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Generate Bitcoin Address From Public Key

Public Key | Bitcore

Public Key | Bitcore

Represents a bitcoin public key and is needed to be able to receive bitcoin, as is usually represented as a bitcoin Address . See the official Bitcoin Wiki . A PublicKey in Bitcore is an immutable object and can be instantiated from a Point , string, PrivateKey , Buffer or a BN . var privateKey = new PrivateKey();// from a private keyvar publicKey = new PublicKey(privateKey);// from a der hex encoded stringvar publicKey2 = new PublicKey('02a1633cafcc01ebfb6d78e39f687a1f0995c62fc95f51ead10a02ee0be551b5dc'); A public key point should be on the secp256k1 curve, instantiating a new PublicKey will validate this and will throw an error if it's invalid. To check that a public key is valid: if (PublicKey.isValid('02a1633cafcc01ebfb6d78e39f687a1f0995c62fc95f51ead10a02ee0be551b5dc')){ // valid public key} It's important to note that there are two possible ways to represent a public key. The standard is compressed and includes the X value and parity (as represented above in the documentation). There is also a longer version that is uncompressed which includes both X and Y values. Using this encoding will generate a different bitcoin address, so be careful when selecting the encoding. Uncompressed public keys start with 0x04; compressed public keys begin with 0x03 or 0x02 depending on whether they're greater or less than the midpoint of the curve. These prefix bytes are all used in official secp256k1 documentation. > var bitcore = require('bitcore');// compressed public key starting with 0x03 (greater than midpoint of curve)> var compressedPK = bitcore.PublicKey('030589ee559348bd6a7325994f9c8eff12bd'+ '5d73cc683142bd0dd1a17abc99b0dc');> compressedPK.compressed;true> compressedPK.toAddress().toString();'1KbUJ4x8epz6QqxkmZbTc4f79JbWWz6g37'// compressed public key starting with 0x02 Continue reading >>

What's A Bitcoin Address? Public Keys, Private Keys, And Addresses Explained

What's A Bitcoin Address? Public Keys, Private Keys, And Addresses Explained

One of the things I get asked all the time is what is a bitcoin address?. Theres the full technical answer for someone who wants to build bitcoin technologies, but theres a lot less to know to bea user of bitcoin nowadays. For example, I bet you didnt know that email runs on a protocol called SMTP (Simple Mail Transfer Protocol) which plays a similar role in email that the bitcoin protocol does in transferring bitcoin (although with some key differences). But if I asked you to fire off an email to [email protected] you could have something ready to send in less than a minute. Sending bitcoin is a similar level of complexity, only you dont need to write a message to send bitcoin. Even Fluffy can send an email with her eyes closed. A lot of people seem to worry about learning the complex mathematics behind the bitcoin protocol before buying and using bitcoin. This might have been true pre-2014 before hoards of startups set out to make bitcoin accessible, but today its simply not the case. So Im going to give you the basic information you need to know to be a userof bitcoin, but not a mathematical expert. So lets get started! A bitcoin address is one of the key concepts that make the currency and the blockchain work. It isnt quite as straightforward to define or explain as an email address. You first need to know about two other parts of bitcoin in order to see how the address fits into the picture: a private key and a public key. The main difference is that you dont use the same address to send bitcoin as you do to receive it. Instead, there are three key terms to know: Private key : a 64 character long code using any combination of the letters A-F and the numbers 1-9. You can see an example of a private key on the image above.This is what you use to send money out of you Continue reading >>

Bitcoin Public And Private Keys

Bitcoin Public And Private Keys

There is more to a bitcoin wallet than just the address itself. It also contains the public and private key for each of your bitcoin addresses. 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. If you dont back up your private key and you lose it, you can no longer access your bitcoin wallet to spend funds. As mentioned, there is also a public key. This causes some confusion, as some people assume that a bitcoin wallet address and the public key are the same. That is not the case, but they are mathematically related. A bitcoin wallet address is a hashed version of your public key. Every public key is 256 bits long sorry, this is mathematical stuff and the final hash (your wallet address) is 160 bits long. The public key is used to ensure you are the owner of an address that can receive funds. The public key is also mathematically derived from your private key, but using reverse mathematics to derive the private key would take the worlds most powerful supercomputer many trillion years to crack. Besides these key pairs and a bitcoin wallet address, your bitcoin wallet also stores a separate log of all of your incoming and outgoing transactions. Every transaction linked to your address will be stored by the bitcoin wallet to give users an overview of their spending and receiving habits. Last but not least, a bitcoin wallet also stores your user preferences. However, these preferences depend on which wallet type youre using and on which platform. The Bitcoin Core client, for example, has very few preferences to tinker around with, making it less confusing for Continue reading >>

Public Key

Public Key

A public key is a cryptographic code that allows a user to receive cryptocurrencies into his or her account. The public key coupled with the private key are significant tools required to ensure the security of the crypto economy. When a user initiates his/her first-ever transaction with bitcoin or altcoins , a unique pair of public key and private key is created. Each of the keys are a long string of alphanumeric characters that help to keep a users holdings secure in the digital ecosystem. The private key is known to the user alone and serves as the users digital ID. The private key authorizes the user to spend, withdraw, transfer or carry out any other transaction from his or her account. A sophisticated algorithm is applied to the private key to generate the public key, and both keys are stored in a digital wallet . When a transaction is initiated by a user to send, say bitcoins, to another person, the transaction has to be broadcasted to the network where distributed nodes (i.e. people behind computers) confirm the validity of the transaction before finalizing it and recording it on the blockchain . Before the transaction is broadcasted, it is digitally signed using the private key. The signature proves ownership of the private key, although it does not divulge the details of the private key to anyone. Since a public key is fashioned from the private key, the users public key is used to prove that the digital signature came from his private key. Once the transaction has been verified as valid, the funds are sent to the recipients public address. The public address is a hashed version of the public key. Because the public key is made up of an extremely long string of numbers, it is compressed and shortened to form the public address. In effect, the private key gener Continue reading >>

Hash - Hashing From A Public Key To A Bitcoin Address In Php - Stack Overflow

Hash - Hashing From A Public Key To A Bitcoin Address In Php - Stack Overflow

Hashing from a public key to a bitcoin address in php I am trying to follow the instructions required to turn a 65 byte public key into a bitcoin address using php. The instructions are quite explicit. Can anyone help me with the practicality of doing that in php? 1 - Take the corresponding public key generated with it (65 bytes, 1 byte 0x04, 32 bytes corresponding to X coordinate, 32 bytes corresponding to Y coordinate) 0450863AD64A87AE8A2FE83C1AF1A8403CB53F53E486D8511DAD8A04887E5B23522CD470243453A299FA9E77237716103ABC11A1DF38855ED6F2EE187E9C582BA6 2 - Perform SHA-256 hashing on the public key 600FFE422B4E00731A59557A5CCA46CC183944191006324A447BDB2D98D4B408 3 - Perform RIPEMD-160 hashing on the result of SHA-256 4 - Add version byte in front of RIPEMD-160 hash (0x00 for Main Network) 00010966776006953D5567439E5E39F86A0D273BEE 5 - Perform SHA-256 hash on the extended RIPEMD-160 result 445C7A8007A93D8733188288BB320A8FE2DEBD2AE1B47F0F50BC10BAE845C094 6 - Perform SHA-256 hash on the result of the previous SHA-256 hash D61967F63C7DD183914A4AE452C9F6AD5D462CE3D277798075B107615C1A8A30 7 - Take the first 4 bytes of the second SHA-256 hash. This is the address checksum 8 - Add the 4 checksum bytes from point 7 at the end of extended RIPEMD-160 hash from point 4. This is the 25-byte binary Bitcoin Address. 00010966776006953D5567439E5E39F86A0D273BEED61967F6 9 - Convert the result from a byte string into a base58 string using Base58Check encoding. This is the most commonly used Bitcoin Address format // step 1$publickey='0450863AD64A87AE8A2FE83C1AF1A8403CB53F53E486D8511DAD8A04887E5B23522CD470243453A299FA9E77237716103ABC11A1DF38855ED6F2EE187E9C582BA6';$step1=$publickey;echo "step1 ".$publickey."";// step 2$step2=hash("sha256",$step1);echo "step2 ".$step2."";// step 3$step3=hash('r Continue reading >>

Generate Bitcoin Wallet Addresses From Extended Public Key With Php

Generate Bitcoin Wallet Addresses From Extended Public Key With Php

Generate Bitcoin Wallet Addresses from Extended Public Key with PHP Reusing the same Bitcoin wallet address is a big privacy issue. If you have a simple e-shop or a website which asks for donations you may want to consider generating unique addresses for each transaction instead. There are numerous payment systems such as Bitpay that do all the hard work for you. The drawback is that they are in charge of your private keys. You may implement your own simple solution using an extended public key (XPUB) from a hierarchically deterministic (HD) wallet, however. The whole process is explained in BIP 32 .I suggest you read it first to get a general idea of how addresses are derived. For this tutorial, we will use Electrum, OS X Sierra, Apache2.4, PHP 7.1 and Bit-Wasp/bitcoin-php . When it comes to a Bitcoin wallet, any HD wallet (such as Mycelium ) will work.The setup process should be the same on any UNIX-like system, especially Linux. The PHP library and its dependencies requirePHP 5.6+.Open a terminal and check your current version: PHP 7.1.0 (cli) (built: Jan 2 2017 20:09:35) ( NTS ) Zend Engine v3.1.0-dev, Copyright (c) 1998-2016 Zend Technologies If your version is smaller than 5.6 you have to upgrade your PHPfirst. Before we can install bitcoin-php library we need to make sure composer is installed. If it says something like:Composer version 1.3.0 2016-12-24 00:47:03 you can safely skip this step. It will download the library and dependencies. This process may take a few minutes. If it didn't output any errors move to the next step. I wrote a little class that loads all the necessary bitcoin-php classes and wraps certain methods for easy use. wgetFirstly, we need to get an extended public key. Open Electrum, click Wallet, thenMaster Public Keys and copy the string. O Continue reading >>

How To Generate A Private Key From My Bitcoin Address - Quora

How To Generate A Private Key From My Bitcoin Address - Quora

Answered Mar 2, 2018 Author has 110 answers and 134.7k answer views The private key is already generated. It depends what kind of wallet do you have. 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. If your wallet is in an exchange like Coinbase, you wont be able to access to the private key because its their policy. But, if you are using a wallet like Exodus, Jaxx, Blockchain Info; you can contact support service to give you instructions about how to find your private key. Jaxx wallet for example you go to Menu, Tools and Display Private Keys: In Copay wallet, you need to go Settings, Bitcoin Wallets (choose your wallet), More options, Wallet Information and finally Extend Private Key. You cannot generate the private key if you only have the Bitcoin address; thats like trying to get the security number of a vault just by knowing where is the vault located. Everyone could get it. If you have a paper wallet, the Private key was generated when you generate the Bitcoin address . Its a bit hard to help you since we have no information about what kind of wallet you have. Any bitcoin tip is appreciated and you can send it to: Continue reading >>

Six Things Bitcoin Users Should Know About Private Keys

Six Things Bitcoin Users Should Know About Private Keys

Six Things Bitcoin Users Should Know about Private Keys Private keys have been an integral component of Bitcoin since its first description in 2008. Wallet software often attempts to shield users from the need to understand what private keys are and how they work. Even so, most users eventually come face to face with private keys, too often with unpleasant results. A basic understanding of private keys can help prevent loss of funds and other mishaps, but it can also offer useful insights into how Bitcoin works. This guide outlines the most important private key concepts for using Bitcoin effectively. Although Bitcoin is best known as an electronic cash system , 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 play a central role in authenticating these messages and allowing users to identify each other. An example helps illustrate the problems that private keys solve. Imagine Alice wants to pay Bob using a coin with a face value of 1. Her plan is to create a transaction identifying Bob as the payee. After doing so, Alice plans to publish the transaction to the Bitcoin network. In using this system, Alice faces two fundamental problems: Alice needs a way to identify both herself and Bob in the transaction. She cant employ a trusted authority such as a government registry or email provider because that would create a central point of control and failure the very thing Bitcoin was created to eliminate. 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 i Continue reading >>

Pete Corey - Generating Bitcoin Private Keys And Public Addresses With Elixir

Pete Corey - Generating Bitcoin Private Keys And Public Addresses With Elixir

Generating Bitcoin Private Keys and Public Addresses with Elixir Lately Ive been working my way through Mastering Bitcoin , implementing as many of the examples in the book in Elixir as I can. Ive been amazed at how well Elixir has fared with implementing the algorithms involved in working with Bitcoin keys and addresses. Elixir ships with all the tools required to generate a cryptographically secure private key and transform it into a public address string. Lets walk through the process step by step and build our our own Elixir module to generate private keys and public addresses. What are Private Keys and Public Addresses? A Bitcoin private key is really just a random two hundred fifty six bit number. As the name implies, this number is intended to be kept private. From each private key, a public-facing Bitcoin address can be generated. Bitcoin can be sent to this public address by anyone in the world. However, only the keeper of the private key can produce a signature that allows them to access the Bitcoin stored there. Lets use Elixir to generate a cryptographically secure private key and then generate its most basic corresponding public address so we can receive some Bitcoin! As I mentioned earlier, a Bitcoin private key is really just a random two hundred and fifty six bit number. In other words, a private key can be any number between 0 and 2^256. However, not all random numbers are created equally. We need to be sure that were generating our random number from a cryptographically secure source of entropy . Thankfully, Elixir exposes Erlangs :crypto.strong_rand_bytes/1 function which lets us easily generate a list of truly random bytes. Lets use :crypto.strong_rand_bytes/1 as the basis for our private key generator. Well start by creating a new PrivateKey module Continue reading >>

Technical Background Of Version 1 Bitcoin Addresses

Technical Background Of Version 1 Bitcoin Addresses

Technical background of version 1 Bitcoin addresses Conversion from ECDSA public key to Bitcoin Address This article may be too technical for some users. The more basic article on Bitcoin Addresses may be more appropriate. A Bitcoin address is a 160-bit hash of the public portion of a public/private ECDSA keypair. Using public-key cryptography , you can "sign" data with your private key and anyone who knows your public key can verify that the signature is valid. A new keypair is generated for each receiving address (with newer HD wallets , this is done deterministically).The public key and their associated private keys (or the seed needed to generate them) are stored in the wallet data file.This is the only file users should need to backup .A "send" transaction to a specific Bitcoin address requires that the corresponding wallet knows the private key implementing it.This has the implication that if you create an address and receive coins to that address, then restore the wallet from an earlier backup, before the address was generated, then the coins received with that address are lost; this is not an issue for HD wallets where all addresses are generated from a single seed.Addresses are added to an address key pool prior to being used for receiving coins. If you lose your wallet entirely, all of your coins are lost and can never be recovered. Bitcoin allows you to create as many addresses as you want, and use a new one for every transaction.There is no "master address": the "Your Bitcoin address" area in some wallet UIs has no special importance.It's only there for your convenience, and it should change automatically when used. Bitcoin addresses contain a built-in check code, so it's generally not possible to send Bitcoins to a mistyped address. However, if the address Continue reading >>

Cryptography How To Get A Bitcoin Address From Public Key?

Cryptography How To Get A Bitcoin Address From Public Key?

Assistant Vice President R&A UI at Barclays Cryptography how to get a Bitcoin Address from publickey? Recently topics like Bitcoin, blockchain, cryptocurrency are widely popular not only in developers circles but generally. As I am very interested and excited about cryptography and its practical application I decided to write an article with practical examples about one of the common operations in Bitcoin lifecycle. Rather than using imaginary pseudo-language I used my favorite Back-End language: Golang or shorter go. When initially setting up, a Bitcoin client software creates new public/private ECDSA key pair which is used to sign and later verify a validity of transaction claim. The same key is used to generate a Bitcoin Address for the owner. So how do we get a Bitcoin Address from the key pair? A Bitcoin address is only a hash, so the sender cant provide a full public key in scriptPubKey. When redeeming coins that have been sent to a Bitcoin address, the recipient provides both the signature and the public key. The script verifies that the provided public key does hash to the hash in scriptPubKey, and then it also checks the signature against the public key. ( ) To calculate a bitcoin address we need public part of ECDSA ( a shorter acronym for Elliptic Curve Digital Signature Algorithm) key pair. It consists of two very long (32 bytes each) numbers between 0 and n where n is the curve order. Those numbers are coordinates that we get by calculating elliptic curve from a private key. In order to display them, those 64 bytes of data is converted to hexadecimal format. It takes 130 hex characters at 4 bits per character to display the full key. Lets assume we are building an API that will accept a public key from a client and our task is to convert that public key in Continue reading >>

Bitaddress.org

Bitaddress.org

A Bitcoin wallet is as simple as a single pairing of a Bitcoin address with its corresponding Bitcoin private key. Such a wallet has been generated for you in your web browser and is displayed above. To safeguard this wallet you must print or otherwise record the Bitcoin address and private key. It is important to make a backup copy of the private key and store it in a safe location. This site does not have knowledge of your private key. If you are familiar with PGP you can download this all-in-one HTML page and check that you have an authentic version from the author of this site by matching the SHA256 hash of this HTML with the SHA256 hash available in the signed version history document linked on the footer of this site. If you leave/refresh the site or press the "Generate New Address" button then a new private key will be generated and the previously displayed private key will not be retrievable. Your Bitcoin private key should be kept a secret. Whomever you share the private key with has access to spend all the bitcoins associated with that address. If you print your wallet then store it in a zip lock bag to keep it safe from water. Treat a paper wallet like cash. Add funds to this wallet by instructing others to send bitcoins to your Bitcoin address. Check your balance by going to blockchain.info or blockexplorer.com and entering your Bitcoin address. Spend your bitcoins by going to blockchain.info and sweep the full balance of your private key into your account at their website. You can also spend your funds by downloading one of the popular bitcoin p2p clients and importing your private key to the p2p client wallet. Keep in mind when you import your single key to a bitcoin p2p client and spend funds your key will be bundled with other private keys in the p2p cl Continue reading >>

Private Key Programming The Blockchain In C#

Private Key Programming The Blockchain In C#

Private keys are often represented in Base58Check called a Bitcoin Secret (also known as Wallet Import Format or simply WIF), like Bitcoin Addresses. Key privateKey = new Key(); // generate a random private keyBitcoinSecret mainNetPrivateKey = privateKey.GetBitcoinSecret(Network.Main); // generate our Bitcoin secret(also known as Wallet Import Format or simply WIF) from our private key for the mainnetBitcoinSecret testNetPrivateKey = privateKey.GetBitcoinSecret(Network.TestNet); // generate our Bitcoin secret(also known as Wallet Import Format or simply WIF) from our private key for the testnetConsole.WriteLine(mainNetPrivateKey); // L5B67zvrndS5c71EjkrTJZ99UaoVbMUAK58GKdQUfYCpAa6jypvnConsole.WriteLine(testNetPrivateKey); // cVY5auviDh8LmYUW8AfafseD6p6uFoZrP7GjS3rzAerpRKE9Wmuzbool WifIsBitcoinSecret = mainNetPrivateKey == privateKey.GetWif(Network.Main);Console.WriteLine(WifIsBitcoinSecret); // True Note that it is easy to go from BitcoinSecret to private Key. On the other hand, it is impossible to go from a Bitcoin Address to Public Key because the Bitcoin Address contains a hash of the Public Key, not the Public Key itself. Process this information by examining the similarities between these two codeblocks: Key privateKey = new Key(); // generate a random private keyBitcoinSecret bitcoinSecret = privateKey.GetWif(Network.Main); // L5B67zvrndS5c71EjkrTJZ99UaoVbMUAK58GKdQUfYCpAa6jypvnKey samePrivateKey = bitcoinSecret.PrivateKey;Console.WriteLine(samePrivateKey == privateKey); // True PubKey publicKey = privateKey.PubKey;BitcoinPubKeyAddress bitcoinPublicKey = publicKey.GetAddress(Network.Main); // 1PUYsjwfNmX64wS368ZR5FMouTtUmvtmTY//PubKey samePublicKey = bitcoinPublicKey.ItIsNotPossible; Generate a private key on the mainnet and note it. Send bitcoins to it. As much Continue reading >>

Why Generate Truly Random Privatekeys?

Why Generate Truly Random Privatekeys?

[spotted] 21 BTC (cumulative) sent to an address whose private key is compromised To develop our applications, we are constantly handling authentication protocols (basic, digest, oauth,). We even use hash functions and in 2016, when Apple required that all connections be in https, we could no longer ignore the main principles of symmetric and asymmetric encryption. And still When I generated accounts every 2 minutes while doing my tests on Ethereum, I had the impression to reserve myself addresses unnecessarily, I realize now that this reasoning is fundamentally wrong for several reasons. First, the probability of a collision when creating an address is infinitely small, orders of magnitude are so huge that it is difficult to represent them. Then, even if two people tried to brute-force keys for 100 years, these addresses would have to be used on the Blockchain transactions for that to be relevant. Conclusion, no reason to feel guilty if you generate thousands of addresses, consider rather that they already exist all but you can not control them. So we have a system without storage / persistence that allows from a private key to generate a public key and an address. This is obviously a one-way system. Do not try to hack it, there is no flaw in this system, it is both ultra secure and very user friendly. Without dependency (third party or hardware) I can sign transactions on the Blockchain with the only constraint, the knowledge of my secret code. On the other hand, if your private key is compromised, a hacker can quietly take away your cryptos and you will not be able to do anything. If you find this shocking, make an analogy with your mailbox. When you send me an email, I know your public address (your email), imagine that your password is your date of birth (private Continue reading >>

4. Keys, Addresses - Mastering Bitcoin, 2nd Edition [book]

4. Keys, Addresses - Mastering Bitcoin, 2nd Edition [book]

You may have heard that bitcoin is based on cryptography, which is a branch of mathematics used extensively in computer security. Cryptography means secret writing in Greek, but the science of cryptography encompasses more than just secret writing, which is referred to as encryption. Cryptography can also be used to prove knowledge of a secret without revealing that secret (digital signature), or prove the authenticity of data (digital fingerprint). These types of cryptographic proofs are the mathematical tools critical to bitcoin and used extensively in bitcoin applications. Ironically, encryption is not an important part of bitcoin, as its communications and transaction data are not encrypted and do not need to be encrypted to protect the funds. In this chapter we will introduce some of the cryptography used in bitcoin to control ownership of funds, in the form of keys, addresses, and wallets. Ownership of bitcoin is established through digital keys, bitcoin addresses, and digital signatures. The digital keys are not actually stored in the network, but are instead created and stored by users in a file, or simple database, called a wallet. The digital keys in a users wallet are completely independent of the bitcoin protocol and can be generated and managed by the users wallet software without reference to the blockchain or access to the internet. Keys enable many of the interesting properties of bitcoin, including decentralized trust and control, ownership attestation, and the cryptographic-proof security model. Most bitcoin transactions requires a valid digital signature to be included in the blockchain, which can only be generated with a secret key; therefore, anyone with a copy of that key has control of the bitcoin. The digital signature used to spend funds is als Continue reading >>

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