AES Encryption In C#

This article demonstrates how to use AesManaged class to apply  an AES algorithm to encrypt and decrypt data in .NET and C#.

Step 1

Create AesManaged,
AesManaged aes = new AesManaged();  

Step 2

Create Encryptor,
ICryptoTransform encryptor = aes.CreateEncryptor(Key, IV);  

Step 3

Create MemoryStream,
MemoryStream ms = new MemoryStream();  

Step 4

Create CryptoStream from MemoryStream and Encrypter and write it.
using(CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write))   
{  
    // Create StreamWriter and write data to a stream    
    using(StreamWriter sw = new StreamWriter(cs))  
    sw.Write(plainText);  
    encrypted = ms.ToArray();  
}  

The complete code is listed in Listing 1. To test the code, create a .NET Core project in Visual Studio and copy and paste the code. 

using System;  
using System.IO;  
using System.Security.Cryptography;  
class ManagedAesSample {  
    public static void Main() {  
        Console.WriteLine("Enter text that needs to be encrypted..");  
        string data = Console.ReadLine();  
        EncryptAesManaged(data);  
        Console.ReadLine();  
    }  
    static void EncryptAesManaged(string raw) {  
        try {  
            // Create Aes that generates a new key and initialization vector (IV).    
            // Same key must be used in encryption and decryption    
            using(AesManaged aes = new AesManaged()) {  
                // Encrypt string    
                byte[] encrypted = Encrypt(raw, aes.Key, aes.IV);  
                // Print encrypted string    
                Console.WriteLine($ "Encrypted data: {System.Text.Encoding.UTF8.GetString(encrypted)}");  
                // Decrypt the bytes to a string.    
                string decrypted = Decrypt(encrypted, aes.Key, aes.IV);  
                // Print decrypted string. It should be same as raw data    
                Console.WriteLine($ "Decrypted data: {decrypted}");  
            }  
        } catch (Exception exp) {  
            Console.WriteLine(exp.Message);  
        }  
        Console.ReadKey();  
    }  
    static byte[] Encrypt(string plainText, byte[] Key, byte[] IV) {  
        byte[] encrypted;  
        // Create a new AesManaged.    
        using(AesManaged aes = new AesManaged()) {  
            // Create encryptor    
            ICryptoTransform encryptor = aes.CreateEncryptor(Key, IV);  
            // Create MemoryStream    
            using(MemoryStream ms = new MemoryStream()) {  
                // Create crypto stream using the CryptoStream class. This class is the key to encryption    
                // and encrypts and decrypts data from any given stream. In this case, we will pass a memory stream    
                // to encrypt    
                using(CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write)) {  
                    // Create StreamWriter and write data to a stream    
                    using(StreamWriter sw = new StreamWriter(cs))  
                    sw.Write(plainText);  
                    encrypted = ms.ToArray();  
                }  
            }  
        }  
        // Return encrypted data    
        return encrypted;  
    }  
    static string Decrypt(byte[] cipherText, byte[] Key, byte[] IV) {  
        string plaintext = null;  
        // Create AesManaged    
        using(AesManaged aes = new AesManaged()) {  
            // Create a decryptor    
            ICryptoTransform decryptor = aes.CreateDecryptor(Key, IV);  
            // Create the streams used for decryption.    
            using(MemoryStream ms = new MemoryStream(cipherText)) {  
                // Create crypto stream    
                using(CryptoStream cs = new CryptoStream(ms, decryptor, CryptoStreamMode.Read)) {  
                    // Read crypto stream    
                    using(StreamReader reader = new StreamReader(cs))  
                    plaintext = reader.ReadToEnd();  
                }  
            }  
        }  
        return plaintext;  
    }  
}