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 inContinue reading >>
As Pieter Wuille mentioned, public keys are derived by performing point multiplication with the curve's base point and the secret exponent/private key. The resulting (x,y) coordinate is the public key. The Bitcoin address, just like the private key, is also displayed in base58check format. To get the address, we do the following. Question: How many public keys per private key / address? I'm curious about the structure of the relationship(s) between Bitcoin addresses, public keys, and private keys. My previous assumption was that from each private key would derive only one public key, and one address via nested RIPEMD160 and SHA256 one-way hash functions. Question: How many public keys per private key / address? I'm curious about the structure of the relationship(s) between Bitcoin addresses, public keys, and private keys. My previous assumption was that from each private key would derive only one public key, and one address via nested RIPEMD160 and SHA256 one-way hash functions.
Although Bitcoin can be used without understanding private keys, this can lead to confusion or worse. Learn how private keys work to better understand Bitcoin and the security of your money. Six Things Bitcoin Users Should Know about Private Keys - Bitzuma. Feb 26, 2018 This article will explain at a high-level Private and Public Key Cryptography used in Bitcoin and it’s unique security feature. We will be looking at how Public Keys are generated, why this is.
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 iContinue reading >>
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 addressContinue reading >>
Public & Private Keys Explained (Litecoin/Bitcoin) Public & Private Keys Explained (Litecoin/Bitcoin) By now you have most probably already heard of the term Public & Private keys, but what exactly are they and more to the point what do they even do? By now you have most probably heard of the terms public and private keys. But what exactly are they and wellmore to the point what they actually do? Well to put it simply they are very sophisticated cryptography and one of the most important aspect of cryptocurrency in terms of user security. A lot of people described them being keys they actually tend to look a lot more like this. In essence these keys both send and receive transactions. We can imagine a public key as being the location of a post box. Anyone can put that is into that post box, but they cannot get them back out. Instead the postman who owned the private key has to come along and open the post box in order to retrieve the letters. This is similar to how a litecoin address works. The public key is usually shown in the form of a litecoin address which is a random assortment of upper and lower case letters along with numbers from anywhere between 30 and 34 characters in length and starting with the letter L. Now you or I can send Litecoins to this address but we cannot retrieve them. Just like we cant take letters out of the post box without the key. Only the owner of this address which has the corresponding private key is allowed to take the money out and spend it. So just note that if at any point you in this case the postman there shares his private key with anyone the coins in this metaphorical postbox risk being stolen. In fact, this very thing happened live on television to Matt Miller when he accidentally showed off his private key from a paper wallet.Continue reading >>
I'm looking for a regex that will validate a base 58 bitcoin private key. I found this one for public addresses: var regex = /^[5KL][1-9A-HJ-NP-Za-km-z]{50,51}$/ All valid WIF private keys will match this, and the only extra stuff this will match is 'WIF private key'-ish strings with invalid checksums. Shortest possible WIF key (all 00 bytes, missing the compressed 01 byte) 51 length5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAbuatmU Longest possible WIF key (all ff bytes with the extra 01 compression byte) 52 lengthL5oLkpV3aqBjhki6LmvChTCq73v9gyymzzMpBbhDLjDpKCuAXpsi From : Such encodings will always yield a 51-character string that starts with '5', or more specifically, either '5H', '5J', or '5K'. The correct expression is /^5[HJK][1-9A-Za-z][^OIl]{48}/ sebastian serrano Mar 5 '14 at 3:31 This doesn't disallow O, I, and l for the third character, allows underscores and non-word characters for the final 49, and requires 52 characters instead of 51. 5JO????????????????????????????????????????????????? for example, passes just fine, even though it contains invalid characters and is too long, and 5Jooooooooooooooooooooooooooooooooooooooooooooooooo, despite being valid, fails. drewbug Oct 25 '14 at 8:24Continue reading >>
Why does the length of a bitcoin key vary? some interesting bitcoin trivia - the first time a compressed public key is used to spend on the blockchain is in tx 94af4607627535f9b2968bd1fbbf67be101971d682023d6a3b64d8caeb448870 , which spends 0.01337 btc. clearly someone was showing off lol mulllhausen Nov 11 '14 at 12:45 the compressed pubkey was 0271f1e54016d623897fa9b973c2f084376ff61651ee5b71eef0d98a8be56a75cc btw mulllhausen Nov 11 '14 at 12:55 The length of a key doesn't vary. Private keys are always 32 bytes, and public keys are always 65 bytes (or 33 bytes for a compressed public key). Public key hashes are always 20 bytes. The length of addresses vary because in Bitcoin's base58 encoding, leading zero bytes are expressed as a single '1'. Other bytes require more than one character in order to be expressed in base58. Do you have private keys and public keys reversed in the above answer? It seems to me that private keys are longer. shoeless joe Nov 20 '11 at 19:34 @shoelessjoe I don't think so. Public keys are definitely 64 bytes plus the leading 0x04 byte, and I assume that the 256 in 'secp256k1' refers to the size of the private key in bits. theymos Nov 21 '11 at 1:33 You said 'Private keys are always 32 bytes, and public keys are always 65 bytes.' That makes public keys longer than private keys? shoeless joe Nov 29 '11 at 18:13 @shoelessjoe Yes. I think this is the case with all public-key crypto, actually. theymos Nov 30 '11 at 22:12 In fact, we could move to compressed public keys, which are 257 bits long (33 bytes). Slightly longer than the private key indeed, but almost nothing. Pieter Wuille Dec 4 '11 at 14:56Continue reading >>
A Bitcoin address, or simply address, is an identifier of 26-35 alphanumeric characters, beginning with the number 1 or 3, that represents a possible destination for a bitcoin payment.Addresses can be generated at no cost by any user of Bitcoin.For example, using Bitcoin Core , one can click 'New Address' and be assigned an address.It is also possible to get a Bitcoin address using an account at an exchange or online wallet service. There are currently two address formats in common use: Common P2PKH which begin with the number 1, eg: 1BvBMSEYstWetqTFn5Au4m4GFg7xJaNVN2. Newer P2SH type starting with the number 3, eg: 3J98t1WpEZ73CNmQviecrnyiWrnqRhWNLy. Like e-mail addresses, you can send bitcoins to a person by sending bitcoins to one of their addresses.However, unlike e-mail addresses, people have many different Bitcoin addresses and a unique address should be used for each transaction.Most Bitcoin software and websites will help with this by generating a brand new address each time you create an invoice or payment request. Creating addresses can be done without an Internet connection and does not require any contact or registration with the Bitcoin network.It is possible to create large batches of addresses offline using freely available software tools.Generating batches of addresses is useful in several scenarios, such as e-commerce websites where a unique pre-generated address is dispensed to each customer who chooses a 'pay with Bitcoin' option.Newer 'HD wallets' can generate a 'seed' token which can be used to allow untrusted systems (such as webservers) to generate an unlimited number of addresses without the ability to spend the bitcoins received. Bitcoin addresses are case-sensitive. Bitcoin addresses should be copied and pasted using the computer's clipboard wContinue reading >>
A private key in the context of Bitcoin is a secret number that allows bitcoins to be spent. Every Bitcoin address has a matching private key, which is saved in the wallet file of the person who owns the balance. The private key is mathematically related to the Bitcoin address, and is designed so that the Bitcoin address can be calculated from the private key, but importantly, the same cannot be done in reverse. Because the private key is the 'ticket' that allows someone to spend bitcoins, it is important that these are kept secure. Private keys can be kept on computer files, but they are also short enough that they can be printed on paper. An example of a utility that allows extraction of private keys from your wallet file for printing purposes is pywallet. In order to create a transaction with a private key, it must be available to a program or service that allows entry or importing of private keys. Some wallets allow the private key 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 entire balance held by the private key to another address in the wallet or securely controlled by the service in question. An example of private key sweeping is the method used on MtGox's Add Funds screen and BIPS Import screen. Just as with any other deposit, there is risk of double-spending so funds are deposited to the MtGox account after a six-confirmation wait (typically one hour). In contrast BlockChain .info's My Wallet service and Bitcoin-QT each provide a facility to import a private key without creating a sweep transaction [1] . In Bitcoin, private key is a 256-bit number, which can be represented one of several ways. Here is a private ke Continue reading >>
A private key is a randomly generated number. But to be more exact, because bitcoin uses 256-bit numbers, a randomly generated private key starts out looking like this: 1110111100100011010110101010110011111001000011011001111101001010101011011101100011001001001011100100101100100101011000101110000111011001111010111001011111110000110111111001101110100011101101010000100000100101100001110011100111001011000000010011110110110010 Yes, this is still a number. Its just in binary, which is a elemental way of storing numbers in a computer. Because you know, Bitcoin is a computer program after all. Anyway, we can easily convert this private key from binary to decimal: ef235aacf90d9f4aadd8c92e4b2562e1d9eb97f0df9ba3b508258739cb013db2 It doesnt make a difference. Theyre all the same number, and theyre all the same private key. Because after all, a private key is just a number. A raw private key is commonly shown in hexadecimal format. A 256-bit number is a number that can be stored inside 256 bits of data. A bit is the smallest unit of data inside a computer. In fact, a bit is so small, it can only hold a value of 1 or 0. Nonetheless, you can still use bits to represent other kinds of data, such as everyday numbers. For example, heres how you would store a few different numbers in a computer using bits: Anyway, a 256-bit number is simply a number that can be represented by using 256 of these bits (at most). Or in other words, a 256-bit number is between: min: 0max: 115792089237316195423570985008687907853269984665640564039457584007913129639935 So as you can see, 256 bits gives you room to use some pretty big numbers. And thats all 256-bit numbers are numbers that fit inside 256 bits of data. The total number of 256-bit numbers is equal to 2256. I wasnt lying when I said they are generaContinue reading >>
The seed is a random phrase that is used to generate your privatekeys. constant forest adore false green weave stop guy fur freeze giggle clock Your wallet can be entirely recovered from its seed. For this, selectthe restore wallet option in the startup. The seed phrase created by Electrum has 132 bits of entropy. Thismeans that it provides the same level of security as a Bitcoin privatekey (of length 256 bits). Indeed, an elliptic curve key of length nprovides n/2 bits of security. I have forgotten my password. What can I do? It is not possible to recover your password. However, you can restoreyour wallet from its seed phrase, and choose a new password.If you lose both your password and your seed, there is no wayto recover your money. This is why we ask you to save your seedphrase on paper. To restore your wallet from seed phrase. Create a new wallet, selectthe type, choose I already have a seed and proceed to input your seedphrase. My transaction has been unconfirmed for a long time. What can I do? Bitcoin transactions become confirmed when miners accept to writethem in the Bitcoin blockchain. In general, the speed of confirmationdepends on the fee you attach to your transaction; miners prioritizetransaction that pay the highest fees. Recent versions of Electrum use dynamic fees, in order to make surethat the fee you pay with your transaction is adequate. This featureis enabled by default in recent versions of Electrum. If you have made a transaction that is unconfirmed, you can: Wait for a long time. Eventually, your transaction will either beconfirmed or cancelled. This might take several days. Increase the transaction fee. This is only possible forreplaceable transactions. To create this type of transaction, youmust have enabled Replace by Fee in your preferences,Continue reading >>
MultiChain addresses and private keys are similar to those in bitcoin The format of addresses and private keys in MultiChain is similar to that of bitcoin addresses and private keys . However there are some differences, which ensure that addresses and keys created on one MultiChain blockchain are extremely unlikely to be valid on a second chain. This in turns prevents a developer error from accidentally performing an operation on one chain which was intended for another. On a technical level, bitcoins scheme uses a single version byte for addresses, meaning that it can only define 256 separate address spaces. By contrast, MultiChains scheme uses up to 4 version bytes and an additional 4-byte value which modifies a checksum. This allows 264 or over 1019 separate address spaces to be defined. In MultiChain these values are generated randomly when a new chain is created and represented by the address-pubkeyhash-version and address-checksum-value values in the blockchain parameters . There are also address-scripthash-version and private-key-version parameters which define the version bytes for pay-to-scripthash addresses and the exporting of private keys. These *-version parameters can be between 1 and 4 bytes in length, but they must all be the same length. If you want MultiChains addresses and private keys to be fully compatible with bitcoins, use the following values in the blockchain parameters : address-pubkeyhash-version=00, address-scripthash-version=05, private-key-version=80, address-checksum-value=00000000 Steps which differ from the corresponding bitcoin address calculations are indicated below. 283D01856115B7970B622EAA6DAFF2B9ECE30F1B66927592F6EA70325929102B Take the corresponding public key generated with it, which can be in compressed or uncompressed format.Continue reading >>
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 forContinue reading >>
What's the difference between public key and public address? So I've heard the two used interchangeably (incorrectly) From the technical papers I've read, it seems that you hash a public key to get your address. In order to receive Bitcoin, don't you just need to give someone a public key? Why go through that extra step to create a address, when you can give out your public key? There's a few things to understand in order to answer that. The first is what a hash is. The short version is that it's a function that returns a value of a specific length. So whether the input is 'Hi' or 'Hello' or 'This is an even longer piece of data', the hash function will return the same length of output, and that output will always be the same size, and the output will always be the same for a given input. The other aspect of a hash function is that it is 'one way'. It is very easy to put input into the hash function and get output, but it's basically impossible to get some hash output and determine from that what the input was. The hash is considered broken and unusable if you are able to do that. The only way to map hash outputs to inputs is to just churn through inputs and outputs and record them in a lookup table. And hackers do that - they're called rainbow tables. That's why websites often add 'salt' to something before they hash it. That 'salt' is simply a small bit of extra arbitrary random data to add in, so that rainbow tables won't work. For example, your poor password 'password1' is in a rainbow table, but if the site adds random letters like 'x$Q7fG' and takes the hash of 'x$Q7fGpassword1', that's probably not already in a rainbow table. The next thing to know is about public and private keys. Whether it's elliptic curves or RSA, the general idea is the same. You have a 'prContinue reading >>
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 secure.Private keys can be kept on computer files, but in some cases are also short enough that they can be printed on paper. 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.Bitcoins can be easily 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] . In Bitcoin, a private key is usually a 256-bit number (some newer wallets may use between 128 and 512 bits), 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. E9873D79C6D87DC0FB6A5778633389_SAMPLE_PRIVATEContinue reading >>
is bitcoin address the same as Public key ? is bitcoin address the same as Public key in my wallet's ? thanks for any help i need it, i have tried to google this but did not understand this. Advertised sites are not endorsed by the Bitcoin Forum. They may be unsafe, untrustworthy, or illegal in your jurisdiction. Advertise here. Quote from: simplyred on December 27, 2017, 11:17:06 PM is bitcoin address the same as Public key in my wallet's ? thanks for any help i need it, i have tried to google this but did not understand this. Not exactly. See this article on the Bitcoin Wiki , specifically the section titled 'How to create Bitcoin Address.' Bitcoin uses public-key cryptography. A private key is used to sign transactions, and the public key verifies that signatures are valid. For each 'Bitcoin address' in your wallet, a public/private keypair is generated. Specifically, the address is a hash of the associated public key: A Bitcoin address is a 160-bit hash of the public portion of a public/private ECDSA keypair. 0450863AD64A87AE8A2FE83C1AF1A8403CB53F53E486D8511DAD8A04887E5B23522CD470243453A 299FA9E77237716103ABC11A1DF38855ED6F2EE187E9C582BA6 -- which goes through five rounds of hashing, has a checksum added, and is converted into a base58 string to produce this Bitcoin address: Quote from: simplyred on December 27, 2017, 11:17:06 PM is bitcoin address the same as Public key in my wallet's ? No, though many people confuse the two. A Bitcoin address is a base-58 encoding of a hash of a public key. 1. Determine the public key from the private key. 2. Hash the public key using SHA-256 to get a 256-bit value. 3. Hash the result of #2 with RIPEMD-160 to get a 160-bit value. 4. Encode the result of #3 using base-58 encoding scheme to produce a Bitcoin address. Buy bitcoins wContinue reading >>
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