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# MCQ | Quantum Cryptography

Here, we have a **set of multiple-choice questions and answers (quiz) on Quantum Cryptography**.

Submitted by Monika Sharma, on March 23, 2020

**1) Which possible Attacks in Quantum Cryptography can take place?**

- Possible Attacks in Quantum Cryptography and Birthday Attack
- Birthday attack and Boomerang attack
- Brute force attack and Faked-State-Attack
- Possible Attacks in Quantum Cryptography and Faked-State Attack

**Answer:** d. Possible Attacks in Quantum Cryptography and Faked-State Attack

**Explanation:**

**Photon Number Splitting (PNS) Attack:**

As we know that it is not possible to send a single photon thus a pulse is sent. So, some of the photons from a pulse can be captured by Eve and after matching bits by Amit and Bobby, Eve can use the same polarizer as done by Bobby and thus get the key without being detected in cryptography.

**Faked-State Attack:**

Mainly, Eve uses a replica of Bob’s photon detector and thus captures the photons intended for Bobby and further passed it to Bobby. Thus, Eve knows about the encoded bit, Bobby thinks that he received it from Amit.

**2) _____ and ______ protocol models can be extended to Entangled particles theory.**

- SARG04 and HTTP
- FTP and SSP
- SARG04 and SSP
- HTTP and FTP

**Answer:** c. SARG04 and SSP

**Explanation:**

SARG04 and SSP protocol models can be extended to Entangled particles theory.

**3) Study with quantum computers of future being expected to solve the discrete logarithmic problem and the popularly know cryptography methods such as AES, RSA, DES, quantum cryptography becomes which solution?**

- Quantum Solution
- Foreseen Solution
- Cryptographic Solution
- Block Cipher Solution

**Answer:** b) Foreseen Solution

**Explanation:**

As we study already that with quantum computers of future being expected to solve the discrete logarithmic problem and the popularly know cryptography methods such as AES, RSA, DES, quantum cryptography becomes the foreseen solution in this.

**4) Which two principles of quantum mechanics on which quantum cryptography are dependent?**

- Heisenberg Uncertainty Principle and Photon Polarization Principle.
- Fundamental Principle and Bohr's Model Principle
- Momentum Principle and Photons Principle
- Planck's Principle and Fundamental Principle

**Answer:** a. Heisenberg Uncertainty Principle and Photon Polarization Principle.

**Explanation:**

Quantum mechanics on which quantum cryptography depends are Heisenberg Uncertainty Principle and Photon Polarization Principle**.**

**5) How many elements are used in cryptography tools?**

- 1
- 4
- 6
- 3

**Answer:** d. 3

**Explanation:**

It has 3 elements as first is sender and second is the receiver and third is the channel in fact which connects both sender and receiver.

**6) Quantum cryptography is the science of exploiting quantum mechanical properties to perform _____.**

- Cryptographic system
- Cryptographic tasks
- Decryption system
- None of the mentioned above

**Answer:** b. Cryptographic tasks

**Explanation:**

Quantum cryptography is the science of utilizing quantum mechanical phenomena to perform cryptographic tasks. The best-known example of quantum cryptography is quantum key distribution which gives an information-theoretically secure solution to the key exchange problem.

**7) The greatest threat is to public cryptography or asymmetric algorithms used for ____.**

- Digital signatures and
- Key exchange
- Both A and B
- None of the mentioned above

**Answer:** c. Both A and B

**Explanation:**

It is public cryptography, or asymmetric algorithms, that are under the greatest threat, as they are utilized for digital signatures and key exchange. For example, one of the most well-known quantum algorithms is the Shor algorithm, which may be used to break the RSA and Elliptic Curve methods once a universal quantum computer is available.

**8) Amongst which of the following is/ are true with reference to step-by-step breakdown of the process of quantum cryptography,**

- The sender sends a photon through a polarizer with randomly assigned polarizations and bit assignment
- Photon uses a beam splitter that can be horizontal, vertical, or diagonal to decode or read the polarization of each photon
- Receiver tells the sender the random assignments of a beam splitter for each photon in the same sequence it was sent
- All of the mentioned above

**Answer:** d. All of the mentioned above

**Explanation:**

Referring to the step-by-step breakdown of the quantum cryptography process, the first sender sends a photon through a polarizer with randomly assigned polarizations and bit assignments; the second sender sends a photon through a polarizer with randomly assigned polarizations and bit assignments; the third sender sends a photon through a polarizer with randomly assigned polarizations and bit assignments; the fourth sender sends a photon through a polar After decoding or reading the polarization of each photon with a beam splitter, which can be horizontal, vertical, or diagonal in orientation, the photon is returned to its sender, who is informed of the random assignments of a beam splitter for each photon in the same sequence as it was sent.

**9) A quantum state is a superposition of classical states,**

- True
- False

**Answer:** a. True

**Explanation:**

It is possible to apply a quantum state to a measurement or a unitary operation since it is a superposition of classical states that is expressed as a vector of amplitudes.

**10) Post-Quantum Cryptography is a classical cryptographic scheme that is conjectured to be secure against ____.**

- Quantum adversaries
- Quantum integration
- Quantum hash
- None of the mentioned above

**Answer:** d. Quantum integration

**Explanation:**

In cryptography, post-quantum cryptography is a classical cryptographic technique that is conjectured to be secure against attackers who possess quantum computing capabilities. The quantum adversary approach is one of the most adaptable lower-bound methods for quantum algorithms, and it is also one of the most widely used. The variants of this method are the same: spectral adversary and spectral adversary.

**More...**

- MCQ | Cryptography Basics
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