/* 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);
}
/* CryptoNight Step 3: Bounce randomly 1,048,576 times (1<<20)
* through the mixing scratchpad, using 524,288 iterations of the
* following mixing function. Each execution performs two reads
* and writes from the mixing scratchpad.
*/
private static void MixScratchpadV0(CNState cnState,
ICryptoNight cnParams,
byte[] scratchpad)
{
MixScratchpadState mixingState = new MixScratchpadState(cnState);
for (int i = 0; i < cnParams.Iterations() / 2; i++)
{
for (int iteration = 1; iteration < 3; iteration++)
{
/* Get our 'memory' address we're using for this round */
int j = E2I(mixingState.a, cnParams.Memory());
/* Load c from the scratchpad */
CopyBlockFromScratchpad(scratchpad, mixingState.c, j);
/* Perform the mixing function */
if (iteration == 1)
{
MixScratchpadIterationOne(mixingState);
}
else
{
MixScratchpadIterationTwo(mixingState);
}
/* Write c back to the scratchpad */
CopyBlockToScratchpad(scratchpad, mixingState.c, j);
SwapBlocks(ref mixingState.a, ref mixingState.b);
}
}
}
private static byte[] CryptoNightV0(byte[] input, ICryptoNight cnParams)
{
/* CryptoNight Step 1: Use Keccak1600 to initialize the 'state'
* buffer, encapsulated in cnState
*/
CNState cnState = new CNState(Keccak.Keccak.keccak1600(input));
byte[] scratchpad = FillScratchpad(cnState, cnParams);
MixScratchpadV0(cnState, cnParams, scratchpad);
EncryptScratchpadToText(cnState, cnParams, scratchpad);
return(HashFinalState(cnState));
}
public static byte[] SlowHash(byte[] input, ICryptoNight cnParams)
{
switch (cnParams.Variant())
{
case 0:
{
return(CryptoNightV0(input, cnParams));
}
case 1:
{
return(CryptoNightV1(input, cnParams));
}
default:
{
throw new ArgumentException(
"Variants other than 0 and 1 are not supported!"
);
}
}
}
private static byte[] CryptoNightV1(byte[] input, ICryptoNight cnParams)
{
if (input.Length < 43)
{
throw new ArgumentException(
"Input to CryptoNightV1 must be at least 43 bytes!"
);
}
/* CryptoNight Step 1: Use Keccak1600 to initialize the 'state'
* buffer, encapsulated in cnState
*/
CNState cnState = new CNState(Keccak.Keccak.keccak1600(input));
byte[] scratchpad = FillScratchpad(cnState, cnParams);
byte[] tweak = VariantOneInit(cnState, input);
MixScratchpadV1(cnState, cnParams, scratchpad, tweak);
EncryptScratchpadToText(cnState, cnParams, scratchpad);
return(HashFinalState(cnState));
}
