can be realised using Transport Layer Security. Remote attestation of the device and key exchange for payload encryption are performed. The data is transferred to the device and stored in sealed blobs, see [@TPM06 Chapter 12], only accessible in the determined state of this unique device. This approach suffers from latency produced by the Steps 2-4, in particular attestation creates computational load and produces some traffic.

An approach to meet this challenge is shown on the right hand side of Figure \[graphs\]. SyncS encrypts the data with a public part of a key pair. The use of the corresponding private part is restricted by a PCR value. To grant trust in this public key the SyncS requires a certificate issued by a PCA, and a certified PCR value, signifying[, [e.g.]{},]{} the presence of an e-mail application in a certain configuration and a well defined environment. The PCA which certifies the platform keys can actually be used here to issue certificates augmented by the information of the PCR value. This variant of an AIK is further called a *binding key*. Step 1 transmits the public portion of a key pair to the designated PCA for content encryption keys. Remote attestation is 