If I understand correctly, there is no fees for the Iota transactions.
No reward for the miners and Tangle security.

Is it possible to spam the system with fake transactions? If no fees, you can spam the Tangle for free.

Interesting. Very interesting. It's a "user motivation" to give hash rate to secure the system. Very very interesting.

You don't pay fee with tokens but with computation... every user should give computation power. Very very very interesting

This is a case where common sense loses against math, I thought like you but mthcl proved that I was wrong. Surprisingly, if a transaction got included into the majority of the tips (i.e. adaptation period is over) then we get near the same assurance against a double-spending as in a blockchain-based coin.

Well that seems to make common sense that we entangle such that all transactions are included in the majority of the tips, then the consensus is those transactions are more likely final than the ones in the minority of the tips, since there doesn't appear to be an incentive to favor tangling with minority tips over majority tips. But that seems to imply that before I combine two tree branches into my signature, I must insure there is no double spend in the (combined) history otherwise my signature is invalid and no other node should include my branch tip as input to their node in the graph. Thus it seems each payer has to keep an entire history and table of conflicting branches (at least back to check points but aren't check points the antithesis of unmanaged, decentralized crypto-currency)? Are payer nodes supposed to entrust this verification to other nodes?

Okay I think I can see intuitively how participants have an incentive to maximally tangle (extend the depth of) the graph and not broaden it too much, but I will still need to go deeper to analyze attack vectors.

So far my main intuitive concern seems to stem around the apparently much more intensive (exponentially more?) resources that payers will need to have versus in a system where they can autonomously sign a transaction without context of other transactions in the network.

Also I can't see how anonymity technology such as ring signatures can be integrated into a system like this, nor Lightning Networks. My mistake. I realize the inputs and outputs of the transaction are orthogonal to the DAG. So yes transactions could still be signed with on-chain anonymity I presume. Afaics, Lightning Networks appears to not be compatible with the anonymity methods we've used for block chains.

It is very interesting the concept of a chain without the aliasing error of stepwise blocks. Somehow I think this stuff is important, but I haven't yet figured out the sweet spot for this technology. I need to understand more about the benefits and tradeoffs.

Okay so placement into the DAG (consensus) graph can be assisted by a service provider. Payer signs the TX and that signature authorizes the service provider. Service provider signs the graph node. Or service provider sends the DAG node choice to payer who signs it, giving authority to place his signed TX at DAG node.

This has some nuances of difference versus the autonomous ability to directly formulate and send a transaction to the consensus block chain network (although in practice existing PoW systems devolve into essentially sending to pools in most scenarios, but this maybe could be fixed in other ways). But I don't as of yet see a problem with using a service provider.

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Changing the topic, one of the issues which I doubt is on your radar and probably not a priority in your view, is that a DAG system apparently can't order transactions (or can you?) and I believe ordering will be important for implement anonymity ring signatures entirely correctly (something I had pointed out to Monero but still need to get back to Shen and his 2007 prior art and such to make sure if I was correct or not).

How long does it take for a transaction to become "confirmed" such that it is very, very unlikely it can't be double-spent into the DAG?

Do you have other means to obtain equivalent untraceability or do you feel anonymity isn't important for these transactions?

Do you have any rough idea of the confirmation delay?

That isn't the only use case of fast confirming transactions, regardless whether microTX or normal values.


So off-chain mixing of TX inputs and outputs. But algorithms for that which work without any trust such as CoinShuffle are slow. And off chain mixing is not autonomous, violates the end-to-end principle, has a simultaneity requirement waiting for other users to join your mix.

(I have suggested a novel use of CoinShuffle for hiding IP addresses where it is a useful addition to on-chain mixing, but that is irrelevant to my point here)

Every design has some weakness, so don't fret. I am just trying to determine what the parameters are.


Comparable to a 6 confirmation probability against double-spend in Bitcoin?

https://bitcoil.co.il/Doublespend.pdf

A similarity to Bitmessage, one should do some work to send message, here Iota sends token. On the other hand, what's the difference between Iota and Bitmessage?

Someone from outside should do this comparison, I may be biased.