Download, Application Verification, Installation, and Usage Manual for the Cuvex Desktop App
Introduction
The Cuvex Desktop App has been developed as a backup alternative to the cold decryption process of the Cuvex device. The aim is to provide Cuvex clients with a software solution that enables them to decrypt their cryptograms in the event that they lose access to their Cuvex device due to unforeseen circumstances in the future.
This app should only be used in case of necessity. We do not recommend using this app for day-to-day management, as, no matter how secure we have designed it, it remains an application intended for installation on personal computers.
Initial Recommendations
1. Use Only in Case of Necessity: This app should only be used as a last resort. Whenever possible, decrypting your secrets with an original Cuvex device is the best and safest option.
2. Install on a New Computer: If feasible, install the app on a completely new computer that has no other applications installed.
3. Download from Our GitHub: You will find versions for Linux, Windows, and Apple (ARM and Intel versions) on our GitHub. It is advisable to download and validate the version you need, and then completely delete it from your PC. For your safety, in case of necessity, always download and validate the latest version published on our GitHub to ensure that no one has tampered with the version you store on your PC. If you wish to store the software locally, we recommend saving it on a dedicated external memory drive that is not connected to the internet, such as a USB drive designated solely for this purpose.
You may download all versions, regardless of which one you currently need, as you never know which one may be required in the future. Additionally, you can access the complete source code of the app, and it is advisable to keep a full backup copy.
4. Hash Verification Codes: Each version you download includes a verification code (SHA256 Checksums) published at the top of the corresponding download page on GitHub.
It is crucial to save these hash codes linked to each version of the app so that you can verify it before installation, whether now or in the future.
A) Download our Apps and the source code from our GitHub.
First, navigate to the download page for the Cuvex Desktop project, where you will find the hash codes for each app and the source code. Copy the alphanumeric text associated with the version you wish to use and save it in a text file on your PC.
Next, scroll down the same page and select the version you want to download from the "Assets" section for validation and installation. Click on the chosen version, and the download will begin to your PC.
B) After downloading the appropriate version of the app for your PC, proceed to verify that it is the original version created by the Cuvex team and has not been altered by validating its hash.
Once you have downloaded the correct version for your PC, before installing it, you must verify its authenticity. Please follow the instructions below.
Guide to Verify the Integrity of a File Using Hashes.
This guide will show you how to verify the integrity of a downloaded file using cryptographic hashes. This practice ensures that the file has not been tampered with by a third party and that you are installing the official version of our desktop software.
The complete process is detailed here, including the necessary commands for calculating and comparing hashes on Windows, macOS, and Linux, along with step-by-step instructions.
C) Export the Binary from the Cuvex card you wish to decrypt using the Cuvex desktop App.
The next step is to export the content of the Cuvex card you want to decrypt. This process is straightforward with the Cuvex smartphone App.
Make sure you have the latest version of the Cuvex App installed from the official app stores.
1. Then, open your Cuvex App; you should have the card you want to decrypt linked to your app. If not, select the external design of the card you wish to link from the available options or by tapping the “Link More Cards” button.
2. Once you have selected the external design, simply hold your card close to your smartphone's NFC reader,
which will read the card's information and display the next screen.
3. After linking the card to your Cuvex app, you will see the “Export Card Binary” button.
IMPORTANT:
This option is only visible for cards that contain cryptograms created with Firmware version 1.1.0 and higher. If your card contains a cryptogram created with an earlier firmware version, it can only be decrypted on the Cuvex device.
To have a cryptogram that can be decrypted with the Cuvex desktop app, you must check the firmware installed on your Cuvex device; if it is lower than 1.1.0, you will need to update it to re-encrypt your secret with the version that supports decryption with the Cuvex desktop App.
4. Once you press “Export Card Binary,” the App will prompt you to bring the card containing your encrypted secret close to the NFC reader again. The App will read your card again to extract all the information it contains in binary format.
IMPORTANT:
The Cuvex app NEVER decrypts the content of the card; it only exports it so you can physically extract it from the card and temporarily store it on your PC to decrypt it with the Cuvex desktop app. The app does not store the binary file extracted from the card; it is completely deleted from the app and, consequently, from your smartphone as soon as it is shared.
The best place to store the exported file from the Cuvex card is on the card itself. There is no danger in storing it on your PC or sharing it via email or other means, as it is an encrypted secret file using AES 256 GCM. However, it is always best practice to avoid keeping such a file on any device connected to the internet. After decrypting your secret on your PC, it is advisable to delete the file extracted from the card from any medium or support used for handling or sharing it.
Once the file has been extracted, you should save it on the PC where you will install the Cuvex desktop software.
D) Install the Application and Begin the Decryption Process.
Once you have verified the authenticity of the Cuvex desktop software for decrypting cryptograms, you may proceed with the installation and execution, as outlined in step 2.
* For Windows, extract the downloaded file and launch it as you would any other Windows application—simply double-click the program icon.
* For Mac, also extract the downloaded file and run it like any standard macOS application by double-clicking the program icon. Important: Make sure to enable the permission to install software from unknown developers.
Since this software is not signed by Apple, an alert will appear indicating that the application cannot be opened because it is not from an identified developer. To resolve the issue, follow these steps:
1. On your Mac, go to the Apple menu > System Settings and click Privacy & Security in the sidebar (you may need to scroll down).
2. Go to Security and click Open Anyway. This option will be available for about an hour after attempting to open the app.
3. Enter your login password and click OK.
This will relaunch the program, allowing it to run.
The Cuvex desktop application is very user-friendly. As you’ll notice, the program will require you to disconnect your PC from the Internet to proceed.
For your security, as we’ve mentioned from the start, using the Cuvex desktop program for decrypting cryptograms should always be your last resort. However, if you do need to use it, it’s strongly recommended to do so with your PC disconnected from the Internet.
If you do not disconnect from the Internet, the program will automatically close, preventing further action.
Once disconnected, the first step is to load the binary file from your Cuvex card, which contains your encrypted cryptogram, into the program.
Simply click the OK button, which will open a file navigation menu on your PC. Locate the file that was exported by the Cuvex smartphone app from your Cuvex card, which holds the encrypted cryptogram—a process we explained in step 3 above.
Once the file to be decrypted has been loaded, the desktop app will display information about the card, including the card’s Alias, the number of signers, and the number required for decryption.
To proceed with decryption, simply click the “Proceed” button in the lower right corner. The software will then open a pop-up window where you must enter the required passwords to decrypt. Note that this pop-up may open behind the main program window; if you do not see it, please move the main window aside.
Important: The pop-up window will prompt you to enter each password individually. If your cryptogram is multi-signature, each password must be entered in a new pop-up window. The software will prompt you one by one until all required passwords are captured to decrypt your cryptogram.
The order of password entry does not matter; they can be entered in any sequence.
Once all necessary cryptograms have been entered, the software will execute the decryption process and display the secret in a human-readable format.
