An algorithm that could break supposedly future-proofed encryption methods has cryptographers scrambling to understand the threat, though there is no immediate danger of hackers gaining access to encrypted data.

Quantum computers threaten to one day crack the widely used encryption algorithms that keep banking, email and other data safe, so researchers having been working to develop “post-quantum” algorithms to replace them. Many of these are based on “lattice problems”, an area of mathematics that involves regular patterns, or lattices, in space. The algorithms have been approved as secure by…