Can I retrieve missing Bitcoins that failed to process as Wallet is corrupt?

I have been using an old wallet until last year – Bitcoin Version v0.8.5-beta. QT Version 4.8.3.

I stopped using it as it has become corrupt. I had made several transactions that were not successful before I realized it was corrupt. They are showing in my transactions list as a question mark with 0 confirmations, however the transaction amount has been deducted from my wallet total.

I backed up the wallet.dat file after each transaction and overwrote the previous backup when I did this.

Can I retrieve the missing bitcoins?

Buy coins using a australian bank account from Germany

I am German living in Germany but do own an Australian bank account. I would like to use that money to buy bitcoins but somehow am not able to at the big exchange markets.
Whenever I identify myself it assignms me a German profile (which is fine) and only allows money transfer from european countries.

Is there a simple way to do this?
Sorry for this newbie question…

Retrieve Bitcoin wallet details

We have a bitcoin wallet which we tried to update as it was dormantfor some 8 years plus but we were unable to do so as we haven’t got the Bitcoin wallet details.

Is there any way of retrieving my Bitcoin wallet details as we don’t have the wallet ID details.

What causes quadratic hash problem?

I read ScriptSig content during signature (quadratic hashing) discussing quadratic hash problem.

Quadratic hash problem is the issue that signing (or verifying) transaction time grows with the square of the number of inputs (O(n^2) where n is the number of inputs).

Why is that so? I reason the following:

  1. For each input you construct different template. O(n)
  2. This template must be double-SHA-hashed. – Double-SHA-hash duration is dependent linearly on the size of the template?
  3. Double hashed template (of fixed length) is then signed. – as the leght is fixed this step is of fixed duration

As step 2 is dependent linearly on the size of the template, thus it is linearly dependent on the number of inputs, giving final time dependency relation O(n^2)?

More precisely O(n^2+m) where m is the number of outputs (as this contributes in step 2)?

Dynamic Transaction Hash Confirmation

I am working on a donation based community website (using PHP) where participants register for an account to participate. Each account carries the participant’s bitcoin address. A participant makes a commitment to donate say $10 and is paired with another participant (recipient). The donor confirms payment by pasting his/her Transaction hash id on his dashboard to confirm payments. I currently use Blockchain.info API to read the transaction details and check the inputs and outputs of the transaction to ensure that they contain both donor and recipient BTC addresses and the expected amount.
My problem is that most wallet providers generate new BTC address after each transaction making it difficult for my code to confirm transaction as the address will not match if new ones are generated.

How do I confirm transactions for dynamic BTC addresses using PHP OR how would you handle this use case?

Thanks

Blockchain.info testnet websocket doesn’t work

When I try to connect testnet websocket provided by blockchain.info api. Connection doesn’t establish, when i looked into the code. It says for testnet it uses “wss://ws.testnet.blockchain.info/inv” url. I guess that blockchain.info stops the service for testnet. Is there any other websocket api provider for bitcoin testnet?