Paycoin is a Bobsurplus coin.

You've been warned.

Investors Beware:

• Darkcoin is NOT anonymous.  Every transaction can be automatically traced with a Darkcoin de-anonymizer.
• Darkcoin is prone to several cost-less DOS attacks that can destroy the whole network.
• Darkcoin code was written by amateurs who do not properly understand cryptography.

Source: http://www.reddit.com/r/DRKCoin/comments/2nyifp/darkcoin_seriosuly_flawed_zero_anonymity_and/


From reddit:

hello friends,
please do not get confused by the fact, that I am a fresh user. In fact, I am very actively involed in crypto currencies but remaining anonymous requires certain countermeasures.

IN SHORT
It does not require many words to describe the problem. Darkcoin's code base remembers me of my childhood where I started coding on my AMIGA. Functions that easily can be implemented in O(1) are in fact implemented in polynomial complexity (like O(n5) or something). But this is not the problem.

The biggest problem is, that while indeed being savvy the developers have not much background knowledge about crypto and (in general) the very exact details about the bitcoin/darkcoin/whatever protocol.

After excessively revieweing the code and verifying everything on an offline testbox very scary facts popped up:

• Darkcoin is prone to DOS attacks, there are at least 3 (confirmed) ways you can DOS the complete network at no cost at all. You do not even lose your collateral tx.
• More critical: Darkcoin has no anonymity. There is a very easy and reliable way to link inputs to outputs in every single Darksend (as well as automatic denonimating) transaction.

As I know the open source community, I will not get anything from publishing my ideas and helping to fix them. So I want to inform you, that I will shortly setup a "Darkcoin Deanonymizer" which will for every single darksend transaction be able to link incoming and outcoing transactions.

ALRIGHT, DUE TO EXCESSIVE TROLLING ACCUSATIONS I DISCLOSE ONE OF THREE DOS ATTACKS ON DARKCOIN HERE --- just for a start

Alright, I will disclose one of three DOS attacks right now.

Attack: You can destroy all darksend processes by not signing and not losing any of your collaterals ... sabotage for free basically.

Reason: When you push your collateral to the masternode it is incorrectly checked for validity.

Check: IsCollateralValid() in darksend.cpp - line 874ff

It basically checks:

• are all inputs correct
• are all outputs correct
• wtxCollateral.IsAcceptable(true, false)

however, transaction with a nLockTime in the future are also passing "IsAcceptable". So push a collateral with a locktime 10000 blocks ahead, and you will never lose it because it will not make it into any block thus easily can be replaced by another one with a higher nSequence number.

This is SERIOUS and can destroy the whole network.

3 other DOS points are there as well.

delete