Google are malicious. Stop using them.

I have not backed up the vast majority of my private keys, only my seed phrases. I haven't even looked at the vast majority of my private keys. There is no need to, and indeed, exporting and handling raw private keys is an unnecessary risk for the vast majority of bitcoin users. If you are using a BIP39 or other HD wallet, then all you need to back up is your seed phrase.

You are confusing individual private keys with extended private keys. Individual private keys are used to generate addresses. Extended private keys are used to generate child private keys.

If someone compromises an individual private key, then they compromise that address only.
If someone compromises an extended private key, then they compromise that address and all child addresses. They cannot compromise sibling or parent addresses without additional information.

Here is a site which you will find useful:

https://nioctib.tech/

Take the TXID of any transaction you are interested in, paste it in to the top and click "Search", and then click on the symbol of the piece of paper which says "Raw". It will give you a color coded breakdown of all the parts of the transaction data. Hover your mouse over each part to see what it is.

If you are not sure about how to understand the locking scripts, then look the same transaction up at https://mempool.space/ and click the "Details" button to see the locking scripts decoded with relevant bytes replaced with OP codes.

You only know 1 character of a 30+ character password? In that case, there is no point even trying to brute force it, since 29 unknown characters is far beyond the scope of what is realistic.

I would also use btcrecover as suggested above to do this, but you need more information to go on. What did the password look like? Was it completely random or did include names, words, dates, etc? What character set did it use? Uppercase, lowercase, numbers, symbols, etc?

As nc50lc says, if you have the seed phrase for the second of those two master public keys you can simply recover it as normal and retrieve the funds on it.

If there are other funds in a 2-of-3 multi-sig as you suggest, then at a minimum you need two different seed phrases and the third master public key. Based on the Github link you provided, you will need the seed phrase for your "Primary Key", the seed phrase for your "Backup Key", and the master public key from the "Blocktrail Key".

That is something which is suspiciously missing from the paper linked to by OP as well. It's all well and good saying "We have a xxx qubit computer which can solve the ECDLP for 256 bit private keys", but if you have to run your xxx qubit computer for ten years to find a single private key, then it isn't going to pose much of a risk to bitcoin.

There are quite a few in development: https://en.wikipedia.org/wiki/Post-quantum_cryptography

The last discussion regarding quantum computers on the mailing list I am aware of is from April last year: https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2022-April/020209.html
This discussion focuses on NTRU, which is a lattice-based algorithm: https://en.wikipedia.org/wiki/NTRU

Picking one now, when the threat from quantum computers is very likely still decades away, seems very premature though. There is a good chance that whatever we picked today would be at best outdated and at worst insecure by the time it actually mattered.

The BIP39 seed is simply the number generated from PBKDF2 using your seed phrase and any optional passphrase. It is in no way related to the RIPEMD160 of the address you are trying to recover access to. All you are doing by feeding the BIP39 seed box with your RIPEMD160 is essentially generating completely random addresses and hoping for a match. As I've explained above, there is literally no point whatsoever in doing this. It is impossible to find a match with any address, let alone a specific address.

There is absolutely no correlation in the distribution of address prefixes here. You are simply seeing what you want to see.

You can stop driving yourself insane and completely wasting your time by generating random addresses, and instead focus on trying to recreate the brain wallet.

Yeah, this. I also get called Leo by people who know me on the forum, but no one can confirm whether or not that is a pseudonym too. Even if you have a name in your username, I can't say if that's real. Is jackg called Jack? Is DaveF called Dave? I have no idea, and I also have no desire to invade their privacy and find out.

Also this. There are more than a few people on here I would love to grab a drink with, but unfortunately that will never happen for privacy reasons.

If someone is making trades of that size, then they aren't going to Coinbase and just dropping an order for 500 BTC on their order books. They will be trading OTC, and will have much more in the way of legal protections and guarantees than the 99.9% of regular centralized exchange users.

I think the vast majority of people should use decentralized peer to peer exchanges, in order to benefit from the security and privacy they provide, and not lose their coins in the next centralized exchange which goes bankrupt. But I would never recommend a project which styles itself as "DeFi". As with every other fad in this space, the vast majority of DeFi projects are not decentralized in the slightest, and many of them turn out to be outright scams.

Plenty more reasons you can add to that list, looking at all the reasons that other exchanges have collapsed over the last few months. They can be insolvent because they were gambling your money away or handing out incredibly risky under- or non-collateralized loans. Another exchange or bank which they use can shut down, be insolvent, deny them service, etc., and they can end up insolvent because of that. Your government could stop them operating in your jurisdiction, freezing your account and meaning you can no longer access your coins. You can end up a piece of malware on your device which steals your account details or session and empties your accounts. The list is endless.

This is the bare minimum for good 2FA. Having your 2FA authentication using the same device which you use to log in to the account in the first place means compromise of that one device will compromise both of your factors.

This search is trivial to do if you set up btcrecover properly. You have three unknowns for the first character, and 58 unknowns for the character in the middle. Even assuming the worst case scenario of the checksum only being 5 characters, giving you another unknown character in the 6th from last position, then there are only 3*58*58 possibilities, since the last 5 characters don't need to be brute forced since they will be calculated from the rest of the key. This is only 10,092 possibilities, which can be searched in under a second.

You won't be able to calculate a valid checksum for your private key since it contains invalid characters. That website will simply throw an "Invalid Base58 encoding" error if you try.

As I covered above, this does not mean your checksum is incorrect. A checksum error simply means the checksum does not match the rest of the key. Given that the rest of the key is invalid as it contains invalid characters, there is no checksum in existence which will be valid. Every possible checksum will return the same error. You are focusing on the wrong things here.

The checksum encodes 8 hex characters in to base58 characters, meaning it will be either the last 5 or 6 characters which are the checksum.

I am happy to attempt to brute force it for free, at least for all the straightforward character replacements and similar we discussed earlier. Completely understand if you don't want to risk it though.

The real message of this thread is don't take health advice from the internet. Like 90% of the things being said in this thread are wrong.

Yes obviously you should have a healthy diet, keep your weight under control, and exercise regularly, and yes doing all these things can help to improve your diabetic control. However, I can't stress enough how much anybody shouldn't just stop taking their prescribed medications (for any condition) without first consulting with their doctor. Suddenly stopping certain medications can be life threatening.

Transaction malleability refers to the ability of a third party to change an already signed transaction. In this case you are referring to a service for broadcasting transactions, but this could also refer to any node which could change the transaction prior to relaying it to other nodes, or any miner which could change the transaction prior to including it in a block.

Transaction malleability does not allow the third party to change anything about the important parts of the transaction. They cannot change which coins are spent, which addresses these coins came from, which addresses they are going to, how much is going to each address, and how much is being spent as a fee. All of this information is covered by the transaction signature, and so if someone tries to change any of it, the signature would no longer be valid and the entire transaction would be rejected.

There are some parts of a transaction which are not covered by the signature, though, and so can be changed by a third party. While the core parts of the transaction stay the same as above, the outcome of any such change means the transaction has a different TXID. For most cases this is completely irrelevant. However, as we know, when you spend a bitcoin UTXO, the network identifies the UTXO you are spending based on the TXID of the transaction which created that UTXO. So if someone was to spend a UTXO from an unconfirmed transaction, and then that unconfirmed transaction was altered to have a different TXID before it was mined, the transaction spending those unconfirmed UTXOs would now be invalid, since it is referring to a TXID which no longer exists.

The whole point of segwit was to fix transaction malleability. The smaller transaction virtual size (which most people think was the real reason behind segwit) was a byproduct of fixing transaction malleability. While transaction malleability doesn't affect the vast majority of people, fixing it allows safely generating chains of unconfirmed transactions, which is core to how things like Lightning work.

So in summary the answer is no, a service for broadcasting transactions can't do any real harm to anyone who uses it (apart from invading their privacy, obviously). And if you want to avoid the possibility of transaction malleability altogether, just use segwit.

To fix that address I simply decoded it to hex, calculated the correct checksum, and then re-encoded it in Base58. You could probably use a site like https://gobittest.appspot.com to do this online if you wanted.

I really don't know why you want to, though. None of this is in any way relevant whatsoever to your private key with the incorrect characters. Have you tried brute forcing it with btcrecover yet as I suggested above? Do you want me to try for you?

This changes nothing. You cannot know what an address starts with until you derive it, by which point you have already done all the computationally expensive parts. It doesn't matter if you set up a vanity generator to only search for an address which exactly matches yours. Even with all the computing power in the world, the human race would be extinct before it even came close to finding a match.

Your other coins weren't stolen by someone reverse engineering the private key from the address. This is impossible. They would have been stolen by someone finding a back up, or finding the string you used to generate the brain wallet, or from an insecure brain wallet generator.

Maybe not give up entirely, but I would give up going down the path of blindly generating addresses or trying to reverse engineer my private key from my address. Again, these things are impossible. The only way you will be successful is by either finding a back up of your private key or by remembering the string used to generate the brain wallet in the first place.

Which is a far riskier way of doing things.

The complicated part of generating a paper wallet is setting up an airgapped computer with a clean install of a reputable open source Linux distro. Once you've done that, you still need to download, verify, and transfer to this computer the software you are going to use. This is the same for either Bitcoin Core or bitaddress. Then the only difference after that is whether you load a piece of software or whether you load an HTML file. It really is not that much more complicated to use Bitcoin Core than it is to use bitaddress.

Further, given the huge number of people who have lost coins from websites generating insecure paper wallets (even when offline), and that bitaddresses uses javascript which is a very poor choice when it comes to generating entropy, I would strongly suggest not using any website to generate a paper wallet.

The problem is that the strings provided by lionheart78 are not valid.

I don't know where he got them from, or is he just made them up himself, but the WIF key he provided is the wrong length and contains invalid characters, and is not a valid private key. The address he provided is similarly invalid, with an invalid checksum. The correct checksum for that string would give the following (valid) address: 1cDwMSxYstvetZTFn54X5m4GFgztvxDw4

A WIF is just a different way of encoding the private key. You cannot convert from the public key to the private key in any format. All you can do is convert back and forth between the address and the pubkeyhash, but that doesn't help you whatsoever.

The earth will be consumed by the dying sun before you find it. That's not an exaggeration. There are 2¹⁶⁰ possible addresses. Even if you could somehow check a trillion addresses every second without ever stopping, then by the time the earth is consumed by the sun in 5 billion years, you will have checked approximately 0.00000000000000001% of all addresses.

As I said above, the only way you can recover it is by remember the brain wallet. If you have a rough idea as to what it might be, then you might be able to attempt to brute force it, but you'll need something to go on.

Binance have suffered multiple hacks in the past. They were hacked in 2019 for $40 million worth of bitcoin. They were hacked in 2022 for $570 million worth of various altcoins and tokens. They were hacked in 2019 for the KYC data of thousands of users. Binance is not safe.

"Almost always", which means that some users just lose everything and there is nothing they can do about it.

Keeping your coins on any centralized exchange means they are not yours and you could lose them all at any time. It doesn't matter if the exchange in question is Binance. It is not safe.