verify x-509 certificate signature and validity c code

Question

I am searching for small free open source X-509 certificate verification code written in C language for embedded device that do the following:

• read X509 certificate and parse it
• check if it signed by specific CA certificate
• check the validity period for the certificate

The code should be without any dependencies like OpenSSL

Answer 1

Here are some good sources to look at:

• wolfSSL

• tropicssl

As far as I know, wolfSSL is pretty popular for embedded applications. You will probably find good support when porting it. I haven't taken a closer look at tropicssl but it looks good, too.

And of course, you can always try to port OpenSSL as well, you may begin from here:

• OpenSSL