How Cryptography Works

By Alisha Gomes

Image Credit: Flickr @ (Richard Patterson)

Writing a letter you hope no one will read? Want to secure your savings in a bank account? Whether you need to practice secure communication between two parties or make your data confidential, you may want to use cryptography. Cryptography has been around for thousands of years and whether you realize it or not, you most likely use the same, albeit more technological, practices that people in the early twentieth century were using. Like geology or astronomy, cryptography is also a science that should be more commonly known in order to grasp a better understanding about the world around us. Cryptography, in simple terms, is the science of encrypting and decrypting data. The next time you log into your bank account with a password, think about the complex calculations and processes that are going on in your computer at the very moment.

Encryption, when it comes to today’s world, is achieved by using algorithms that either encrypt or decrypt information. These algorithms have what is called a key, which is a piece of information that regulates the output of a cryptographic algorithm. This piece of information is a large integer number and is stored in 1024 or 4096 bits of memory. An RSA cryptosystem is how most of us secure data transmission. In this system, also called two-key encryption, there are two keys: a public key and a private key. The public key is used for encryption while the private key is used for decryption.

To better understand the idea of keys let’s look at an example: Jim and Olivia want to communicate securely between each other and utilize keys to help them achieve this goal. When Jim sends a message to Olivia, he takes his message and turns it into an integer number. Then he raises the number from the message to the power of his public key. The encrypted text is then sent to Olivia. Olivia receives the message and raises it to the power of her private key. This, as a result, decrypts Jim’s message.

These keys convert the data sent from one party to what is called “digital gibberish” by the use of the public key and back into the original form by the use of the private key.

Since the message that Jim has sent to Olivia is turned into an integer number and then is raised to the power of the public key, it can be noted that the longer the key is, the more difficult it will be to decrypt the message. For example an 8-bit key would have 256 (2^8) possible keys while a 56-bit key would have over 72 quadrillion possible keys.

With the increasingly technological world we are living in, there is a greater need to improve the quality of encryption practices. For now, however, this is how cryptography works.


What Did You Learn?


1. Why is cryptography important?

Cryptography is important because as our world advances there will be a larger need for more security for our devices. Cryptography allows for the exchange of information between two or more parties securely without interference from those who want to use this information to their advantage.

2. What is an encryption key?

A key is a piece of information that regulates the output of a cryptographic algorithm. This piece of information is a large integer number and is stored in 1024 or 4096 bits of memory. In simpler terms, an encryption key is the transformative factor that encrypts information.

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