The scientists in the Vienna research group demonstrated this concept of blind quantum computing in an experiment: they performed the first known quantum computation during which the user’s data stayed perfectly encrypted. The experimental demonstration used photons, or light particles, to encode the data. back to the user who can then interpret and utilize them. Even if the quantum computer or an eavesdropper tries to read the qubits, they gain no useful information without knowing the initial state; hence they are “blind.” The process works in the following manner. The user pre- pares qubits – the fundamental units of quantum comput- ers – in a state known only to that user, and sends those qubits to the quantum computer. The quantum computer entangles the qubits according to a standard scheme. The actual computation is measurement-based: simple mea- surements on qubits implement the processing of quantum information. The user tailors the measurement instructions to the particular state of each qubit, and sends them to the quantum server. The results of the computation are sent According to the analysis done by the National Institute of Standards and Technology (NIST), the most important uses of public key cryptography today are for digital signatures and key establishment. The construction of a large-scale quantum computer would render many of these public key cryptosystems insecure. This includes, in particular, sys- tems based on the difficulty of integer factorization, such as RSA, as well as ones based on the hardness of the discrete log problem. Hence, the search for algorithms believed to be resistant to attacks from both classical and quantum computers has focused on public key algorithms. 30 | THE DOPPLER | SPRING 2019 Quantum Safe Encryption