/**
* Generate an HMAC, as specified in [RFC2104], of the encrypted form of the data (message),
* which the DataIntegrity element will verify by using the Salt generated in step 2 as the key.
* Note that the entire EncryptedPackage stream (1), including the StreamSize field, MUST be
* used as the message.
*
* Encrypt the HMAC as in step 3 by using a blockKey byte array consisting of the following bytes:
* 0xa0, 0x67, 0x7f, 0x02, 0xb2, 0x2c, 0x84, and 0x33.
**/
protected void UpdateIntegrityHMAC(FileInfo tmpFile, int oleStreamSize)
{
// as the integrity hmac needs to contain the StreamSize,
// it's not possible to calculate it on-the-fly while buffering
// TODO: add stream size parameter to GetDataStream()
AgileEncryptionVerifier ver = builder.GetVerifier();
HashAlgorithm hashAlgo = ver.HashAlgorithm;
Mac integrityMD = CryptoFunctions.GetMac(hashAlgo);
integrityMD.Init(new SecretKeySpec(integritySalt, hashAlgo.jceHmacId));
byte[] buf = new byte[1024];
LittleEndian.PutLong(buf, 0, oleStreamSize);
integrityMD.Update(buf, 0, LittleEndian.LONG_SIZE);
FileStream fis = tmpFile.Create();
try {
int readBytes;
while ((readBytes = fis.Read(buf, 0, buf.Length)) > 0)
{
integrityMD.Update(buf, 0, readBytes);
}
} finally {
fis.Close();
}
byte[] hmacValue = integrityMD.DoFinal();
AgileEncryptionHeader header = builder.GetHeader();
int blockSize = header.BlockSize;
byte[] iv = CryptoFunctions.GenerateIv(header.HashAlgorithm, header.KeySalt, AgileDecryptor.kIntegrityValueBlock, blockSize);
Cipher cipher = CryptoFunctions.GetCipher(GetSecretKey(), header.CipherAlgorithm, header.ChainingMode, iv, Cipher.ENCRYPT_MODE);
byte[] hmacValueFilled = GetBlock0(hmacValue, AgileDecryptor.GetNextBlockSize(hmacValue.Length, blockSize));
byte[] encryptedHmacValue = cipher.DoFinal(hmacValueFilled);
header.SetEncryptedHmacValue(encryptedHmacValue);
}
public virtual void Update(byte[] foo, int s, int l)
{
mac.Update(foo, s, l);
}
