Cryptography - That Computer Engineer


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Tuesday, July 18, 2017


This is the among the most talked about topic in the cyber security. Cryptography allows communicating with people in remote places and connections in such a form that the data transferred remains secured. Ónly those for whom it is intended can read and process the data. The data can be in any form of video, audio, text, etc.

encrypted message on screen

Fundamental Objective

The fundamental objective of the cryptography is to enable two people for a secure communication over a public channel.

Who are cryptographers?

Cryptography involves certain techniques to secure data. A cryptographer is responsible for designing a code that will convert information (in any form) to a form that is unintelligible to an unintended audience.

Who is cryptanalyst?

A cryptanalyst is a person who is a master in the art of breaking the secure system created by a cryptographer to secure the data transmission.


A cryptosystem consists of 5 systems:

  1. Set of possible plaintext (P)
  2. Ciphertext space (C)
  3. Key space (K)
  4. Set of all possible encryption algorithm (E)
  5. set of all possible decryption algorithm (D)


Suppose there are two friends named: Tom and Harry. Also, consider a 3rd party person named: Jerry, who is not authorized to access the data transmission between Tom and Harry. Tom and Harry are texting each other using a normal messaging app. Using some cryptographic mechanism the data is transferred between Tom and Harry only, such that, Jerry is not able to read the conversation. This is because the data is converted into some other form for transmission.

Tom can manipulate data by adding something extra to the data. This extra data added is called as Key. The key is shared between Harry and Tom only. When the manipulated data is received by Harry, he uses Key to extract the real data. In this case, he subtracts the extra data added. Since the key is shared by only Tom and Harry, Jerry won't be able to extract data even if got access to the manipulated data. In this manner, the data transfer between Tom and Harry remained secured. 


It is the method of converting plain text (data) to something that appears to be meaningless (cipher text).


It is the method of conversion of the cipher text to plain text.

Check out this article Intellectual Property Protection to learn about various protection schemes used by an organization.

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