Mar 22, 2020 bitkeys.work Bitcoin Address Database 28,655,297 addresses, updated March 22, 2020. Bitcoin rich list top to bottom, private keys are generated random on the fly, for fun, in a hope to collide with an address with BTC balance. I have evidence that some bitcoin address generation code in the wild is using private keys that can easily be discovered on a regular basis. This is either intentional or by mistake. Some wallets have been compromised by what is probably an innocent looking piece of code. Oct 15, 2019 What is a Bitcoin private key. A Bitcoin private key is an alphanumeric digital password encrypted in different formats in accordance with the wallet you use. The private key can be presented in different forms. Usually, this is a set of randomly generated numbers and symbols, the number of which varies, which makes it difficult to hack.
- How Are Bitcoin Private Keys Generated Money
- Bitcoin Private Reddit
- How Are Bitcoin Private Keys Generated Florida
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)
How Are Bitcoin Private Keys Generated Money
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.
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.
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
Bitcoin Private Reddit
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.
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!
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.
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.
This page contains sample addresses and/or private keys. Do not send bitcoins to or import any sample keys; you will lose your money.
A private key in the context of Bitcoin is a secret number that allows bitcoins to be spent.Every Bitcoin wallet contains one or more private keys, which are saved in the wallet file.The private keys are mathematically related to all Bitcoin addresses generated for the wallet.
Because the private key is the 'ticket' that allows someone to spend bitcoins, it is important that these are kept secret and safe.Private keys can be kept on computer files, but are also often written on paper.
Private keys themselves are almost never handled by the user, instead the user will typically be given a seed phrase that encodes the same information as private keys.
Some wallets allow private keys to be imported without generating any transactions while other wallets or services require that the private key be swept.When a private key is swept, a transaction is broadcast that sends the balance controlled by the private key to a new address in the wallet.Just as with any other transaction, there is risk of swept transactions to be double-spending.
In contrast, bitcoind provides a facility to import a private key without creating a sweep transaction.This is considered very dangerous, and not intended to be used even by power users or experts except in very specific cases. Importing keys could lead to the Bitcoins being stolen at any time, from a wallet which has imported an untrusted or otherwise insecure private key - this can include private keys generated offline and never seen by someone else[1][2].
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An example private key
In Bitcoin, a private key is a 256-bit number, which can be represented one of several ways.Here is a private key in hexadecimal - 256 bits in hexadecimal is 32 bytes, or 64 characters in the range 0-9 or A-F.
Range of valid ECDSA private keys
Nearly every 256-bit number is a valid ECDSA private key. Specifically, any 256-bit number from 0x1 to 0xFFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFE BAAE DCE6 AF48 A03B BFD2 5E8C D036 4140 is a valid private key.
The range of valid private keys is governed by the secp256k1 ECDSA standard used by Bitcoin.
Hierarchical Deterministic (HD) Wallet Keys
- Main article: Hierarchical deterministic wallet
Wallet software may use a BIP 32 seed to generate many private keys and corresponding public keys from a single secret value. This is called a hierarchical deterministic wallet, or HD wallet for short. The seed value, or master extended key, consists of a 256-bit private key and a 256-bit chain code, for 512 bits in total. The seed value should not be confused with the private keys used directly to sign Bitcoin transactions.
Users are strongly advised to use HD wallets, for safety reasons: An HD wallet only needs to be backed up once typically using a seed phrase; thereafter in the future, that single backup can always deterministically regenerate the same private keys. Therefore, it can safely recover all addresses, and all funds sent to those addresses. Non-HD wallets generate a new randomly-selected private key for each new address; therefore, if the wallet file is lost or damaged, the user will irretrievably lose all funds received to addresses generated after the most recent backup.
Base58 Wallet Import format
- Main article: Wallet import format
When importing or sweeping ECDSA private keys, a shorter format known as wallet import format is often used, which offers a few advantages.The wallet import format is shorter, and includes built-in error checking codes so that typos can be automatically detected and/or corrected (which is impossible in hex format) and type bits indicating how it is intended to be used.Wallet import format is the most common way to represent private keys in Bitcoin.For private keys associated with uncompressed public keys, they are 51 characters and always start with the number 5 on mainnet (9 on testnet). Private keys associated with compressed public keys are 52 characters and start with a capital L or K on mainnet (c on testnet). This is the same private key in (mainnet) wallet import format:
When a WIF private key is imported, it always corresponds to exactly one Bitcoin address.Any utility which performs the conversion can display the matching Bitcoin address.The mathematical conversion is somewhat complex and best left to a computer, but it's notable that the WIF guarantees it will always correspond to the same address no matter which program is used to convert it.
The Bitcoin address implemented using the sample above is: 1CC3X2gu58d6wXUW_SAMPLE_ADDRESS_DO_NOT_SEND_MffpuzN9JAfTUWu4Kj
Mini private key format
- Main article: Mini private key format
Some applications use the mini private key format. Not every private key or Bitcoin address has a corresponding mini private key - they have to be generated a certain way in order to ensure a mini private key exists for an address. The mini private key is used for applications where space is critical, such as in QR codes and in physical bitcoins. The above example has a mini key, which is:
Summary
How Are Bitcoin Private Keys Generated Florida
Any Bitcoins sent to the address 1CC3X2gu58d6wXUW_SAMPLE_ADDRESS_DO_NOT_SEND_MffpuzN9JAfTUWu4Kj can be spent by anybody who knows the private key implementing it in any of the three formats, regardless of when the bitcoins were sent, unless the wallet receiving them has since made use of the coins generated.The private key is only needed to spend the bitcoins, not necessarily to see the value of them.
If a private key controlling unspent bitcoins is compromised or stolen, the value can only be protected if it is immediately spent to a different output which is secure.Because bitcoins can only be spent once, when they are spent using a private key, the private key becomes worthless.It is often possible, but inadvisable and insecure, to use the address implemented by the private key again, in which case the same private key would be reused.
See Also
References
- ↑Bitcoin StackExchange - Why doc says importing private keys is so dangerous?
- ↑Bitcoin StackExchange - Why so many warnings about importing private keys?