Wireless Application Protocol and the Wireless Transport Layer Security

1
Wireless Application Protocol and the Wireless
Transport Layer Security

• Mark A. Shaw
• CS 522 Project Presentation

2
Introduction

• WAP
• SonyEricsson develop Intelligent Terminal
  Transfer Protocol (ITTP) for Value Added
  Services (VAS) - 1995
• Unwired Planet (n.k.a Phone.com) develop Handheld
  Device Markup Language (HDML) and Handheld Device
  Transfer Protocol (HDTP) - 1996
• Nokia develop Smart Messaging, Timetabling Markup
  Language (TTML) 1997
• WAP Forum formed in June 1997
• WTLS
• Security Layer for WAP
• Based on Transport Layer Security v.1.0 (SSL)
• Optimized Handshaking
• Long Lasting Secure Sessions

3
WAP Architecture
4
WAP Development

• WAP is designed to work on any of the existing
  wireless services, using standards such as
• Short Message Service (SMS)
• High-Speed Circuit-Switched Data (CSD)
• General Packet Radio Service (GPRS)
• Unstructured Supplementary Services Data (USSD)

5
WAP Limitations
LimitedBandwidth
Im Popular!
LimitedDisplay
LimitedKeyboard
6
WAP Protocol Stack
Application Layer (WAE)
Other Services Applications
Session Layer (WSP)
Transaction Layer (WTP)
Security Layer (WTLS)
Transport Layer (WDP)
Bearers
iDEN
GSM
CDMA
CDPD
IS-136
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WAP Protocol Stack (Cont)

• Makes applications independent of bearers and
  other hardware
• External applications and services may access the
  layers directly
• Modified to allow for
• Lower Bandwidth (9.6kbps 14.4kbps)
• Network latency (6 10 seconds on SMS)
• Unreliable connections

8
Wireless Transport Layer Security (WTLS)

• WTLS is an optional layer
• Privacy thru encryption
• Authentication nonrepudiation thru digital
  certificates
• Compression
• Elliptic Curve Cryptography (ECC)

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WTLS Cont

• WTLS is a variant of TLS optimized for
• use in wireless applications
• Authentication Asymmetric Key Crypto
• Class 1 No Authentication
• Class 2 Server Authentication
• Class 3 Mutual Authentication
• Privacy Symmetric Key Crypto
• Data Integrity MACs

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WTLS Class 1 Authentication

• ClientHello -----------gt
• ServerHello
• lt----------- ServerHelloDone
• ClientKeyExchange
• ChangeCipherSpec
• Finished -----------gt
• lt----------- Finished
• Application Data lt----------gt Application Data

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WTLS Class 2 Authentication

• Server Authentication Only
• ClientHello -----------gt
• ServerHello
• Certificate
• lt----------- ServerHelloDone
• ClientKeyExchange
• ChangeCipherSpec
• Finished -----------gt
• lt----------- Finished
• Application Data lt----------gt Application Data

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WTLS Class 3 Authentication

• Mutual Authentication
• Client Hello -----------gt ServerHello
• Certificate
• CertificateRequest
• lt----------- ServerHelloDone
• Certificate
• ClientKeyExchange (only for RSA)
• CertificateVerify
• ChangeCipherSpec
• Finished -----------gt
• lt----------- Finished
• Application Data lt----------gt Application Data

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WTLS Security Issues

• WTLS allows for weak encryption algorithms
• Plain-text data recovery attack
• Datagram truncation attack
• Message forgery attack
• Exportable key-search shortcut

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WAP Future?

• Diminishing Popularity
• Replaced in favor of 802.11
• Outdated Specifications

15
Resources

• http//www.openmobilealliance.org/tech/affiliates/
  wap/wapindex.html
• Nokia WAP Developer Forumhttp//www.forum.nokia.c
  om/main/0,6566,033,00.html
• WAP-210, Wireless Application Protocol
  Architecture Specification
• WAP-191, Wireless Markup Language Specification
• WAP-193, WMLScript Language Specification
• WAP-261, Wireless Transport Layer Security
  Specification
• WAP-161, WMLScript Crypto API Library
• WAP-187, WAP Transport Layer E2E Security
  Specification
• WAP-217, WAP Public Key Infrastructure Definition
• http//www.hut.fi/jtlaine2/wtls/
• Computer Networks, Andrew S. Tanenbaum, 4th
  Edition
• Network Security with OpenSSL, Viega, Messier
  Chandra
• Secure Network Programming Cookbook for C and
  C, Viega, Messier, Spafford

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The End

• Questions?