Topic: Can someone briefly explain the different ways how private keys are stolen? (Read 1682 times)

@CIYAM, you could use a vanity address as the entire prefix, and the generator would attempt to match that. It would take forever though. But there is still a miniscule or negligible chance it will be cracked. It's very very very small, but it's not zero. It might as well be zero for all practical purposes.

What I mean is, it's not going to happen, but for the sake of technicality, I am also saying that the possibility is there. It's as possible as getting a collision on a SHA256 hash. Or as possible as monkeys typing the complete works of Shakespeare. Which basically means it won't happen. But it could.

This is going in circles but you know what I mean.

Vanitygen is actually a bruteforcing application as mentioned by the programmer.

Wow! Thank you. I actually noticed this before I saw your post here. I had opened Electrum a few minutes ago and saw this pmt and wondered "what the...". First ever tip I have ever received. Thanks again.

I'm in a process of code reviewing Electrum now - along with coding some new features like SOCKS support so it can be used more safely in public access locations. So far I'm quite impressed with it and would choose it for an offline wallet. It has a very small footprint.

No need for point 4 (as it is actually point 3) and there is no issue of cracking a private key due to using a vanity address (if you generate multiple vanity addresses with the same prefix they will always be different addresses).

Proof in point - check out my vanity address and you'll find there are quite a few bitcoins there - welcome to steal them if you can.

Dropped something into your tip jar for a great post, BkkCoins!

Private keys or bitcoins have been stolen in the following ways:

1. a program that takes your wallet.dat file and sends it to someone else.
2. a program that replaces your clipboard with someone else's public key (so when you paste your payment, you are actually sending coin to another address and not what you intended.
3. someone generated the same private key as yours, usually cracking a brainwallet or something similar, or a vanity address.
4. someone has the same private key because yours is so predictable.

Mac = low market share, low number of units compared to Windows.

I use Windows, but I'm not getting hacked soon because I know how to use it, I'm better protected than most, I operate a clean system, I don't download crap that is not in a sand box, I can reboot or restore or reformat my system to a known clean status, I use common sense and don't click on random things.

The best cold storage is where no one else can easily get to it. Whether that's a disconnected system or a printed paper wallet stored in a safe that no one knows about.

Multi-sig transactions will enhance security because then the bad guys would have to torture more than one person to get to your bitcoins.

Yes, potentially. All malware involves being able to execute program code on your system. That code may do various things like scan memory, scan disk files, monitor net traffic or keystrokes. Typically code like this is looking for known data values or signatures. Since about 100-200 processes run on a typical modern desktop at any moment it's not feasible to manually watch what's running. Virus checkers try to catch known malware but fail when unknown exploits manage to get run on your system.

Hackers get access in various ways. Perhaps a user executes something of unknown origin and that initiates a process of compromise. Let's say you download a video torrent but when you try to watch it you get prompted to run some program. Being unaware of how things work you click Ok and that's it. Within a few milliseconds the code you allowed to run has copied itself into dozens of other programs, maybe it's altered various system utils to not show it's presence. Allowing remote access to a system (often required for servers) opens new methods of gaining access. So being connected to the internet raises the threat level significantly.

This depends on what you mean. If you are referring to the blockchain.info wallet then it's considered quite secure as your keys are encrypted and only ever usable on your local system. This is better than allowing someone to hold your coins for you. But any time your keys are decrypted and open there is potential for attack. There are various tricks that unaware users may not notice that could allow gaining access to passphrases which in turn can be used to access keys. All security is a weighing of probabilities. What is the probability you will get hit by a car crossing the street? More than if you never cross a street again.

There are various methods for cold storage of keys. It's hard to say what's safer than what. Is keeping $100 bills stuffed under your mattress better than a secret board in the closet? Who really knows. Any time you have physical storage of anything you are still always open to attack in various ways. Redundancy is good, diversity is good, simple technology (like printed paper in a safety deposit box) is good. You have to weigh the likely scenarios in your own life to come to some idea of what will work for you. This doesn't just go for bitcoins but anything you want to store safely.

There is lots of opinion on this but no one absolutely knows for sure. Every step you take to reduce vulnerability is a win. I use Linux partly because I like the philosophy but also because it represents a large reduction in exposure to attack. That may be due partly to low market share but also better security controls. Almost every program I use is open source and comes vetted and free from the repository system. I really think twice before allowing some unknown code to run on my system. Is that foolproof? No, but it's better than being careless.

None of these questions have simple answers. There is no ultimately safe answer to anything.

If your wallet is unencrypted then anyone or any software that has access to your computer could potentially copy your wallet and with this copy steal all your bitcoins.

If your wallet is encrypted (using the standard client) then your private keys are much safer as a copy of the wallet cannot be used to steal the coins without knowing the pass phrase.

Of course your pass phrase could be determined by a key logger (not sure how much of a problem this is on Mac but certainly a real threat under Windows) then you are back at square one.

It is also true that during the time the wallet keys are unencrypted (after you type in your password) they could be located in physical memory (but this threat is very unlikely).

Two factor authentication is one solution and the other is to use a computer that has never been connected to the internet to create private keys (there are a few threads on this around).

Your wallet file contains the priv key. If a target PC has been successfully compromised, an attacker will look for your wallet file on the hard drive, possibly with the use of scripted malware. If they find an un-encrypted wallet, they copy this file, access the wallet on their own system and move the coins (if any) to a different wallet.

Blockchain wallets are only as safe as the servers hosting them. Usually they are safer than a typical home user's PC.

The best storage is cold offline wallet. Backup methods vary, it is best to have multiple backups on paper printout, flash, optical or other media, or encrypted cloud storage.

Like, for instance, if I see my private key displayed on my screen, that means it's been loaded in my memory and if someone were to have access to my system, they could search it?

What goes on when a hacker has access to a computer? What are the various processes that occur?

Are blockchain wallets safe? safer with yubikey? how exactly do blockchain wallets work, and how would someone compromising my system get access to my coins?

The best storage is cold on an encrypted drive, correct?

Are mac any more or less vulnerable than other systems? or has it just simply been a causation of low market share?