Introduction
Cryptography is one of the most important tools in our collective toolbox for securing information, yet it is also one of the least understood. The goal of this article is to give you an introduction to modern public key cryptography and its use in securing data so that you can understand what it does and why you need it. This will serve as a good foundation for further study into cryptography
What is Cryptography?
Cryptography is the art and science of secure communication in a world of relentless adversaries and imperfect secrecy.
Its goal is to ensure confidentiality, integrity, authentication, non-repudiation, authenticity, data origin authentication and anti-replay for messages exchanged between two parties or multiple parties in a computer network. Encryption applies symmetric cryptography to convert readable information into an unreadable format called cipher text (or crypto text). Decryption applies asymmetric cryptography to convert cipher text back into readable information
History of Cryptography
The history of cryptography goes way back. It’s thought that ancient civilizations used ciphers to send secret messages, and the word cryptography is derived from two Greek words: “kryptós,” meaning “hidden,” and “graphein,” meaning “writing.”
In modern times, cryptography has been used for more than just hiding messages. Cryptography can be used to encrypt data — that is, convert it into a form that prevents anyone without the proper key from reading it. This encryption process plays an important role in securing private information online. It also provides the basis for cryptocurrency (a form of digital money), which requires participants to use public-key cryptography so they can safely send coins between one another without fear of being hacked or counterfeited by someone else pretending to be them or their recipient.
What is a Cipher?
A cipher is a cryptographic system that uses a secret key to encrypt and decrypt data. The term cipher is derived from the Latin word cifra, which means zero or empty.
The most commonly used ciphers are substitution and transposition ciphers. In this section, you will learn about substitution ciphers, which use one alphabet to represent another alphabet. For example, if we replace each letter in our text with its corresponding number (e.g., A = 1), then we can create a simple substitution cipher by replacing each number with its corresponding letter (e.g., 1 = A).
Caesar Shift Cipher
The cipher is named after Julius Caesar because he used it to send messages.
It uses a shift value of 1, which means that all letters are shifted forward three places in the alphabet. For example, if we start with “A”, we get “B”. If we start with “B”, we get “C”.
The plaintext:
ABCDEFG HIJKLMN OPQRST UVWXYZ
becomes ciphertext:
BCDEFG HIJKLMN OPQRST UVWXYZA
Public Key Cryptography
Imagine that you want to send your friend a secret message. In public key cryptography, both parties have a public key and a private key. The public key is made public, but the private key is kept secret.
Public Key Cryptography Example
Let’s look at a simple example of how public key cryptography works.
In this example, Alice wants to send Bob a message securely. She knows Bob’s public key (which Bob has published somewhere), but not his private one. She sends Bob her message; Bob then uses his private key(which only he knows) to decrypt it and read the contents.
Cryptography
Cryptography is the art and science of secure communication in a world of relentless adversaries and imperfect secrecy.
It’s not difficult to understand why cryptography is so important in our modern world. Our most sensitive data — financial information, medical records, government secrets — is all stored digitally on computers that are vulnerable to attack by hackers or other malicious people who could steal it and use it maliciously against us. To protect our information from these attackers, we need a way to encrypt it so they can’t read it without knowing the decryption key (a secret piece of information). There are many different ways that you can do this; some are faster than others but all require some mathematical processing power to work correctly. This means cryptography itself is a science that uses mathematics to encrypt/decrypt data; but cryptography also has an artistic side: how does one design an algorithm (i.e., computer program) for encryption such that only authorized parties can decipher communications?
Conclusion
I am excited to begin my new journey as a student at Alchemy University. I have been interested in blockchain technology for many years and this is a great opportunity to learn more about it.
The Alchemy University program is designed to help you understand the fundamentals of cryptography, and gives you the tools to start learning how to use it.
I’ve been working through the first few weeks of the course and have learned all about how cryptography works, what makes it secure and why it’s important.
I hope that this article has helped you understand a bit more about what cryptography is as well as some of its history and uses today.
