CryptographyQuantum – a double-edged sword for cryptography
Quantum computers pose a big threat to the security of modern communications, deciphering cryptographic codes that would take regular computers forever to crack. But drawing on the properties of quantum behavior could also provide a route to truly secure cryptography.
Quantum computers pose a big threat to the security of modern communications, deciphering cryptographic codes that would take regular computers forever to crack. But drawing on the properties of quantum behavior could also provide a route to truly secure cryptography.
Defense, finance, social networking – communications everywhere rely on cryptographic security. Cryptography involves jumbling up messages according to a code, or key, that has too many combinations for even very powerful computers to try out.
But quantum computers have an advantage. Unlike regular computers, which process information in “bits” of definite ones and zeros, quantum computers process information in “qubits”, the states of which remain uncertain until the final calculation.
The result is that a quantum computer can effectively try out many different keys in parallel. Cryptography that would be impenetrable to regular computers could take a quantum computer mere seconds to crack.
Practical quantum computers that can be used to break encryption are expected to be years, if not decades, away. But that should not be of any reassurance: even if a hacker cannot decipher confidential information now, they could save it and simply wait until a quantum computer is available.
“The problem already exists,” said Professor Valerio Pruneri of the Institute of Photonic Sciences in Barcelona, Spain, and the coordinator of a quantum security project called CiViQ. “A hacker can take what is stored now, and break its key at a later date.”
The answer, says Prof. Pruneri, is another quantum technology. Known as quantum key distribution (QKD), it is a set of rules for encrypting information – known as a cryptography protocol – that is almost impossible to crack, even by quantum computers.
Eavesdrop
QKD involves two parties sharing a random quantum key, according to which some separate information is encoded. Because in quantum theory it is impossible to observe something without corrupting it, the two parties will know whether someone else has eavesdropped on the key – and therefore whether it is safe, or not, to share their coded information.
