Client Hello

ACME Challenge

Automated Certificate Management Environment

Performance

TLS 1.2 (and earlier)

  • New Connection: 4 RTT + DNS
  • Resumed Connection: 3 RTT + DNS

TLS 1.3

  • New Connection: 3 RTT + DNS
  • Resumed Connection: 3 RTT + DNS

TLS 1.3 + 0-RTT

  • New Connection: 3 RTT + DNS
  • Resumed Connection: 2 RTT + DNS
  • encrypted HTTPS requests become just as fast as an unencrypted HTTP requests.
  • Replay Attack