Arm Limited

Openwave Systems Inc.

Telefonaktiebolaget Lm Ericsson (publ)

Nicholas Wood

James Clarke

Michael E S Luna

Memory access circuitrycontrols access to memory based on ownership information defining, for a given memory region, an owner realm specified from among two or more realms, each realm corresponding to at least a portion of a software processes miming on processing circuitry. The owner realm has a right to exclude other realms from accessing data stored within the given memory region. On activation of a target realm, it is detected whether a parameter signature derived from security configuration parameters established for the target realm matches an expected signature; and in response to detecting a mismatch between the parameter signature and the expected signature, an activation restriction is applied to the target realm to prevent the activation of target realm or prevent correct functioning of the target realm following activation.

Parameter signature for realm security configuration parameters

A method comprises: a first data processing device requesting attestation of a second data processing device; the second data processing device generating a device-specific attestation message in dependence upon a device-specific key, a hardware configuration of the second data processing device and a software configuration of software running on the second data processing device; the second data processing device generating an application-specific attestation message in dependence upon an interaction protocol by which the first data processing device and the second data processing device interact; the second data processing device cryptographically binding the application-specific attestation message to the device-specific attestation message; the first data processing device verifying the application-specific attestation message, the verifying step comprising detecting a trusted status of the application-specific attestation message by verifying the device-specific attestation message cryptographically bound to the application-specific attestation message; and the first data processing device establishing an interaction with the second data processing device according to the interaction protocol, in dependence upon the verified application-specific attestation message.

Attestation using device-specific and application-specific attestation messages

Memory access circuitry controls access to memory based on ownership information defining, for a given memory region, an owner realm specified from among two or more realms, each realm corresponding to at least a portion of a software processes running on processing circuitry. The owner realm has a right to exclude other realms from accessing data stored within the given memory region. When security configuration parameters for a given realm specify that the given realm is associated with a trusted intermediary realm identified by the security configuration parameters, the trusted intermediary realm may be allowed to perform at least one realm management function for the given realm, e.g. provision of secret keys and/or saving/restoring of security configuration parameters. This can enable use cases where multiple instances of the same realm with common parameters need to be established on the same system at different times or on different systems.

Trusted intermediary realm

An intermediary node on a data communications network implements a flow control algorithm to control network congestion. The intermediary node receives messages destined for servers or other upstream nodes from clients or other downstream nodes and determines whether to forward the messages based on the flow control algorithm, which may be adaptive. The algorithm may consider explicit back-off messages received from upstream nodes, failure of upstream nodes to respond to messages forwarded by the intermediary node, and/or other criteria. When a back-off condition applies, the intermediary node refrains from forwarding messages it receives and sends back-off messages to nodes initiating the messages. Back-off messages may include a back-of time period and/or other back-off criteria.

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Belfast, United Kingdom

Nicholas Wood