public async Task <bool> CheckChainAsync(IReadOnlyList <Block> blockchainToValidate)
{
// Check if the genesis block is the same
if (_hashProvider.ComputeHashString(blockchainToValidate[0]) !=
_hashProvider.ComputeHashString(await _blocks.GetGenesisBlockAsync()))
{
var message = $"Genesis blocks aren't the same";
_logger?.LogError(message);
throw new BlockchainAssertionException(message);
}
// Compare every block to the previous one (it skips the first one, because it was verified before)
try
{
for (var i = 1; i < blockchainToValidate.Count; i++)
{
CheckBlock(blockchainToValidate[i], blockchainToValidate[i - 1]);
}
}
catch (Exception ex)
{
var message = $"Invalid block sequence";
_logger?.LogError(message);
throw new BlockchainAssertionException(message, ex);
}
return(true);
}
public Transaction Build()
{
// Check required information
if (_utxo == null)
{
throw new ArgumentException($"It's necessary to provide a list of unspent output transactions.");
}
if (_outputAddress == null)
{
throw new ArgumentException($"It's necessary to provide the destination address.");
}
if (_totalAmount == null)
{
throw new ArgumentException($"It's necessary to provide the transaction value.");
}
// Calculates the change amount
var changeAmount = _utxo.Sum(x => x.Amount) - _totalAmount - _feeAmount;
var transactionId = CryptoUtil.RandomString();
// For each transaction input, calculates the hash of the input and signs the data
var inputIndex = 1;
var inputs = _utxo.Select(utxo =>
{
var keyPair = Ed25519.GenerateKeyPairFromSecret(_secretKey);
var hash = _hashProvider.ComputeHashString(new
{
Transaction = utxo.TransactionId,
utxo.Index,
utxo.Address
});
utxo.Signature = Ed25519.Sign(keyPair, hash);
return(utxo);
}).Select(x => new TransactionItem
{
TransactionId = x.TransactionId,
Index = x.Index,
Address = x.Address,
Amount = x.Amount,
Signature = x.Signature,
Type = TransactionDataType.Input
}).AsList();
// Add target receiver
var outputIndex = 1;
var outputs = new List <TransactionItem>
{
new TransactionItem
{
Index = outputIndex++,
TransactionId = transactionId,
Amount = _totalAmount.Value,
Address = _outputAddress,
Type = TransactionDataType.Output
}
};
// Add change amount
if (changeAmount > 0)
{
outputs.Add(new TransactionItem
{
Index = outputIndex,
TransactionId = transactionId,
Amount = changeAmount.GetValueOrDefault(),
Address = _changeAddress,
Type = TransactionDataType.Output
});
}
// The remaining value is the fee to be collected by the block's creator
var transaction = new Transaction
{
Id = transactionId,
Type = _type,
Data = new TransactionData
{
Inputs = inputs,
Outputs = outputs.AsList()
}
};
transaction.Hash = _hashProvider.ComputeHashBytes(transaction);
return(transaction);
}
public static string ToHashString(this Block block, IHashProvider hashProvider)
{
return(hashProvider.ComputeHashString(block));
}
public string ToHashString(IHashProvider provider)
{
return(provider.ComputeHashString(this));
}