Bitcoin Address Private Key Generator
- Bitcoin Address Private Key Generator V2 4 Full Version
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- Bitcoin Address Private Key Generator Free
- Bitcoin Wallet Address Private Key Generator
- Private Key Generator Free
Every Bitcoin address is based on a secret key, from which the public key (associated to a Bitcoin address) is calculated. Once you have the private key for an address,you have the control of that address and can use it to transfer funds.
Can I verify a sub public key came from it's parent public key in a HD wallet without involving any private keys? 0 How to make sure, Bitcoin private key and bitcoin address generator tools are generating valid key pair? Bitcoin Random Page generates a set of keys based of the page number. Bitcoin Page Ascending runs in ascending order from this page to the last page. Bitcoin Page Descending runs in descending order from this page to the first page. If the Bitcoin checker finds anything whilst using any modes it will store it in your Key Basket for you.
This secret key is a 32-bytes unsigned integer. You can generate a lot of secret keys, calculate the public keys associated to them and see if they contain bitcoins.If it’s the case, you can transfer the money to an address you control, because you have the secret key.
Such an attack is completely infeasible, because the private key space is really, really huge. There are 115792089237316195423570985008687907853269984665640564039457584007913129639936 secret keys available (1077).
Oh, and they are all listed on directory.io ! Of course, this website is kind of a joke, and all is calculated on the fly when you request a specific page.It also shows the danger of entering your secret key on an unknown website, for example to see if it was compromised…
However, we can bruteforce only a tiny fraction of this space, concentrating on secret keys with some distinctive features. This is what I will explain.
Private keys are numbers…¶
So, why not try really tiny numbers ?
I have made a script that tries every secret key, counting from 1. After some seconds, I found dozens of already used addresses, with private key smaller than 100 000 !
In particular, the 1EHNa6Q4Jz2uvNExL497mE43ikXhwF6kZm address (corresponding to the private key 1) was already used quite a lot, as 4 bitcoins already flowed through it.
Brainwallet¶
Brainwallet is a website that allow people to create private keys from a passphrase. It calculates the private key from the sha256 of the passphrase.
By using a password dictionary, we can search for private keys corresponding to classic password that were already used.A search allowed me to find nearly 10 000 addresses that have contained Bitcoins at some point in time ! I was never able to find any address containing money, and nearly every time they had contained only really small amounts of money, buthere is an interesting sample :
If we look at the history of transactions on these addresses we can see that in a lot of cases, a few seconds after money was deposed in them, it was withdrew to another account.
In particular, it was often sent to one of these accounts :
We can see that the first address already stole 0.36 Bitcoins, 2 seconds after they were transferred to the address corresponding to the key « alfanumerico » !This address seems to contain more than 1 Bitcoin, probably stolen all automatically…Notice that the address starts with « brain », maybe it could have something to do with Brainwallet, no ?
Another interesting fact, the second address stole very tiny amounts of money from classical addresses, and we can even see that a comment was left about one of these transactions :
A Bitcoin theft that left a comment to another, advising him to stop stealing tiny amounts of money and wait for bigger amount on more difficult addresses…
Technical considerations¶
To bruteforce Bitcoins like that, you need to find the address associated to a private key, as fast as possible.But, you will also need to know if each of the address was already used in a transaction.
For that, you will need to iterate trough the entire blockchain. You can then fill a Bloom filter with every address seen in it.Once it is built, you will be able to know if an address was used in the network with a really small lookup time.
As we have seen, it seems that some people even built a gigantic database, mapping from “classic” addresses to their associated private keys. They seems to be able to steal moneyonly seconds after it was deposited…
Conclusion¶
Well, it seems that there is money to make, and here is the proof that some people are already on it…
This also demonstrate that you can use a service like Brainwallet, but you need to choose a really strong passphrase, that will resist bruteforce. If any computer or any other human can think of it,you are doomed !
Instead of attacking every potential transaction that used a weak private key, it’s also possible to focus on weak random number generators, or implementation problems in ECDSA.This is also a reality, and you can check out this blog post for more.
In cryptocurrencies, a private key allows a user to gain access to their wallet. The person who holds the private key fully controls the coins in that wallet. For this reason, you should keep it secret. And if you really want to generate the key yourself, it makes sense to generate it in a secure way.
Here, I will provide an introduction to private keys and show you how you can generate your own key using various cryptographic functions. I will provide a description of the algorithm and the code in Python.
Do I need to generate a private key?
Most of the time you don’t. For example, if you use a web wallet like Coinbase or Blockchain.info, they create and manage the private key for you. It’s the same for exchanges.
Mobile and desktop wallets usually also generate a private key for you, although they might have the option to create a wallet from your own private key.
So why generate it anyway? Here are the reasons that I have:
- You want to make sure that no one knows the key
- You just want to learn more about cryptography and random number generation (RNG)
What exactly is a private key?
Formally, a private key for Bitcoin (and many other cryptocurrencies) is a series of 32 bytes. Now, there are many ways to record these bytes. It can be a string of 256 ones and zeros (32 * 8 = 256) or 100 dice rolls. It can be a binary string, Base64 string, a WIF key, mnemonic phrase, or finally, a hex string. For our purposes, we will use a 64 character long hex string.
Why exactly 32 bytes? Great question! You see, to create a public key from a private one, Bitcoin uses the ECDSA, or Elliptic Curve Digital Signature Algorithm. More specifically, it uses one particular curve called secp256k1.
Now, this curve has an order of 256 bits, takes 256 bits as input, and outputs 256-bit integers. And 256 bits is exactly 32 bytes. So, to put it another way, we need 32 bytes of data to feed to this curve algorithm.
There is an additional requirement for the private key. Because we use ECDSA, the key should be positive and should be less than the order of the curve. The order of secp256k1 is FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141, which is pretty big: almost any 32-byte number will be smaller than it.
Naive method
So, how do we generate a 32-byte integer? The first thing that comes to mind is to just use an RNG library in your language of choice. Python even provides a cute way of generating just enough bits:
Looks good, but actually, it’s not. You see, normal RNG libraries are not intended for cryptography, as they are not very secure. They generate numbers based on a seed, and by default, the seed is the current time. That way, if you know approximately when I generated the bits above, all you need to do is brute-force a few variants.
When you generate a private key, you want to be extremely secure. Remember, if anyone learns the private key, they can easily steal all the coins from the corresponding wallet, and you have no chance of ever getting them back.
So let’s try to do it more securely.
Bitcoin Address Private Key Generator V2 4 Full Version
Cryptographically strong RNG
Along with a standard RNG method, programming languages usually provide a RNG specifically designed for cryptographic operations. This method is usually much more secure, because it draws entropy straight from the operating system. The result of such RNG is much harder to reproduce. You can’t do it by knowing the time of generation or having the seed, because there is no seed. Well, at least the user doesn’t enter a seed — rather, it’s created by the program.
In Python, cryptographically strong RNG is implemented in the secrets module. Let’s modify the code above to make the private key generation secure!
That is amazing. I bet you wouldn’t be able to reproduce this, even with access to my PC. But can we go deeper?
Specialized sites
There are sites that generate random numbers for you. We will consider just two here. One is random.org, a well-known general purpose random number generator. Another one is bitaddress.org, which is designed specifically for Bitcoin private key generation.
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Can random.org help us generate a key? Definitely, as they have service for generating random bytes. But two problems arise here. Random.org claims to be a truly random generator, but can you trust it? Can you be sure that it is indeed random? Can you be sure that the owner doesn’t record all generation results, especially ones that look like private keys? The answer is up to you. Oh, and you can’t run it locally, which is an additional problem. This method is not 100% secure.
Now, bitaddress.org is a whole different story. It’s open source, so you can see what’s under its hood. It’s client-side, so you can download it and run it locally, even without an Internet connection.
So how does it work? It uses you — yes, you — as a source of entropy. It asks you to move your mouse or press random keys. You do it long enough to make it infeasible to reproduce the results.
Are you interested to see how bitaddress.org works? For educational purposes, we will look at its code and try to reproduce it in Python.
Quick note: bitaddress.org gives you the private key in a compressed WIF format, which is close to the WIF format that we discussed before. For our purposes, we will make the algorithm return a hex string so that we can use it later for a public key generation.
Bitaddress: the specifics
Bitaddress creates the entropy in two forms: by mouse movement and by key pressure. We’ll talk about both, but we’ll focus on the key presses, as it’s hard to implement mouse tracking in the Python lib. We’ll expect the end user to type buttons until we have enough entropy, and then we’ll generate a key.
Bitaddress does three things. It initializes byte array, trying to get as much entropy as possible from your computer, it fills the array with the user input, and then it generates a private key.
Bitaddress uses the 256-byte array to store entropy. This array is rewritten in cycles, so when the array is filled for the first time, the pointer goes to zero, and the process of filling starts again.
The program initiates an array with 256 bytes from window.crypto. Then, it writes a timestamp to get an additional 4 bytes of entropy. Finally, it gets such data as the size of the screen, your time zone, information about browser plugins, your locale, and more. That gives it another 6 bytes.
After the initialization, the program continually waits for user input to rewrite initial bytes. When the user moves the cursor, the program writes the position of the cursor. When the user presses buttons, the program writes the char code of the button pressed.
Finally, bitaddress uses accumulated entropy to generate a private key. It needs to generate 32 bytes. For this task, bitaddress uses an RNG algorithm called ARC4. The program initializes ARC4 with the current time and collected entropy, then gets bytes one by one 32 times.
This is all an oversimplification of how the program works, but I hope that you get the idea. You can check out the algorithm in full detail on Github.
Doing it yourself
For our purposes, we’ll build a simpler version of bitaddress. First, we won’t collect data about the user’s machine and location. Second, we will input entropy only via text, as it’s quite challenging to continually receive mouse position with a Python script (check PyAutoGUI if you want to do that).
That brings us to the formal specification of our generator library. First, it will initialize a byte array with cryptographic RNG, then it will fill the timestamp, and finally it will fill the user-created string. After the seed pool is filled, the library will let the developer create a key. Actually, they will be able to create as many private keys as they want, all secured by the collected entropy.
Initializing the pool
Here we put some bytes from cryptographic RNG and a timestamp. __seed_int and __seed_byte are two helper methods that insert the entropy into our pool array. Notice that we use secrets.
Seeding with input
Here we first put a timestamp and then the input string, character by character.
Generating the private key
This part might look hard, but it’s actually very simple.
First, we need to generate 32-byte number using our pool. Unfortunately, we can’t just create our own random object and use it only for the key generation. Instead, there is a shared object that is used by any code that is running in one script.
What does that mean for us? It means that at each moment, anywhere in the code, one simple random.seed(0) can destroy all our collected entropy. We don’t want that. Thankfully, Python provides getstate and setstate methods. So, to save our entropy each time we generate a key, we remember the state we stopped at and set it next time we want to make a key.
Second, we just make sure that our key is in range (1, CURVE_ORDER). This is a requirement for all ECDSA private keys. The CURVE_ORDER is the order of the secp256k1 curve, which is FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141.
Bitcoin Address Private Key Generator Free
Finally, for convenience, we convert to hex, and strip the ‘0x’ part.
In action
Let’s try to use the library. Actually, it’s really simple: you can generate a private key in three lines of code!
Bitcoin Wallet Address Private Key Generator
You can see it yourself. The key is random and totally valid. Moreover, each time you run this code, you get different results.
Conclusion
As you can see, there are a lot of ways to generate private keys. They differ in simplicity and security.
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Generating a private key is only a first step. The next step is extracting a public key and a wallet address that you can use to receive payments. The process of generating a wallet differs for Bitcoin and Ethereum, and I plan to write two more articles on that topic.
If you want to play with the code, I published it to this Github repository.
I am making a course on cryptocurrencies here on freeCodeCamp News. The first part is a detailed description of the blockchain.
I also post random thoughts about crypto on Twitter, so you might want to check it out.