TCPA
The electronics industry realized that these security issues would be a major hindrance to the development of electronic communication and transactions, and thus began working on an appropriate answer. Founded in 1999 by Compaq, Hewlett Packard, IBM, Intel, and Microsoft the Trusted Computing Platform Alliance (TCPA) defined and developed the concept of Trusted Computing as a security standard.

In the meantime more than 160 companies all along the value chain have joined this impressive industry approach. As the world market leader in secure controllers, Infineon Technologies has contributed to all specifications of the TCPA organization. The basis for the concept that will change PCs, notebooks, PDAs, mobile phones, etc. into Trusted Clients is the so-called TPM (Trusted Platform Module), which provides functionality for strong authentication, secure storage and protection of the PC’s integrity. Infineon Technologies is one of the first companies to provide a product built to the TCPA specification.

The TCPA concept
The TPM has the following tasks:

		Monitoring the trustworthiness of the platform it is bound to
		Providing strong authentication mechanisms for identifying the platform
		Providing secure storage for the user’s keys and secrets
		Providing additional cryptographic services to applications

In addition, the TCPA expects the TPM to meet three further requirements:

		Cost effectivity
		Complete exportability of the platform it is integrated in
		It must not infringe on the platform owner’s privacy.

Trustworthy status
To perform this task, the TPM monitors the booting process of, for example, a PC. During this process, so-called hash values (basically a checksum) for the relevant components are created: BIOS, device drivers, loaders of the operating system. These values are stored in the TPM and can be compared to the reference values that define the trustworthy status of the platform.

By reporting the result to either the owner or a communication partner, the TPM provides crucial information to base a security policy on. A system that reports a non-trustworthy state can be disconnected by the system administrator from the network or at least be investigated to find out the reason of this status.

Strong authentication
Up to now it has been difficult for system administrators to determine whether a system connected to their network is a company system or not. It might be necessary, for example, to limit download of critical documents only to corporate computers (as you don’t want to have them on the hard drive of the PC in an airport lounge, thanks to your traveling businessman). Because the TPM provides the capabilities of a built-in smart card, strong authentication can be provided to give a higher level of assurance to secure networks.

Secure storage
The main CPU of a PC or notebook is build to execute the loaded application quickly and correctly. It is not built to distinguish between “good” and “evil” software. Viruses and Trojan horses are able to steal information on or en route to the main CPU. To protect the most important data (such as a digital signature key) it must be stored in well protected, separate hardware that is also able to provide the necessary performance to utilize this data (e.g. to digitally sign a document). The TPM provides this functionality with a secure non-volatile memory and efficient cryptographic coprocessors.

Additional cryptographic services
Serving standard cryptographic service providers (CSP) like Microsoft® CAPI and RSA’s PKCS#11, the TPM performs additional cryptographic requests. Secure creation of keys, calculation of a hash value and many other functions are provided to the requesting applications. Because the applications already use software cryptography, the additional increase in security by the TPM hardware is tremendous.

Framework
As mentioned earlier, the TPM concept had to meet certain requirements. First of all, the TPM should be cost effective by not adding too much to the overall costs of the platform. Secondly, care had to be taken that no export restrictions were added to the platform. Consequently, the TPM does not offer freely available encryption services to applications. Thirdly and most importantly, the TPM must not compromise the privacy of the user. This was realized by giving the TPM owner full control over its functionality (the TPM can even be disabled). Even when enabled, the TPM can only respond to so-called third-party challenges if allowed to by the owner. Allowing the creation of identities that might be different for each service provides additional protection of the user’s privacy.

The TPM market
The first definition provided by the TCPA is reflected in the integration of TPMs in PCs and notebooks. Given the market power of the promoter and member companies as well as the possibilities provided by TPM functionality, the TCPA concept has the potential to be realized on every PC and notebook platform. This would mean a market of about 200 million pieces by 2005. For the future, it is very likely that the TPMs will move into PDAs, mobile phones, and other devices because they face the same security requirements as clients of a worldwide network.

The Infineon TPM product (SLD 9630 TT 1.1)

Hardware
The basis for the Infineon TPM is the mature technology of the 66P secure controllers. In addition to the well proven, true random number generator and asymmetric RSA coprocessor (which was upgraded to 2048-bit key length) Infineon has realized the hash coprocessor (SHA-1 and MD5) and the LPC interface. Security measures such as active shielding, as well as frequency and temperature sensors, are part of the product just as they are in all the other 66P based products. This gives the Infineon TPM the highest level of security protection in the world.

Firmware and Software
To make integration into customer platforms as secure and convenient as possible, Infineon provides firmware (which runs on the secure controller), the TCPA Software Stack (TSS) and support for integration into the customer’s own BIOS.

Services
In addition to the product, Infineon also provides two services required by the TCPA specification:

		The TPM, including the firmware, must be certified according to the TCPA’s Common Criteria protection profile. This evaluation is the basis for the customer’s Trusted Client certificate.
		Infineon ensures the security critical personalization of TPMs. During this process, a unique public/ private key pair certified by Infineon is created for and stored inside each TPM.

Summary
Security is considered to be the next differentiation feature for PCs and notebooks. The TCPA specifications leave room for differentiation, but ensure interoperability and compliance. Integrating the TPM into such systems makes them more secure as well as trustworthy.

Infineon Technologies is very much involved in the standardization process and accepted as a leader in security components. With the SLD 9630 TT 1.1, Infineon has introduced its first TPM on the market. Further development of a roadmap that includes secure devices for PCs, notebooks, and other network appliances will keep Infineon in the lead in this exciting and growing market.

This article was first published in SECURE magazine (02/2002). It has been presented here in slightly edited form. To read the original article, please visit SECURE Magazine.