The Evolving Architecture of the Web Nick Sullivan Head of - - PowerPoint PPT Presentation

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The Evolving Architecture of the Web Nick Sullivan Head of - - PowerPoint PPT Presentation

Jun 29, 2023 19 likes •793 views

The Evolving Architecture of the Web Nick Sullivan Head of Cryptography CFSSL Universal SSL Keyless SSL Privacy Pass Geo Key Manager Recently Standards work TLS 1.3 C on peting Goals make browsing more performant private HTTP DNS

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The Evolving Architecture of the Web

Nick Sullivan
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SLIDE 2 Head of Cryptography CFSSL Universal SSL Keyless SSL Privacy Pass Geo Key Manager Recently Standards work TLS 1.3
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private performant

make browsing more

Conpeting Goals

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HTTP DNS

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HTTP

Client ISP Web Server Operating System Browser Static Content Cache

HTTP

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DNS

Client Resolver Authoritative
 Server Operating System Browser

DNS

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SLIDE 8 Clients Hosts
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SLIDE 9 Geographically Centralized Administratively Diverse One IP per Hostname Hosts Clients HTTP
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SLIDE 10 What a network observer can see Hosts Clients HTTP Unique Client IP Unique Server IP Server URL Website content
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Client IP Server IP Anonymity set 1 1

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IPv4

4.3 Billion Addresses

Not enough for every user

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SLIDE 13 What a network observer can see Hosts Clients HTTP Client Proxy IP Unique Server IP Server URL Website content Proxy
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Tor VPN Carrier NAT Latency Cost 3 round-the-world 1 round-the-world Small

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Client Server Anonymity set k 1

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New T rends

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HTTPS

Client ISP Host Operating System Browser

HTTPS

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TLS 1.2

Client ISP Host Operating System Browser
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TLS 1.3: coming soon

Client ISP Host Operating System Browser
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SLIDE 20 What a network observer can see Hosts Clients HTTP Unique Client IP Unique Server IP Server URL Website content HTTPS
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Client Server Anonymity set 1 1

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IPv4

4.3 Billion Addresses

Not enough for every website

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SLIDE 23 Geographically Centralized Administratively Diverse One IP per Hostname Hosts Clients HTTP
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SLIDE 24 More Geographically Centralized More Administratively Centralized Multiple Hostname per IPs Hosts Clients Shared Hosts HTTP HTTPS
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SNI

Virtual Hosting

Send the hostname to the server so it can choose the certificate

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SLIDE 26 Source: Akamai
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SLIDE 27 What a network observer can see Hosts Clients HTTP Client Unique IP Shared Server IP Hostname HTTPS Shared Hosts
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Client Server

(Shared IP+Hostname)

Anonymity set 1 1

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Internet Scans and IPv6

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Privacy Evolves

Certificate Transparency

Wildcard certificates

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Edge Sesvices

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  • Websites and are delegating
to globally distributed parties
  • Authorized to terminate TLS
  • Reduced Latency
  • Improved DDoS resilience
  • Anycast to reduce number of
IPs needed

Edge Services

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SLIDE 33 More Geographically Centralized More Administratively Centralized Multiple IPs per Hostname Hosts Clients Shared Hosts HTTP HTTPS
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SLIDE 34 Geographically Distributed Administratively Centralized Multiple IPs per Hostname Anycast Hosts HTTP HTTPS Hosts Clients
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SLIDE 35 Client ISP Host Operating System Browser Edge

HTTPS

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SLIDE 36 Client ISP Host Operating System Browser Edge

HTTPS

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Questioos

Can we improve privacy? Can we improve latency? Can we improve both???

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SLIDE 38 Client Operating System Browser SNI: burrito.com Edge

HTTP 1.1

Resolver SNI: beans.com Q: beans.com A: 1.2.3.5 Q: burrito.com A: 1.2.3.4 burrito.com beans.com
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Safety in Numbess

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SLIDE 40 Client Operating System Browser SNI: burrito.com Edge

Meek

Resolver Q: burrito.com A: 1.2.3.4 burrito.com Origin beans.com Host burrito.com Host
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SLIDE 41 Client Operating System Browser SNI: burrito.com Edge

Meek

Resolver Q: burrito.com A: 1.2.3.4 burrito.com

Mismatch: SNI, Host, SAN

GET https://beans.com Origin GET beans.com beans.com Host burrito.com Host
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SLIDE 42 Client Operating System Browser SNI: burrito.com Edge

HTTP/2

Resolver GET https://beans.com Q: beans.com A: 1.2.3.4 Q: burrito.com A: 1.2.3.4 burrito.com beans.com

Connection Coalescing

GET https://burrito.com
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SLIDE 43 Client Operating System Browser SNI: burrito.com
 SNI: burrito.com Edge

HTTP/2

Resolver GET https://beans.com Q: burrito.com A: 1.2.3.4 burrito.com beans.com

ORIGIN Frame

GET https://burrito.com ORIGIN: beans.com
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SLIDE 44 What a network observer can see Hosts Clients HTTP Client Unique IP Shared Server IP First Hostname HTTPS Anycast Hosts
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Anonymity set 1 ~20 Client Server

(Shared IP+Certificate)
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SLIDE 46 Client Operating System Browser SNI: burrito.com Edge

HTTP/2

Resolver GET https://beans.com Q: burrito.com A: 1.2.3.4 burrito.com

CERTIFICATE Frame

GET https://burrito.com ORIGIN: beans.com beans.com CERTIFICATE:
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SLIDE 47 Client Operating System Browser SNI: burrito.com Edge Resolver Q: burrito.com A: 1.2.3.4 burrito.com
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What this changes

Having a certificate gives you routing authority

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Anonymity set 1 k

k is the set of domains on certificates that can be obtained through “First Hostname”

Client Server

(Shared IP+First Hostname)
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Meek-like circumvention protection

Only send the CERTIFICATE frame on certain resources

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SLIDE 51 Client Resolver Authoritative
 Server Operating System Browser

DNS

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SLIDE 52 Client Resolver Root Server Operating System Browser

Cache Miss

TLD Server Authoritative Q: e.we.com me.we.com me.we.com me.we.com Client Subnet
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SLIDE 53 Client Resolver Root Server Operating System Browser

Caching

TLD Server Authoritative Q: e.we.com me.we.com Client Subnet me.we.com me.we.com
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SLIDE 54 Client Resolver Root Server Operating System Browser

QNAME Minimization

TLD Server Authoritative Q: e.we.com .com .we.com me.we.com Client Subnet
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SLIDE 55 ISP

DNS Over HTTPS

Client Authoritative
 Server Operating System Browser Edge
 Resolver

DOH

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SLIDE 56 Client DOH
 Resolver Root Server Operating System Browser

DOH Resolver

TLD Server Authoritative Q: e.we.com .com .we.com me.we.com Client Subnet ISP
 Resolver
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Latency

ISPs


 Closer to user Smaller cache UDP

Edge DoH


 Globally Distributed TLS 1.3 0RTT

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Challenges in the Enterprise

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SLIDE 59 Client Browser SNI: burrito.com Edge

HTTP/2

DoH Resolver GET https://beans.com burrito.com

ORIGIN/CERT + DoH

GET https://burrito.com ORIGIN: beans.com beans.com CERTIFICATE: SNI: resolver.com Q: burrito.com A: 1.2.3.4 resolver.com
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SLIDE 60 Client Browser Edge

HTTP/2

DoH Resolver burrito.com

ORIGIN/CERT + DoH

SNI: resolver.com resolver.com SNI: burrito.com
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SNI

Encryption

Encrypt SNI with client ephemeral key + server public key from DNS

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SLIDE 62 Client Browser eSNI: E(burrito.com) Edge

TLS 1.3

DoH Resolver burrito.com

O/C + DoH + eSNI

SNI: resolver.com Q: burrito.com A: 1.2.3.4, PubKey resolver.com
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SLIDE 63 What a network observer can see Hosts Clients HTTP Client Unique IP Shared Server IP First Hostname (SNI) HTTPS Anycast Hosts
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Anonymity set 1 K

K is the set of domains that can be served on the IP

Caveat: If Server IP is static, then this give a hint about first hostname.

Client Server

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SLIDE 65 Client SNI: resolver.com Edge

HTTP/2

Resolver GET https://beans.com Q: beans.com A: 1.2.3.5 resolver.com

DOH “VPN”

ORIGIN: beans.com beans.com CERTIFICATE: Browser
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SLIDE 66 Client SNI: resolver.com Edge

HTTP/2

Resolver resolver.com

DOH “VPN”

Browser
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Client IP Server IP Anonymity set 1 K

K is the set of domains that can be served on the IP

No dynamic IP requirement
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Where are we now?

ORIGIN implemented in Firefox CERTIFICATE being standardized by IETF DOH supported by Google DNS, 1.1.1.1 eSNI about to be submitted to IETF
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ORIGIN

Privacy improvement limited by shared certs Latency skip both DNS and HTTPS Security certificate compromise risk
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CERTIFICATE

Privacy hide any bean in any burrito Latency extends origin benefits to any cert Security exchange DNS for CT or OCSP stapling
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DOH

Privacy first hop improvement Latency depends on provider, TLS 1.3 Security security against attacks, allows passive DNS
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eSNI

Privacy first domain privacy given dynamic IPs Latency depends on DoH for reliability Security risk of more MiTM
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Open Questions

How much privacy does this actually give people? Does this incentivize further consolidation? Does increased performance and privacy outweigh the legitimate need for external visibility?
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Website Fingerprinting

Removing explicit signals does not protect you from passive ones

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Consolidation

Better performance when using a popular provider

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Is visibility necessary?

Safety vs. Security

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The Evolving Architecture of the Web

Nick Sullivan