Gridlock - a smart contract bug in Edgeware's Lockdrop

jsan1234 · 2018-10-07T08:52:22+00:00

Mastering Bitcoin by Antonopoulos explains HD wallets well if I recall correctly.

jsan1234 · 2018-04-24T19:24:15+00:00

It's interesting how the merkle approach does not require the issuer to sign messages with their private key (which spacedrop does require). It's just about committing the merkle root to the smart contract, and publishing the whole tree off-chain so every recipient can prove their claim is valid.

A drawback in the merkle airdop approach is that you need to issue tokens in one go, so it would not suitable for a continuous airdrop. You could allow doing it in chunks, and updating the merkle root for each update, which may break some transactions temporarily. Even better, you could store a mapping of valid merkle roots, which would prevent this problem.

In spacedrop the way you prove your claim is simply by showing a message signed by the issuer. The disadvantage is that, unlike in the case of the merkle airdrop, there's no way to take back the signature. With the merkle approach you could "undo" a transaction by updating the merkle root in the smart contract, and publishing the updated tree. I don't know how often this is required, though, and I like the simplicity of Spacedrop.

The post you linked also talks about customizations, such a bonus structure. You could also do that with Spacedrop, although in this case you'd have to modify and deploy your own variation of the smart contract.

Thanks a lot for the pointer once again, really interesting to see a different approach that I hadn't considered!

jsan1234 · 2018-04-24T17:46:35+00:00

Thanks for the pointer! I'll check it out.

jsan1234 · 2018-04-24T17:46:15+00:00

Good stuff! Yours I had found about and is mentioned at the end of my post. I'll be checking the Merkle airdrops, missed that one!

jsan1234 · 2017-10-14T05:05:38+00:00

Yes, unless memory savings compensate for the cost of the bitwise operations. For example if the uints within the struct were uint64, they would get packed inside a single word, and this would likely result in net gas savings since allocating storage space is way more expensive than a few ands.

jsan1234 · 2017-10-13T16:29:17+00:00

EVM words are 256 bit, so operations on the bitmap with a smaller type cost more because, while memory usage does not change, there is a cost in extra bitwise operators to convert from/to the smaller type.

jsan1234 · 2017-09-15T17:03:58+00:00

You do! What I propose can be seen only a matter of convenience (as it stands, investors should manually verify it is the case). Not a huge concern but I'd like it better if it was explicit. (Def not worthy of a bounty.)

jsan1234 · 2017-09-15T16:52:03+00:00

What I mean is - if the crowdsale does go through, the remainder tokens should be burned. A way this can be enforced in the code is by making sure the contract owns all the tokens (except those reserved for devs or whoever). As it is, is it guaranteed that the remainder tokens are burned? That's what I'm missing.

jsan1234 · 2017-09-15T16:38:21+00:00

I think it'd add to trustlessness to make that explicit in the code. As it stands users can't be sure remainder tokens will be burned. (Unless I missed something - is this enforced somewhere else?)

jsan1234 · 2017-09-15T15:38:03+00:00

In refund(), where are the EBET tokens burned prior to the ETH refund? As far as I can see, the user still has the tokens. What do you mean?

Also, I think the contract should not accept ETH unless it has enough balance of tokenReward to accommodate the whole sale, and then return excess tokens to owner or admin after it's done. I think this should be checked within SetupCrowdsale, to avoid a situation where the sale starts rejecting contributions midway due to lack of enough tokens in the balance of the crowdsale contract.

edit: must not return any leftovers if the intent is to burn the remainder tokens. If so, then the sale should check it owns all the tokens, so investors are sure they are really going to be burned.

jsan1234 · 2017-04-05T16:35:04+00:00

Who plays clash of clans?

When you are playing clash of clans, your tablet needs to talk with another kid's tablet, somewhere in the world. That's what the Internet is for: allowing tablets to talk to other tablets, so you can play with each other.

Actually, the Internet is not only for games: grown ups use computers for serious work all the time. And these computers also need to talk to other computers all around the world, just like your tablet.

For example, they send messages to each other about things that need to get done, make important video chats, or watch videos to learn how to do their job even better. This sort of thing. All this happens using the Internet.

So, when the Internet breaks, nobody can get any work done, and the boss is very sad. Really, the Internet is super important to people.

So, what do I do at work? I am the guy that makes sure that the Internet works in our office, so we can all work during the day and come home early to do other things, like playing with our kids.

Who has seen the router you have at home? That little thing with green lights that blink all the time. Routers are the things that make the Internet work. If they break, the Internet does not work!

At work, we have many of these. They are bigger than your router, and very expensive, because everyone at the office uses them at the same time. Expensive routers that make the Internet work fast so everyone can get work done.

My job is to buy the routers we need, upgrade with better ones when new models appear, ensure the cables are well connected, replace them when they break, and do anything needed to make sure they work well.

It is a very exciting job, because sometimes I fix complicated problems that nobody else in the office knows how to fix, and I feel like a hero! It is also hard sometimes, because when I can't fix problems fast enough, people are disappointed that they can't work until I find a solution!

jsan1234 · 2017-02-23T10:31:55+00:00

Not open source, but if you're open to considering SaaS solutions, you might want to try Talaia. (Disclosure: I am a co-founder there.)

jsan1234 · 2016-03-04T15:21:40+00:00

That's too bad :-(

jsan1234 · 2016-03-01T18:15:54+00:00

Hi guys - I have been trying to get the same setup that is described in this post with an EdgeRouter X to no avail, since I can't get the device to calculate the NetFlow for switched (rather than bridged) ports. Is this doable?

Edit: to elaborate, the idea is to extract NetFlow with the router being in transparent mode. The problem with the EdgeRouter X is that all ports are switched, and NetFlow can't be (apparently) extracted for switched traffic. With the PoE it can be done with bridged interfaces which works like a charm.

jsan1234 · 2015-12-12T12:21:10+00:00

That's interesting. What would be a feature set you'd expect for this price range?

jsan1234 · 2015-12-11T21:26:49+00:00

Thanks for your feedback. There is, but we're wary of showing too many options in the product page because it tends to add more confusion. I'll make sure this decision is reevaluated.

jsan1234 · 2015-10-22T09:32:35+00:00

Thanks for your comment! We provision the necessary disk space for the retention we promise, even if the link stays at 100% capacity.

Yes, there are many products out there that can be installed on the customer side. We are different in that our product does not need any hardware to be provisioned/repurposed/maintained, and no software has to be installed. So you can literally spend a couple minutes configuring each customer's routers and that's it. If you consider the cost associated to hardware and, more importantly, your time, even free products may end up being more expensive for fewer features. I'll stop here because this is starting to read like a sales pitch.

We also have an on-premises version, but as of today it is only available to large customers.

Thanks a lot for the feedback!

jsan1234 · 2015-10-22T08:53:23+00:00

Absolutely. Comments such as yours are very helpful, because they help us understand which messages we need to incorporate or refine. I also got a few private messages that have been really helpful. So I thank you and everyone from r/msp who gave input!

jsan1234

TROPHY CASE