Portecle VS KeyStore Explorer

Android stores CA certificates in its Java keystore in /system/etc/security/cacerts.bks. I copied the file to my computer, added my certificate using portecle 1.5 and pushed it back to the device. Source: about 1 year ago

Portecle provides a user-friendly GUI for creating, managing and examining key- and certificate-related information. Allows you to easily interact with and keep track of you keystores, keys, certificates, certificate requests, certificate revocation lists and more. Appreciation for the recommendation goes to peanutbuttersmack. Source: about 2 years ago

Yes, that's clear but you need the private key to create a CSR. I'm guessing since you are using a Java app you should either have a JKS (old fashioned) or a P12 (pkcs12) keystore, one of those should contain the private key, you can use keystore explorer to extract the data. Https://keystore-explorer.org/. Source: about 1 year ago

Personally, I've also had decent experiences with Keystore Explorer: https://keystore-explorer.org/ I actually wrote about using it on my blog, which has plenty of screenshots: https://blog.kronis.dev/tutorials/lets-run-our-own-ca. - Source: Hacker News / over 1 year ago

Then let me tell you about keystore explorer https://keystore-explorer.org/ which will make your life a lot easier (and less chance that there are more then 1 keys inside your keystore. Source: over 1 year ago

I... Kind of like it? Not the fact that using such a GUI would be almost impossible, like the humorous example of an "engineer oriented UI" in the Silicon Valley series https://www.reddit.com/r/SiliconValleyHBO/comments/4nvvnl/pied_pipers_easytouse_tools/ which might be confusing for most people. But rather the fact that all of the complexity the software has is laid bare, so that nobody could mistakenly assume... - Source: Hacker News / almost 2 years ago

I suggest trying KeyStore Explorer. This tool supports most common certificate and wallet files. I have used in multiple occasions when standard tools couldn't do the task. Source: almost 2 years ago