/* CryptoNight Step 2: Iteratively encrypt the results from Keccak
* to fill the large scratchpad
*/
private static byte[] FillScratchpad(CNState cnState,
ICryptoNight cnParams)
{
/* Expand our initial key into many for each round of pseudo aes */
byte[] expandedKeys = AES.AES.ExpandKey(cnState.GetAESKey());
/* Our large scratchpad, 2MB in default CN */
byte[] scratchpad = new byte[cnParams.Memory()];
byte[] text = cnState.GetText();
/* Fill the scratchpad with AES encryption of text */
for (int i = 0; i < cnParams.Memory() / Constants.InitSizeByte; i++)
{
for (int j = 0; j < Constants.InitSizeBlock; j++)
{
/* Need to pass the array with an offset because we manip
* it in place */
AES.AES.AESBPseudoRound(expandedKeys, text,
j * AES.Constants.BlockSize);
}
/* Write text to the scratchpad, at the offset
* i * InitSizeByte */
Buffer.BlockCopy(text, 0, scratchpad,
i * Constants.InitSizeByte, text.Length);
}
return(scratchpad);
}
/* CryptoNight Step 4: Sequentially pass through the mixing buffer
* and use 10 rounds of AES encryption to mix the random data back
* into the 'text' buffer.
*/
private static void EncryptScratchpadToText(CNState cnState,
ICryptoNight cnParams,
byte[] scratchpad)
{
/* Reinitialize text from state */
byte[] text = cnState.GetText();
/* Expand our initial key into many for each round of pseudo aes */
byte[] expandedKeys = AES.AES.ExpandKey(cnState.GetAESKey2());
for (int i = 0; i < cnParams.Memory() / Constants.InitSizeByte; i++)
{
for (int j = 0; j < Constants.InitSizeBlock; j++)
{
int offsetA = j * AES.Constants.BlockSize;
int offsetB = (i * Constants.InitSizeByte) + offsetA;
XORBlocks(text, scratchpad, offsetA, offsetB);
/* Need to pass the array with an offset because we manip
* it in place */
AES.AES.AESBPseudoRound(expandedKeys, text, offsetA);
}
}
cnState.SetText(text);
}
