I developed apps here with OpenSSL and QT. The reason is, first of all, OpenSSL is the most powerful PKI-related technology among the libraries I have touched. (Of course, I haven’t tried many things ^^;; )

And I personally use it, but there is no license problem. Sometimes mbedTLS is also used, but in terms of encryption technology, mbedTLS is as good as OpenSSL. However, it lacks support for PKI technologies such as OCSP, TSP, and CMP in various formats of complicated ASN.1.

And OpenSSL is supported on any platform. I don’t think there is any other module that has been used for as long and as diversely as OpenSSL. Since most of the PKI technologies follow standards, It is a part that needs verification, but I think verification of PKI and encryption is sufficient. I’ve used modules used by PKI-related companies, but I’ve never seen anything as diverse as OpenSSL.

In fact, the downside of OpenSSL is that it is a bit difficult to code. ASN.1 uses a lot of macros for processing It has so many features, so it’s so complicated. So I have a lot to study ^^ Another reason to use QT is because it is easy to use for UI development. I once developed using MFC with Visual Studio, but QT is much easier to develop than MFC. The UI for Windows is water, and Linux and MAC are also supported.

(Note that iPhone and Android are also supported, but I have never used them ^^:: )

At one time, when developing with MFC, there was always difficulty in supporting Linux and MAC, but QT solved this problem at once. The development code is also much easier to maintain. BerEditor, CertMan, and CryptokMan were all easy to compile on MAC or Linux.

Personally, I can’t do it because of the hassle of development environment, testing and version management. In fact, Linux and MAC have also been ported well.

These tools are also intended to be shared for MAC and Linux. When will it be ….