static public bool CheckMAC(ArraySegment <byte> blob, ArraySegment <byte> mac, byte[] macKey)
{
byte[] computedMAC;
using (HMACSHA256 hmac = new HMACSHA256(macKey))
computedMAC = hmac.ComputeHash(blob.Array, blob.Offset, blob.Count);
return(ArraySegmentExt.Equals(computedMAC, mac));
}
static public byte[] Decrypt(ArraySegment <byte> encryptedBlob, ArraySegment <byte> iv, byte[] encryptionKey)
{
using (Rijndael rijndael = Rijndael.Create())
{
rijndael.Key = encryptionKey;
rijndael.IV = ArraySegmentExt.GetByteArray(iv);
rijndael.Mode = CipherMode.CBC;
rijndael.Padding = PaddingMode.None;
using (ICryptoTransform decryptor = rijndael.CreateDecryptor())
using (MemoryStream ms = new MemoryStream())
using (CryptoStream cs = new CryptoStream(ms, decryptor, CryptoStreamMode.Write))
{
cs.Write(encryptedBlob.Array, encryptedBlob.Offset, encryptedBlob.Count);
return(ms.ToArray());
}
}
}
