MOBILE SECURITY: Crossing the wireless security gap
- 01 August, 2001 11:54
Organisations have high hopes for wireless commerce. Gartner Group analyst Bob Egan calls wireless "the growth hormone for e-commerce". But before wireless e-commerce or even wireless access to the corporate network takes off, organisations are going to have to nail down wireless security.
It's not that wireless isn't secure as it stands now - many companies are doing secure wireless transactions today. Rather, wireless security is difficult to implement, requiring organisations to piece together myriad technologies. Few vendors offer a complete security package, and large pieces of the security puzzle are beyond the control of corporate IT, resting instead with carriers and wireless device manufacturers.
Most organisations would prefer to support only a single security model for e-commerce, preferably the Internet model in use today, notes Jeff Reed, vice president of e-commerce consulting firm Logical, a division of London-based Datatec. E-commerce in the wired world today relies primarily on Secure Sockets Layer (SSL), which is used to transmit everything from personal identification numbers (PIN) and passwords to credit card numbers.
But when you try to move this approach to the wireless world, you immediately encounter problems, starting with mobile phones with wireless application protocol (WAP) capabilities. Unlike desktop and laptop computers or even personal digital assistants (PDA), WAP phones are pretty limited when it comes to security and lack the CPU power and memory necessary for RSA encryption, a key element of SSL.
Encryption ensures confidentiality by preventing eavesdropping, and WAP devices include their own security protocol, Wireless Transport Layer Security (WTLS). This is equivalent to SSL but uses less resource-intensive encryption algorithms, such as elliptic-curve cryptography (ECC).
There's nothing wrong with WTLS except that "it is not compatible with SSL," which is the industry standard, notes Jeffrey Robinson, manager of corporate development at RSA Security. So WTLS messages must be converted into SSL before an e-commerce site or corporate network can read them.
Conversion presents a security problem. Wireless messages travel through the air to the carrier's transmitter, where they are received and passed to a gateway that funnels them into the conventional wired network for transmission to the destination. At the gateway, the WTLS message is converted into SSL. For a brief moment, the message sits unencrypted inside the gateway, creating a security vulnerability.
To some observers, this gap in encryption presents an intolerable threat. Others take a more practical view. "We're not losing any sleep over it," says Philip Wood, director of international wireless at US-based Charles Schwab & Co. The messages spend only a few milliseconds in the clear on a machine buried deep inside the carrier's facility. "Somebody would have to break into a carrier site and do a data dump at that precise moment," he explains.
Egg PLC is a wireless Web-based bank in London. To guard the gateway conversion from WTLS to SSL, it runs its own gateway internally. Each message still spends a moment in the clear, but it happens within the Egg facility. "The best solution would be SSL end-to-end," says Iain Hunneybell, Egg's Internet customer authentication manager.
No Denying PKI
Encryption addresses part of the wireless security challenge. But it doesn't provide the solid authentication required for nonrepudiation, which is a mechanism that validates the information sender's identity to the receiver so that the receiver can be sure the user is who they say they are.
"For authentication and nonrepudiation, PKI, where certificates and keys are bound to the user, is the way to go. Everything is initiated through those keys," explains Paul Mansz, vice president of architecture at Canada-based 724 Solutions, a provider of wireless e-commerce applications. Several public-key infrastructure (PKI) products for wireless are starting to emerge, such as US-based Certicom's MobileTrust.
With PKI, organisations issue digital certificates to users to validate user's identity. The certificate is encrypted and accompanies each transaction. By using the public and private key and a certificate authority to validate the certificate, authorised parties can decrypt the certificate to authenticate the user with greater assurance than can be achieved through PIN-based authentication.
With this approach, however, a third party is needed to validate the digital certificate. Vendors that have introduced digital certificates include Certicom, RSA Security, Entrust Technologies, Baltimore Technologies and VeriSign.
Charles Schwab has opted for a smart-card system from Stockholm-based mobile phone vendor Ericcson and French smart-card provider Gemplus.
In the system, currently being deployed in Hong Kong, the wireless device reads the smart card, which carries the Schwab customer's private key and digital certificate. The customer then enters his account number and PIN.
The smart-card system allows for nonrepudiation, but it's available only where there are Global System for Mobile Communications (GSM) wireless networks, forcing Schwab to use two different security strategies - one for the US and one for Asia and Europe.
When it comes to authentication, wireless adds a disturbing wrinkle. A wireless phone can be easily stolen or lost. If the owner's digital certificate and key are in the phone, as a smart card or otherwise embedded, it presents an opportunity for considerable mischief. By combining smart cards with the requirement to separately enter a PIN, organisations can thwart such threats. But entering data such as account names and PINs on a mobile phone "isn't easy to do. We need simpler approaches," says John Pescatore research director for Internet security at Gartner Group.
On the Horizon
One emerging security tool is biometric devices, which use unique physical identifiers such as voiceprints, fingerprints or retina images to positively identify the user. With biometrics, even if someone should steal your mobile phone, they wouldn't be able to imitate your voice or fingerprint. "By 2004, we expect biometrics will have reached the price/performance level to allow it to be integrated into PDAs and mobile phones," Pescatore says.
US-based Keyware offers a system that lets users register their voiceprints for authentication purposes. The voiceprints can be stored on a central server or on a smart card within the wireless device. However, the voiceprint technology is still in its infancy.
Many of the obstacles confronting wireless security will disappear with the widespread adoption of third-generation wireless technology. The third-generation phones will be IP-based and sport more processing power, memory and bandwidth, which will allow SSL security end-to-end.
By combining third-generation wireless with smart cards and biometrics, organisations will finally have a unified security system that works for both the wireless and wired worlds.
Secure Sockets Layer (SSL) consists of a set of cryptographic protocols that use public-key technology to authenticate the site you are visiting and encrypt the data stream to keep the data transmitted confidential and unmodified.
Wireless Transport Layer Security (WTLS) functions similar to SSL, which is alternatively known as Transport Layer Security (TLS). WTLS provides for client or server authentication and allows for encryption based on negotiated parameters between the handheld device and the WAP gateway.
Public Key Infrastructure (PKI) is a set of policies and procedures for establishing a secure method for exchanging information within, which includes the use of certification authorities (CAs) and digital signatures as well as all the hardware and software used to manage the process.