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.

• How Are Private Keys Generated Bitcoin Money
• What Are Private Keys Bitcoin
• What Is A Private Key In Bitcoin

Your bitcoin private key is a randomly generated string (numbers and letters), allowing bitcoins to be spent. A private key is always mathematically related to the bitcoin wallet address, but is impossible to reverse engineer thanks to a strong encryption code base. A simple Bitcoin wallet consists on one of more pairs of public and private keys (I'm saying simple here as some wallet structure allow for deterministic public key generations and private keys that can only spend part of the wallet, but the principle with public/private keys remains the same).

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?

Leaked bitcoin private keys collected by us. We collected leaked bitcoin private keys from different sources. Generated base with parts of whole range, collected from GitHub, forums and sites. Also we generated brain wallet addresses and vanity addresses. All private keys are totally free. But we did not recomendate to take used keys.

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.

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

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.

Private keys have been part of Bitcoin from the beginning. Wallet software often tries to shield users from the need to directly handle and understand private keys. Even so, most users eventually come face to face with private keys, too often with unpleasant results.

A basic understanding of private keys can protect you from losing money and other mishaps, but it can also offer useful insights into how Bitcoin works. This guide outlines Bitcoin’s the most important private key concepts.

Bitcoin may be best known as an electronic cash system, but underneath it all runs a secure messaging system built on the Internet. Instead of relaying emails, texts, or web pages, the Bitcoin network processes value-transfer messages called transactions. Private keys help authenticate these messages and identify each other.

An example helps illustrate the problems that private keys solve. Imagine that Alice wants to pay Bob using an electronic coin with a face value of ฿1. To do so, she must create a transaction identifying Bob as the payee. Then Alice needs to publish the transaction to the Bitcoin network.

To use this system, Alice must solve two fundamental problems:

1. Alice needs a way to identify both herself and Bob in the transaction. She can’t employ a trusted authority such as a government registry or email provider because that would create a central point of failure — the very thing Bitcoin was created to eliminate.
2. Alice needs a way to prevent others from changing her transaction and forging transactions in her name.

Bitcoin solves both problems through a system called public key cryptography. This system uses two pieces of information to authenticate messages. A public key identifies a sender or recipient, and can be distributed to others. A private key creates an unforgeable message signature. Unlike the public keys, the private key must be kept secret. Public and private keys are mathematically linked through a signature algorithm, a mathematical procedure for creating identities, signing messages, and validating signatures.

With this overview in mind, here are six things about private keys to keep in mind as you use Bitcoin.

A Bitcoin private key is simply an integer between one and about 10⁷⁷. This may not seem like much of a selection, but for practical purposes it’s essentially infinite.

If you could process one trillion private keys per second, it would take more than one million times the age of the universe to count them all. Even worse, just enumerating these keys would consume more than the total energy output of the sun for 32 years. Bitcoin’s entire security model rests on the infeasibility of mapping this vast keyspace.

Because private keys contain many digits, an alternative called Wallet Import Format (WIF) has been devised. This format begins with the number “5” and contains a sequence of letters and numbers. For example, here’s a private key represented in WIF format:

5KJvsngHeMpm884wtkJNzQGaCErckhHJBGFsvd3VyK5qMZXj3hS

Given the importance of keeping private keys secret, they are sometimes encrypted. Unique product key windows 8 generator. A popular method produces strings of text that look like WIF encoding, but starting with the number “6.” Decrypting a private key encoded in this way requires the password that was set when the private key was encrypted.

To prevent forgery, Bitcoin requires that each transaction bear a digital signature. This signature, like a private key, is just a number selected from a very large range. Wallet software generates a signature by mathematically processing a transaction together with the correct private key.

Anyone with a signature and public key can easily authenticate a message. However, the only way to produce a valid message signature is to use the private key matching the published public key. In other words, digital signatures are practically impossible to forge.

Unlike a physical signature you might write on a check, a transaction signature changes if the transaction changes even slightly. The way the signature will change is unpredictable, ensuring that only a person in possession of a private key can provide the correct signature.

Notice that the internal format of a transaction is less important than the idea that transactions are digitally signed messages whose authenticity can be quickly and cheaply checked. For details on transactions and how they’re used in Bitcoin, see A Visual Language for Bitcoin Transactions.

Any valid transaction bearing a valid signature will be accepted by the Bitcoin network. At the same time, any person in possession of a private key can sign a transaction. These two facts taken together mean that someone knowing only your private key can steal from you.

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Many avenues are open to thieves who steal private keys. Two of the most popular are storage media and communications channels. For this reason, extreme caution must be taken whenever storing or transmitting private keys.

Software wallets usually store private keys in a “wallet file” on the main hard drive. Wallets often place this file in a standard, well-known directory, making it an ideal target bitcoin-specific malware.

To counter this threat, software wallets offer an option to encrypt the wallet file. Any attacker gaining access to your wallet file would then need to decrypt it. The difficulty of decryption depends on the quality of the encryption and strength of the password being used. Wallet files can be encrypted on many software wallets by adding a password.

Although wallet backups are a good idea, they can potentially leak private keys. For example, it may be tempting to save a backup of your software wallet to a cloud storage service such as Dropbox. However, anyone capable of viewing this backup online (a potentially long list of people) would be in a position to steal some or all of your funds. A similar problem could arise through emailing backups to yourself or leaving a private key around the house. Encryption can reduce, but not eliminate the risk.

Preventing the accidental release of private keys is the main purpose of “cold storage.” For more information, see A Gentle Introduction to Bitcoin Cold Storage.

A public key is obtained by subjecting a private key to a set of mathematical operations defined in a set of standards known as Elliptic Curve Cryptography (ECC). Whereas a private key is an integer, a public key is a 2D coordinate composed of two integers. To make a public key easier to process, it can be transformed into a single value. One approach appends the y-coordinate to the x-coordinate. This technique produces an “uncompressed” public key. A “compressed” public key uses only the x-coordinate with a symmetry flag.

Each of these steps is irreversible. An address can’t generate a public key, nor can a public key generate a private key. This relationship is known as a mathematical trapdoor — a function that’s easy to perform in one direction, but practically impossible to perform in the opposite direction. This unidirectionality underpins Bitcoin’s security model.

Just as private keys can be shortened to make them more usable with displays and keyboards, so too can public keys. An address results from applying a multi-step transformation to a public key. This results in a string of text and digits, usually starting with the number “1”.

Notice that no network is needed at any point in the generation of a private key or the corresponding address. Every computer on the Bitcoin network knows about the mathematical relationship between public and private keys. This enables each participant to select private keys and sign transactions independently of the Bitcoin network. The vast private keyspace ensures that any properly-selected key will be unique.

Knowledge of a private key is the only verification needed to spend an electronic coin. Private keys should therefore be kept secret. However, careless selection of a private key can lead to theft just as easily as its accidental release.

For example, imagine that we want to use a private key that’s easy to remember. The number 1 is both easy to remember and a valid Bitcoin private key. But how secure would it be?

The private key 1 generates this address:

If you follow the link, you’ll notice that the address has already been involved in over 1,000 transactions for a total of over 7 BTC within the last few years. If you wanted, you could easily spend any available funds at this address because the private key is known to you.

Now imagine you’re a thief determined to steal bitcoin. One strategy might be to compile a list of easy-to-remember private keys. Next, generate the addresses for these keys and monitor the Bitcoin network for incoming payments to one of them. When one arrives, immediately sign a transaction moving the funds to another address you control.

Contrast the ease of this scheme with a situation in which a private key was chosen by a perfect random number generator. With no clue what the key might be, brute force iteration would be the only option. As we’ve already seen, carrying out this plan is physically impossible.

How Are Private Keys Generated Bitcoin Money

What would happen if the random number generator were not quite random? For example, what if all output private keys were clustered about a constant value within a narrow range?

Any attacker aware of such a defect could drastically reduce the necessary search space. Under the right conditions, it would become practical to monitor all of the addresses based on the faulty random number generator and steal funds from any one of them at will.

The need to select a good private key becomes especially important with brain wallets. One method to create a brain wallet starts with a passphrase such as “to be or not to be”, then applies a mathematical function to convert this text to a private key. Applying the most popular conversion algorithm (SHA-256) to this passphrase generates the address:

As you can see, this address was used as late as 2016 to store funds, which were immediately withdrawn.

Unfortunately, it’s not always easy to tell what qualifies as an insecure brain wallet passphrase and what doesn’t. Attackers can exploit this uncertainty and the inexperience of new users to steal funds. For example, a thief might compile an enormous database of common phrases and passwords. Such a database might number in the trillions of entries or more, but would still be searchable in its entirety with little computational effort.

Compare this situation to the one with website passwords. If you register for a web service using a password someone else happens to have chosen, you don’t take over their account because your username must be unique. Bitcoin private keys are different in that they serve the dual role of user identification (via address generation) and authentication (via digital signatures).

Secure private keys are generated with a high degree of unpredictability so they can’t be guessed before or after the fact.

For the most part, wallet software hides the process of generating, using, and storing private keys. However, private keys can become visible from time to time. When this happens, understanding private keys and how they interact with your specific software becomes important.

Paper wallets present the most common route by which private keys show up outside of software wallets. Although they come in a multitude of formats, the essential feature of any paper wallet is a printed private key.

What Are Private Keys Bitcoin

Many software wallets support sweeping. A sweep creates a new transaction paying one of the software wallet’s existing addresses. This procedure may or may not empty the address associated with the private key. For more information on the dangers of manipulating bare private keys, see Five Ways to Lose Money with Bitcoin Change Addresses.

What Is A Private Key In Bitcoin

Should your wallet application begin to malfunction, its private keys can often be imported into another application. This rescue procedure provides the second main route through which private keys become visible to end users. A closely-related procedure consists of restoring the state of a software wallet through a backup file.

Bitcoin can be thought of as an open messaging system secured by public key cryptography. In contrast to other systems protected by username and password logins, Bitcoin is secured through digital message signatures created with a unique private key. This single point of access places a very high value on the secure generation, use, and storage of private keys.