I created a self signed CA and use it to generate/sign a client cert using openssl. Then I use the self signed client cert to do TLS client authentication with my server (which also uses the self signed CA). The issue I have is when I validate the self signed CA, by calling SecTrustEvaluateAsyncWithError, it always complains this error “'DigiCert Global Root G3' certificate is not trusted". However that CA (DigiCert Global Root G3) is not my self signed CA (my CA is 'MQTTSampleCA' and I attached a dump of the my CA cert in the PR in the end of this post), so I'm confused why the API keeps complaining that CA. After some researching, I see that is a well known CA so I download its cert from https://www.digicert.com/kb/digicert-root-certificates.htm, install and trust it on my iOS device, but that doesn't help and I still get the same error. I provide all the repro steps in this PR: https://github.com/liumiaojq/EmCuTeeTee/pull/1, including how I generate the certs and the source codes of a test app that I used to do cert validation. I appreciate if anyone can share insights how to resolve this error.