Secure Client- Server Delegated Computation: Difference between revisions

Secure Delegated Computation was an open problem in classical computation until Gentry's work in 1994 on Homomorphic Encryption using Lattice Based Cryptography [[Secure Client- Server Delegated Computation#References|(1)]]. An analogue was required in case of delegating quantum data. Childs proposed the first work in the field in 2005 [[Secure Client- Server Delegated Computation#References|(2)]]. Unlike the classical scheme, this protocol could not only hide the input and output of the client from the sever but also client's computation. This was a breakthrough as there exists no such scheme in classical cryptography which could provide this additional functionality, called 'blindness'. Arrighi and Salvail  later showed [[Secure Client- Server Delegated Computation#References|(3)]] that hiding of computation was possible only for a few functions. They also coined the notion of [[Secure Verifiable Client-Server Delegated Quantum Computation|verifiability]]. In 2009, Broadbent, Fitzsimons and Kashefi developed prepare and send universal blind quantum computation, which was the first scheme to solve this problem for any quantum circuit. This property, also known as universality, opened the gates for further research in this field. New protocols came into picture, some using the measurement based quantum computation framework like blind quantum computation and some devising homomorphic encryption for quantum data. Out of which, prepare-and-send universal blind quantum computation has been proven to be universally composable i.e. it is secure in any and every scenerio possible. The only other protocol which is proven to be universally composable is [[Quantum Key Distribution]]. All the above protocols required quantum communication until the latest work by Urmila Mahadev in 2018, classical fully homomorphic encryption for quantum circuits. It requires no quantum operation on the client's side. pseudo-secret random qubit generator is a functionality different from delegation of quantum computation. It comes with multiple uses, one of which being universal blind quantum computation. This protocol also requires no quantum computation on client's side in order to instruct server to prepare her secret random qubits, of which she has complete knowledge but not the server.<br/>