with an AIK — *viz* *certify* it in the parlance of the TCG. Creation of a key is done by executing the `TPM_CMK_CreateKey` command, which returns an asymmetric key pair where the private portion is encrypted by the TPM for use within the TPM only. The resulting key pair is loaded into the TPM by `TPM_LoadKey` and thereafter certified by `TPM_CertifyKey`. By certifying a specific key the TPM makes the statement that “this key is held in a TPM-shielded location, and it will never be revealed”. For this statement to have veracity, a challenger or verifier must trust the policies used by the entity that issued the identity and the maintenance policy of the TPM manufacturer.

This indirection creates to each AIK a certified key (by the namely AIK) that can be used for signing data, in particular the payload data of a ticket to be submitted to, and accepted by, a service. We call this key pair the *certified signing key* (CSK). CSK, AIK, together with a certificate by the PCA (see below) attesting the validity of that AIK, are the ingredients that realise a ticket for a single operation[, [e.g.]{},]{}a service access.

Ticket Acquisition and Redemption {#sec:AcqRed}
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