TSS_Version_1.2_Level_1_FINAL.pdf

TCG wishes to thank all those who contributed to this specification. This version builds on

the work published in version 1.1b and those who helped on that version have helped on

this version.

A special thank you goes to the members of the TSS workgroup who had early access to

this version and made invaluable contributions, corrections and support.

David Challener

TSS Workgroup Chair

Start of informative comment:

The TCG 1.2 Main specification defines a subsystem with protected storage and protected

platform’s main processor and memory space where processing power and storage exceed

that of the TPM. The modules and components that provide this supporting functionality

comprise the TSS.

The TSS 1.2 specification contains additions to the TSS 1.1b specification that correspond

to enhancement that were made in the main TPM specification. Code written using the TSS

1.1b specification should continue to work when executed against a TSS 1.2 stack.

However, the reverse is not always the case, as there is new functionality included in the

1.2 main specification that is reflected in the TSS.

That enhancement comes in several areas:

New Functionality:

requires new APIs.

Delegation: In the 1.1b specification, the only way to let someone or something to

use a key was to give them the use_authentication data. Needless to say, this removed the

possibility of retracting that permission. Delegation allows a finer control, so that use of a

function may be delegated to another person / piece of software, without losing the ability

to retract that permission.

Context Saving – Since loading keys into the TPM turned out to be time consuming,

context saving gives the TPM the ability to cache its internal memory outside the chip

without causing a security vulnerability. In 1.1b, this functionality was optional. In 1.2 it

is now mandatory.

battery, that could be used to do time stamping. However, it is possible to do something

similar by correlating a tick counter with an external time stamping source, and then using