Cryptography and cryptographic protocols

Hans Delfs, Helmut Knebl

Samuel J. Lomonaco

The recent application of the principles of quantum mechanics to cryptography has led to a remarkable new dimension in secret communication. As a result of these new developments, it is now possible to construct cryptographic communication systems which detect unauthorized eavesdropping should it occur, and which give a guarantee of no eavesdropping should it not occur. CONTENTS P3. Cryptographic systems before quantum cryptography P7. Preamble to quantum cryptography P10. The BB84 quantum cryptographic protocol without noise P16. The BB84 quantum cryptographic protocol with noise P19..The B92 quantum cryptographic protocol P21. EPR quantum cryptographic protocols P25. Other protocols P25. Eavesdropping stategies and counter measures P26. Conclusion P29. Appendix A. The no cloning theorem P30. Appendix B. Proof that an undetectable eavesdropper can obtain no information from the B92 protocol P31. Appendix C. Part of a Rosetta stone for quantum mechanics P44. References

Robbi Rahim

Abstract Cryptography is one type of protection that is widely used to secure information, encryption and decryption and the use of keys is a common process used to secure information; and also the cryptographic processes have a classic problem that is the distribution of keys that are vulnerable to interception when the key is sent by the sender to the receiver, the cryptographic protocol (Authentication) could be used to minimize key distribution problem because there is no need for key exchanges. Shamir’s Three-Pass Protocol, Secret Splitting, Bit-Commitment Protocol and Blind Signature are few cryptographic protocols that can be used to help with key distribution issues, this article performs systematic approach to protocol cryptography for security level and the using other algorithms to combine with protocol.

Sindhu Chitikela

The need for secure transmission in the fields of banking and defense has led to the interest in quantum cryptographic protocols which are theoretically more secure than any classical cryptographic protocol. However, the current implementations of the quantum cryptographic protocols have weaknesses. The main goal of this work is to find ways to strengthen quantum cryptographic protocols by using new implementation schemes. We present a method to improve the randomness of the sequence of polarization states used in BB84, the two-stage and the three-stage protocols. An analysis of quantum cryptography in the presence of noise is given. We also study a variant of the three-stage protocol where the intensity of the photons is tracked. We have developed a further improvement to this protocol where the state of the photons is also estimated.