Securing sensitive data in transit through unsecure connections or at rest in a remote server is already a major challenge for CISOs and security teams, but public key cryptography is no longer enough. Today’s encrypted data is being harvested and stored awaiting the development of powerful quantum computers that will break RSA, ECC and others. If your data must be guaranteed secure in the coming age of quantum computers, you need to be using symmetric cryptography, which requires distributing secret keys between communicating users.

Quantum Key Distribution (QKD) provides the solution to resolve the problem of distributing the encryption keys between the sender and the receiver through an unsecure channel. QKD generates symmetric encryption keys between two locations without sending the keys between the sites, making use of physical entanglement properties of exchanged light particles through an ordinary optical fibre. This is particularly important for industries like finance, government agencies, defence, health sectors and critical infrastructures.

QKD allows for symmetric cryptography, immune to attacks from Quantum computers
QKD allows for symmetric cryptography, immune to attacks from Quantum computers

QKD security is based on quantum physics and provides the ability to detect if a photon (particle of light) has been read by an eavesdropper and by extension detect if the information received can be trusted or dropped. This technology provides a future-proof cryptographic solution which doesn’t rely on mathematics or computing performances and provides long-term data security against today’s and tomorrow’s cyber-threats.

With 20 years of experience in this technology and even longer experience in manufacturing high quality products, Toshiba offers two variants of QKD devices: a multiplexed system which can be operated on data-carrying fibre, and a long-distance system for the highest possible key rate and range.

Features of Toshiba QKD

Toshiba Fibre QKD terminal
Toshiba Fibre QKD terminal

Multiplexed QKD system

The Multiplexed QKD system allows operation on fibre which is already carrying data, thereby removing the requirement for costly dark fibre. It uses a quantum channel with a wavelength in the telecom O-Band, leaving the C-band free for customer traffic. It can operate in the conventional mode with a fibre pair carrying uni-direction traffic, or with a single fibre carrying bi-direction quantum and classical signals.

Long Distance QKD System

The Long Distance QKD System operates with a quantum channel in the telecom C-band for the longest possible range and highest possible secure key rate. It can tolerate a limited bandwidth of multiplexed data within the C-band.


Product nameMultiplexed SystemLong Distance System
Key Rate (Typical)40 kb/s @ 10 dB loss300 kb/s @ 10 dB loss
Range (using ideal SM fibre)Up to 70 kmUp to 120 km
Fibre RequirementOne or Two FibresTwo Fibres
Multiplexing compatibilityOption to multiplex
customer data in C-band
Key Exchange ProtocolEfficient BB84 protocol with decoy states and phase encoding
Security ParameterKey failure probability < 10 -10
Detection TechnologyProprietary self-differencing semiconductor detectors
DimensionsStandard 19″ rack mount, height = 3U

Toshiba Fibre QKD website