Daniel's Notes

Cryptography

3 min read

Overview

Cryptography is the practice of securing information and communications by converting plain text into coded or encrypted text that can only be accessed by the intended recipient. The term “cryptography” comes from the Greek words “kryptos” meaning “hidden” and “graphein” meaning “to write”. Cryptography uses mathematical concepts and algorithms to protect data privacy, enable secure transactions, and prevent unauthorized access.

Terminology

  • Plaintext: the message before it has been encrypted
  • Ciphertext: the message after it has been encrypted
  • Key: the secret to decrypting the message
  • Encrypt: Converting from plaintext to ciphertext
  • Decrypt: Converting form ciphertext to plaintext

Types of Cryptography

Cryptography itself can be divided into two branches, known as transposition and substitution. In transposition, the letters of the message are simply rearranged, effectively generating an anagram. … The alternative to transposition is substitution.

The main techniques used in cryptography include:

Symmetric Key Cryptography

This uses a single shared key between the sender and receiver to encrypt and decrypt messages. It is faster and simpler but requires securely exchanging the key.

Hash Functions

Hashing functions convert plain text into a fixed-length hash value without using a key. This makes it impossible to recover the original plain text.

Asymmetric Key Cryptography

This uses a pair of keys - a public key for encryption and a private key for decryption. The public key can be shared widely while the private key is kept secret by the recipient.

Assessing the Security Level

Applications of Cryptography

Cryptography has many important applications, including:

  • Securing computer passwords and login credentials
  • Enabling secure digital currencies and transactions
  • Providing secure web browsing and communication
  • Enabling electronic signatures and authentication
  • Protecting the integrity of cryptocurrencies

Advantages of Cryptography

The key advantages of cryptography include:

  • Controlling access to sensitive information
  • Enabling secure communication and transactions
  • Protecting against various types of cyber attacks
  • Helping organizations comply with data privacy regulations

Overall, cryptography is a critical tool for ensuring the confidentiality, integrity, and security of digital information in the modern world.

Cryptography Concepts

Programming Libraries

Further Reading and Resources

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