Why RaiBlocks is not secure.[...]
5. The Man in the Middle attack.If an attacker succeeds to put himself between a merchant and the RaiBlocks network he can just filter the double spending payment packets, and the merchant will never know that he is receiving a double spending. The Raiblocks network will discard that payment while the merchant will accept it.
https://s18.postimg.org/7pnm6yweh/doublespend.png[...]
This kind of FUD can be done to every cryptocurrency. So once and for all :
Every cryptocurrency, every online bank is vulnerable to Mitm attacks, if such attack successfully happens.
Example for bitcoin: If a hacker successfully performs a Mitm attack between a buyer and seller, he can just give to the buyer his own bitcoin address instead of the seller's. End of the story. And there are a myriad of more sophisticated attacks depending on whether you have a temporary or persistant Mitm attack.
Fortunately, Mitm attacks (over ssh) are rare, difficult and simply not accessible to the vast majority. They can still happen though and countermeasures (such as ssl pinning) are outside of the scope of crypto currencies underlying technology.
Basically if you are afraid of Mitm attacks, don't open a bank account, don't use any crypto currency, or better, don't use internet (or LANs) and make payments only in cash.
