We’re sometimes asked why we only offer certificates with ninety-day lifetimes. People who ask this are usually concerned that ninety days is too short and wish we would offer certificates lasting a year or more, like some other CAs do.
Ninety days is nothing new on the Web. According to Firefox Telemetry, 29% of TLS transactions use ninety-day certificates. That’s more than any other lifetime. From our perspective, there are two primary advantages to such short certificate lifetimes: