# Post-quantum cryptography: securing data in the age of quantum computers

- July 31, 2023
- Posted by: OptimizeIAS Team
- Category: DPN Topics

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**Post-quantum cryptography: securing data in the age of quantum computers**

**Subject :Science and tech**

**Section: Awareness in IT and computers**

**Context:**

- Governments and organisations across the world are rushing to develop quantum computing platforms and advanced security algorithms to defend against such machines. One such example is the
**U.S. National Institute of Standards and Technology’s Post-Quantum Cryptography Standardisation project**. - India has launched the
**National Quantum Mission.**

**Security algorithm:**

- Much of our current security is based on
**techniques**such as**RSA, elliptic curves, Diffie-Hellman key exchange**and almost all of them rely on a few**“hard” mathematical problems**, such as**factorisation**and the**discrete logarithm problem**. - In
**1994**,**Peter Shor**developed a**quantum algorithm**that can break all of these with ease. - While
**Shor’s technique**poses a threat to certain security algorithms, there are**alternative methods**that remain unaffected. **Lov Grover’s quantum algorithm**can often be fixed by increasing the key or password lengths.- Some common
**“symmetric” security algorithms**such as**AES**are not badly affected. (Symmetric key algorithms use the same password to lock and unlock the information.)

**Post-quantum cryptography:**

**Post-quantum cryptography**involves exploring alternative techniques to counter vulnerabilities against**quantum attacks**.- In
**cryptography**,**post-quantum cryptography (PQC)**refers to**cryptographic algorithms**(usually public-key algorithms) that are thought to be secure against a cryptanalytic attack by a quantum computer.- The problem with currently popular algorithms is that their security relies on
**one of three hard mathematical problems:**the**integer factorization problem**, the**discrete logarithm problem**or the**elliptic-curve discrete logarithm problem**. - All of these problems could be easily solved on a sufficiently powerful quantum computer running
**Shor’s algorithm**.

- The problem with currently popular algorithms is that their security relies on
- While
**Shor’s algorithm**poses particular concerns for certain methods, the field has rapidly evolved with promising approaches such as**lattice algebra, multivariate cryptography, isogeny-based techniques,**and**code-based cryptography**. - One promising technique,
**supersingular isogeny Diffie-Hellman key exchange**, was considered secure by many until it was utterly broken by**Wouter Castryck**and**Thomas Decru**last year.

**Bits of physics:**

- We have developed circuits that can do logical computations incredibly fast and with astounding reliability.
- New kinds of gates can be built using the
**laser**, maybe a prism**“naturally”**computes a square root or something. - The principles of quantum mechanics enabled a set of gates that were utterly impossible to build using electronics.
- In other words, using quantum states to represent logic allows us to compute very differently.
- This new, different kind of computation is very powerful. Many things that were complex and cumbersome when run on electronic logic become incredibly simple on a quantum system.

**Challenges:**

- This comes with its own problems.
- Current attempts are incredibly
**error-prone**and have many missing pieces.

- Current attempts are incredibly
- However, many experts believe that this is inevitable and we will eventually develop such machines.

**Quantum computer:**

- A
**quantum computer**is a computer that exploits**quantum mechanical phenomena.** - At small scales,
**physical matter exhibits**properties of both particles and waves, and**quantum computing**leverages this behaviour using specialised hardware. **Classical physics**cannot explain the operation of these quantum devices, and a**scalable quantum computer**could perform some calculations**exponentially faster**than any modern**“classical” computer**.- In particular, a
**large-scale quantum computer**could break widely used encryption schemes and aid physicists in performing physical simulations; however, the current state of the art is largely experimental and impractical, with several obstacles to useful applications.

**National Quantum Mission (NQM):**

- It’ll be implemented by the
**Department of Science & Technology (DST)**under the**Ministry of Science & Technology.** - The mission planned for
**2023-2031**aims to seed, nurture, and scale up scientific and industrial R&D and create a vibrant & innovative ecosystem in**Quantum Technology (QT)**. - With the launch of this mission,
**India**will be the**seventh country**to have a dedicated quantum mission after the**US, Austria, Finland, France, Canada and China**.