Incompatibility with JCMathLib 1.0.1

Question

Incompatibility with JCMathLib 1.0.1

mvondracek opened this issue 4 years ago · comments

Hello, I found a strange bug which makes this template incompatible with JCMathLib.

I tried to use JCMathLib 1.0.1. Method ECPoint#multiplication hangs in jcmathlib.jcmathlib.Bignat.sqrt_FP on line 1709 in while loop. I first thought this is a bug in JCMathLib, but I cannot replicate this issue when using JCMathLib for applet without this template.

So to isolate this issue I used fork of this repository, branched from master, added JCMathLib 1.0.1 in compact single file form, and added tests which demonstrate that ECPoint#multiplication hangs both while running in JUnit and in simulated applet. Here are the changes to demonstrate this issue. master...mvondracek:jcmathlib

Any idea what's wrong? Are there any incompatible changes between official jCardSim and com.klinec:jcardsim:3.0.5.9?

Dušan Klinec · Answer 1 · Sun Apr 26 2020 02:58:27 GMT+0800 (China Standard Time)

TBH no idea. @petrs any thoughts?

Dušan Klinec · Answer 2 · Tue May 19 2020 21:39:34 GMT+0800 (China Standard Time)

ping @mvondracek, do you have any new info/insights? I am way too busy to debug this on my own atm.

Dušan Klinec · Answer 3 · Wed May 20 2020 18:30:23 GMT+0800 (China Standard Time)

try bumping jcardsim to 3.0.5.11 and set

System.setProperty("com.licel.jcardsim.randomdata.secure", "1");

before loading the applet to the simulator.

Petr Svenda · Answer 4 · Fri May 22 2020 17:03:50 GMT+0800 (China Standard Time)

hmm, no idea - but there is some new work planned for JCMathLib (adding support for cards with PLAIN_XY KeyAgreemnt which will speedup operations a lot) and we can check this issue while doing it

Dušan Klinec · Answer 5 · Sat May 23 2020 20:31:32 GMT+0800 (China Standard Time)

Also, try:

try bumping jcardsim to 3.0.5.11
bumping gradle plugin to 1.7.2
set:

System.setProperty("com.licel.jcardsim.randomdata.secure", "1");

Martin Vondráček · Answer 6 · Mon May 25 2020 02:18:20 GMT+0800 (China Standard Time)

Hello, thank you for your suggestions! I updated branch with bug example, but it did not solve the problem.

Unfortunately, I do not have time to debug it at the moment, neither. Our team was working on PV204 project while we detected this issue. So as our work on the project is finished, this is more of a bug report than critical problem blocking our team.

So at least this can be a note to future users that JCMathLib does not work with this template for now... Thanks anyway.

Antonín Dufka · Answer 7 · Tue Sep 07 2021 17:45:23 GMT+0800 (China Standard Time)

Hi, this issue should now be fixed in JCMathLib (OpenCryptoProject/JCMathLib#23) when bIsSimulator flag is set.

More recent versions of jCardSim (including those in this template) have problems with some underlying operations used to implement multiplication and point doubling. When bIsSimulator flag is set, JCMathLib avoids these operations and should work in the simulator as expected.

Dušan Klinec · Answer 8 · Mon Sep 13 2021 16:03:17 GMT+0800 (China Standard Time)

Closing issue, in case of a regression, reopen pls.
Thanks @dufkan