Lifeboat Foundation

Quantum key distribution is one kind of important cryptographic protocols based on quantum mechanics, in which any outside eavesdropper attempting to obtain the secret key shared by two users will be detected. The successful detection comes from Heisenberg’s uncertainty principle: the measurement of a quantum system, which is required to obtain information of that system, will generally disturb it. The disturbances provide two users with the information that there exists an outside eavesdropper, and they can therefore abort the communication. Nowadays, most people need to share some of their private information for certain services such as products recommendation for online shopping and collaborations between two companies depending on their comm interests. Private Set Intersection Cardinality (PSI-CA) and Private Set Union Cardinality (PSU-CA), which are two primitives in cryptography, involve two or more users who intend to obtain the cardinalities of the intersection and the union of their private sets through the minimum information disclosure of their sets^1,2,3.

The definition of Private Set Intersection (PSI), also called Private Matching (PM), was proposed by Freedman⁴. They employed balanced hashing and homomorphic encryption to design two PSI protocols and also investigated some variants of PSI. In 2012, Cristofaro et al.¹ developed several PSI-CA and PSU-CA protocols with linear computation and communication complexity based on the Diffie-Hellman key exchange which blinds the private information. Their protocols were the most efficient compared with the previous classical related ones. There are also other classical PSI-CA or PSU-CA protocols^5,6,7,8. Nevertheless, the security of these protocols relies on the unproven difficulty assumptions, such as discrete logarithm, factoring, and quadratic residues assumptions, which will be insecure when quantum computers are available^9,10,11.

For the sake of improving the security of PSI-CA protocols for two parties, Shi et al.³ designed a probabilistic protocol where multi-qubit entangled states, complicated oracle operators, and measurements in high N-dimensional Hilbert space were utilized. And the same method in Ref.³ was later used to develop a PSI-CA protocol for multiple parties¹². For easy implementation of a protocol, Shi et al.¹³ leveraged Bell states to construct another protocol for PSI-CA and PSU-CA problems that was more practical than that in Ref.³. In both protocols Ref.³ and Ref.¹³, only two parties who intend to get the cardinalities of the intersection and the union of their private sets are involved. Although Ref.¹² works for multiple parties, it only solves the PSI-CA problem and requires multi-qubit entangled states, complicated oracle operators, and measurements. It then interests us that how we could design a more practical protocol for multiple parties to simultaneously solve PSI-CA and PSU-CA problems. Inspired by Shi et al.’s work, we are thus trying to design a three-party protocol to solve PSI-CA and PSU-CA problems, where every two and three parties can obtain the cardinalities of the intersection and the union of their respective private sets with the aid of a semi-honest third party (TP). TP is semi-honest means that he loyally executes the protocol, makes a note of all the intermediate results, and might desire to take other parties’ private information, but he cannot collude with dishonest parties. We then give a detailed analysis of the presented protocol’s security. Besides, the influence of six typical kinds of Markovian noise on our protocol is also analyzed.

As the Signal protocol becomes the industry standard, it’s worth understanding what sets it apart from other forms of end-to-end encrypted messaging.

If you’re a user of Google’s Messages app on your Android smartphone, then you will now likely have the RCS update intended to bring standard text messaging into the current century. RCS is now available in all major countries except China, Russia and Iran. Building on standard SMS capabilities, this adds chat functionality to compete with WhatsApp and iMessage. But, in truth, it doesn’t compete at all. There’s a glaring issue that doesn’t look like being properly fixed anytime soon. This is now bad enough that you should now go use something else.

The issue, of course, is end-to-end encryption. Six months ago, reports emerged that Google was developing this level of security to upgrade RCS. As of this week, this is now finally available for public beta testing. On the surface, its intent is to deliver Android users with an iMessage alternative. But there is a glaring issue—and it’s a deal breaker. This deployment of end-to-end encryption on RCS is not available for groups—that’s seemingly too complex to handle right now. And there’s also no word yet as to when this limited upgrade might be rolled out.

With that in mind, Android users should opt for a different iMessage-like alternative. Fortunately, there is a simple solution available now. While its standard messenger is not end-to-end encrypted by default, Android offers users the option to select an alternative default messenger that does. Signal is the best secure messenger available. And while its install base is modest in comparison to WhatsApp or iMessage, it’s growing fast.

Quantum computing is a new paradigm in computing that utilizes the benefits of quantum mechanics to enhance the computing experience. Quantum computers will no longer rely on binary digits (0 and 1 states), that computers have relied on since the early beginnings, but will instead use quantum bits, which can be in a superposition of states. Quantum bits, or qubits, have the advantage of being in many states at once, offering parallel computing advantages. For example, they have long been regarded as far superior to classical computers for applications in data encryption.

Although the concept of quantum computers has been known for several decades, practical realizations are still lacking. The main limiting factor has been the critical influence of the environment on a qubit. Most physical systems need to be in perfectly controlled conditions in order to remain in the superposition state, whereas any interaction (mechanical, thermal, or other) with the environment perturbs this state and ruins the qubit. Such perturbation is termed “decoherence” that has plagued many potential qubit systems.

Graphene, having spurred research into numerous novel directions, is naturally also considered as a candidate material host for qubits. For example, back in 2013, a team of researchers from MIT found that graphene can be made into a topological insulator – meaning that electrons with one spin direction move around the graphene edges clockwise, whereas those that have the opposite spin move counterclockwise. They made this happen by applying two magnetic fields: one perpendicular to the graphene sheet, to make the electrons flow at sheet edges only, and another parallel to the sheet, that separates the two spin contributions. Electron spin has long been considered a candidate qubit, because it is inherently a quantum system that is in a superposition of states. In graphene, the spins move along the sheet edges robustly, without much decoherence. Furthermore, the same research showed switching the spin selection on and off, an important feature of q-bit transistors.

A cryptographic master tool called indistinguishability obfuscation has for years seemed too good to be true. Three researchers have figured out that it can work.

Circa 2006

Quantum cryptography (QC) is still in a very early stage and there are very few commercial products available. But this doesn’t prevent researchers to look at new solutions. For example, physicists from the University of Wien, Austria, are testing qutrits instead of the more common qubits. These qutrits can simultaneously exist in three basic states — instead of two for the qubits. This means that QC systems based on qutrits will inherently be more secure. But if QC using qubits has been demonstrated over distances exceeding 100 kilometers, the experiments with qutrits are today confined within labs. For more information, read this abstract of a highly technical paper or continue below.

Let’s Encrypt has warned that older Android phones won’t support many secure websites after they lose key certificates by September 2021.

Quantum computers are now a reality, although they are still too rudimentary to factor numbers of more than two digits. But it is only a matter of time until quantum computers threaten Internet encryption.

Nature caught up with Shor to ask him about the impact of his work — and where Internet security is heading.

Nature talks to Peter Shor 25 years after he showed how to make quantum computations feasible — and how they could endanger our data.

Hackers can now reverse engineer updates or write their own custom firmware.