Quantum Cryptography over 14 Km of Installed Optical Fiber
Cryptography, the science of secret communications, is becoming increasingly important with the growth of computer networks and electronic transactions. When sensitive information is transferred from place-to-place it becomes vulnerable to eavesdropping or tampering with potentially catastrophic consequences. Thus, two of the main goals of cryptography are: the encryption of a message to render it unintelligible to a third party; and authentication of a message to certify to the legitimate recipient that it has not been altered in transit. Both of these objectives can be accomplished, with provable security, if the sender (conventionally referred to as “Alice”) and recipient (“Bob”) possess a secret random bit sequence (“key” material), which is therefore a valuable resource. For example, Alice may encrypt her messages to Bob by first rendering them into binary numbers and then adding the random key bits to the message modulo 2 (no “carries”). Bob can decrypt this communication by subtracting his key bits. This encryption system is known as the “onetime pad” and is secure because the encrypted transmission from Alice to Bob has all the characteristics of purely random numbers, and therefore gives no clue as to how it is to be decrypted.
KeywordsCentral Peak Quantum Cryptography Dark Count Noise Rate Encrypt Transmission
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