Secure Client- Server Delegated Computation: Difference between revisions

It involves a partially classical Client performing both classical and quantum communication with the Server during the preparation stage and output correction. There is no communication between the two parties during computation stage. Protocols falling under this category are Quantum Fully Homomorphic Encryption (QFHE). Client hides her input states with the help of some classical encryption using [[Supplementary Information#Homomorphic Encryption|HE]] and prepares quantum gadgets (using [[Supplementary Information#entanglement|entanglement]]) which the Server uses perform computation on the encrypted state. This requires some steps which cannot be realised by classical HE scheme. Later Client decrypts the outcome sent by Server to get the correct result.  Just like UBQC, QFHE protocols can also be realised by a [[Prepare and Send Quantum Fully Homomorphic Encryption|Prepare and Send QFHE]] protocol where client prepares and sends the input states to the Server. If the task performed by the Server can be verified by the Client, the protocol is called, Verifiable Quantum Fully Homomorphic Encryption (VQFHE). Same as QFHE, VQFHE can be realised by [[Prepare and Send Verifiable Quantum Fully Homomorphic Encryption|Prepare and Send VQFHE]]. For both QFHE and VQFHE, Measurement Only protocols are an open case. Version for quantum input/output is also available in the descriptions.

It involves a fully classical Client perform only classical communication with the Server during the preparation stage and output correction. There is no communication between the two parties during computation stage. It uses only classical [[Supplementary Information#Homomorphic Encryption|HE]] and no quantum gadgets to realize a quantum functionality for classical input/output. Quantum offline communication would be needed in case of quantum input/output. Protocols falling under this category are quantum capable Classical Fully Homomorphic Encryption [[Classical Fully Homomorphic Encryption for Quantum Circuits|(FHE) for Quantum Circuits]]. A verification of FHE for Quantum Circuits protocol is still an open question.