Can i trace a hacker by collecting data from Bitcoin api?

In Japan, MtGox, the biggest bitcoin exchange went down and went bankrupt due to hackers.

So I’m working on a project in my College to enhance security of bitcoin transactions using the data mining concept on data collected through Blockchain API.

Is it possible to detect anomalous patterns and thereby to detected the presence of a hacker to then report it to the responsible authority?

Why is OP_SUBSTR disabled? (and OP_LEFT, OP_RIGHT)

Why are the substring opcodes disabled?
I understand that OP_CAT is disabled because it can blow up the stack easily (in combination with OP_DUP).
But the substring opcodes reduce the stack size.


I’d like to use OP_LEFT to implement a proof of work requirement to
spend a transaction. A substring operation is needed because OP_ADD
(for salting) and OP_GREATERTHAN only work on 32bit values.

Can you detect that the addresses generated by an HD wallet came from a single wallet?

Can someone who is looking at the blockchain detect that 2 or more addresses generated by a single HD wallet are actually generated by that single seed/HD wallet ?

Can someone who does know that 2 or more addresses came from a single HD wallet derive the seed or any keys ?

I’m using Bitpay’s Copay app on Windows 10 mobile.
It’s an HD wallet and it holds several addresses with a bitcoin balance.
As I understand it a HD wallet generates new addresses from an initial seed which I have backed up.

Out of curiosity I transferred some bits to a new receiving address generated by the same wallet, and I noticed the wallet UI says I “moved” the bits, not “sent” or “received” them.
I assume this is just the wallet being smart and letting me know the bits came from this same wallet, but this brings me to the question of, have I just linked these three (including change) addresses together for anyone on the blockchain to see ?

How much extra disk space does txindex=1 require?

For example for a 1 MB block, does the extra Tx index database take up another 100 kB on average?

And a follow-up: once my node has completed -reindex after setting txindex=1 can I COPY the blockchain AND the TX index database together to other nodes? I know the blockchain can be copied but I’m not sure if the new node needs to reindex the blockchain itself or if the index database copies over as well.

Multibit HD only sees one peer

Multibit HD is only connecting with one peer. This issue randomly started a few weeks ago. Initially, I had to keep restoring my wallet to a previous date since my balance kept reverting to uncomfirmed. Annoying but it was a work around, until it only started connecting with one peer. Restoring the wallet does not resolve this issue.

Bitcoin Core works just fine. Ports 8330 and 8333 are open. The issue happens both on, and off, a vpn.

Any thoughts on how to troubleshoot this issue, or at least get my coins out?