This snippet generates a random 256-bit Key and IV to be used for encryption purposes using the AES algorithm. Better when used from LINQPad.

Random_AES_Key_and_IV.cs

var aesAlgorithm = new System.Security.Cryptography.AesManaged();
aesAlgorithm.GenerateIV();
aesAlgorithm.GenerateKey();
var key = aesAlgorithm.Key;
var iv = aesAlgorithm.IV;
Console.WriteLine(key.Length);
Console.WriteLine(key);
Console.WriteLine(iv.Length);
Console.WriteLine(iv);