How can the current time be set for certificate validation

[moritz89]

• How does mbedtls get the current time to verify certificates?
  • I remember reading that the compile time is used?
• Does setting the time with settimeofday affect the time used by mbedtls to verify certificates validity?

[RobertByrnes]

Hi, mbed-tls uses system time (time()) in embedded systems with linux or similar. However as ESP / Arduino etc is bare metal and doesn't have a real time clock we have to get the time from NTP or from GSM.

If you set the time with settimeofday, future SSL/TLS handshakes and certificate validations will use the new time.

[moritz89]

Great. So then the process of

1. connect to internet (LTE/WiFi)
2. sync time
3. connect to server

is the sensible steps to take. Would that mean setting time with settimeofday() far in the future past will cause the SSL/TLS handshake to fail?