How WAP security is enabling the rapid development of wireless
e-commerce applications for today and tomorrow
Introduction
With the advent of e-commerce and e-banking, the Internet has
changed the way many people purchase goods and manage their
finances. Online trading, banking and shopping are available today
to millions of Internet users. These services are now emerging on
the wireless Internet, allowing subscribers to access bank
accounts, trade stocks and purchase goods right from the screen of
their wireless phone. This new avenue onto the Internet has been
made possible by the Wireless Application Protocol (WAP), a de
facto standard developed by the WAP Forum, a group of over 200
telecommunications and software companies. According to Strategy
Analytics, there will be over 525 million WAP-enabled handsets in
the marketplace by the year 2003.WAP has stimulated application
development by providing a common, secure protocol that allows
applications to be written for use across existing wireless
networks. Hundreds of applications that take advantage of this
common application environment are now available. Many of these
applications use WAP's security mechanism to ensure that
transactions over the wireless Internet are safe and secure.
Examples include wireless banking from Bank of Montreal, wireless
stock trading from Ameritrade and Charles Schwab Canada, and
wireless e-commerce from Amazon.com.This paper explains the WAP
security model and the WTLS mechanism, which provide a safe and
secure environment for wireless Internet transactions today. It
explains the key issues that any data security system must address
and it describes how the WAP model addresses these issues. It also
presents ideas for future improvements that the WAP Forum is
considering for the next generation of WAP security.
The wireless
Internet is already hereWireless Internet access represents the
next wave of the Internet. This trend is being spurred by the
mobile phone industry's widespread support of the Wireless
Application Protocol. By enabling WAP applications, a full range of
wireless devices, including mobile phones, smartphones, PDAs and
handheld PCs, gain a common method for accessing Internet
information.Strategy Analytics has reported that in 2003, 95 per
cent of all handsets shipped will include WAP support. According to
the Strategis Group, there are more than 32 million professional
mobile data users in the US marketplace today and demand in this
segment will continue to grow. With expanding subscriber bases and
demand for new wireless data services driving phone sales,
operators and manufacturers expect increased revenues from the sale
of wireless Internet services and devices.Analysts expect dynamic
growth in the mobile market, with a forecast of more than one
billion mobile phones in use within the next three to four years.
According to Gartner Group, mobile phones are expected to be the
most common client device accessing the Internet worldwide by 2005.
Ovum has reported that smartphones and data-centric terminals will
account for as much as two-thirds of the estimated $67 billion
handset market in 2004.All of these statistics demonstrate the
enormous demand for wireless Internet services and applications.
WAP enables rapid application deployment and provides access to the
broadest consumer base possible because WAP was designed to operate
on top of any type of wireless data network. Whether network
operators are deploying CDMA, CDPD, GPRS, GSM, iDEN, PDC or TDMA
data solutions, application providers can reach subscribers across
multiple operator networks with a single application.Sparked by an
open, web-based protocol, network operators, handset manufacturers
and content developers have all implemented solutions that have led
to a groundswell of support for WAP deployments around the world.
Applications exist today to view a variety of web content, manage
email from the handset and gain better access to network operators'
enhanced services. Beyond these information services, content
providers are now developing solutions for the latest Internet
opportunity - wireless e-commerce.Recently, Ameritrade made its
service WAP-capable for US mobile phone users. Thomas K. Lewis,
Jr., co-chief executive officer of Ameritrade Holding Corporation,
noted in a recent press release that the addition of wireless web
access is another step in Ameritrade's continuing effort to extend
the ability of its customers to invest when and how they choose.
"Ameritrade is a customer-oriented organisation," Lewis said. "We
know that our customers want to be empowered to act on their
investment decisions at any given moment."As more subscribers
demand WAP services, the need for wireless Internet security will
continue to grow. In the mid 1990s, a push to provide strong
encryption occurred in the hopes of fostering electronic commerce.
For years, the "next killer app" hype surrounded electronic
commerce. But until Secure Sockets Layer (SSL) and encryption
became widespread de facto security standards, electronic commerce
was only a curiosity, not a mass-market opportunity. By 1998, the
security infrastructure was in place, triggering a dramatic
increase in electronic commerce transactions. 1998 became the year
of e-commerce, with Internet operations challenging traditional
"bricks and mortar" operations for the first time. Now the industry
is poised to take its next big leap forward into the wireless
world.In June 1999, the WAP Forum formally approved WAP Version
1.1. WAP 1.1 includes the WTLS specification, which defines how
Internet security is extended to the wireless Internet. WTLS is
poised to do for the wireless Internet what SSL did for the
Internet - open whole new markets to e-commerce opportunities.
Network operators providing application developers and end users
with effective WAP-based wireless security are capitalising on this
emerging trend.
Security on the InternetA first step to
understanding how the WAP security model works is to review how SSL
security makes e-commerce secure over the Internet. Today's
security solutions keep information away from individuals who
should not have access to confidential or financial data. Security
protects mission-critical information that can be used against a
corporation or used to create fraudulent transactions.
Additionally, security provides peace of mind, ensuring that
individuals and institutions are comfortable conducting business
and exchanging information online.There are four different concerns
that a security system can address: privacy, integrity,
authenticity and non-repudiation.
Privacy ensures that only
the sender and the intended recipient of an encrypted message can
read the contents of that message. To guarantee privacy, a security
solution must ensure that no one can see, access or use private
information, such as addresses, credit card information and phone
numbers, as it is transmitted over the Internet.
Integrity
ensures the detection of any change in the content of a message
between the time it is sent and the time it is received. For
example, when a user instructs a bank to transfer $1,000 from one
account to another, integrity guarantees that the account numbers
and dollar amount in the user's message cannot be altered without
the bank or the user noticing. If the message is altered in any way
during transmission, the security system must have a way of
detecting and reporting this alteration. In many systems, if an
alteration is detected, the receiving system requests that the
message be re-sent.
Authentication ensures that all parties
in a communication are who they claim to be. Server authentication
provides a way for users to verify that they are really
communicating with the website to which they believe they are
connected. Client authentication ensures that the user is who they
claim to be. Examples of authentication in the real world include
presenting a driving licence to verify that a consumer writing a
cheque is the person named on that cheque, and presenting a
corporate photo ID to prove that a telephone technician really
works for the telephone company.
Non-repudiation provides a
method to guarantee that a party to a transaction cannot falsely
claim that they did not participate in that transaction. In the
real world, handwritten signatures are used to ensure this. When a
consumer writes a cheque, presenting a driving licence ensures the
identity of the writer (authentication), while the signature on the
cheque ensures that the consumer was in fact present and agreed to
write the cheque (non-repudiation).Over the Internet, the Secure
Sockets Layer (SSL) protocol, digital certificates and either user
name/password pairs or digital signatures are used together to
provide all four types of security. The following explains these
different techniques.Public key cryptography is an encryption
method that is a key component of SSL. It uses pairs of keys and
mathematical algorithms to convert clear text into encrypted data
and back again. The pair consists of a registered public key and a
private key that is kept secret by its owner. A message encrypted
with the public key can be decrypted only by someone with the
private key. Likewise, a message encrypted with the private key can
be decrypted only by someone with the public key.Public key
cryptography uses very advanced algorithms to encrypt small amounts
of information but is impractical for encrypting large quantities
of data. Faster bulk encryption algorithms use a shared secret key
between the communicating parties to encrypt most secure messages
on the Internet. These algorithms are extremely difficult to decode
when the shared secret key contains a large number of bits. SSL
uses public key cryptography to exchange this key at the beginning
of a secure Internet conversation, thus ensuring that it remains a
secret for the duration of the conversation.SSL uses public key
cryptography, bulk encryption algorithms and shared secret key
exchange techniques to provide privacy over the Internet. To
provide integrity, SSL uses hashing algorithms that create a small
mathematical fingerprint of a message. If any part of the message
is altered, it will not match its fingerprint when the message is
checked at the receiving end. In this case, the sender is asked to
re-send the message.Because anyone can generate key pairs, it is
possible for a malicious party to put up an impostor website and
then falsify information in a transaction by providing a public key
to a user. To prevent this kind of fraud, digital certificates are
used to provide an authenticated way to distribute public and
private keys. Digital certificates are also used to authenticate
the parties of an Internet conversation so that users and content
providers can both be confident they know with whom they are
communicating.There are two different kinds of digital certificates
- server certificates and client certificates. Server certificates
are used to authenticate that a web server is what it claims to be.
Client or personal certificates are used to authenticate the
identity of an individual user on the Internet. Both types of
certificates include the certificate holder's identity and public
key, and other information used to authenticate the certificate.
Most importantly, the certificate is itself encrypted with the
private key of a certificate authority, creating an independent
binding of the public key and the certificate holder. Third party
companies like VeriSign and RSA Security operate as certificate
authorities, providing a respected, independent resource to issue
keys and certificates to their holders.When a web browser requests
a secure conversation with a web server, the server provides the
browser with its server certificate. The browser authenticates the
web server by confirming that a valid certificate authority
encrypted the certificate. It then uses the public key stored in
the certificate to encrypt a shared secret key to send to the web
server. The shared secret key is used to encrypt the rest of the
conversation. By using a server certificate, the web server and
browser can have a secure conversation that is private and
authenticated, with guaranteed integrity.Note that in this example
only the server has been authenticated. Client certificates can be
used to authenticate a user to the web server but today, most web
applications rely on a simple user name and password to
authenticate the user of the browser client.The remaining issue to
address is non-repudiation. As with client authentication, most web
applications today simply rely on the entry of a user name and
password to provide non-repudiation. Applications can request a
digital signature from a client, which requests that the user
specifically authorise a transaction. The authorisation is then
encrypted utilising the user's private key from their client
certificate. Not surprisingly, a digital signature is analogous to
a real signature on a cheque and serves the same purpose. So far
though, the adoption of client certificates for individuals on the
Internet has been slow.Good network security solutions require that
content providers and clients manage and maintain their digital
certificates and other security information carefully. Public Key
Infrastructure (PKI) solutions help companies manage this
information so that it is secure and easy to organise. PKI contains
three common functional components: the certificate authority to
issue certificates (in-house or out-sourced); a repository for
keys, certificates and certificate revocation lists on an
LDAP-enabled directory service; and a management function,
typically implemented via a management console. Additionally, PKIs
can provide key recovery in case a user loses their private key due
to a hardware failure or other problem.Different combinations of
all of these security techniques are used for different
applications, depending on which forms of security are important
and the degree to which the solution needs to be balanced with the
convenience for the user. For example, certificate-based client
authentication and non-repudiation are not widely used on the web
today because most users don't want to be bothered with the
administrative tasks of obtaining and safely maintaining a client
certificate.
Security in a WAP environmentThere are three
parts to the WAP security model. First, the WAP gateway simply uses
SSL to communicate securely with a web server, ensuring privacy,
integrity and server authenticity.Second, the WAP gateway takes
SSL-encrypted messages from the web and translates them for
transmission over wireless networks using WAP's WTLS security
protocol. Messages from the handset to the web server are likewise
converted from WTLS to SSL. In essence, the WAP gateway is a bridge
between the WTLS and SSL security protocols.The need for
translation between SSL and WTLS is incurred by the very nature of
wireless communications: low bandwidth transmissions with high
latency. Because SSL was designed for desktop and wired
environments with robust processing capabilities connected to a
relatively high-bandwidth and low-latency Internet connection, cell
phone users would be disappointed by the delays required to process
SSL transactions. Furthermore, to put SSL functionality into
handsets would raise cell phone costs and destroy the low-cost
pricing paradigm that is driving industry growth.WTLS was
specifically designed to conduct secure transactions without
requiring desktop levels of processing power and memory in the
handset. WTLS processes security algorithms faster by minimising
protocol overhead and enables more data compression than
traditional SSL solutions. As a result, WTLS can perform security
well within the constraints of a wireless network. These
optimisations mean that smaller, portable consumer devices can now
communicate securely over the Internet.The translation between SSL
and WTLS takes milliseconds and occurs in the memory of the WAP
gateway, allowing for a virtual, secure connection between the two
protocols. Suppliers of the WAP gateway and network operators take
every measure possible to keep the WAP gateway itself secure
by:Ensuring that the WAP gateway never stores decrypted content on
secondary mediaUsing a process of decryption/re-encryption that is
security conscious and optimised for speed so that the unencrypted
content of a message is erased from the volatile internal memory of
the WAP gateway as quickly as possibleSecuring the WAP gateway
physically so that only authorised administrators have access to
the system consoleLimiting administrative access to the WAP gateway
so that it is not available to any remote site outside the
carrier's firewallApplying all other security precautions used to
protect billing systems and the Home Location Register to the WAP
gatewayOn the wireless side of the transaction, the WAP gateway
uses WTLS to provide privacy, integrity and authentication between
itself and the WAP browser client. It is based on the Internet
standard security protocol TLS 1.0, which, in turn, is based on SSL
3.0, providing the functionality of a strong Internet security
standard over a wireless airlink. WTLS goes beyond TLS 1.0 by
incorporating new features such as datagram support, optimised
handshake and dynamic key refreshing.Although the WAP security
model does not call for non-repudiation or client authentication, a
particular gateway provider's implementation can provide this with
the use of client certificate and digital signature technology.
Applications can implement client authentication and
non-repudiation by following the standard web development practice
of requiring users to enter a username and password.WTLS and the
WAP security model provide an extremely secure solution that
leverages the best technologies from the Internet and wireless
worlds. When the WAP gateway is deployed in an operator environment
according to standard operator security procedures, subscribers and
content providers can be assured that their personal data and
applications are secure.
Next generation WAP securityThe
current WAP security model requires a strong relationship between
the network operator and the content provider to implement the most
secure solutions possible. The WAP Forum has recognised that as the
market for highly secure applications increases, a more flexible
and extensible solution will be needed. When working across many
different wireless networks, application developers must be assured
that their content remains encrypted from the time it leaves their
application server until it arrives at the WAP handset. Phone.com
has been participating in the WAP process to develop this more
advanced security solution, which must address the enterprise's
need for higher security and the operator's need for proper
integration with WAP gateways in the wireless network.Solutions are
now coming to market before the WAP Forum has established a
standard approach to providing end-to-end secure content. Besides
being proprietary, these solutions promote installing a WAP Gateway
at a content provider or in an enterprise. Since WAP Gateways were
designed for use in an operator's network, this creates a number of
difficulties for content providers, subscribers and wireless
network operators.Operating a WAP gateway at the content source
places a burden on the content provider to maintain a system that
is compatible with a variety of network protocols and SMSCs. For
each network and SMSC combination, the content provider will have
to support a different configuration on their gateway. This goes
against one of the original goals of the WAP Forum to provide
content solutions that are network independent and increases the
effort required for the content developer to deliver services to
the wireless Internet.Content providers are burdened with handset
provisioning and activation issues. The content site must either
limit their offering to a small number of handset models or take on
the burden of supporting a broad array of devices.Because these
solutions are proprietary, they do not work across all WAP
handsets. In some cases, they work with only a single handset
model, limiting the subscriber population that content providers
can reach.Subscribers will find it difficult to switch between an
operator's network-based WAP gateway and the content provider's or
enterprise's gateway. This manual switching requires changing raw
handset parameters each time the subscriber wishes to contact a
different site. Furthermore, when the subscriber experiences
difficulty, both the network operator and the content provider will
experience increased support costs.Subscribers will have more
difficulty getting quality of service issues resolved. Where does a
subscriber call to report a problem with a handset that was
supplied by a content provider and is connecting to the content
provider's WAP gateway but service is being provided by a network
operator? Do they call the operator? The content provider? The
handset manufacturer?Operators must trust equipment operated
outside their network that interacts closely with their network
elements. This can lead to traffic management problems, e.g.,
systems out of their control could flood their networks with SMS
messages. This has an adverse effect on the content provider as
well because their system must compete with others like it for an
unknown amount of network resources, which may lead to poor quality
of service for the subscriber.A solution intended for enterprises
and content sites should be designed to meet their unique needs and
address the real issues of offering seamless, quality service that
integrates well with an operator's WAP gateway. A well-designed
enterprise WAP solution should:Insulate the content site from the
implementation details of the wireless network so that applications
remain network and SMSC-independentLeverage the existing activation
and provisioning systems in the operator's network to shield
content developers from these issuesEnable access from any
WAP-compatible handsetProvide a simple, transparent way for
subscribers to access enterprise WAP sites. It should be as easy to
access one of these sites as it is today to access a standard WAP
content siteMake it easy to identify whether a quality of service
issue lies with the operator's network systems or the content
provider's web server. This allows network operators and content
providers to ensure customer satisfaction by helping to resolve
service issues quicklyAllow the network WAP gateway to work closely
with the enterprise WAP solution so that network resources can be
properly utilised and shared across the wireless Internet
subscriber population.Allow application developers to integrate WAP
technology that can encrypt content using WTLS and send it through
the Internet to operators' networksOffer the proper interfaces to
integrate with the content provider's existing Public Key
Infrastructure (PKI) solution, allowing for ease of integration
into the provider's existing e-commerce systemsProvide a clear
upgrade path from existing WTLS 1.1-compatible applications to this
new grade of WAP securityEnabling content developers to build
solutions that are network independent and secure from end-to-end
is essential. With a high-quality, well-designed solution that
integrates seamlessly with network WAP gateway solutions, both
content developers and network operators will benefit from the
continued growth of value-added subscriber applications.
WAP
security: today and tomorrowApplication providers and wireless
network users should feel confident that today's transactions
leverage the best security provisions that SSL offers through the
robust WTLS implementation. Already, key Internet applications for
handsets have been deployed, including e-banking, stock trading,
e-commerce, and other exchanges of private and mission-critical
data.With WTLS optimised to ensure transactions are conducted in a
secure and user-friendly way, and WAP-capable handsets reaching the
market, subscribers are beginning to embrace wireless e-commerce in
the same fashion that consumers have adopted wired e-commerce over
the last 18 months. As application developers realise returns on
WAP applications, the market is expected to grow rapidly, leading
to a wealth of secure, wireless e-commerce applications.
Application developers are further assured of their investment
since the WAP Forum is already working to develop even more secure
solutions for the future.
(c) 2000 Phone.com