Quantum cryptography – commonly lauded as an absolutely secure avenue of data transfer – has been broken.

The advanced technology was thought to be unbreakable due to laws of quantum mechanics that state that quantum mechanical objects cannot be observed or manipulated without being disturbed.

In quantum cryptography, regular information is encrypted and decrypted with a quantum key. Any attempts to copy a quantum cryptographic key in transit will be noticeable as extra noise, and cause the communication to be aborted.

But a research team at Linköping University in Sweden claim that it is possible for an eavesdropper to extract the quantum cryptographic key without being discovered.

In a research paper, published in the International engineering journal IEEE Transactions on Information Theory, Larsson has proposed a change in the quantum cryptography process that he expects will restore the security of the technology.