How do I make Bitcoin Core listen on IPV6?

I know my ISP provides IPV6. It was previously broken, but restarting my router fixed it. I confirmed my IPV6 connectivity on several websites. Then I restarted Bitcoin Core so it would see the new IPV6 address on startup, but says my IPV6 address can’t be reached. Any advice?

Is Bitcoin still uncontrolled with all those mining pools?

It is always stated that Bitcoin is uncontrolled and it does not make sense to cheat and double-spend because you will need more computing power than everyone else combined. Isn’t that changed with mining pools? I can see top biggest mining pools controlling 75% of computing power. If they are in agreement, can’t they (by "they" I mean pool managers) cheat on almost every transaction? Aren’t pools becoming kind of uncontrolled authority in Bitcoin community, what is controlling them?

Filesystem is corrupt. How to find wallet.dat?

A customer of mine brought me a 2TB crashed harddrive. The drive itself is not damaged physically, but the file tables (MFT / NTFS) are corrupt so there is zero ability to recover files with their original names.

The contents of the drive is not important, except for the customer’s wallet.dat file which contains “a substantial amount of bitcoins” (sic).

Finding this file among 2TB of data is pretty much a needle in a haystack.

So, question: Does wallet.dat contain anything unique, anything that can be binary searched for, anything that makes it say “hey, I’m wallet.dat!”?

Why would a Tx’s inputs not be assumed to be owned by a single service?

From question 3 in a project titled Blockchain: CSI (in what looks like a very cool class, run by University of Virginia!):

Problem 3. The Heuristic 1 (Section 4.3) used to detemine sets of public addresses owned by the same entity is based on the assumption that all inputs to a bitcoin transaction are controlled by the same entity. According to the paper, “the sender in the transaction must know the private signing key belonging to each public key used as an input, so it is unlikely that the collection of public keys are controlled by multiple entities (as these entities would need to reveal their private keys to each other).” Explain why this is not actually true. (A good answer will consider in more detail what is needed in the unlocking script to spend each input.)

How is this a flawed assumption?

In the ASIC-age, is it worth starting mining Bitcoin at home?

I have recently learned about Bitcoin and would like to get rich quickly into mining.

I have control of a

  • laptop
  • library full of ancient computers
  • powerful gaming PC
  • cluster of GPUs
  • an old ASIC, I got for three times its worth off eBay
  • a cluster of EC2 servers

My power bill is

  • frightfully expensive
  • dirt cheap
  • subsidized by my neighbors included in rent
  • non-existant, because I produce a power surplus

Is it worth getting started with mining?

Unconfirmed Transaction disappeared when I pressed “repair wallet”

I bought some bitcoins and send them to an a receiving address on Multibit HD, It has been maybe 3 or 4 hours without any confirmations, so I decided to press “repair wallet”, which said it would resynchronize etc.

Now the “+Unconfirmed transaction” bit isn’t even showing anymore and it isn’t in the payments section. Here is the bitcoin transaction:

I need Fiat -> BTC merchant service

Hello bitcoin community.

I’m running startup and we think how to accept payments. Our customers are far not geeks and they don’t know what BTC is. However, I’d prefer to collect BTC on may wallet, not fiat. I’ve solved all tax issues in my country and I can deliver invoices to my customer where we will use fiat currency they paid in. But I’m looking for some merchant service that automatically turns fiat they pay through Visa/SWIFT or probably even PayPal into BTC using actual exchange rate. Could anyone suggest something?