Questions tagged [public-key]

This tag should be used for questions regarding public keys. A public key is the public half of the public/private keypair. Anyone can use a public key check that a signature is correct, but they can't generate the signature themselves with the public key.

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72 votes
4 answers
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What is a compressed Bitcoin key?

The standard Bitcoin client in version 0.6 apparently introduces compressed keys. What are they? Are there any drawbacks to using them? Any incompatibilities with older software? Reductions in ...
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60 votes
6 answers
24k views

What is relation between scriptSig and scriptPubKey?

Scenario: A is sending 1 BTC to B. scriptSig appears in the Input Script. scriptSig = <sig> <pubKey> Here, public key is the Public Key of the sender, A. (this is the public key ...
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30 votes
5 answers
18k views

How are public & private keys in an address created?

I understand the high level concept I am more interested specific details. How is a private key generated. How exactly is public key generated, how is address generated from public key.
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25 votes
3 answers
39k views

Is it possible to get the public key of a bitcoin address I do not have the private keys for with the standard client?

It is possible to get it from here: https://blockchain.info/de/q/pubkeyaddr https://blockchain.info/q Is it possible with the standard client? How? I am aware that the blockchain only contains the ...
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  • 1,999
24 votes
1 answer
4k views

Why does hashing public keys not actually provide any quantum resistance?

In the discussions about taproot, it was mentioned that outputs will include the public key directly instead of hashing them. It is stated that, currently, hashing does not really provide quantum ...
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22 votes
2 answers
54k views

How are public and private keys related to the wallet?

I understand that all the Bitcoin protocol is based on an asymmetric cryptography. A user gets 2 keys (public and private). How do these keys connect to the Bitcoins? How are the keys are related ...
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20 votes
2 answers
16k views

Why does the length of a bitcoin key vary?

Why does the length of a bitcoin key vary? Why aren't they all the same length?
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  • 2,247
20 votes
2 answers
6k views

Why do you use Bitcoin addresses instead of public keys?

Why do you hash the public key twice? Are there security benefits to abstracting away from the public key? Is it because the address can represent multiple things? I'm missing something. Could you ...
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  • 331
20 votes
1 answer
15k views

What is a private key and a public key?

What exactly is a private key and public key in relation to Bitcoin? What are they, how are they used, and how does one find out what their private and public keys are?
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18 votes
2 answers
15k views

Does a wallet containing multiple addresses have a single private key?

Title says it all. Would one private key enable you to recover all the addresses in your wallet? Or does a wallet just contain a series of key-pairs?
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16 votes
1 answer
3k views

Can private keys remain offline for their entire life?

I am new to Bitcoin and this question is based on 3 assumptions that may be incorrect. Assumption 1: If I understand correctly, the Bitcoin address is generated algorithmically independent of the ...
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15 votes
3 answers
4k views

Why is it not possible to get the private key out of the public key?

From how I understand it, the equation for the public key is defined as so: K = k * G With K being the public key, k the private key and G the generator point. Is G a constant? (as far as I read, ...
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15 votes
3 answers
3k views

How would one "Encrypt" a message using a Bitcoin *public key* and use its private key to decrypt it?

I have the following text string: This is a test message. Using my bitcoin public key (bitcoin address?), how can I encrypt this message? How would I decrypt the message using a bitcoin private key?
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14 votes
3 answers
8k views

Key derivation in HD wallets using the extended private key vs hardened derivation

I am reading the book Mastering Bitcoin and confused about wallet key derivations in Chapter 4. Keys, Addresses, Wallets. The book first mentions a private child key derivation where the child ...
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14 votes
1 answer
3k views

What are the potential attacks against ECDSA that would be possible if we used raw public keys as addresses?

According to this answer about why addresses are hashes rather than public keys there are potential attacks that are possible if you have the public key rather than the address, what are these attacks?...
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14 votes
3 answers
21k views

All Bitcoin Public Keys with non-zero balance

I want to get a database or otherwise retrieve a set off all bitcoin public keys (not addresses) that have non zero balances. What would be the easiest way to do that? Is there an API that could do ...
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12 votes
2 answers
993 views

How would we know the real Satoshi?

Should Satoshi decide to reveal his or her true identity, how can one know the person is the real creator of Bitcoin, rather than a person who hacked the forum login, email address or the like? In ...
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12 votes
5 answers
5k views

What would happen if you send bitcoins to a non-existent Bitcoin address?

If one were to send bitcoins to an address that has not been created yet, what would happen? Would the coins be lost forever? Would they just sit there until the address and key pair are generated?
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11 votes
3 answers
42k views

How do I get my public address in Bitcoin Core?

In a world of pain at the moment. I downloaded Bitcoin Core, and before I realised I'd need the complete downloaded Blockchain, my friend transferred some coins to my address. I did some research ...
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  • 135
11 votes
2 answers
2k views

How does ScriptPubKey know the public key of an Bitcoin address?

I am currently having a blonde moment. The ScriptPubKey provides a hashed version of the receivers public key. scriptPubKey OP_DUP OP_HASH160 OP_EQUALVERIFY OP_CHECKSIG However, if I give ...
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  • 111
10 votes
2 answers
4k views

Why are Bitcoin addresses starting with 1s or 1S so rare?

I've generated 10000-50000 key pairs using Chrome Bit Kit app or www.bitaddress.org and have noticed the scarcity of public keys which begin with 1S and/or 1s. Why is this the case?
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10 votes
3 answers
7k views

parsing bitcoin input and output addresses from scripts

can someone walk me through the process of combining script inputs and outputs to reveal the base58 encoded input and output addresses. take for example, block 728. this has two raw script inputs: ...
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  • 1,693
9 votes
3 answers
17k views

Is it possible to use xpub address to monitor balance from previously generated addresses?

I'm trying to find a way where I can view balance of my ledger nano s wallet without always attaching it to computer all the time. I found something called xpub address which allows me to generate ...
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  • 195
9 votes
2 answers
9k views

Public Key + Private Key enough to backup?

I invested in bitcoins and unfortunately I have problems to understand the system. Perhaps you can answer me the following questions? 1.a) I know my public and my private key. Do I still have to ...
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9 votes
2 answers
11k views

What if duplicate wallet addresses are created? [duplicate]

I'm a newbie to Bitcoin, so I apologize if this seems like a "noob" question. So, from what I've read: anyone can create a new Bitcoin wallet. Upon creation, a wallet address is automatically ...
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  • 293
8 votes
2 answers
7k views

What are the DER signature and SEC format

I often see those 2 elements in bitcoin documentations and tutorials but I have not yet find a proper definition on the internet for DER signature and SEC format.
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  • 2,391
8 votes
1 answer
3k views

When importing private keys, will compressed or uncompressed format be used?

I am looking into implementing support for compressed public keys on Vanity Pool. However, I have my concerns about importing solutions into a desired vanity address under that format. From what I can ...
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8 votes
2 answers
13k views

What exactly happens when a new wallet is created?

I am asking for what is being created when there is a new wallet created. And the second part of my question is considering public key. Is the public key the same thing as the address? I read that ...
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  • 568
8 votes
1 answer
9k views

How to generate specific private keys from 12-word backup and wallet address?

A single seed can lead to billions of addresses. Some wallets are unable to scan and find all used addresses. Is it a way to infer the private key from 12-word backup and wallet ID / (public key). ...
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  • 388
8 votes
2 answers
5k views

How can I get the uncompressed public key from the compressed public key in openssl?

Given a private key, I can get the uncompressed or compressed version of the public key like so. EC_KEY* pKey = EC_KEY_new_by_curve_name(NID_secp256k1); std::vector<unsigned char> getPubKey(...
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7 votes
1 answer
5k views

difference between Master Public/private Key and Public/private Key?

what is difference between Master Public Key (MPK) and Public Key? what is difference between Master Private Key and Private Key? should I use master public key (MPK) when generating address or public ...
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  • 227
7 votes
2 answers
5k views

python-bitcoinlib | Create Private Keys, Public Keys and Addresses - How to Do It?

I'm trying to use the python-bitcoinlib library but its docs aren't entirely clear to me. I'm a programmer but quite new to Python, and not very versed in the Bitcoin protocol. What's the process, ...
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7 votes
1 answer
807 views

How to get the Public Keys of a bitcoin User

Is there some way in which I could get the public key of a Bitcoin user ? Lets say I have transaction with another Bitcoin user. Is there some means by which I can retrieve the public key of the ...
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  • 758
7 votes
2 answers
8k views

What is the difference between your address and your public keys

I'm beginning to learn about cryptocurrencies, and I'm having a lot of trouble because some terms are used in different contexts. I know that public keys are generated through a private key. So, are ...
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  • 171
7 votes
1 answer
7k views

How to get public master key of a Ledger wallet?

I have a ledger Nano S and would like to know how to extract the public master key of its wallet, in order to do HD key derivation in an external process. Is there a way or is this info never exposed ...
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  • 1,668
7 votes
1 answer
2k views

If addresses are hashes of public keys, how are signatures verified?

I've skimmed through the https://en.bitcoin.it/wiki/Protocol_specification and it seems that when sending someone bitcoins, I would sign the transaction data (not quite sure which parts exactly) with ...
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6 votes
2 answers
17k views

Does the private key of Bitcoin change everytime the address changes?

I have read from many sites that an address should change every time a Bitcoin transaction is made. Does the private key change along with the Bitcoin address. How is the address obtained from the ...
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6 votes
2 answers
966 views

Why can't we switch private and public keys?

If private and public keys are performing the same task (although asymmetrically), but I mean each one can encrypt something that only the other one can decrypt, can I create a paper wallet and share ...
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  • 63
6 votes
1 answer
4k views

What makes an extended public or private key?

I was under the impression that an extended public key was comprised of the public key + chain code, and I'm unfamiliar with what comprises the extended private key. However this does not seem to be ...
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  • 1,369
6 votes
2 answers
4k views

Why is it impossible to derive public key from address?

This is my first bitcoin transaction. Why this transaction doesn't show my public key? help message on the same page says that, It's impossible to determine the public key from a Bitcoin address, ...
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  • 1,844
6 votes
1 answer
19k views

How can I convert a bitcoin public key to a bitcoin address?

How can I convert a bitcoin public key to a bitcoin address? Note: I am using PHP. Is there an existing bitcoin API or PHP-API to do that converting ?
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  • 191
6 votes
1 answer
564 views

What is the use of hashing the public key to obtain the bitcoin address?

What is the use of hashing the public key to obtain the bitcoin address (except to compress it) rather than using the public key directly? Why not deal with public keys directly?
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  • 450
6 votes
2 answers
510 views

How many different formats can a public address take?

I'm creating an offline index to report off of the block chain. I plan on indexing each transaction based on the address displayed in the TX. Are all addresses Base58? I believe I also read about ...
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5 votes
1 answer
3k views

How can a deterministic wallet have one private key but multiple public keys

If we take for example bread wallet. There is one mnemonic to remember, which means one private key? But when you use the app, your public address constantly changes. So more than one public key? ...
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5 votes
2 answers
578 views

How does Nextcoin convert 256-bit Curve25519 public keys into ~20 arabic numerals?

Nextcoin seems to convert 256-bit Curve25519 256-bit public keys into "account numbers" that have only arabic numbers and seem to only have a length of 20. How is that done? Examples In the ...
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5 votes
3 answers
428 views

How does ImportPrivateKey get the Address if I don't explicitly send it?

Suppose I just used vanitygen to create this key: Pattern: 1a Address: e1aMGYXuGpUwDGH9gz3ZBs8UH746nRdEk6 Privkey: 5KhCszBi22hEZZixPEQkLAMtUVkxbGaxBFsH7a9iefqrxHmSXgH All I had to do to import this ...
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5 votes
1 answer
117 views

Isn't bribe smearing possible because no payee signature is required?

The Bitcoin protocol does not require the payee to sign for a payment; only the payer signs (the payer signs a hash of the payee and payer's public keys). In other words, a payee signature is not ...
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  • 51
5 votes
2 answers
4k views

What is the public key used to generate the Genesis block?

I'm trying to create and build a working fork of Bitcoin -- in order to understand how it works at the source code level. I see a lot of articles explaining how to create altcoins but they are not ...
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  • 153
5 votes
1 answer
12k views

What's the relationship of Bitcoin addresses to public keys?

A Bitcoin wallet can handle multiple private keys. In ECC, you can have 2^256 private keys, and for each key, you can have 2^256 public keys. Assuming that's right (please correct me if I'm wrong), ...
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  • 63
5 votes
2 answers
7k views

How to generate Ed25519 public key from private key using libsodium?

Not all crypto currencies are using secp256k1 technology for keypair generation and digital signatures. Curve25519 technology (frequently used to support ECDH key exchanges) is being used by a few ...
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