Using this principle, QC provides unconditional security to protect our data. A unit of **quantum** information is also called as qubit or **quantum** bit. A qubit can have values 0 or 1 which can retain superposition state of these two bits. Using **Quantum** **cryptography**, secret key is obtained, and then it can be used with classical cryptographic techniques as the one- time-pad to allow the parties to interact. In **Quantum** Key Distribution, we consider two peoples as Alice and bob which obtains some **quantum** states and measures them. A QKD system contains two channels such as a **quantum** channel which is only used to transmit single photon transparent optical path and a classical channel which is channel can be a conventional IP channel. The key can be generated by communicating through **quantum** channels and then they communicate through classical channels to determine their measurements results leads to secret key bit. QKD systems continually generate new private keys that share automatically on both sides.

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Depending on the theory of physics, **quantum** **cryptography** does not make it possible to eavesdrop on transmitted information. **Quantum** cryptographic transmission encrypts the 0s and 1s of digital signal on individual particles of light known as photons. The modern optical transmission states that the digital signal (0’s and 1’s)represents strength and weakness of light as they are made up of tens of thousands of photons in which each express the same information. Even if the signal is eavesdropped (i.e., several photons are stolen) during transmission, it is not detected. On the other hand, if any third party detects the signal, then the information on the photons is suddenly transformed, meaning that it is immediately noticeable that Eve has appeared and the third party is not able to decrypt the information.

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Since digital signatures also based on public key **cryptography** and once it is easy to break them, then digital signatures will also not be secure any more. For that purpose also **quantum** **cryptography** has received a lot of attention. Here we will present one simple approach to generate **quantum** digital signature using **quantum** public **cryptography** based on **quantum** trapdoor one-way function

Above characteristics can be considered negative but these drawbacks are turned into positive applications for **quantum** **cryptography**. Heisenberg Uncertainty principle says that we cannot measure **quantum** state of system without disturbing it. So when light particle is polarized, we can know the polarization only at the time of measuring it.

These two classes of eavesdropping strategies are among the most frequently discussed attacks in the literature on **quantum** **cryptography**. The intercept- resend attack is the most ‘classical’ attack and one of the very few attacks which can be realised with present-day technology, while the superior channel attack has been shown to be the ideal eavesdropping strategy for some **quantum** **cryptography** schemes. I have proven that the scheme discussed here is secure against these two attacks. This, however, is no general proof of security. In par- ticular active eavesdropping using, for example, an entangling cloner which has been suggested as an ideal attack for some continuous variable crypto-schemes [17] is not included here and requires further analysis.

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To achieve this goal the original message (plain text) is encoded into a coded message known as cipher text. This process of converting from plain text to cipher text is known as enciphering or encryption; restoring the plain text from cipher text is called deciphering or decryption. The central problem in **cryptography** is the key distribution problem, for which there are essentially two solutions: one based on mathematic laws and one based on physics (**Quantum** **Cryptography**). While classical **cryptography** relies on the computational difficulty of factoring large integers, **quantum** **cryptography** relies on the universal laws of **quantum** mechanics.

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ABSTRACT: **Cryptography** provides security for the information and personal details. **Quantum** **cryptography** is an approach to securing communications by applying the phenomena of **quantum** physics. **Quantum** **cryptography** is a new method for secret communications offering the ultimate security assurance of the inviolability of a Law of Nature. Unlike traditional classical **cryptography**, which uses mathematical techniques to restrict eavesdroppers, **quantum** **cryptography** is focused on the physics of information. The combination of 3AQKDP (implicit) and 3AQKDPMA (explicit) **quantum** **cryptography** is used to provide authenticated secure communication between sender and receiver. The uses of computer communications networks technologies have increased the incidents of computer abuse. Because of these incidents, most organizations facing pressure to protect their assets. Most digital networks generally rely on modern cryptosystems to secure the confidentiality and integrity of traffic carried across the network. The current modern cryptosystems based on mathematical model introduce potential security holes related to technological progress of computing power, the key refresh rate and key expansion ratio, the most crucial parameters in the security of any cryptographic techniques. For that reason efforts have been made to establish new foundation for **cryptography** science in the computer communications networks. “I am fairly familiar with all forms of secret writings, and am myself the author of a trifling monograph upon the subject, in which I analyse one hundred and sixty separate ciphers; but I confess that this one is entirely new to me. The object of those who invented the system has apparently been to conceal that these characters convey a message ...”

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In this report we discuss the results of our project for the Radboud Honours Academy, concerning **Quantum** Key Distribution (QKD). We originally started this project with a much larger research subject in mind, namely **quantum** **cryptography** and **quantum** computers. At the beginning of this year, none of us had even heard of **quantum** cryp- tography. It was professor Klaas Landsman who introduced this as a research subject for the first year of the Honours programme. But after a short time, we felt that narrowing this subject was necessary: we decided to to forget about **quantum** computers and focus on currently commercially available systems implementing QKD protocols. In particular, our goal was to investigate the business versus the hacking culture. By exploring both the suppliers of **quantum** cryptographic devices and the people who want to hack these sys- tems, we wanted to get a complete and realistic a picture of the physical implementations of **quantum** **cryptography** that are nowadays possible.

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Alongside the development and standardization of post-**quantum** algorithms in the NIST Post- **Quantum** **Cryptography** Standardization project, there have been various efforts to begin preparing the TLS ecosystem for post-**quantum** **cryptography**. We can see at least three major lines of work: (draft) specifications of how post-**quantum** algorithms could be integrated into existing protocol formats and message flows [SWZ16, CC19, KK18, WZFGM17, SS17, SFG19]; prototype implementations demonstrating such integrations can be done [Bra16, Lan18a, BCNS15, BCD + 16, Ope19b, Ope19c, KS19, KLS + 19] and whether they would meet existing constraints in protocols and software [CPS19]; and performance evaluations in either basic laboratory network settings [BCNS15, BCD + 16] or more realistic network settings [Bra16, Lan18b, Lan19, KLS + 19, KS19]. This paper focuses on the last of these issues, trying to understand how post-**quantum** cryptography’s slower computation and larger communication sizes impact the performance of TLS.

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M.E Student, Dept of CSE, P. R. Patil college of Engineering and Technology, Amravati, Maharashtra, India Professor, Dept of IT, P. R. Patil college of Engineering and Technology, Amravati, Maharashtra, India. ABSTRACT: **Quantum** **cryptography** is an approach toward secure communication by applying the phenomena of **quantum** physics. As compared to the classical **cryptography**, **quantum** **cryptography** provides more secure communication whose security depends only on the validity of **quantum** theory. It is an emerging technology in which two parties may simultaneously generate shared, secret cryptographic key material using the transmission of **quantum** states of light. **Quantum** **cryptography** is one of the few commercial applications of **quantum** physics at the **quantum** level. The **quantum** relies on two important elements of **quantum** mechanics- the Heisenberg uncertainty principle and principle of photon polarization. This paper focuses on the principle of **quantum** **cryptography** and how this technology contributes in security of network.

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Different **quantum** cryptographic protocols have different ways of **quantum** transmission, but they have one thing in common: the principle of **quantum** mechanics (such as the Heisenberg Uncertainty Principle). In the actual communication system, Alice randomly selects the photon polarization state and the base vector of single photon pulse in the **quantum** channel and sends it to Bob. Then Bob randomly selects base vectors for measurements. The bit string that is measured is recorded as a codebook. However, the acceptance of information is affected by the presence of noise and Eve. In particular, Eve may use various methods to interfere with and monitor Bob, such as **quantum** copy, interception, forwarding, etc... According to the Uncertainty Principle, the external interference will lead to the change of the photon polarization state in the **quantum** channel and affect the measurement results of Bob, so that the behavior of the listeners can be detected and determined. This is also an important feature of **quantum** **cryptography** that is distinguished from other cryptosystems. Data Screening

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Justin Mullins [23] has focused that, **Quantum** **cryptography** solves the problem of key distribution. Cipher text is added with the key .If the receiver knows the key, he (or) she can easily decode the message by subtracting key from the cipher text. Townsend [25] has discussed that depending on link effect, secure QKD results are reduced key rates. The satellite based QKD is feasible of secure key exchange with low earth orbit. Bennett C.H., et al [27] has introduced that, the first QKD protocol and uses two-dimensional **quantum** systems or qubits as information carriers. A protocol for Coin-tossing by exchange of **quantum** messages, which is secure against traditional kinds of cheating.

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additional passes of classical data transmission. If Eve tries to differentiate between two non-orthogonal states, it is not possible to achieve information gain without collapsing the state of at least one of them . Proofs of the security of **quantum** **cryptography** are given variously in References pactical issues have been considered in References, and optical implementations are discussed in References . The issue of using attenuated lasers rather than single photon sources is considered .. In short, **quantum** **cryptography** is ideally suited for OBS since it is fundamentally based on the **quantum** properties of a photon. Besides leading to a theoretically unbreakable encryption scheme, the **quantum**- based encryption technology is well matched for use in an end-to-end photonic environment, which the OBS environment typifies.

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develop these challenges, key management (KM) in the cloud environment will be one of the choices. Efficient KM in random locations where big data being approached to the cloud storage is considered. Even strong security is established by the users, data storage and transmission in cloud environments cannot be controlled by the users without cloud service providers. This challenge is also one of the interesting topics. According to [3], size of the big data has been doubling every 2 years since 2011. Very soon (maybe by 2020), the size of big data will be 2.5 zettabytes (2.5 x 10 21 bytes) of information could be encrypted using **quantum** **cryptography** (QC).

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Single factor authentication in online banking is no longer sufficient to protect accounts. Our objective is to propose an authentication method for the online banking security. Our proposed model can be seen in figure 4. The starting point is the user’s request. In the event of a request, the user is redirected to authentication service, carrying with him/her some kind of Pass code or PIN. After verifying that pass code or PIN the user will access that **Quantum** cryptosystem. **Quantum** **Cryptography** / **Quantum** Key Distribution involvement is needed only to authenticate.

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The idea was first proposed in the 1970’s but was not applied to information security until the early 1990's. **Quantum** **cryptography** is only used to solve the key distribution problem, not actually transmit any useful data. It does so by transmitting photons of light through either fiber optics or free space [2]. These photons of light adhere to the Heisenberg uncertainty principle or **quantum** entanglement.

We hack a commercial actively-quenched avalanche single-photon detector (PerkinElmer SPCM- AQR) commonly used for **quantum** **cryptography**. This study complements the recent hacking of passively-quenched and gated detectors by the same method, and thus demonstrates its generality. Bright illumination is used to blind the detector, such that it exits single-photon detection mode and instead operates as a mere classical photodiode. In this regime, the detector clicks controllably if a bright pulse is applied above a classical sensitivity threshold, allowing for an attack on **quantum** **cryptography** that eavesdrops the full secret key. The SPCM-AQR detector model exhibits three redundant blinding mechanisms: (1) overload of an opamp in the bias control circuit, (2) thermal blinding of the APD itself, and (3) overload of the DC/DC converter biasing the APD. This conﬁrms that multiple loopholes may be left open if one does not examine closely non-idealities in components used for **quantum** **cryptography** implementations. To reach the security envisioned by theoretical proofs, this practice must change.

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