Using the quantum properties of single photons to exchange binary keys between two partners for subsequent encryption of secret data is an absolutely novel technology. Only a few years ago quantum cryptography or better: quantum key distribution (QKD) was the domain of basic research laboratories at universities. But during the last few years things changed. QKD left the laboratories and was picked up by more practical oriented teams that worked hard to develop a practically applicable technology out of the astonishing results of basic research.

One major milestone towards a QKD technology was a large research and development project funded by the European Commission that aimed at combining quantum physics with complementary technologies that are necessary to create a technical solution: electronics, software, and network components were added within the project SECOQC (Development of a Global Network for Secure Communication based on Quantum Cryptography) that teamed up all expertise on European level to get a technology for future encryption.

The practical application of QKD in a standard optical fibre network was demonstrated October 2008 in Vienna, giving a glimpse of the future of secure communication. Although many steps have still to be done in order to achieve a real mature technology, the corner stone for future secure communication is already laid.

QKD will not be the Holy Grail of security, it will not be able to solve all problems for evermore. But QKD has the potential to replace one of the weakest parts of symmetric encryption: the exchange of the key. It can be proven that the key exchange process cannot be corrupted and that keys that are generated and exchanged quantum cryptographically will be secure for ever (as long as some additional conditions are kept).

This book will show the state of the art of Quantum Cryptography and it will sketch how it can be implemented in standard communication infrastructure. The growing vulnerability of sensitive data requires new concepts and QKD will be a possible solution to overcome some of today s limitations."

This book provides an overview of state-of-the-art implementations of quantum random number generators (QRNGs), and especially examines their relation to classical statistical randomness models and numerical techniques for computing random numbers. The reader - who ideally has a background in classical statistics, computer science, or cryptography - is introduced to the world of quantum bits step by step, and explicit relations between QRNGs and their classical counterparts are identified along the way. Random number generation is a major pillar of cryptography. Capitalizing on the randomness inherent in quantum phenomena is a rapidly evolving branch of quantum cryptography with countless applications for the future. The value of quantum randomness for cryptographic purposes is empirically demonstrated in statistical evaluations of QRNGs' performance compared to classical techniques for true and pseudorandom number generation. The book then provides an overview of technical implementations of QRNGs, before a concluding discussion of major achievements and remaining obstacles in the field rounds out the coverage, while also opening the door for future research directions.

Using the quantum properties of single photons to exchange binary keys between two partners for subsequent encryption of secret data is an absolutely novel technology. Only a few years ago quantum cryptography or better: quantum key distribution (QKD) was the domain of basic research laboratories at universities. But during the last few years things changed. QKD left the laboratories and was picked up by more practical oriented teams that worked hard to develop a practically applicable technology out of the astonishing results of basic research.

One major milestone towards a QKD technology was a large research and development project funded by the European Commission that aimed at combining quantum physics with complementary technologies that are necessary to create a technical solution: electronics, software, and network components were added within the project SECOQC (Development of a Global Network for Secure Communication based on Quantum Cryptography) that teamed up all expertise on European level to get a technology for future encryption.

The practical application of QKD in a standard optical fibre network was demonstrated October 2008 in Vienna, giving a glimpse of the future of secure communication. Although many steps have still to be done in order to achieve a real mature technology, the corner stone for future secure communication is already laid.

QKD will not be the Holy Grail of security, it will not be able to solve all problems for evermore. But QKD has the potential to replace one of the weakest parts of symmetric encryption: the exchange of the key. It can be proven that the key exchange process cannot be corrupted and that keys that are generated and exchanged quantum cryptographically will be secure for ever (as long as some additional conditions are kept).

This book will show the state of the art of Quantum Cryptography and it will sketch how it can be implemented in standard communication infrastructure. The growing vulnerability of sensitive data requires new concepts and QKD will be a possible solution to overcome some of today s limitations."