/// <summary>
/// Given a block header, checks if the proof of work is valid on the block header. That is, if the header values, nonce, mix hash and difficulty are all suitable.
/// </summary>
/// <param name="blockNumber">The number of the block which we wish to validate.</param>
/// <param name="headerHash">Hash of a portion of the block header which is used with the nonce to generate a seed for the proof.</param>
/// <param name="mixHash">The resulting mix hash for the provided nonce after running the hashimoto algorithm.</param>
/// <param name="nonce">The nonce which, along with the other provided values, will calculate the mix hash to be verified.</param>
/// <param name="difficulty">The difficulty controls filtering for a plausible solution to the block which we wish to mine.</param>
/// <returns>Returns true if the proof of work is valid, returns false is the proof is invalid.</returns>
public static bool CheckProof(BigInteger blockNumber, byte[] headerHash, byte[] mixHash, byte[] nonce, BigInteger difficulty)
{
// Verify the length of our hashes and nonce
if (headerHash.Length != KeccakHash.HASH_SIZE || mixHash.Length != KeccakHash.HASH_SIZE || nonce.Length != 8)
{
return(false);
}
// Flip endianness if we need to (should be little endian).
byte[] nonceFlipped = (byte[])nonce.Clone();
if (BitConverter.IsLittleEndian)
{
Array.Reverse(nonceFlipped);
}
// Obtain our cache
Memory <byte> cache = Ethash.MakeCache(blockNumber); // TODO: Make a helper function for this to cache x results.
// Hash our block with the given nonce and etc.
var result = Ethash.HashimotoLight(cache, blockNumber, headerHash, nonceFlipped);
// Verify our mix hash matches
if (!result.MixHash.ValuesEqual(mixHash))
{
return(false);
}
// Convert the result to a big integer.
BigInteger upperBoundInclusive = BigInteger.Pow(2, EVMDefinitions.WORD_SIZE_BITS) / BigInteger.Max(difficulty, 1);
BigInteger resultInteger = BigIntegerConverter.GetBigInteger(result.Result);
return(resultInteger <= upperBoundInclusive);
}
/// <summary>
/// Mines a given block starting from the provided nonce for the provided number of rounds.
/// </summary>
/// <param name="blockNumber">The number of the block which we are mining.</param>
/// <param name="difficulty">The difficulty of the block which we are mining.</param>
/// <param name="miningHash">The mining hash (partial header hash) of the block which we are mining.</param>
/// <param name="startNonce">The starting nonce we will use and iterate through to try and find a suitable one for the reward.</param>
/// <param name="rounds">The number of steps to take from our starting nonce before giving up. Use ulong.MaxValue to try all.</param>
/// <returns>Returns the nonce and mixhash if block is successfully mined, otherwise both are null.</returns>
public static (byte[] Nonce, byte[] MixHash) Mine(BigInteger blockNumber, BigInteger difficulty, byte[] miningHash, ulong startNonce, ulong rounds)
{
// Verify the length of our hashes and nonce
if (miningHash == null || miningHash.Length != KeccakHash.HASH_SIZE)
{
return(null, null);
}
// Get our cache, set our start nonce and rounds remaining
Memory <byte> cache = Ethash.MakeCache(blockNumber);
ulong nonce = startNonce;
BigInteger roundsRemaining = rounds;
// Obtain our upper bound.
BigInteger upperBoundInclusive = (BigInteger.Pow(2, EVMDefinitions.WORD_SIZE_BITS) / BigInteger.Max(difficulty, 1)) - 1;
// Loop for each round.
for (ulong i = 0; i <= rounds; i++)
{
// Increment our nonce.
nonce++;
// Obtain the bytes for it
byte[] nonceData = BitConverter.GetBytes(nonce);
// Flip endianness if we need to (should be little endian).
if (!BitConverter.IsLittleEndian)
{
Array.Reverse(nonceData);
}
// Obtain our mix hash with this nonce.
var result = Ethash.HashimotoLight(cache, blockNumber, miningHash, nonceData);
BigInteger resultInteger = BigIntegerConverter.GetBigInteger(result.Result);
// If our result is below our difficulty bound.
if (resultInteger <= upperBoundInclusive)
{
// Flip endianness if we need to (returning nonce should be big endian).
if (BitConverter.IsLittleEndian)
{
Array.Reverse(nonceData);
}
// Return our nonce and mix hash.
return(nonceData, result.MixHash);
}
}
return(null, null);
}
