SpiceCrypt: A Python library for decrypting LTspice encrypted model files (github.com)

by luu 19 comments 60 points
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19 comments

[−] rshm 61d ago
Coming from a brief failed attempt of using ghidra to see if keys were part of binary, this is a welcome news.

Next on wishlist is someone doing the same for encrypted fpga verilog blobs.

[−] Schlagbohrer 61d ago
yes please. I want to destroy the business model of making me pay money for hardware (understandable because it is made of atoms) and then making me pay for software blocks / DLC to be able to use the hardware
[−] userbinator 62d ago
The file header contains two 32-bit keys used to derive a substitution table index and step value for decryption.

In other words, obfuscation.

[−] jtsylve 61d ago
This is my work. Thanks for sharing! I'm happy to answer any questions, and feedback and requests are welcome.
[−] hananova 61d ago
A deep thanks for the choice of license. I’m also curious how long until you get a DMCA claim (despite the well-reasoned legal basis as described in the readme.)
[−] jtsylve 61d ago
A baseless claim may come (and if so, I'll write about it), but this use case is the textbook example of why these exemptions exist, so I can't see how any legal threats could be actionable.
[−] snthpy 61d ago
What is LTspice?
[−] flowerthoughts 61d ago
It's one of the most widely used electronic circuit simulator. It's basically a graphical interface to wire up differential equations, together with physical models of components (mostly semiconductors.)

There are other SPICE implementations, but Linear Technologies provides this program for free, and lots of manufacturers provide LTspice models for their components (of varying quality.)

[−] snthpy 61d ago
Cool, thanks.
[−] ur-whale 61d ago

> What is LTspice?

It's the best circuit simulator, whose creators did pretty much everything right with the following exceptions:

   - using the wrong key for undo

   - failing to understand that open-sourcing their baby would have made it 10 times better and 10 times more popular. But when you grow up in the hardware world, these concepts are very, very hard to understand.
[−] willis936 61d ago
A few minor things:

Last year LTSpice actually switched to sane hotkeys. Hell has frozen over and our hands rejoice.

We should be careful with "best" without more qualifiers. It's a swiss army knife, but not very sharp. It's no replacement for an RF suite.

[−] Archit3ch 61d ago

> best circuit simulator

QSPICE (made by the author of LTspice) claims to be 10x faster.

Also, LTspice cannot do symbolic transformations, so that places an upper limit to its utility.

[−] _fizz_buzz_ 61d ago
LTSpice is awesome, but the user interface is an acquired taste ...
[−] IshKebab 61d ago
Seems to be standard in the EDA world. Look up how you copy/paste in Eagle. Or what happens to wires when you move a component in a KiCAD schematic.
[−] Schlagbohrer 61d ago
Now if only they could decrypt Texas Instruments' models
[−] jtsylve 61d ago
File a feature request on github with some background details and I'll look into it!
[−] jtsylve 58d ago
v2 Adds support for PSpice, which should hopefully cover the TI models. Let me know if not. https://github.com/jtsylve/spice-crypt
[−] jtsylve 60d ago
I've got it working. Will update soon.
[−] Schlagbohrer 59d ago
Wow!
[−] matthewdipo 61d ago
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