Simple Encryption and Decryption in C#

Updated on January 4, 2021     Kisan Patel

Problem:
Encrypting & Decrypting a String in C#
Decrypting PKCS#7 encrypted data in C#
Encrypt string with Bouncy Castle AES/CBC/PKCS7
AES PKCS7 padding
Decrypt PKCS#7 Message in C#
C# Encrypt/Decrypt from Java AES/CBC/PKCS5Padding

Solution:

using System;
using System.Text;
using System.Security.Cryptography;
					
public class Program
{
	public static string Encrypt(string text)
	{
		var b = Encoding.UTF8.GetBytes(text);
		var encrypted = getAes().CreateEncryptor().TransformFinalBlock(b, 0, b.Length);
		return Convert.ToBase64String(encrypted);
	}

	public static string Decrypt(string encrypted)
	{
		var b = Convert.FromBase64String(encrypted);
		var decrypted = getAes().CreateDecryptor().TransformFinalBlock(b, 0, b.Length);
		return Encoding.UTF8.GetString(decrypted);
	}

	static Aes getAes()
	{
		var keyBytes = new byte[16];
		var skeyBytes = Encoding.UTF8.GetBytes("12345678901234567890123456789012");
		Array.Copy(skeyBytes, keyBytes, Math.Min(keyBytes.Length, skeyBytes.Length));

		Aes aes = Aes.Create();
		aes.Mode = CipherMode.CBC;
		aes.Padding = PaddingMode.PKCS7;
		aes.KeySize = 128;
		aes.Key = keyBytes;
		aes.IV = keyBytes;

		return aes;
	}

	
	public static void Main()
	{
		string encryptMe;
		string encrypted;
		string decrypted;

		encryptMe = "Hello World!";
		Console.WriteLine("encryptMe = " + encryptMe);

		encrypted = Program.Encrypt(encryptMe);
		Console.WriteLine("Encypted: " + encrypted);
		
		decrypted = Program.Decrypt(encrypted);
		Console.WriteLine("Dencypted: " + decrypted);
	}
}