There are two principal roles of the GTA. These are:

1) the issuing of identity certificates to the next layer down the hierarchy, called Master Trust Authorities (MTAs), which will allow the MTA to certify the layer below, called Scheme Trust Authorities (STAs). The certificates identify the name and location of the MTA.

2) the setting of the level for the liability risk model for each of the elements in the GTA Infrastructure. These certificates offer a sufficiently high level of integrity to be judged as fit for purpose by the GTA members. Additionally, in future, different certificates may be issued to allow for the specialisation of MTAs in terms of the schemes they can offer. The design of the certificate is sufficiently flexible to allow for such an evolution. The GTA provides a mechanism whereby the MTA certificate can be revoked and the revocation list checked.

The use of an identity certificate in the GTA Infrastructure is the first objective of the GTA, followed by the definition of a library of attribute certificates that may be used in schemes operating within the GTA Infrastructure. Where the attribute certificate is used it is linked to an identity certificate. These initiatives will not preclude schemes-specific attribute certificates.

Responsibilities of the GTA

The GTA is responsible for the following:

1. Establishing and maintaining rules and regulations relating to GTA membership and operation. GTA membership is under consideration with the criteria for membership being determined by the GTA Board. (The reference documents produced by the GTA will provide a basis for the consistent definition of Certificate Policy by STAs)

2. Establishing and maintaining rules and regulations relating to MTAs, and registering approved MTAs.

3. Establishing the operational rules for the inclusion of schemes under the GTA umbrella. These typically focus upon aspects such as certification policies and practices, risk and liability, key security, and audit requirements. There could be clear differentiation according to the degree and type of regulation of STAs, which could potentially allow the trust infrastructure below the GTA to encompass all PKI users.

4. Making operational decisions on managing a centralised root key and providing related services (certification, revocation, publishing, key replacement etc). The GTA only certifies MTAs. This may also require it to certify officers of the GTA or MTAs as having the authority to act on behalf of the GTA or an MTA.

5. Establishing a timetable for the introduction of GTA services