为了进一步提升安全性，Let's Encrypt计划从2027年2月10日起，将免费SSL/TLS证书的有效期从90天缩短至64天。对于已经使用支持ARI（ACME续期信息）标准的现代化ACME客户端的管理员而言，这一变更不会带来任何影响。但对于仍采用固定续期计划或手动操作方式的管理员来说，明年冬季将是必须完成系统更新的最后期限，否则证书可能会意外失效。
Let's Encrypt is continuing a push toward improved security by reducing free SSL/TLS certificate lifetimes from 90 days to 64 days, starting on February 10, 2027. For administrators already implementing modern ACME clients that support ARI (ACME Renewal Information), the change should be seamless. For those still relying on hardcoded renewal schedules or manual processes, next winter will be the deadline to update before certificates start expiring unexpectedly.
2026年10月14日起，Let's Encrypt将开始对64天有效期的证书进行测试，有意参与的用户可提前测试自己的系统配置。
Starting on October 14, 2026, Let's Encrypt will begin testing the 64-day certificates, and interested users can opt-in to test their setups before production goes live.
在Let's Encrypt于2016年初正式提供服务之前，证书的有效期通常可长达1至3年。该服务最初设定90天的有效期，旨在促使各类自动化续期机制得以普及。较短的证书有效期能有效降低私钥泄露带来的安全风险，并推动整个互联网行业加速采用HTTPS协议。
Prior to Let's Encrypt's launch in early 2016, certificates were often issued for as long as 1 to 3 years at a time. The service start with 90-day certificates to force renewal automation that didn't previously exist. Shorter certificate validity periods limited vulnerabilities from private key thefts and accelerated HTTPS adoption across the web.