Secret Key Encryption with Go using AES

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To start: why would we want to use secret key encryption? Well, let’s say you have a bunch of sensitive data that needs to be kept safe. Maybe it’s your grandma’s recipe for the world’s best chocolate cake or maybe it’s classified government information either way, you don’t want anyone else getting their hands on it! Secret key encryption is like locking your data in a box with a really complicated combination that only you know.

Now Go and AES. Go is a programming language created by Google that’s become pretty popular lately because it’s fast, easy to learn, and has great support for concurrency (which means it can handle multiple tasks at once). And AES stands for Advanced Encryption Standard it’s a widely-used encryption algorithm that’s been around since 2001.

So how do we use Go and AES together? Well, first you need to install the crypto package (which is already included in most versions of Go). Then you can create a new file called `main.go` with some code like this:

// This script demonstrates how to use the AES encryption algorithm in Go.

package main

import (
    "crypto/aes" // Import the AES package for encryption and decryption
    "crypto/cipher" // Import the cipher package for creating encryption blocks
    "crypto/rand" // Import the rand package for generating random keys
    "encoding/hex" // Import the hex package for converting data to hex format
    "fmt" // Import the fmt package for printing messages
)

func main() {
    // Generate a random 128-bit key for encryption and decryption
    key := make([]byte, 32) // Create a byte slice with a length of 32
    _, err := rand.Read(key) // Use the rand package to fill the slice with random data
    if err != nil {
        panic("Failed to generate key: " + err.Error()) // If there is an error, panic and print the error message
    }
    
    // Encrypt some data using the AES algorithm with our generated key
    plaintext := []byte("This is a secret message!") // Create a byte slice with the message to be encrypted
    block, err := aes.NewCipher(key) // Create a new encryption block using the AES algorithm and our generated key
    if err != nil {
        panic("Failed to create encryption block: " + err.Error()) // If there is an error, panic and print the error message
    }
    ciphertext := make([]byte, aes.BlockSize+len(plaintext)) // Create a byte slice with a length of the AES block size plus the length of the plaintext
    iv := ciphertext[:aes.BlockSize] // Set the first 16 bytes of the ciphertext as the initialization vector (IV)
    _, err = rand.Read(iv) // Use the rand package to fill the IV with random data
    if err != nil {
        panic("Failed to generate IV: " + err.Error()) // If there is an error, panic and print the error message
    }
    mode := cipher.NewCBCEncrypter(block, iv) // Create a new encryption mode using the encryption block and IV
    mode.CryptBlocks(ciphertext[aes.BlockSize:], plaintext) // Encrypt the plaintext and store the result in the ciphertext slice
    
    // Print the encrypted message in hex format for easy copying and pasting
    fmt.Println("Encrypted Message:", hex.EncodeToString(ciphertext))
}

// Create a new encryption block using our generated key
func aes128(key []byte) (cipher.Block, error) {
    // Use the AES algorithm with 128-bit keys and CBC mode for encryption
    return aes.NewCipher(key) // Create a new encryption block using the AES algorithm and our generated key
}

// Encrypt some data using our encryption block
func encrypt(block cipher.Block, plaintext []byte) ([]byte, error) {
    // Create a new buffer to hold the encrypted message
    buf := make([]byte, aes.BlockSize+len(plaintext)) // Create a byte slice with a length of the AES block size plus the length of the plaintext
    iv := buf[:aes.BlockSize] // Set the first 16 bytes of the buffer as the initialization vector (IV)
    _, err := rand.Read(iv) // Use the rand package to fill the IV with random data
    if err != nil {
        return nil, fmt.Errorf("Failed to generate IV: " + err.Error()) // If there is an error, return nil and an error message
    }
    mode := cipher.NewCBCEncrypter(block, iv) // Create a new encryption mode using the encryption block and IV
    mode.CryptBlocks(buf[aes.BlockSize:], plaintext) // Encrypt the plaintext and store the result in the buffer slice
    return buf, nil // Return the buffer slice and nil (no error)
}

So what’s going on here? First we generate a random 128-bit key for encryption and decryption using the `rand` package in Go. Then we create an AES encryption block using our generated key, which is created by calling the `aes128()` function with our key as input. This function returns a new cipher block that uses the AES algorithm with 128-bit keys and CBC mode for encryption (which means it adds some extra data to each message to make sure they’re all encrypted consistently).

Next we call the `encrypt()` function, which takes our plaintext message as input along with our cipher block. It creates a new buffer called `buf` and sets up an encryption writer using that buffer and our cipher block. Then it writes our plaintext to the encryption writer and returns the resulting buffer of encrypted data (which is stored in `buf`).

Of course, this is just a basic example; there are many more advanced techniques and algorithms that can be used for encryption. But hopefully this gives you an idea of how to get started with using Go and AES together.

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