The quantum computer poses a serious threat to current cryptographic techniques. Information sitting in a database for 25 years risks disclosure by those with access to such technology, with potentially serious consequences. These might include the misuse of items relating to military security, foreign policy or banking strategies. Without quantum-safe encryption, everything that has been, or will ever be, transmitted over a network is vulnerable to eavesdropping and public disclosure, and current cryptographic principles were not designed for quantum attacks.
New methods do provide some protection against quantum threats. Such measures comprise techniques based on quantum properties of light that are secure and prevent interception of messages (quantum key distribution, or QKD), as well as quantum-resistant algorithms (QRA). ID Quantique believes a quantum-safe state for data needs to be reached by 2020, and that the planning required to achieve this must start now. Encrypted data is currently being captured and stored by governments for cracking when quantum-ready computers become available, in what are known as 'download now, decrypt later' attacks.
All cryptographic systems based on current asymmetric key encryption will be broken, as will any existing public key infrastructures (PKI) that also rely on it.
Symmetric key encryption will require longer keys, but is considered to be quantum-resistant. Technologies, such as quantum random number generators (QRNG) and quantum key distribution (QKD), protect the data transport from quantum computing attacks. ID Quantique currently makes such products.
QRAs can also be used to improve security, but they are not provably secure, and the algorithms involved are neither yet mature, nor well tested.