Quantum Computing News

The Quantum Shield: How IBM, Signal and Threema Are Redesigning Secure Messaging for the Future

Signal and Threema with IBM

To counter the threat posed by quantum computers in the future, IBM Research’s cryptography researchers are presently working with the creators of the encrypted messaging services Signal and Threema. Eventually, these sophisticated devices could be able to crack a large portion of the encryption used by the current internet. Millions of individuals use messaging applications every day to stay in touch with friends, family, and enterprises. These apps became the vital foundation of contemporary communication as the mobile revolution developed.

Since its 2014 inception, Signal has become one of the most widely used encrypted messaging services worldwide. The service is very serious about its commitment to cross-platform communication that cannot be intercepted by Signal or any other entity. Users may participate in end-to-end encrypted group chats and video conversations, which hold the encryption keys needed to decrypt data on user devices rather than on Signal’s servers.

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It would take an estimated billion years for even the most sophisticated classical supercomputers to break the present encryption standard. But as quantum computing transitions from theoretical physics to actual engineering, a significant computer revolution is taking place, with IBM at the forefront. Quantum computers use qubits to process data, whereas classical computers use bits that are represented as discrete 1s or 0s. Qubits may concurrently represent complex combinations of states with a characteristic called superposition, while entanglement connects qubits to investigate enormous computational possibilities. This makes it possible for quantum machines to perform some jobs tenfold quicker, including factoring the extraordinarily big numbers employed in the mathematical encryption problems that now protect data.

Security experts have sought to develop new algorithms that these systems cannot decipher as the development of powerful quantum computers approaches reality. The first set of three “post-quantum” cryptography standards was released by the US National Institute of Standards and Technology (NIST) in 2024. Two of these standards were developed by IBM Research scientists, while the third was co-designed by a scientist who has since joined IBM Research. These criteria are not always appropriate, even though they are an essential first step in helping companies get ready for a post-quantum world.

Certain applications need more sophisticated encryption, for which there is now no effective quantum-safe counterpart. Compared to traditional methods, the less effective schemes now in use generate a lot more communication data, which would be expensive for businesses to transmit. No firm wants to employ more cryptography than they actually require, according to Vadim Lyubashevsky, principal research scientist at IBM Research. This problem of applicability prompted researchers to consider the next steps beyond the original standards, concentrating on sophisticated cryptographic primitives for intricate technological systems.

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Researchers began exploring ways to make group messaging on Signal quantum-safe by leveraging links to the platform’s developers. The Signal team has developed a strong security architecture, aiming to know as little as possible about its users, including metadata about message originators and group members. “Harvest now, decrypt later,” in which an attacker harvests encrypted data now to crack it later with a strong enough quantum system, is one of the biggest security threats of our day. Signal began protecting user data from these attacks in 2023 and introduced SPQR, another protocol upgrade, in 2025.

Even with these measures, malicious actors may try to crack encryption for group membership as quantum computers get increasingly powerful. Researchers discovered that Signal’s bandwidth for preserving this metadata may be increased by up to 100 times by simply substituting existing components with quantum-safe counterparts. The protocols have to be completely redesigned to guarantee communication efficiency and speed.

The Signal server serves as the gatekeeper in the current private group protocol; however, IBM researchers suggested that group members serve as the “guards.” This novel architecture is more effective for systems that are both quantum-safe and classically secure. The server’s role in this system is to store encrypted group data and control who is able to write to a group. Each group would employ pseudonym keys for its members, which would allow the server to verify that a particular member carried out an activity without connecting that action to a user’s true identity. To guarantee responsibility, other group members are still able to relate activities to the appropriate individual.

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ML-DSA, a lattice-based algorithm that has been standardized by NIST, was updated to include key re-randomization to carry out this redesign. To identify if users are administrators or members and whether servers or members have been infiltrated, the team also created a new security model. The goal of this complete overhaul is to make Signal’s private group system effective, modular, auditable, and quantum-safe while upholding privacy assurances against Signal’s own servers.

This week at Real-World Crypto (RWC), Signal’s team is presenting their results on feasible implementation. Threema, a Swiss messaging system, is working with IBM to add quantum-safe encryption. Threema is investigating the possibility of integrating ML-KEM, a standardized key encapsulation technique for broad encryption, onto its platform in collaboration with the same IBM team.

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Threema CEO Robin Simon noted that this collaboration and the pooling of skills establish the groundwork for the quantum-secure communication of tomorrow. Leading examples of how companies are addressing the need to upgrade technology to be quantum-safe include Signal and Threema. In the post-quantum age, researchers want to maintain the security of all internet communication by proactive efforts such as this.