AES Mode CBC with PKCS7 Padding

gistfile1.cs

 private static readonly byte[] iv = // array de 16 bytes


        private static string decrypt(string message, string key)
        {
            var encryptedBytes = Convert.FromBase64String(message);
            var aesAlg = makeAesCryptoServiceProvider(key);
            var decryptor = aesAlg.CreateDecryptor();

            using (var memory = new MemoryStream(encryptedBytes))
            {
                using (var crypto = new CryptoStream(memory, decryptor, CryptoStreamMode.Read))
                {
                    using (var stream = new StreamReader(crypto))
                    {
                        return stream.ReadToEnd();
                    }
                }
            }
        }

        private static string encrypt(string message, string key)
        {
            var aes = makeAesCryptoServiceProvider(key);
            var encryptor = aes.CreateEncryptor();
            using (var memory = new MemoryStream())
            {
                using (var crypto = new CryptoStream(memory, encryptor, CryptoStreamMode.Write))
                {
                    using (var stream = new StreamWriter(crypto))
                    {
                        stream.Write(message);
                    }
                }
                return Convert.ToBase64String(memory.ToArray());
            }
        }

        private static AesCryptoServiceProvider makeAesCryptoServiceProvider(string key)
        {
            return new AesCryptoServiceProvider
                       {
                           Mode = CipherMode.CBC,
                           Padding = PaddingMode.PKCS7,
                           Key = Encoding.UTF8.GetBytes(key),
                           IV = iv
                       };
        }