeam]

That does indeed look like what I want. I also noticed that the current library uses the deprecated DLL, which was a little concerning.

Okay, I downloaded it. Wow, that's not a little weekend project you did! The help pages are coming up blank, but it's probably a security issue on our end, I'll investigate.

[TheXman]

 

24 minutes ago, quickbeam said:

The help pages are coming up blank

The most common resolution to that problem is to unblock the chm file.

[quickbeam]

It was probably similar. It would prompt me each time I opened it if I trusted it. I would say yes, but the help window came up blank. Eventually I clicked a checkbox to not ask the question again, and that time it worked. Unintuitively, the checkbox probably unblocked the file instead of answering yes.

[rudi]

Hello,

 

you could do an external call of a powershell script, in case the very nice UDF by @TheXman should have issues, as mentioned.

 

This might be a start to do so: https://stackoverflow.com/questions/75340972/how-to-aes-decrypt-a-string-in-powershell-with-a-given-iv-and-key-as-string