Implementation

Encryption & Decryption Using Golang

Prerequisites

Ensure you have Go installed on your system. You can download it from the official Go website.

package main

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"io"
)

// Function to encrypt plaintext using AES-GCM
func encrypt(plaintext, key string) (string, error) {
	// Convert the key to bytes
	keyBytes, err := hex.DecodeString(key)
	if err != nil {
		return "", fmt.Errorf("failed to decode key: %v", err)
	}

	// Create a new AES cipher using the key
	block, err := aes.NewCipher(keyBytes)
	if err != nil {
		return "", fmt.Errorf("failed to create cipher: %v", err)
	}

	// Create a new GCM (Galois/Counter Mode)
	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return "", fmt.Errorf("failed to create GCM: %v", err)
	}

	// Create a random nonce of the appropriate length
	nonce := make([]byte, gcm.NonceSize())
	if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
		return "", fmt.Errorf("failed to generate nonce: %v", err)
	}

	// Encrypt the plaintext using the nonce and GCM
	ciphertext := gcm.Seal(nonce, nonce, []byte(plaintext), nil)
	return hex.EncodeToString(ciphertext), nil
}

// Function to decrypt ciphertext using AES-GCM
func decrypt(ciphertext, key string) (string, error) {
	// Convert the key and ciphertext to bytes
	keyBytes, err := hex.DecodeString(key)
	if err != nil {
		return "", fmt.Errorf("failed to decode key: %v", err)
	}

	ciphertextBytes, err := hex.DecodeString(ciphertext)
	if err != nil {
		return "", fmt.Errorf("failed to decode ciphertext: %v", err)
	}

	// Create a new AES cipher using the key
	block, err := aes.NewCipher(keyBytes)
	if err != nil {
		return "", fmt.Errorf("failed to create cipher: %v", err)
	}

	// Create a new GCM (Galois/Counter Mode)
	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return "", fmt.Errorf("failed to create GCM: %v", err)
	}

	// Split the nonce and actual ciphertext
	nonceSize := gcm.NonceSize()
	nonce, ciphertextBytes := ciphertextBytes[:nonceSize], ciphertextBytes[nonceSize:]

	// Decrypt the ciphertext using the nonce and GCM
	plaintext, err := gcm.Open(nil, nonce, ciphertextBytes, nil)
	if err != nil {
		return "", fmt.Errorf("failed to decrypt: %v", err)
	}

	return string(plaintext), nil
}

func main() {
	// Example key (32 bytes for AES-256, 16 bytes for AES-128)
	key := "6368616e676520746869732070617373" // Example: "change this pass"

	// Plaintext to encrypt
	plaintext := "Hello, Golang Encryption!"

	// Encrypt the plaintext
	encrypted, err := encrypt(plaintext, key)
	if err != nil {
		fmt.Printf("Encryption failed: %v\n", err)
		return
	}
	fmt.Printf("Encrypted Text: %s\n", encrypted)

	// Decrypt the ciphertext
	decrypted, err := decrypt(encrypted, key)
	if err != nil {
		fmt.Printf("Decryption failed: %v\n", err)
		return
	}
	fmt.Printf("Decrypted Text: %s\n", decrypted)
}

OUTPUT :

Encrypted Text: 11ff3af66539bd5dea8decfbfe7dc0202eb5a82dbaf9f615e86e829ef3a4e293648a5dd72313e5f25f4c43837094c8be6ca99e3a21
Decrypted Text: Hello, Golang Encryption!