Quantum Risk Looks More Immediate For Signal Than For Bitcoin

Long confined to speculation about bitcoin, quantum computing is now entering a much more sensitive field: that of encrypted messaging. Behind the debate on blockchain security, another more immediate threat is emerging: that of private data intercepted today, then decrypted tomorrow. Researchers and industry warn about this shift, which moves the front line towards tools like Signal or Threema.

A more immediate threat to Signal than to bitcoin

Quantum computing is often presented as a threat to bitcoin. Indeed, cryptographer Ethan Heilman explains that the short-term risk would be greater for applications like Signal than for bitcoin, not because a quantum attack is already possible, but because some communications can be intercepted today, stored, then attacked later.

The issue is no longer just the future solidity of a decentralized monetary network, but the potential vulnerability of private conversations already exchanged. In this context, it is reminded that Signal and Threema, launched respectively in 2014 and 2012, rely on end-to-end encryption and store keys on users’ devices. The stakes therefore concern sensitive data that may be collected today awaiting more advanced computing capabilities.

Ethan Heilman issues the warning in direct terms. He states : “the short-term threat is much greater for an application like Signal than for bitcoin, due to attacks involving storing encrypted messages today to try to exploit them later”.

He adds: “in theory, someone could record communications today, then attack them later once in possession of a quantum computer”.

• The reasoning is based on the logic of “collect today, decrypt later”. Even without an operational quantum computer today capable of breaking these systems, the value of interception can already exist. Malicious actors could accumulate data betting on future decryption capabilities. This is what makes messengers more exposed in the short term ;

• Encrypted messengers are used by individuals, journalists, governments, and political leaders. This gives this warning a broader scope than a simple technical debate about bitcoin and blockchains.

IBM, Signal and Threema move to the adaptation phase

The second dimension concerns not the warning itself, but the responses already underway. In a post published on March 9, 2026, IBM Research indicates that its researchers are working with Signal and Threema to prepare communication systems resistant to future quantum machines.

IBM recalls that in 2024, NIST published a first set of three post-quantum cryptography standards. The group also explains that the issue is not limited to message encryption, but also concerns finer protocol components, such as some metadata linked to discussion groups.

Signal had already begun this transition. In a post dedicated to PQXDH, the company explains that it has added a post-quantum mechanism to protect new discussion sessions against the risk of future decryption. Then, on October 2, 2025, Signal announced SPQR, described as a new step intended to strengthen the protocol’s resistance against quantum threats while maintaining guarantees of persistent confidentiality and post-compromise security.

IBM adds that scaling these protections presents a very concrete efficiency problem. A simple transposition of current components to post-quantum equivalents could cause “an up to hundred-fold increase in Signal’s bandwidth”. This finding is what drives the teams to thoroughly review the protocols.

As Signal, Threema, and IBM accelerate on post-quantum, one question arises : what if the quantum fear is just a pretext to rethink communication security more broadly? Behind the technological alert, perhaps the entire architecture of digital confidentiality is entering a new phase.