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Table of contents
Use of Cryptanalysis
Attacks in Cryptanalysis
Responsibilities of Cryptanalyst
Frequently Asked Questions
Who is a cryptanalyst?
What is the role of a cryptanalyst?
Does cryptanalysis is an illegal process?
What is a ciphertext-only attack?
Last Updated: Mar 27, 2024

Analysis in Cryptography Cryptanalysis

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In this article, we will discuss the analysis in cryptography or also known as cryptanalysis.

There are mainly two categories in cryptology: cryptography and cryptanalysis. Our primary focus will be to know about the term cryptanalysis, which is also one of the critical parts of cryptology.


But before that, let's talk about cryptography in brief.


Cryptography is one of the subjects in computer science that focus on secure communication between the sender and receiver and also discusses the methods we can use to secure digital data like digital signature uploaded on the internet.

With Cryptography, we do not need to worry about the confidentiality and integrity of the data during transmission.

You need to know a few terms we will frequently use during the explanation.

  • Plaintext: The standard text we will convert into a non-readable format.
  • Ciphertext: The text we will generate after converting the plain text by applying cryptography techniques.
  • Key: A key is a string of characters or bits that helps us convert plain text into cipher text and is only known to the sender and receiver.
  • Encryption: Encryption converts plain text into cipher text with the help of a secret key.
  • Decryption: Decryption converts cipher text into standard or plain text with the help of a secret key.
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types of cryptology

Cryptanalysis is the field of cryptology to study and observes encryption and decryption methods or techniques. In cryptanalysis, the person analyses the encryption methods by testing them with different scenarios providing a more secure solution and fixing any vulnerabilities or loopholes. The person who studies the field of cryptanalysis is known as a cryptanalyst. A cryptanalyst will try to decode the ciphertext with as little information as possible.

In comparison, cryptography focuses on creating the algorithm to provide encryption and decryption of the data. Cryptanalysis studies those algorithms and tries to find a flaw in these algorithms. After reviewing the cryptography algorithms, the cryptanalyst provides a report to improve these algorithms.

Use of Cryptanalysis

  • Various organizations and companies rely on cryptanalysis to secure their confidential information or data or to maintain secure communication.
  • Cryptanalysis is essential for cryptology to implement ciphers that do not leak sensitive information to a potential threat. 
  • Cryptography provides secure algorithms to encrypt data. Cryptanalysis tries to find flaws in the algorithm by studying its design and workings.

Let's try to understand the working of cryptanalysis through a real-life example.

Assume there are two persons in an organization communicating on a secure network.

working of cryptanalysis

As you can see in the picture, a cryptanalyst or potential attacker is eavesdropping on a network and have access to the cipher text sent from person1 to person2. This is called a man-in-the-middle attack.

The cryptanalyst has the information of the Cipher text, and he will analyze the given cipher text and try to decrypt the message or find the key to decrypt the message. If he can accomplish it, the organization's encryption algorithm could be more secure.

Attacks in Cryptanalysis

Attacks in Cryptanalysis

As mentioned above, you must know the encryption method or information related to this encryption method, like ciphertext or plaintext, to implement cryptanalysis. 

Based on this information, the cryptanalyst can use various attacks or techniques.

Known Ciphertext Attack

  • Ciphertext-only attacks, or known ciphertext attack, is the most commonly used attack by a cryptanalyst. 
  • In most scenarios, the cryptanalyst has access to the ciphertext or some of the encrypted messages.
  • The cryptanalyst needs to learn the rest of the information, like the encryption algorithm or secret key.
  • The cryptanalyst has to analyze the encryption process using the ciphertext only. The ciphertext has to be checked or reviewed to determine whether it is not leaking any information to the attacker because ciphertext is primarily accessible by an individual.

Known Plaintext Attack

  • In the known plaintext attack, the cryptanalyst has access to the ciphertext and some parts of the plaintext. In known plaintext attacks, the cryptanalyst's primary motive is to find the secret key or encryption algorithm.
  • For example, let's assume you got to know about the plaintext and ciphertext sent over a network. Now, as a cryptanalyst, you need to determine whether the plaintext and ciphertext are leaking any information about the secret key and encryption algorithm because the organization may use that private key and encryption algorithm frequently. 
  • It is not an issue in modern-day cryptography because modern-day encryption algorithms are plaintext attack resistant. The known-plaintext attack was primarily active during wars to analyze the old encryption techniques.

Chosen Plaintext Attack.

  • In a chosen-plaintext attack, the attacker can select an arbitrary plaintext and encrypt that plaintext.  
  • The chosen plaintext attack is mainly used when an attacker has access to an encryption device. Then the attacker or cryptanalyst can choose a plaintext and get the corresponding ciphertext.
  • The motive is to perform the encryption many times with different plaintext with some similarity and analyze the results to obtain essential information. 
  • In chosen plaintext attack, the cryptanalyst observes similar patterns received during plaintext encryption.

Chosen Ciphertext Attack

  • The working of chosen ciphertext attack is the same as chosen plaintext attack, but in this attack, the attacker chooses a ciphertext and sees its corresponding plaintext.
  • It is applied to the decryption function of the cryptography system.

Man-in-the-middle Attack

  • In a Man-in-the-middle attack, the attacker will intercept communication between two parties. 
  • He will be eavesdropping on the channel and will try to find some information or data during the communication.
  • He can encrypt or decrypt the message assuming he has access to the secret key.
  • He can also alter the text or message for the receiver.
  • An organization must build a robust and authentic communication or transaction channel to avoid such attacks.

Responsibilities of Cryptanalyst

Cryptanalyst work ethically means any analysis they do will only be for the betterment of the algorithm and to prevent any hacker's attack on a system. There are a few responsibilities that you should know of a cryptanalyst.

  • To Prevent theft, copying, modification, or deletion of sensitive data.
  • To Identify, evaluate, and focus on the cryptographic security system and algorithm flaws.
  • To Design security solutions to guard against weaknesses.
  • To Construct statistical and mathematical models to assess data and address security issues.
  • To Test the precision and dependability of computational models.
  • Investigating, exploring, and testing new applications and theories of cryptology.

Frequently Asked Questions

Who is a cryptanalyst?

The person who studies cryptanalysis is known as the cryptanalyst.

What is the role of a cryptanalyst?

The part of a cryptanalyst is to analyze cryptography algorithms and find their vulnerabilities in them.

Does cryptanalysis is an illegal process?

No, it is government recognized process implemented by ethical professionals.

What is a ciphertext-only attack?

The attacker in a ciphertext-only attack only has access to one or more encrypted messages.


In this blog, we discussed the analysis in cryptography or cryptanalysis. We discussed the differences between cryptography and cryptanalysis. We also demonstrated an example of process cryptanalysis. We have also discussed various attacks a cryptanalyst uses and the responsibilities of a cryptanalyst.

To learn more about cryptography, check out the following articles.

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