What is Cryptography?

  • By Neha Siddhwani
  • 28 March 2023
cryptography guide

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The term cryptography originates from the Greek word kryptos, which means hidden. The prefix "crypt-" refers to something that is hidden or kept secret, while the suffix "-graphy" pertains to writing. Over 4000 years ago, ancient Egyptians used hieroglyphics as a form of cryptography to communicate secretly. 

Over time, this technique was modified by replacing the characters with alphabets based on a secret rule known only to a few, referred to as the key for decoding hidden messages. Since then, cryptography has evolved to become a battleground for some of the world's most skilled computer scientists. 

With a Bachelor of Technology or BTech degree, with a specialisation in Computer Science Engineering (CSE), students will learn the fundamental concepts of cryptographic algorithms, message and web authentication, as well as security issues. 

Let's explore the introduction to cryptography

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Cryptography Definition: What is Cryptography?

Cryptography is the practice of ensuring the security of information by converting it into an incomprehensible form for unintended recipients. This is done by using mathematical operations or algorithms to transform a human-readable message into a nonsensical form, which is meaningless to someone who is not privy to the decryption key.

This human-readable message or information is known as plain text. In contrast, the output of the encryption process that converts plain text into an unreadable form is known as cypher text.

Features of Cryptography

In the modern era of computing, cryptography meaning is mostly associated with the encryption process, whereby plain text is converted into cypher text that can only be decoded by the intended receiver. Conversely, the process of converting cypher text to plain text is known as decryption. Modern cryptography focuses on achieving four key features:

  • Confidentiality: Ensuring that the information is not comprehensible to unintended recipients.
  • Integrity: Ensuring that the information is not tampered with during storage or transit without detection.
  • Non-repudiation: Ensuring that the creator/sender of the information cannot deny their intentions in the creation or transmission of the information.
  • Authentication: Ensuring that the sender and receiver can verify each other's identities and the origin/destination of the information.

What is Cryptography in Security: Examples & Use Cases

  • Authentication: Cryptography is used for authentication in various contexts, such as accessing a bank account, logging into a computer, or using a secure network. Authentication protocols use cryptographic methods to confirm the user's identity and verify that they have the necessary access rights.
  • Computer passwords: Cryptography is commonly used in computer security, specifically in creating and maintaining passwords. Passwords are hashed and encrypted before being stored, so even if a hacker gains access to the password database, they cannot read the passwords.
  • Electronic signatures: Electronic signatures are the digital equivalent of handwritten signatures and are used to sign documents. They are created using cryptography and can be validated using public key cryptography. Electronic signatures are becoming increasingly common and enforceable by law in many countries.
  • End-to-End Encryption: End-to-end encryption is widely used in communication apps such as WhatsApp and Signal, providing users with a high level of security and privacy. It is used to secure two-way communications, including video conversations, instant messages, and email. It ensures that only the intended recipients can read the message, even if it is encrypted. 
  • Cryptocurrencies: Cryptocurrencies such as Bitcoin and Ethereum rely heavily on cryptography to secure transactions, prevent fraud, and maintain network integrity. Complex algorithms and cryptographic keys are used to protect transactions, making it challenging to tamper with or forge them.

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Explain the Cryptography Techniques

Cryptography relies on mathematical functions known as cryptographic algorithms or cyphers, which are combined with keys such as words, digits or phrases to encrypt text. The strength of the cryptographic algorithms and the secrecy of the key determines the usefulness of the encryption. Below are the many techniques of cryptography elaborated in simple terms. 

  • Simple codes use a language to hide the meaning of sentences written in another language. The message is crafted in a way that makes it difficult to decipher, often using niche alphabets to increase complexity.
  • Symmetric encryption is a method used to encrypt and decrypt electronic data using a secret key. It is based on substitution cyphers but has evolved to include other techniques. Symmetric encryption is primarily used for encrypting sizable messages.
  • Asymmetric encryption, on the other hand, employs two keys - a public key and a private key - to encrypt and decrypt plaintext. Only those with access to the private key can decrypt the message, ensuring secrecy through the use of two corresponding keys.
  • Steganography involves concealing confidential information or messages within non-confidential files to avoid detection. In the past, steganography was less advanced, using techniques such as invisible ink or slight variations to hide messages. However, with advancements in technology, steganography has become a common and sophisticated cryptographic technique.
  • Hashing involves converting data into a unique string that can be used to hide any type or form of data. Once data has been hashed, it cannot be decrypted using keys alone.


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FAQ - Cryptography 

How does cryptography works?

Cryptography works by taking a readable message, known as plaintext or cleartext, and transforming it into unreadable ciphertext. This process ensures that only the intended recipient can understand the encoded output while the information remains incomprehensible to everyone else.

Who invented cryptography?

Claude E. Shannon is widely regarded as the pioneer of mathematical cryptography. He worked at Bell Labs for several years, during which he published an article called "A Mathematical Theory of Cryptography."

Is cryptography a good career in India?

In India, cryptography is a sought-after career path with some best-paying technology jobs in sectors such as IT, government, military forces, law enforcement agencies, banking and financial services, research institutes and universities. 

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