Encrypt And Decrypt Using Rijndael Key In C#

The information needs to stay encrypted to ensure its safety and protection. It is common knowledge that there exist various techniques for encrypting data in C# and other programming languages. Vincent Rijmen and Joan Daemon developed the highly reliable Rijndael Key algorithm as a response to the inadequate security provided by the Data Encryption Standard method.

Encryption:

Encryption involves transforming easily understandable messages into a scrambled format to safeguard them from unauthorized individuals who might try to access them.

Decryption:

Decryption involves converting an encrypted message back into its original readable format. Text-based messages serve as the primary means of exchanging information. The term "ciphertext message" denotes a communication that has been encrypted.

Rijndael Key:

Rijndael key is based on the symmetric key encryption technique used in block ciphers . It functions with the help of discrete and invertible layers.

✅ Linear Mix Transform
✅ Not-Linear Transform
✅ Key Addition Transform

In C#, the Rijndael key accommodates block sizes of 128 (by default), 192, and 256 bits along with key lengths of 128, 192, and 256 bits. The relationship between the Rijndael key and AES (Advanced Encryption Standard) is very similar.

To perform Encrypt and Decrypt operations,

✅ Apply the given key and IV to create a Rijndael object.
✅ Subsequently, decrypt the data to carry out the stream transformation and generate the encrypted streams.
✅ After that, write all data to the stream using RijndaelManaged , and then get the encrypted bytes from the memory stream.

Pseudocode:

Example


function Encrypt(plainText, key, IV):
    cipher = new RijndaelCipher(key, IV)
    encrypted = cipher.encrypt(plainText)
    return encrypted
function Decrypt(cipherText, key, IV):
    cipher = new RijndaelCipher(key, IV)
    decrypted = cipher.decrypt(cipherText)
    return decrypted

key = generateKey() // Generate a key (16, 24, or 32 bytes)
IV = generateIV()   // Generate an initialization vector (16 bytes)
plainText = "Hello, World!"
cipherText = Encrypt(plainText, key, IV)
decryptedText = Decrypt(cipherText, key, IV)
print("Original:", plainText)
print("Encrypted:", cipherText)
print("Decrypted:", decryptedText)

Program:

Let's consider a scenario to demonstrate the process of Encrypting and Decrypting data using the Rijndael Key in C#.

Example


using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

public class RijndaelEncryption
{
    private static readonly byte[] Key = GenerateKey(); // 16, 24, or 32 bytes
    private static readonly byte[] IV = GenerateIV(); // 16 bytes

    private static byte[] GenerateKey()
    {
        using (var aes = new RijndaelManaged())
        {
            aes.GenerateKey();
            return aes.Key;
        }
    }

    private static byte[] GenerateIV()
    {
        using (var aes = new RijndaelManaged())
        {
            aes.GenerateIV();
            return aes.IV;
        }
    }

    public static string Encrypt(string plainText)
    {
        try
        {
            using (RijndaelManaged rijAlg = new RijndaelManaged())
            {
                rijAlg.Key = Key;
                rijAlg.IV = IV;

                ICryptoTransform encryptor = rijAlg.CreateEncryptor(rijAlg.Key, rijAlg.IV);

                using (MemoryStream msEncrypt = new MemoryStream())
                {
                    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    {
                        using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                        {
                            swEncrypt.Write(plainText);
                        }
                    }
                    return Convert.ToBase64String(msEncrypt.ToArray());
                }
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine("Encryption error: " + ex.Message);
            return null;
        }
    }

    public static string Decrypt(string cipherText)
    {
        try
        {
            byte[] cipherTextBytes = Convert.FromBase64String(cipherText);

            using (RijndaelManaged rijAlg = new RijndaelManaged())
            {
                rijAlg.Key = Key;
                rijAlg.IV = IV;

                ICryptoTransform decryptor = rijAlg.CreateDecryptor(rijAlg.Key, rijAlg.IV);

                using (MemoryStream msDecrypt = new MemoryStream(cipherTextBytes))
                {
                    using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                    {
                        using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                        {
                            return srDecrypt.ReadToEnd();
                        }
                    }
                }
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine("Decryption error: " + ex.Message);
            return null;
        }
    }

    public static void Main()
    {
        string original = "Hello, World!";
        string encrypted = Encrypt(original);
        Console.WriteLine($"Encrypted: {encrypted}");

        string decrypted = Decrypt(encrypted);
        Console.WriteLine($"Decrypted: {decrypted}");
    }
}

Output:

Styling for the placeholder element is defined in the following CSS code block:

Example


.placeholder-diagram { background: linear-gradient(135deg, #374151 0%, #1f2937 100%); border-radius: 12px; padding: 40px; margin: 20px 0; text-align: center; }
.placeholder-diagram .placeholder-icon { font-size: 3rem; margin-bottom: 10px; }
.placeholder-diagram .placeholder-text { color: #9ca3af; font-size: 1rem; }

Advantages of Rijndael Key:

There are several advantages of the Rijndael Key in C#. Some main advantages are as follows:

✅ Security: The highly secure symmetric encryption method known as Rijndael (AES) , which provides strong data protection.
✅ Efficiency: Rijndael can encrypt and decode data quickly and efficiently in computers, making it suitable for use in applications
✅ Versatility: Rijndael allows key sizes of 128, 192, and 256 bits, allowing users to select the level of security required for a given use case.
✅ Standardization: The encryption algorithm Rijndael has been standardized to ensure compatibility with different applications.
✅ Resilience: Cryptographers have studied and tested Rijndael extensively and found no attacks that work against the entire algorithm.

Disadvantages of Rijndael Key:

There are several disadvantages of the Rijndael Key in C#. Some main disadvantages are as follows:

✅ Key management: Rijndael requires encryption keys to be carefully managed as with other symmetric encryption techniques. Distributing and storing keys can be difficult, especially in large systems.
✅ Resource intensive: Rijndael encryption and decryption can be resource intensive, especially when dealing with large data sets or in systems with limited computing power
✅ Side-Channel Attack: Without adequate protection, Rijndael implementations are susceptible to side-channel attacks, including timing and capacity-checking attacks
✅ Compatibility: Although Rijndael is a widely accepted standard, sometimes there will be compatibility issues between different implementations or different versions of the algorithm, which can affect interoperability.

Encryption:

Decryption:

Rijndael Key:

Pseudocode:

Program:

Advantages of Rijndael Key:

Disadvantages of Rijndael Key:

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