Certificate to Arduino Command-line

Posted: Friday, January 24, 2025 at 06:59 AM | Categories: Arduino, JavaScript, Internet of Things (IoT)

Before I created the web application described in Automated Public Cert to Arduino Header Conversion, I started with a simple node.js command-line utility. I like command-line tools and starting with the Node version made sense to me. I switched to the web app version once I realized that most people who needed to do the certificate conversion to Arduino wouldn't have node installed on their development systems.

So I stepped away from the incomplete command-line utility then built, deployed, and documented the web app version. Last night, I finished the command-line version and published it. Its called, hopefully not surprisingly, Cert2Arduino and you can find it on npm at Certificate to Arduino Header Converter.

When you execute it, it prompts for the same information the web application does:

1. The path to the downloaded certificate file
2. Whether you want to append a backslash (Arduino's line continuation character: \) or not.
3. The variable name assigned in the Arduino header file generated from the certificate file.

Cert2Arduino

Converts a certificate file to a C char array for use in Arduino sketches.

√ Select the input file to convert: » google.crt
√ Append backslash to output lines? ... no / yes
√ Enter the name for the Arduino certificate variable: ... cert

Input file: D:\dev\node\cert2arduino\google.crt
Output file: D:\dev\node\cert2arduino\cert.h

Done!

Like the web application, it saves the outputted file to a file using the variable name as the file name. The web app allows you to change it, but I didn't do that here.

Anyway, for you node users like me, you now have a tool you can use to convert a downloaded certificate file into an Arduino header file to use in your Arduino sketches.

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Header image: Photo by Sahand Babali on Unsplash