Digital rights management

One of the early motivations behind trusted computing was a desire by media and software corporations for stricter digital rights management technology to prevent users from freely sharing and using potentially copyrighted or private files without explicit permission. Microsoft has announced a DRM technology, PVP-OPM, that says it will make use of hardware encryption.

An example could be downloading a music file from a band: the band's record company could come up with rules for how the band's music can be used. For example, they might want the user to play the file only three times a day without paying additional money. Also, they could use remote attestation to only send their music to a music player that enforces their rules: sealed storage would prevent the user from opening the file with another player that did not enforce the restrictions. Memory curtaining would prevent the user from making an unrestricted copy of the file while it is playing, and secure output would prevent capturing what is sent to the sound system.

Once digital recordings are converted to analog signals, the (possibly degraded) signals could be recorded by conventional means, such as by connecting an audio recorder to the card instead of speakers, or by recording the speaker sounds with a microphone. Even trusted computing cannot guard noninteractive works from analog reconversion.

Users unable to modify software

A user who wanted to switch to a competing program might find that it would be impossible for that new program to read old data, as the information would be "locked in" to the old program. It could also make it impossible for the user to read or modify their data except as specifically permitted by the software.

Remote attestation could cause other problems. Currently web sites can be visited using a number of web browsers, though certain websites may be formatted such that some browsers cannot decipher their code. Some browsers have found a way to get around that problem by emulating other browsers. With TPM, a website could check the internet browser being used and refuse to display on any browser other than the specified one (like Internet Explorer), so even emulating the browser would not work.

Users have no control over data

Sealed storage could prevent users from moving sealed files to the new computer. This limitation might exist either through poor software design or deliberate limitations placed by publishers of works. The migration section of the TPM specification requires that it be impossible to move certain kinds of files except to a computer with the identical make and model of security chip.

Users unable to override

Some opponents of Trusted Computing advocate allowing owner overrides to allow the computer to use the secure I/O path to make sure the owner is physically present, to then bypass restrictions. Such an override would allow remote attestation to a user's specification, e.g., to create certificates that say Internet Explorer is running, even if a different browser is used. Instead of preventing software change, remote attestation would indicate when the software has been changed without owner's permission.

Trusted Computing Group members have refused to implement owner override.[16] Proponents of trusted computing believe that Owner override defeats the trust in other computers since remote attestation can be forged by the owner. Owner override offers the security and enforcement benefits to a machine owner, but does not allow him to trust other computers, because their owners could waive rules or restrictions on their own computers. Under this scenario, once data is sent to someone else's computer, whether it be a diary, a DRM music file, or a joint project, that other person controls what security, if any, their computer will enforce on their copy of those data. This has the potential to undermine the applications of trusted computing to enforce Digital Rights Management, control cheating in online games and attest to remote computations for grid computing.

Loss of anonymity

Because a Trusted Computing equipped computer is able to uniquely attest to its own identity, it will be possible for vendors and others who possess the ability to use the attestation feature to zero in on the identity of the user of TC-enabled software with a high degree of certainty.

Such a capability is contingent on the reasonable chance that the user at some time provides user-identifying information, whether voluntarily or indirectly. One common way that information can be obtained and linked is when a user registers a computer just after purchase. Another common way is when a user provides identifying information to the website of an affiliate of the vendor.

While proponents of TC point out that online purchases and credit transactions could potentially be more secure as a result of the remote attestation capability, this may cause the computer user to lose expectations of anonymity when using the Internet.

Critics point out that this could have a chilling effect on political free speech, the ability of journalists to use anonymous sources, whistle blowing, political blogging and other areas where the public needs protection from retaliation through anonymity.

In response to privacy concerns, researchers developed direct anonymous attestation which allows a client to perform attestation while limiting the amount of identifying information that is provided to the verifier.

Practicality

Any hardware component, including the TC hardware itself, has the potential to fail, or be upgraded and replaced. A user might rightfully conclude that the mere possibility of being irrevocably cut-off from access to his or her own information, or to years' worth of expensive work-products, with no opportunity for recovery of that information, is unacceptable. Legal restrictions on the use and dissemination of information, or mandating its reliable storage for a period of time that may extend to many years in the future, may also, it has been argued, preclude the practical application of TC technology in many of the ways now contemplated. The concept of basing ownership or usage restrictions upon the verifiable identity of a particular piece of computing hardware may be perceived by the user as problematic if the equipment in question malfunctions.

Interoperability

Trusted Computing requests that all software and hardware vendors will follow the technical specifications released by the Trusted Computing Group in order to allow interoperability between different trusted software stacks. However, even now there are interoperability problems between the TrouSerS trusted software stack (released as open source software by IBM) and Hewlett-Packard's stack[17]. Another problem is the fact that the technical specifications are still changing, so it is unclear which is the standard implementation of the trusted stack.

Hardware and software support

* Since 2004, most major manufacturers have shipped systems that have included Trusted Platform Modules, with associated BIOS support.[18] In accordance with the TCG specifications, the user must enable the Trusted Platform Module before it can be used.
* The Linux kernel has included trusted computing support since version 2.6.13, and there are several projects to implement trusted computing for Linux. In January 2005, members of Gentoo Linux's "crypto herd" announced their intention of providing support for TC — in particular support for the Trusted Platform Module.There is also a TCG-compliant software stack for Linux named TrouSerS, released under an open source license.
* Some limited form of trusted computing can be implemented on current versions Microsoft Windows with third party software.
* The Intel Classmate PC (a competitor to the One Laptop Per Child) includes a Trusted Platform Module