Of course for a scam to happen there need to be two parties involved - a scammer and a victim. The scammer is to blame for scamming, he clearly is the bad guy. But the victim is to blame for trusting someone without sufficient reason (I won't go into the clear stealing situation where security was present but subverted).
With Bitcoin, you alone are responsible for your financial safety. Unlike Paypal or other payment systems where you as the buyer can reverse the payment if you've been cheated, Bitcoin (and similar cryptocurrency) payments are final. I think there are good reasons that payment systems have an "undo" mechanism, and if you need such a mechanism, such when dealing with unknown sellers, you should use an escrow which allows you to reverse your payment if you don't receive goods. It's just not built into Bitcoin, so you need to arrange for it out of band.

Onkel Paul

They would probably not be talking about a ransom.

Gox has been under several DDoSes, I don't think all of them were targeted to manipulate BTC exchange rate, there's a good chance that some of them were attempts to extort money from Gox.

Onkel Paul

Hey, looks like you' trying to trick us here:

You have mined these blocks: http://blockchain.info/de/blocks/atypicalgilgamesh

Onkel Paul

Signing is not encryption.

Basically, the signature is the hash of the transaction encrypted with your private key. Checking the signature just means to calculate the hash of the transaction, decrypt the signature with the public key, and check whether the two are equal.
The signature just proves that the holder of the private key has signed the transaction. To check that proof, only the public key is needed, so your private key is never sent anywhere.
But the transaction is fully readable even without checking the signature.

And this is completely independent of the fact whether the "change" of your transaction is sent to the same address or a different one. Normally, the bitcoin client sends the "change" to a new address that it created to obfuscate the flow of money a little bit. There are heuristics to guess which part of a transaction stays with the sender as change, and which part actually goes to a recipient, but AFAIK these can be wrong.

Onkel Paul

Du musst mal ein bisschen die Gedanken sortieren. Nicht alles durcheinander denken, das führt zu nichts :-)

Also erstens: Der technische Umgang mit Bitcoins (also Senden und Empfangen von Bitcoins, Umgang mit dem Client, Adressen Transaktionen, Blockchain, Mining usw.) ist absolut unabhängig vom Handel mit Bitcoins (also wie man am besten normales Geld oder Dienstleistungen in Bitcoins tauscht und umgekehrt). Am besten packt man von diesen Dingen immer nur eins in einen Post, dann riskiert man auch nicht, sich da zu verwuseln.

Zum Verständnis, wie Bitcoin funktioniert, sollte man sich erst mal auf die Technik beschränken. Handel hat überhaupt keinen Sinn, wenn man die Technik nicht grundsätzlich versteht und beherrscht. Dazu musst du nicht im Kopf Hashes ausrechnen oder die Gültigkeit von Signaturen überprüfen, aber es ist schon sinnvoll, die Grundeigenschaften von Hashes und Signaturen zu verstehen, damit du nicht über die einfachsten Dinge stolperst.

Zu der Frage mit den Adressen:
Die Adressen, auf die du Zugriff hast, werden vom Client verwaltet. Du musst sie dir nicht alle selbst merken oder da einen Überblick behalten.
Der Client erzeugt diese Adressen immer zusammen mit einem entsprechenden privaten Schlüssel, der nötig ist, um BTC, die an eine Adresse geschickt wurden, weiterzuschicken, also darüber zu verfügen.
"Leere" Adressen (also solche ohne Guthaben) existieren weiter, denn sie stehen ja weiterhin in der Blockchain. Soweit ich weiß, schmeißt der Bitcoin-Client die privaten Schlüssel für solche Adressen auch nicht weg. Wenn du jemandem eine Adresse gesagt hast, an die er eine Zahlung an dich senden soll, kannst du die Adresse natürlich aus der Liste der Empfangsadressen löschen, wenn die Zahlung angekommen ist, um einen besseren Überblick zu haben. Adressen, auf die immer wieder was kommen soll, behältst du natürlich. Und wenn jemand auf eine Adresse etwas schickt, die du in der Liste gelöscht hast, erkennt der Client trotzdem, dass es sich um eine Zahlung an dich handelt, und zeigt sie als Zugang an (glaube ich jedenfalls, hab es noch nicht ausprobiert).

Alle anderen Teile in deiner Frage haben mit Handel zu tun, da gehe ich jetzt nicht drauf ein, um der Verschwurbelung von Gedanken entgegenzuwirken.

Onkel Paul

The Atmel chip will not get you any usable hashing performance.
The bottleneck is probably not its processing speed, but the communication bus speed.
At 1MBit/s, the time needed to compute one hash in the optimal case is:
send 640 bits of block header (80 bytes): 640 µs
receive 256 bits of hash: 256 µs
send 256 bits of first-stage hash: 256 µs
receive 256 bits of second-stage hash: 256 µs

total: 1408 µs

So one chip can deliver 710 bitcoin hashes per second (if you ignore any additional overhead).

Of course, you could theoretically run 1000 of these chips in parallel if you manage to connect as many serial communication lines - that's still only 710 khashes/s, even quite obsolete PC CPUs can do better.

These chips may be great for their intended purpose, but definitely not for bitcoin mining...

Onkel Paul

As far as I know the simplest way to exchange currencies on ripple is to send yourself some amount of the target currency. Ripple will try to find a path and will tell you how much you have to pay. Of course, this is always based on current offers, so you might pay more than if you create your own offer and wait for someone to fill it.

Onkel Paul

You offer to buy 1 BTC for 6005 XRP, that's ok.
Other BTC sellers offer less, so your offer is a good one.
However, the cheapest BTC on sale are 6400 XRP, so no trade happens (you are not willing or even able to pay 6400 XRP).
You will only be able to buy a BTC when someone wants XRP really desperately and is willing to accept your offer of 6005, or you reduce your expectations and buy as much BTC as your XRP will get you (less than 1 in this case).

Onkel Paul

As always on a market, if nobody takes on your offer even though it is currently the best one, and somebody else makes a better offer, your offer becomes second-best. This is nothing peculiar to ripple, it could happen on Mt.Gox or any other exchange as well.
With a small spread and bigger volume, it's less likely, but on ripple there is very low trade volume and often large spreads, so it can and will happen all the time.
Remember that ripple is beta, don't expect it to have huge markets yet. If you can make a good trade, fine, but you should not depend on it.
Especially you should not count on XRP exchange rate being favorable for your trade goals, Opencoin will release more of them when they think it's the right thing to do.

Onkel Paul

The assumption they are making is that law enforcement (or other folks wanting to get at your data) can secretly install something on your computer (hardware or software) before you access the encrypted data, and retrieve the encryption key (not necessarily the passphrase, but the key used by the encryption algorithm) and store it where they can later use it when they grabbed your encrypted disk.
So unless you constantly watch over your hardware or have reliable tamper-detection, you're not really sure whether your computer is safe.
Even your multiple-factor scheme would break, although it would be safe from a simple keylogger attack.

Onkel Paul

Looks like speculators without any idea what ripple is all about jumped into it. Stupid.

Onkel Paul

It's very simple: The client can not influence which miner gets to mine its transaction. It just creates the transaction (possibly adding a fee), signs it, and sends it to the bitcoin network.
Then miners decide when to include a transaction into a block.
The client can make the transaction more attractive by including a fee under the assumption that miners will select transactions based on this - however, this is not a fixed rule, and miners can do what they want (egoistic miners could for example avoid all the hassle with transactions and mine empty blocks for the block reward only).
As block rewards go down, transaction fees are an incentive for miners to keep mining and to include transactions into their blocks, because without transactions there are no transaction fees...
And miners can only hash full blocks, not single transactions, so the transactions fees are only available to the lucky one who finds a valid hash.

Onkel Paul

Exactly. The ones removing their trust last are the Bagholders.

Onkel Paul

This is indeed economically unreasonable. The people doing it probably want to have a "collector's item".
Like old post stamps, which are unusable for their original purpose since the postal organization that emitted them does not exist anymore, but will be sold and bought anyway.

Onkel Paul

There are variants of the bitcoin-qt client which allow you to send without fee. I don't know exactly how you get and install them, whether you need to compile them yourself or just donwload a binary.
If your goal is to move your balance into a new wallet you might just export your keys from the old one and import into the new one. However, if you feel your old wallet could have been compromised (keys stolen) then transferring the balance is a good idea anyway.

No, all miners see all transactions and try to find a valid hash concurrently. With pools, the "miner" that decides what to put in a block is the pool operator (or rather his software), the pool participants only perform the grunt work of searching for valid hashes, they can't decide and even don't know what goes into a block.
A miner can decide to apply different rules regarding the transactions it will put into a block (for example, it could favor SD transactions or completely ignore them) but this choice only has an effect on the blockchain when this miner happens to find a hash for its block before any other miner finds a hash for the blocks they are working on.

Onkel Paul

That's what you get when you extend trust to someone you shouldn't trust. (There are maybe other areas where TradeFortress can be trusted, I just don't know him well enough. He can't be trusted regarding anything related to ripple, though).

Let me tell you something that really happened to me a long time ago:
When I walked to my car, a guy walked up to me and told me he had lost his wallet, needed a few bucks for a train ticket so he could get home - he would pay me back immediately via bank transfer. He looked like he was sincere and really in need of help, gave me his name and address and he signed a piece of paper that he owed me that money. I was young and naive, so I gave him some money. Of course I never got it back - I was stupid, and he was just a scammer.

Now this is what happened to you:
TradeFortress walked up to you, promising you he would give you 1 Bitcoin (via a ripple IOU) if you trusted him for 100 Bitcoins. You are young and naive, you don't understand how ripple works, and you believed that a promise from TradeFortress is worth real money, so you trusted him.
Now you find that the "piece of paper" where he promised you 1 BTC isn't even usable to wipe your arse since it's just virtual.
You believed that he would keep his promise to give you 1 BTC (in return for the IOU) and now you find out that he never intended to do that.

He calls it a social experiment. I see a very clear parallel to my case where I've been scammed. Who is the scammer here - the paper on which he promised to pay you 1 BTC (which is an analogy of the ripple system and theh IOU expressed in it), or the guy who promised it to you knowing perfectly well that he will not pay?

And just in case you still don't know what the real scam is here: it's not his empty promise of 1 BTC (everybody could promise me 1 BTC - if they don't pay I haven't lost anything) but his tricking you into trusting him for 100 BTC. In the ripple system, this means that up to an amount of 100 BTC you accept "his" worthless BTC IOUs as substitutes for BTC IOUs from actual trustworthy gateways.
If you don't trust a gateway to pay out the BTC they owe you, you definitely should not do business with them, whether in ripple not in the "real world". So now you should immediately reduce the trust level for TradeFortress in ripple to zero and hope that there hasn't been too much BTC rippled through your account - that amount would definitely be gone.

Note that there are valid criticisms regarding to ripple, such as it being based on IOU instead of irrevocable value transfer such as Bitcoin, or the discrepancy between the bold words of openness on their web page and the closed-source server code. These points have been discussed to death, but TradeFortress seems to have chosen to not accept the answers and claims that his questions have not been answered.

Onkel Paul

A client program can create transactions with less or no fees, and of course your miner can decide to accept transactions with zero fees as well.
However, the probability that your miner gets to mine a block is pretty slim, unless you're controlling the mining for a decently-sized pool.

Onkel Paul

Why would SD blocking US visitors from their website affect your project?

Onkel Paul

10 posts in the newbie section plus 4 hours spent in the forum (look at "total time logged in" on the top left)

Onkel Paul

As his goal clearly is to spread FUD and damage ripple's reputation, I would not trust him on this, even if he's a hero member, and I don't think any sane person should trust him either.
He is most likely not willing to pay his IOUs, probably claiming that it's obvious that they are worthless since they are in ripple so nobody should expect him to pay anything.
Whoever accepted his offer just shows his own inability or unwillingness to understand the concept of IOUs and deal with them responsibly.
There are quite a number of gullible folks in the Bitcoin community...

Onkel Paul