Cryptography

Cryptography Tutorial: Learn How To Encrypt And Decrypt Messages!

Cryptography is the art and science of writing and reading messages in code to keep them secret. Messages can be encoded as a sequence of letters or words to disguise their meaning, or as a series of bits that represent the original message using just two symbols: 0 and 1. The first type of encryption is called "cipher." It's the traditional way to encrypt messages. The second type of encryption is called "code." It uses a secret coding system, so people can understand messages without knowing how it works. Here, are some ways to use cryptography tools and techniques to encrypt and decrypt messages!

What is encryption?

To encrypt, or translate, a message you encode it with a secret code. The message can only be decoded by someone who knows the code. The code is the most important part of encryption because it's what makes your message secret.

Encryption is the process of translating information into a secret code that can only be read by somebody with special knowledge, like you. You can use cryptography to encrypt important messages so they're not read by someone who doesn't have the key to decode them. Encryption is one way to keep your information safe.

To encrypt a message with a cipher, you need two main things: an encoding or ciphering alphabet and a decoding or deciphering alphabet. Ciphering alphabets are the letters, numbers, symbols, or other characters you'll use to encode your message with. Decoding alphabets are the letters, numbers, symbols, or other characters you'll use to decode your message.

How does it work?

You'll need a secret key, which you'll share with the person you want to send a message to, and a public key, which you share with everyone. The person you're sending a message to will use your public key to encrypt the message, and then send it back to you. You'll use your secret key to decrypt the message and read it.

Code is different because it doesn't use a secret key. Instead, the code is an algorithm that's made up of instructions that tell computers how to encrypt and decrypt messages. You can create your own code by following instructions for an algorithm, or use a code someone else created.

Here’s an example:

You write your message in secret code:

You see:

So, if you want someone else to read this message, you'll need to give them instructions on how to decode it. With code, you can just show them how to decode it.

Simple encryption/decryption with Alice and Bob

For the sake of this tutorial, we'll use two people: Alice and Bob. Alice and Bob want to exchange messages, but they don't want other people to read them. Alice wants to send the message "Hello" to Bob, but first she needs to encode it.

Let's look at how Alice can encrypt her message "Hello." First, Alice will choose a secret phrase (a "key") and convert it to numbers. For example, if Alice's key is "apple," her conversion might look like this:

Then Alice uses those numbers as the code for her message. In this case, she would convert each letter of the phrase "Hello" into a number and then translate those numbers into the corresponding cipher text. So "H" would be translated as "E," "E" would be translated as "D," and so on.

This might look like:

ENGCYPTION:

NIIRDLNSIIHQWBMIILKQMRLFHHEIILHBNTII

DECRYPTION:

HELLO

Advanced Encryption Standard (AES) 

AES is one of the most popular cryptographic algorithms used to encrypt electronic files. AES replaced DES. It was developed by Vincent Rijmen and Joan Daemen, who were both Belgian cryptographers. AES can use 128-bit, 192-bit, or 256-bit keys.

AES operates on blocks of data of 128 bits at a time, encrypting them with a key and generating a 128-bit block of encrypted data. The effect is that the clear text is transformed into an unintelligible sequence, called ciphertext. The cryptography is relatively easy to break, but not as easy as an old-fashioned cipher, which never changes the letter's position in the alphabet.

Cipher vs. Code 

The two most common forms of encryption are cipher and code. Cipher is the traditional way to encrypt messages with a secret key or algorithm. Code is a more complicated form of encryption, with a secret coding system. Code may be used to encrypt and decrypt messages, with a codebook that includes one-time use codes for each message. This type of encryption is also called "One-Time Pad."

The 256-Bit AES Encryption Algorithm 

One of the most common algorithms for encrypting messages is called the 256-Bit AES encryption algorithm. It uses a technique called "cipher."

It works by taking the original message and turning it into a different message in a way that is difficult to understand without knowing the secret key. This process is called "encoding." The information in the message is "encoded" using a "cipher."

A cipher can be anything that can be used to replace each letter or symbol in the original message. For example, if your cipher is "X," then "X" can be used to replace any letter in the alphabet.

When the message is encoded, it is stored in a table (called a "code book") and it is given an encryption key. The original message and the encryption key are stored together.

The encryption key is necessary to decode the message. If someone did not know this, they would not be able to read the encrypted message. However, if they did know the key, they could easily read and understand the encrypted message.

AES in Python

There are two basic types of cryptography: cipher and code. Cipher is the traditional way to encrypt messages, and code is a more modern type of encryption. The first type of encryption, called cipher, is the traditional way to encrypt messages. It's done by changing the letters in a message to other letters or symbols to disguise the message's meaning. Code is a more modern type of encryption that uses a secret coding system, so people can understand messages without knowing how it works.

In this post, we're going to go over how to do both types of encryption in Python. For cipher, all you need to do is import the module and then use it with the str.upper() function as follows:

import Crypto

message = "Hello World!"

encrypted = Crypto.cipher('aes_128_cbc', 'aes_128_cbc', 'aes_128_cbc', message)

decrypted = Crypto.decipher('aes_128_cbc', 'aes_128_cbc', 'aes_128_cbc', encrypted)

print(decrypted)

The code above will encrypt a message using AES-