quantum cryptography ieee papers free download
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quantum cryptography ieee papers free download
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quantum cryptography ieee papers free download
13-04-2017, 01:12 PM
Quantum cryptography
Quantum cryptography is a new and important chapter. It is a recent technique that can be used to ensure the confidentiality of information transmitted between two parties, usually called Alice and Bob, exploiting the counterintuitive behavior of elementary particles such as photons.
The physics of elementary particles are governed by the laws of quantum mechanics, which were discovered in the early twentieth century by talented physicists. Quantum mechanics fundamentally changes the way we view our world. In the atomic scales, the elementary particles do not have a precise location or velocity, as we intuitively expected. An observer who wanted to obtain information about the location of the particle would destroy information about its velocity - and vice versa - as captured by Heisenberg's famous uncertainty principle. This is not a limitation due to the technology of the observer, but rather a fundamental limitation that no one can ever overcome. The uncertainty principle has long been considered an inconvenient limitation, until recently, when positive applications were found.
Meanwhile, in the mid-twentieth century marked the creation of a new discipline called information theory. The theory of information aims to define the concept of information and to describe mathematically tasks such as communication, coding and encryption. A pioneer of famous scientists such as Turing and von Neumann and formally established by Shannon, he answers two fundamental questions: what is the fundamental limit of data compression and what is the highest transmission rate possible through a communication channel?
Shannon was also interested in cryptography and the way we can transmit sensitive information. He proved that a perfectly secure encryption would need a secret key that is as long as the message to encrypt. But it does not say how to get such a long secret key. This is quite limiting because the secret code needs to be transmitted confidentially, for example, by using a diplomatic bag. If we had a way, say a private line, to transmit it safely, we could directly use this private line to transmit our confidential information.
From the 1970s to today, cryptographers have found several clever ways to send sensitive information via encryption. In particular, classic ciphers encrypt messages using a small secret key, much smaller than the size of the message. This makes confidentiality achievable in practice. However, we know from Shannon's theory that the safety of such schemes can not be perfect.
Leaving aside the problem of sending confidential information, let's go back to information theory. Shannon defined information as a mathematical concept. However, a piece of information must somehow be stored or written in a medium and, therefore, must follow the laws of physics. Landauer was one of the first to realize the consequences of the fact that any piece of information ultimately exists because of its physical support. Shannon's theory essentially supposes a classic physical support. When the medium is of atomic scale, the information transported behaves very differently, and all the specific characteristics of quantum mechanics must be translated into a theoretical language of information, giving rise to quantum information theory.
Quantum cryptography is the science of exploiting quantum mechanical properties to perform cryptographic tasks. The best-known example of quantum cryptography is the distribution of the quantum key that offers a theoretically secure solution to the solution of the key exchange problem. Public key encoding algorithms and signature schemes currently used (for example, RSA and ElGamal) can be broken by quantum opponents. The advantage of quantum cryptography lies in the fact that it allows to complete several cryptographic tasks which are shown or conjectured to be impossible using only classical (ie, non-quantum) communication. For example, it is impossible to copy coded data into a quantum state and the same act of reading coded data in a quantum state changes the state. This is used to detect spying in the distribution of the quantum key.
The physics of elementary particles are governed by the laws of quantum mechanics, which were discovered in the early twentieth century by talented physicists. Quantum mechanics fundamentally changes the way we view our world. In the atomic scales, the elementary particles do not have a precise location or velocity, as we intuitively expected. An observer who wanted to obtain information about the location of the particle would destroy information about its velocity - and vice versa - as captured by Heisenberg's famous uncertainty principle. This is not a limitation due to the technology of the observer, but rather a fundamental limitation that no one can ever overcome. The uncertainty principle has long been considered an inconvenient limitation, until recently, when positive applications were found.
Meanwhile, in the mid-twentieth century marked the creation of a new discipline called information theory. The theory of information aims to define the concept of information and to describe mathematically tasks such as communication, coding and encryption. A pioneer of famous scientists such as Turing and von Neumann and formally established by Shannon, he answers two fundamental questions: what is the fundamental limit of data compression and what is the highest transmission rate possible through a communication channel?
Shannon was also interested in cryptography and the way we can transmit sensitive information. He proved that a perfectly secure encryption would need a secret key that is as long as the message to encrypt. But it does not say how to get such a long secret key. This is quite limiting because the secret code needs to be transmitted confidentially, for example, by using a diplomatic bag. If we had a way, say a private line, to transmit it safely, we could directly use this private line to transmit our confidential information.
From the 1970s to today, cryptographers have found several clever ways to send sensitive information via encryption. In particular, classic ciphers encrypt messages using a small secret key, much smaller than the size of the message. This makes confidentiality achievable in practice. However, we know from Shannon's theory that the safety of such schemes can not be perfect.
Leaving aside the problem of sending confidential information, let's go back to information theory. Shannon defined information as a mathematical concept. However, a piece of information must somehow be stored or written in a medium and, therefore, must follow the laws of physics. Landauer was one of the first to realize the consequences of the fact that any piece of information ultimately exists because of its physical support. Shannon's theory essentially supposes a classic physical support. When the medium is of atomic scale, the information transported behaves very differently, and all the specific characteristics of quantum mechanics must be translated into a theoretical language of information, giving rise to quantum information theory.
Quantum cryptography is the science of exploiting quantum mechanical properties to perform cryptographic tasks. The best-known example of quantum cryptography is the distribution of the quantum key that offers a theoretically secure solution to the solution of the key exchange problem. Public key encoding algorithms and signature schemes currently used (for example, RSA and ElGamal) can be broken by quantum opponents. The advantage of quantum cryptography lies in the fact that it allows to complete several cryptographic tasks which are shown or conjectured to be impossible using only classical (ie, non-quantum) communication. For example, it is impossible to copy coded data into a quantum state and the same act of reading coded data in a quantum state changes the state. This is used to detect spying in the distribution of the quantum key.
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