Nec Corporation

Hubert Ritzdorf

Ghassan Karame

Srdjan Capkun

Claudio Soriente

Damian Gruber

A method for storing a data file (DF) on a storage entity (SE) includes receiving, by a proxy (PE) and from a computing entity (CE), a plurality of hash values corresponding to a plurality of blocks of the DF. The PE may check whether the plurality of blocks of the DF are stored in the SE based on the plurality of hash values. Based on determining that at least a subset of the plurality of blocks of the DF are not being stored in the SE, the PE may compute a secret associated with an encryption key. The PE may transmit, to the CE, the secret. The PE may receive, from the CE, information including storage locations of the subset of the plurality of blocks within the SE and one or more hash values, of the plurality of hash values, associated with the subset of the plurality of blocks.

Method for storing a data file

A method for storing a data file, 'DF' on a storage entity, 'SE' includes a computing entity, &#x2018;CE&#x2019;, chunking the DF into a number of blocks using a one-way-function and a chunking key. The CE may compute a hash value for each of the blocks. One or more proxies, &#x2018;PE&#x2019;, may check whether the blocks are already stored, resulting in a first number of already stored blocks and a second number of blocks not being stored. The CE may encrypt the blocks not being stored using an encryption key, transmit the encrypted blocks to the SE for storing, and inform the PE about the hash value of each of the transmitted blocks and corresponding storage location information of the transmitted blocks.

A method for controlling access to a shared resource for a plurality of collaborative users includes securely providing, on a storage and device entity, the shared resource. The shared resource is created by a resource owner entity. The method further includes specifying access control rules for the shared resource, translating the access control rules into a smart contract, including the smart contract into a blockchain, and if a second user requests access to the shared resource, performing access decisions for the shared resource by evaluating the smart contract with regard to the access control rules.

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Zurich, Switzerland

Hubert Ritzdorf