Trusted delegation system

A trust management system for deciding whether to execute a portion of code on a user system, the portion of code being provided by a code supplier, code suppliers having varying levels of trust, the trust management system comprising:

• a policy file which includes claims about security policies of the user system;
• a certificate repository for storing a plurality of certificates, a certificate being a data record including claims;
• means, coupled to the certificate repository, for receiving certificates and storing the certificates in the certificate repository;
• a code examiner, coupled to receive the portion of code from the code supplier and adapted to analyze the portion of code to determine potential resource use of the portion of code;
• and
• a trust evaluator, coupled to the policy file, the certificate repository and the code examiner, wherein the trust evaluator is adapted to determine a path of trust from a relevant claim to a trusted claim and to authenticate claims in the path of trust, where the path of trust, if required, specifies whether execution of the portion of code is allowed by the policy rules and the potential resource use.

A method of authenticating an untrusted claim in a trust system, comprising the steps of:

• (a) authenticating a key provided with the untrusted claim;
• (b) checking that the key has authorization to make the untrusted claim;
• (c) if the authorization for the key to make the untrusted claim is provided by a second claim which is not itself a trusted claim, repeating steps (a) and (b) to authenticate the second claim;
• and
• (d) repeating steps (a), (b) and (c) with subsequent claims until a trusted claim is reached or a predetermined computing effort is expended.