Maximizing Performance with SPDY & SSL. Billy Hoffman

Transcription

1 Maximizing Performance with SPDY & SSL Billy

2 What is SPDY?

3 Massive Browser Support

4 Massive Server Support

5 Cast of Characters TCP HTTP SSL X.509 Certificate Cryptography (asymmetric & symmetric) SPDY

6 HTTP/HTTPS

7 HTTP/SPDY/SSL Sandwich SPDY encapsulates HTTP requests Single Multiplexed stream Transmits contents over SSL channel

8 Today s Focus Setting the Stage for SPDY Can speak SSL with a server Can create a valid SSL connection Client and Server agree to use SPDY Optimizing SPDY Optimizing SSL Optimizing SPDY Avoiding optimizations that hurt SPDY Tools to help

9 SETTING THE STAGE FOR SPDY

10 SSL Connectivity Hostname resolves IP is reachable Web server is listening on SSL port Web server understands SSL Web server knows which site you want Shared Hosting and SNI

11 Listener on 443 is speaking SSL?

12 Creating a Valid SSL connection Agreement on crypto algorithms X.509 certificate is valid

13 X.509 Cert: Correct Domain?

14 X.509 Cert: Valid Time Period?

15 X.509 Cert: Is it Trusted?

16 X.509 Cert: Is it Trusted? Do I trust the issuer? If not, was it signed by someone I trust? Has it been revoked? CRL lists Online Certificate Status Protocol (OCSP)

17 Agreeing to Use SPDY Client tells server it supports SPDY Server tells client it supports SPDY Client sends SPDY over SSL Else, falls back to HTTP over SSL

18 SSL Handshake Microsoft Technet: Host TLS/SSL Works

19 Announcing SPDY support in the SSL Handshake + Ext:13172/ 13172/ALPN Microsoft Technet: Host TLS/SSL Works + NPN/ALPN

20 ClientHello with Extension 13172

21 ServerHello with NPN

22 Review: Speaking SPDY Client resolves and connects to SSL port Client announces SPDY support inside ClientHello Server announces SPDY support in ServerHello Client validates X.509 cert, finalized SSL connection SPDY conversation happens

23 OPTIMIZING SSL/SPDY

24 The SSL Tarpits SSL handshake requires 2 round trips Certificates can be large Certificates need to be validated Keys can be too large Algorithms can be slow

25 The SSL Handshake is Costly! Microsoft Technet: Host TLS/SSL Works

26 Resume SSL Session Avoid regenerating keys Avoid unneeded trips 2 methods Microsoft Technet: Host TLS/SSL Works

27 Session Identifiers Both sides keep state/cache Reuse based on id Widely supported sessionid: 3a8a Microsoft Technet: Host TLS/SSL Works Big cache of all ids given out, and associated keys/ciphers

28 Session Tickets Client stores Magic Ticket RFC 5077, optional No IIS support Microsoft Technet: Host TLS/SSL Works Encrypted summary of keys/ciphers, signed by server Verifies summary is valid, uses values

29 SSL False Start

30 False Start: Not Gone The Failure of False Start Chrome still does it! Desktop and mobile Any server that supports NPN! (with forward secure) Any server with SPDY support Or SSL + NPN, but only announces HTTP/1.1!

31 Minimize the Certificate Chain

32 OCSP Validation causes delays

33 OCSP Stapling Good in theory, bad in practice Browsers are moving away from OSCP

34 Oversized Asymmetric Keys 1024 is fine 2048 for banks Anything more is overkill

35 Cipher Order/Choice Matters RC4 is the best Unless on a machine with AES- NI Intel i7, Xeons, some AMD Not most virtual machines!!! First match wins

36 Is SSL really helping you? SSL doesn t secure your website Prevents eavesdropping, tampering Not XSS, CSRF, SQL Injection, Unpatched/outof-date software, RCE, LFI, etc. Consider: NULL-MD5, NULL-SHA SSL with no encryption

37 Does this really matter? Seriously? 1024 more bytes in key? 2 more kilobytes in the X.509 cert? Accidently using AES-256? Really?

38 Does this really matter?

39 SPDY Optimization SPDY only works over SSL Ensure that all your traffic if over SSL HTTP 301 direct for http: to https: Add a cache-control header! HTTP Strict Transport Security (HSTS) Like the browser s cache, but for protocol access. Make (semi) far future Wide support (>90% of SPDY capable browsers)

40 Avoid These Optimizations Domain Sharding Hack to request multiplexing, not needed Hurts SPDY by spreading requests out JavaScript CDNs These are a horrible blight on the web! pull/1327

41 TOOLS

42 SSL Labs

43 SPDYCheck.org

44 Now on Github, GPL licensed!

45 SSL/SPDY Optimization Check List Website responds over SSL/443 Website has NPN extension (even without SPDY for False Start) X.509 certificate is valid X.509 chain is short SSL Asymmetric keys are <= 2048 Cipher is RC4 (or AES-128 if supports dedicated instructions)

46 SSL/SPDY Optimization Check List SSL session resumption is enabled (both identifiers and tickets) No SSL compression Website is using latest version of SPDY HTTP permanently (301) redirects to HTTPS (including cache header) HTTPS sends HTTP Strict Transport Security header

47 Great Resources Ivan Ristic (blog.ivanristic.com) Adam Langley ( Mark Nottingham ( Qualys SSL Labs (ssllabs.com) SPDYCheck (spdycheck.org)

48 Free Performance Assessment zoompf.com/free

49 Maximizing Performance with SPDY & SSL Billy