[Ask Coinbase Anything...]

Ask Coinbase Anything...

You've probably heard of Coinbase, but have you met Brian and Fred (the founders)? Now is your chance to ask us whatever is on your mind. We haven't always been the most public figures (turns out running a company is a lot of work!) but we'd like to get to know you a bit better and do a live Q&A video to answer your questions.

When is litecoin support coming? How did we convince Dell, Expedia, and Wikipedia to accept bitcoin? When will Coinbase support storing your own private keys? And why did we cancel your bitcoin order? (sorry about that!) Any question is fair game (and if there is something legally we can't say, we will tell you that too).

This will be an informal chat where we speak off the cuff.

How do I ask a question?

You can post it to this reddit thread and we will try to answer it during the live video AMA
Even better: Tweet @coinbase during the live AMA with your questions and we will read them live on the air
When will the AMA be held?

Thursday Oct 16th, 2014 at 7pm Pacific time
View in my time zone: http://www.timeanddate.com/worldclock/fixedtime.html?msg=Coinbase+AMA+with+Founders+Brian+and+Fred&iso=20141016T19&p1=224&ah=1
Add it to your calendar!

How do I watch the video?

We will tweet out a link 1 hour before the AMA from http://twitter.com/coinbase

Come Meet Us In Europe!

We will also be visiting Europe next week where we recently launched!

If you live in London, Paris, Madrid, or Helsinki, we will be hosting user meetups and giving talks. You should come say hello in person and have a drink on us.

https://coinbase.com/network/transactions/ccb75ea48acc40f249f445ab7b6913e6a805938c022fbc6c9dcbdc67e4cb8847
https://coinbase.com/network/transactions/88eb395b48a6d3875d8d55a6efd34afd2e1d4e397b43f9f790479914fba0c74b

These two transactions accidentally got into our hot wallet and are holding up some transactions in an unconfirmed chain.  They don't have sufficient fees to be included in the normal mining, but we'll pay 5 BTC to someone who can get these mined in a block (along with any other transactions you are already hashing).

Luke-Jr is already working on mining them, but we would like to add some more CPU power to it.  The bug which caused them to enter the hot wallet in the first place has now been fixed.

Thank you for the help!
Brian Armstrong
Coinbase

Hi,

I've run into a strange problem when I try to connect to the official client on testnet (I'm doing some testing locally).

My code sends the version packet, the client updates to show one connection has been made, but it doesn't seem to send any version packet (or anything else) in response.  So the handshake just ends there.

This was all working normally yesterday and I can't think of anything I've changed since then.

Has anyone ever encountered this?  I don't have any port conflicts I can see.  I thought maybe the connection was banned (for misbehaving peer) so I set bantime=0 but this didn't change anything.  It hasn't reached the max number of connections.  Under what other conditions would the official client not send a version packet in response on testnet?

Really stuck here, thanks!!

I noticed this tx in the main chain has an extra OP_NOP on the end:

http://blockexplorer.com/tx/5492a05f1edfbd29c525a3dbf45f654d0fc45a805ccd620d0a4dff47de63f90b

Is this still considered valid if it were to reappear today or is this an exception sort of like the OP_CHECKSIG abuse transactions from a while back? (that would no longer be accepted)
https://en.bitcoin.it/wiki/Incidents#OP_CHECKSIG_abuse

I could probably answer this by reading the code in the official client that checks whether a tx is valid, but I wasn't able to find it just by poking around GitHub.  If someone has a link that would be great.  Thanks!

Hi,

My GetNextWorkRequired calculation seems to be failing on Block 40,319 (previous ones worked fine)

Block 40,320 should go to 0x1c654657 difficulty bits, but my calculation is coming to 0x1d006546

Can anyone see what I'm doing wrong here?  I based this on GetNextWorkRequired in https://github.com/bitcoin/bitcoin/blob/master/src/main.cpp#L762 :
==============

Block 38,304 has time 1265319794
http://blockexplorer.com/b/38304

Block 40,319 has time 1266190073
http://blockexplorer.com/b/40319

actual = 1266190073 - 1265319794
actual = 870279
target = 1209600   (two weeks)

(didn't change more than 4x or 1/4 of target so no adjustment needed here)

Block 40,319 has difficulty 486575299 which decodes to
"000000008cc30000000000000000000000000000000000000000000000000000"

retarget = 0x000000008cc30000000000000000000000000000000000000000000000000000 * actual / target
retarget = 0x00000000654657a76a76a76a76a76a76a76a76a76a76a76a76a76a76a76a76a7

encoding retarget back to bits gives 486565190 or 0x1d006546

Any ideas?  Really appreciate it - thanks!

From reading this: https://en.bitcoin.it/wiki/Running_Bitcoin?utm_source=lasindias.info/blog

It looks like the official client by default connects to up to 125 peers.  I was surprised by how high this was but maybe I'm not understanding the overheard.

For example, does this mean each transaction received has to be relayed to (potentially) 125 peers?  When doing the initial chain download, does the client ever step on it's own toes, for example by doing onblocks to lots of different peers, and then getting lots of redundant inventory messages?

Just trying to understand all the performance implications for another client I'm working on.  Also, what would change if you only connected to say....8 peers?

Thanks!

Hi, I'm trying to figure out what's happening with some custom client code I'm writing.  This is for the initial blockchain download.

When I start up I send the first getblocks with just two hashes (genesis, and zeroes):

000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f
0000000000000000000000000000000000000000000000000000000000000000

This works fine and the client sends me an inv and I download and store those 500 blocks.  It then sends me the latest block it knows about (at the time of this writing block 157940).

I save it as an orphan and then send the following hashes in my next getblocks *but I get no response from the peer*.

500   000000004ff664bfa7d217f6df64c1627089061429408e1da5ef903b8f3c77db
499   00000000806df68baab17e49e567d4211177fef4849ffd8242d095c6a1169f45
498   00000000693a6d6b068cab3e207d570764f6bad293e3e98920246eeda81c496a
497   00000000c39ea29ad310c1f80409e24b3fbfd671c0b3599198b7cfdebf790bde
496   00000000b0c5a240b2a61d2e75692224efd4cbecdf6eaf4cc2cf477ca7c270e7
495   00000000e47349de5a0193abc5a2fe0be81cb1d1987e45ab85f3289d54cddc4d
494   000000004fb61ae8e99040c4e1e3b4d333dbe867f97f63ab4238cba80f59204a
493   0000000008884067dbe80128da09a16315bb208a69e9894287a3c9e0fb671f8b
492   000000008d9b5010b996bbab558e88e9fe8a8b42751dfcaa79217f9a66642e65
491   00000000244c1b0da1196b989d7557168c5e1b4253f253f2aa8bffd05c7f67b4
489   000000007f20688b2b5c654489c4d3b69196eba0129a364f89b97ae8e4cb0e33
485   00000000754312ec7235128b6e6e3539c760f61c1988e4728a5aa1dcd9cbcbde
477   00000000e15bee1a653b171741fdd792b4936a22990c7a08764349f06239001e
461   000000002082739d0e82596fb69243b1ca9db66db623d3fdcf283f18486cdbaf
429   000000008e5da1aa58d17da1bbc95e9b032714e7ea7831e82f2830bf97dc38e7
365   00000000c256b2fa2ac9936f8f78dc8a0d88320a6bb0803ae30f82406af13955
237   000000003ee212a38ae0326c5982e3012754bb6a730f885bd955673982df83ca
0     000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f
na   00000000000002938b9efb41656dd6858a55521b0c25dca3f99b44bc29b68015

I'm showing the height of the block on the left here just for clarity, obviously my getblocks is only sending the hashes as normal.
The last one (height NA) is the prev_block for the orphan I just saved.  I tried putting all zeros here also which should also work, but no matter what I try the peer won't send me the next 500 blocks.  (have tried this with multiple peers multiple times so I don't think it's a bad peer).

I believe I'm formatting it correctly - after 10 latest blocks, it jumps back 2, then 4, then 8 etc.

Does anyone see what I might be messing up here?  Thanks for the help!  I really appreciate it.