C# / Windows Phone 7 - AES Encryption on WP7

You may already know that data-in-transit is secured via SSL. When calling a web service, however, the need may arise to encrypt and decrypt data. There are several cryptography algorithms on Windows Phone 7 that are supported, but we are providing a solid sample implementation using a 128-bit block size and 128-bit key size. AESManaged has a fixed block size of 128 bits and a key size of 128, 192, or 256 bits. Also, the Cipher Mode is defaulted to CBC, with a PKCS7 Padding.

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class AES {        public static byte[] Encrypt (byte[] data, byte[] key, byte[] iv) {         if (data == null || data.Length <= 0)              throw new ArgumentNullException("data");         if (key == null || key.Length <= 0)              throw new ArgumentNullException("key");         if (iv == null || iv.Length <= 0)              throw new ArgumentNullException("key");            byte[] encrypted;            using (AesManaged AESM = new AesManaged()) {                // Defaults             // CipherMode = CBC             // Padding = PKCS7                AESM.KeySize = 128;             AESM.BlockSize = 128;             AESM.Key = key;             AESM.IV = iv;                ICryptoTransform encryptor = AESM.CreateEncryptor();             encrypted = encryptor.TransformFinalBlock(data, 0, data.Length);            }         return encrypted;     }        public static byte[] Decrypt (byte[] cipherText, byte[] key, byte[] iv) {         if (cipherText == null || cipherText.Length <= 0)              throw new ArgumentNullException("cipherText");         if (key == null || key.Length <= 0)              throw new ArgumentNullException("key");         if (iv == null || iv.Length <= 0)              throw new ArgumentNullException("key");            byte[] decrypted;            using (AesManaged AESM = new AesManaged()) {                // Defaults             // CipherMode = CBC             // Padding = PKCS7                AESM.KeySize = 128;             AESM.BlockSize = 128;             AESM.Key = key;             AESM.IV = iv;                ICryptoTransform decryptor = AESM.CreateDecryptor();             decrypted = decryptor.TransformFinalBlock(cipherText, 0, cipherText.Length);            }         return decrypted;     } }

Click here to download the source code of an example application that demonstrates encryption and decryption using the above AES class.