What is Shor's algorithm?
A method, published by Peter Shor in 1994, that would let a large quantum computer work out a private key from its public key.
Shor's algorithm would let a sufficiently large, reliable quantum computerQuantum computer (qubit)A computer that uses quantum physics to solve some problems far faster than ordinary ones. Its working parts are called qubits. solve the maths behind a Bitcoin public keyPublic keyThe partner of a private key. It lets anyone check a signature without revealing the private key under current computing assumptions. far more efficiently than known ordinary-computer methods. The 1994 paper does not provide a running-time estimate for any present-day machine.
That's why Bitcoin developers are debating new kinds of signatures and addresses that don't rely on elliptic curves.