/// <summary>
/// Encrypts data into an <see cref="IEnumerable"/> of <see cref="Fingerprint"/>'s.
/// </summary>
/// <param name="data">The data you want to encrypt.</param>
/// <param name="key">A 256 bit random Key to encrypt the data. You can use the <see cref="GenerateNewKey"/> method to generate one.</param>
/// <param name="iv">A 128 bit random IV. You can use the <see cref="GenerateNewIv"/> method to generate one.</param>
public IEnumerable<Fingerprint> Encrypt(byte[] data, byte[] key, byte[] iv)
{
// Validate data parameter
if (data == null)
throw new ArgumentNullException("data");
if (data.Length == 0)
return new List<Fingerprint>();
// Validate key parameter
if (key == null)
throw new ArgumentNullException("key");
if (key.Length == 0)
throw new ArgumentException("The key parameter can not be empty.", "key");
if (key.Length * 8 != KeyBitSize)
throw new ArgumentException($"The key parameter must be {KeyBitSize} bits long.", "key");
// Validate iv parameter
if (iv == null)
throw new ArgumentNullException("iv");
if (iv.Length == 0)
throw new ArgumentException("The iv parameter can not be empty.", "iv");
if (iv.Length * 8 != BlockBitSize)
throw new ArgumentException($"The iv parameter must be {BlockBitSize} bits long.", "iv");
// Encrypt data with AES
var encryptedData = EncryptPayload(data, key, iv);
// Calculate padding length needed for the encrypted data
var length = encryptedData.Length;
var paddingLength = 10 - (length % 10);
if (paddingLength <= 0) paddingLength = 10;
Array.Resize(ref encryptedData, length + paddingLength);
// Create cryptographically random padding
var padding = new byte[paddingLength];
_randomNumberGenerator.GetBytes(padding);
padding[paddingLength - 1] = (byte) paddingLength;
Array.Copy(padding, 0, encryptedData, length, padding.Length);
// Create BitArray of the encrypted data
var encryptedDataBitArray = new BitArray(encryptedData);
var fingerprints = new List<Fingerprint>();
// Check to make sure the number of bits in the file is divisible by 10
if (encryptedDataBitArray.Length % 10 != 0)
throw new InvalidOperationException();
for (var i = 0; i < encryptedDataBitArray.Length;)
{
var blockBitArray = new BitArray(new bool[]
{
encryptedDataBitArray.Get(i++), // 0x00
encryptedDataBitArray.Get(i++), // 0x01
encryptedDataBitArray.Get(i++), // 0x02
encryptedDataBitArray.Get(i++), // 0x03
encryptedDataBitArray.Get(i++), // 0x04
encryptedDataBitArray.Get(i++), // 0x05
encryptedDataBitArray.Get(i++), // 0x06
encryptedDataBitArray.Get(i++), // 0x07
encryptedDataBitArray.Get(i++), // 0x08
encryptedDataBitArray.Get(i++) // 0x09
});
fingerprints.Add(
_fingerprintManager.GetFromIndex(blockBitArray.ToInt16()));
}
return fingerprints;
}
