What is Bitcoin Private Key? A private key is a secret, alphanumeric password/number used to spend/send your bitcoins to another Bitcoin address. It is a 256-bit long number which is picked randomly as soon as you make a wallet. The degree of randomness and uniqueness is well defined by cryptographic functions for security purposes. Dec 29, 2017 This is part two in my basic visual introduction to the concepts behind a blockchain. We build on the concepts from the previous video and introduce public / private key pairs and signing using an. This private key is converted to a public key by performing an EC point multiplication with the curve's base point. The result is an (x,y) coordinate pair, which constitutes the public key. Finally, RIPEMD160(SHA256(pubkey)), where pubkey is a serialization of those coordinates, is computed, and encoded in base58, together with a checksum.
This article has 3 sections - one for the new Blockchain.info wallets based of BIP39 seeds, one for classic wallet addresses imported into the new wallet and one for the classic old wallets.
For Blockchain.info's newer wallets based on a recovery phrase
Note: Blockchain.info's new wallets make use of a bip39 recovery seed to generate EVERY ADDRESS and PRIVATE KEY in your Blockchain.info account. At this time it is not possible to extract only 1 address' private key so the only option is to make use of the recovery seed to gain access to the address that has your OmniTokens. Extreme care should be taken to perform the following steps on an airgapped/offline machine to preserve the integrity of your recovery seed. You may even want to consider this method a fallback/last resort and after completing the recovery actions discard all addresses/wallets/accounts and start a new Blockchain.info wallet.You have been warned
If you do not already have your Blockchain.info recovery seed/phrase you will need to login to your Blockchain.info account and navigate to the 'Security Center' and then click on the 'Phrase Backup' Option under Level 1 (Note: Once you backup the recovery phrase you will not be able to access it again. Make sure you properly record this info)
If you have more than 1 wallet in your blockchain.info account you will need to determine which wallet contains the address you want to recover.
In blockchain.info's wallet go to 'Settings-> Addresses'. You will see all your wallets listed by name.
If you only have 1 then your Account number for step 6 is 0. If you have more than 1 then use the 'Manage Address' button to display the addresses within each wallet until you find the wallet that contains the address you want to recover/import into Omniwallet.
Count down the list of wallets starting with 0 for the first/'My Bitcoin Wallet' and when you reach the wallet that has the address make note of its number. This will be the account number for step 6.
Once you have your recovery phrase you will need access to the Bip39 generator
We recommend you download the 'bip39-standalone.html' file directly from github to thumbdrive
On your offline machine access/open/load the 'bip39-standalone.html' file
Enter your Blockchain.info recovery phrase/seed in the webpage next to 'BIP39 Mnemonic'
Choose number of words = '12' (or set the number of words for how many were in your recovery phrase)
Scroll down to the 'Derivation Path' (leave BIP44 selected) and enter your account number from step 2 here.
Leave all the rest of the entries set to their default
Scroll down to the 'Derived Addresses' section and you should now see a list of addresses that will match the list of addresses in blockchain.info for your wallet.
Find the address in question and copy its private key.
Once you have this you can go to https://www.omniwallet.org and click 'Create a New Wallet' (or log into a wallet you already created).
Once you have created/logged into your wallet go to the 'My Address' page and click the 'Import Address with Private Key' Button.
Enter the private key you exported from blockchain.info and in a few moments that address should be added to your wallet and displayed in the list below giving you access to your BTC and any Omni Protocol Properties on that address.
If the newly imported address does NOT match the address you are expecting try taking a look at this article: After importing my private key and the address I get is different than what I expected!
For Blockchain.info addresses imported into the New Blockchain.info Wallet from Blockchain.info's Classic Wallets
Login to your wallet on Blockchain.info
Goto the 'Settings' Menu on the left
Goto the 'Addresses' Submenu under 'Settings' Menu
On the right side find the section named 'Imported Addresses'
Click on 'Manage Addresses'
On the new screen find the address you want to export the private key from
Click on the 'More Options' on far right side of that address
Select 'Private Key' and then 'Continue'
Choose the 'Private Key Format' : 'WIF'
Copy the Private Key listed and go to your Omniwallet
Once you have this you can go to https://www.omniwallet.org and click 'Create a New Wallet' (or log into a wallet you already created).
Once you have created/logged into your wallet go to the 'My Address' page and click the 'Import Address with Private Key' Button.
Enter the private key you exported from blockchain.info and in a few moments that address should be added to your wallet and displayed in the list below giving you access to your BTC and any Omni Protocol Properties on that address.
If the newly imported address does NOT match the address you are expecting try taking a look at this article: After importing my private key and the address I get is different than what I expected!
Private Key Definition
For Blockchain.info Classic Wallets
Login to your wallet on Blockchain.info
Click 'Import/Export' link in the second header
Click 'I Understand' to the advanced warning
On the left side menu click 'Export unencrypted'
Enter your secondary password
Select the 'Private Key Format' of 'Bitcoin-QT Format'
In the window underneath you will see a bunch of json formatted text (text enclosed in {} braces).
Search for the last few lines that look like 'addr':'1Pd3','priv':'....'
Your private key will be the shown after the 'priv' and will start with either the number 5 or the letter K
Once you have this you can go to https://www.omniwallet.org and click 'Create a New Wallet' (or log into a wallet you already created).
Once you have created/logged into your wallet go to the 'My Address' page and click the 'Import Address with Private Key' Button.
Enter the private key you exported from blockchain.info and in a few moments that address should be added to your wallet and displayed in the list below giving you access to your BTC and any Omni Protocol Properties on that address.
If the newly imported address does NOT match the address you are expecting try taking a look at this article: After importing my private key and the address I get is different than what I expected!
Anders Public Key And Private Key Generator In Blockchain
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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.
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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 is well-formed but no one owns it (or the owner lost their wallet.dat), any coins sent to that address will be lost forever.
Hash values and the checksum data are converted to an alpha-numeric representation using a custom scheme: the Base58Check encoding scheme. Under Base58Check, addresses can contain all alphanumeric characters except 0, O, I, and l. Normal addresses currently always start with 1 (addresses from script hashes use 3), though this might change in a future version. Testnet addresses usually start with m or n. Mainline addresses can be 25-34 characters in length, and testnet addresses can be 26-34 characters in length. Most addresses are 33 or 34 characters long.
Collisions (lack thereof)
Since Bitcoin addresses are basically random numbers, it is possible, although extremely unlikely, for two people to independently generate the same address. This is called a collision. If this happens, then both the original owner of the address and the colliding owner could spend money sent to that address. It would not be possible for the colliding person to spend the original owner's entire wallet (or vice versa).
But because the space of possible addresses is so astronomically large it is more likely that the Earth is destroyed in the next 5 seconds, than that a collision occur in the next millenium.
How to create Bitcoin Address
The correct way to create a Bitcoin address is to use well tested, open source, peer reviewed wallet software. Manually handling keys has resulted in funds loss over and over again. Unlike other centralized systems losses in Bitcoin are usually unrecoverable.
Here is a brief overview of how address generation works, for informational purposes:
Private Key Bitcoin
0 - Having a private ECDSA key
1 - Take the corresponding public key generated with it (33 bytes, 1 byte 0x02 (y-coord is even), and 32 bytes corresponding to X coordinate)
2 - Perform SHA-256 hashing on the public key
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)
(note that below steps are the Base58Check encoding, which has multiple library options available implementing it) 5 - Perform SHA-256 hash on the extended RIPEMD-160 result
6 - Perform SHA-256 hash on the result of the previous SHA-256 hash
7 - Take the first 4 bytes of the second SHA-256 hash. This is the address checksum
8 - Add the 4 checksum bytes from stage 7 at the end of extended RIPEMD-160 hash from stage 4. This is the 25-byte binary Bitcoin Address.
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9 - Convert the result from a byte string into a base58 string using Base58Check encoding. This is the most commonly used Bitcoin Address format
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See Also
Bitcoin Core documentation
User documentation
Alert system • Bitcoin Core compatible devices • Data directory • Fallback Nodes • How to import private keys in Bitcoin Core 0.7+ • Installing Bitcoin Core • Running Bitcoin • Transaction fees • Vocabulary
Developer documentation
Accounts explained • API calls list • API reference (JSON-RPC) • Block chain download • Dump format • getblocktemplate • List of address prefixes • Protocol documentation • Script • Technical background of version 1 Bitcoin addresses • Testnet • Transaction Malleability • Wallet import format
History & theory
Common Vulnerabilities and Exposures • DOS/STONED incident • Economic majority • Full node • Original Bitcoin client • Value overflow incident
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