37 votes
Accepted

ELI5: What's the difference between a child-key and a hardened child-key in BIP32

Essentially, a hardened child key is is computed with hash(parent private key + index), whereas a non-hardened child key is computed with hash(parent public key + index). So what practical ...
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  • 28.8k
33 votes

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

There's a lot of confusion here, mostly bits and pieces of the whole scheme that is Hierarchical Deterministic derivation, and finally two questions that seem to indicate missing some point about it. ...
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  • 1,814
21 votes
Accepted

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

Yes, this is possible. However, I want to upfront state that this is not advisable for multiple reasons: Bitcoin keys are intended to be single use for privacy reasons, and leveraging them for ...
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21 votes
Accepted

Is any 256-bit combination a Bitcoin private key?

A secp256k1 private key is an integer between 1 and 115792089237316195423570985008687907852837564279074904382605163141518161494336, inclusive. The latter can be written as 2256 - ...
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19 votes
Accepted

What is the wallet "word seed" that is commonly used in popular wallets clients and what does it do?

With HD wallets, a single key can be used to generate an entire tree of key pairs. This single key serves as the "root" of the tree. The word seed is simply a more human-readable way of expressing ...
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  • 8,734
15 votes
Accepted

Why doc says importing private keys is so dangerous?

Key import by itself (from a trusted source of keys, such as your own cold storage or backups) isn't a dangerous thing. However, the vast number of ways one can cause problems for themselves through ...
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  • 326
14 votes

How do I protect my paper wallet from use by a different human who has used a random generator?

"Improbable" is an understatement. There are 2256 possible keys. In the entire universe, there are estimated to be "only" 2100 atoms. So the odds of someone else ending up with the exact same ...
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  • 1,334
13 votes
Accepted

What makes an extended public or private key?

The extended public key contains just a bit more information than the public key and chaincode, but the public key and chaincode are all that matter for key derivation. The rest is just metadata about ...
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  • 62.4k
12 votes
Accepted

Can private keys remain offline for their entire life?

Yes, all three assumptions are correct. You can with some effort keep your private keys offline for their entire life. A description of how to sign transactions offline is found here: How to sign a ...
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  • 64.5k
12 votes
Accepted

The length of the Bitcoin's private keys

Bitcoin uses the secp256k1 elliptic curve with 256 bit private/public key pair cryptography to render ECDSA functionality. The two bitcoin explorer (bx) commands below replicate statements/results in ...
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  • 2,927
11 votes
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difference between Master Public/private Key and Public/private Key?

With "Master public key" you probably refer to deterministic key derivation after bip32. The correct term is "Master extended private key" (acronym xpriv) and "Master extended public key" (acronym ...
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11 votes

How can I get the private key from wallet.dat from 2011 Bitcoin software on WinXP?

The wallet.dat was created with Bitcoin Core (in 2011 it was called "Bitcoin"). You should install the newest version of Bitcoin-Core (0.14.2 by the time of writing). The wallet.dat from 2011 should ...
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11 votes
Accepted

What are the chances of getting duplicate wallet using bitcoinlib in python3?

When you create a private key, this process is (or at least should be) completely random - meaning that in theory, the probability of creating some specific private key is 1/N where N is the number of ...
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  • 336
11 votes
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How can a deterministic wallet have one private key but multiple public keys

No, there is not one private key. There is one Master private key. The master private key is then used to generate more private keys in a deterministic fashion, i.e. using the same master private key, ...
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  • 62.4k
10 votes
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Why do compressed and uncompressed public keys have to produce different addresses?

My question is: Why cant you just uncompress the compressed public key (effectively making it an uncompressed public key) and then derive the address. That way even if you use the compressed key, ...
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9 votes
Accepted

What roles of WIF(Wallet Import Format)?

Are there any good points of WIF It is shorter than decimal/hex representation. And, yes, there is checksum. Can I sign on a transaction by using WIF without the private key? WIF is a ...
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  • 6,650
9 votes
Accepted

Can same private key generate multiple addresses?

One private key maps onto two addresses - one that uses an uncompressed public key, and one that uses a compressed public key. What you might also be interested in is a deterministic wallet - a ...
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  • 42.8k
9 votes

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

You have many private keys Quintessentially, a wallet is a key chain for your private keys plus optional convenience and usability functions. When you create a wallet, at least one but usually lots ...
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  • 64.5k
9 votes
Accepted

What is the safest physical to store a private key only to be accessed after death?

If you are comfortable with a command line, I have used ssss-split and ssss-combine for sharding encryption keys in a n-of-m scheme. These utilities use Shamir's Secret Sharing Scheme to safely break ...
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  • 8,734
9 votes

Can I recover btc sent to an incorrect address? (electrum)

Can I recover btc sent to an incorrect address? Confirmed Bitcoin transactions cannot be cancelled, reversed, undone or recovered. The only person who can give you your money back is the recipient, ...
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8 votes

Import private key to coinbase?

Coinbase no longer supports any sort of wallet import (wonder why?). To quote Coinbase (June 2016 on https://support.coinbase.com/customer/en/portal/articles/2285419-how-do-i-import-an-existing-wallet-...
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8 votes

Is it important to have an unencrypted backup of the private key?

It is important to be able to recover your private keys using only tools you fully control. That protects you against failure of infrastructure you would otherwise need to transfer your funds. There ...
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8 votes
Accepted

Why can't we switch private and public keys?

The ECDSA signature algorithm used by Bitcoin doesn't have symmetry between its private and public keys. If you read about how the algorithm works, they aren't even the same type of mathematical ...
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8 votes

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

If you are posting different questions I suggest, posting them up in different threads. But I'll try to answer all of them. 1) It doesn't work like that. Every address is a pair (private key, public ...
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  • 344
8 votes

Convert WIF to private key

converts WIF private key back to basic private key format import hashlib import base58 import binascii private_key_WIF = input("WIF: ") first_encode = base58.b58decode(private_key_WIF) ...
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8 votes

Importing private keys creates different address

Prepend "p2wpkh-p2sh:" to the private key before importing it into Electrum. For example: p2wpkh-p2sh:5Kkzs8XrJNAmf9VQDFeGBfaRvSByAvPK6DbDXw5BVqswWaXSG2Y
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  • 2,560
8 votes
Accepted

How can my private key be revealed if I use the same nonce while generating the signature?

Let me rewrite your question in a different notation, where all lowercase values are integers and uppercase values are points. The group generator is G (a known constant). The private key is q, its ...
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8 votes
Accepted

How does BIP 39 mnemonic work?

Mnemonics are the private key separated in 12 words which joined together in the very same order produces the private key That is incorrect. A mnemonic represents an entropy that is passed to a ...
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  • 6,978
8 votes
Accepted

A security need for Bitcoin to fork to quantum resistant algorithm in a few years?

asymmetric ciphers Ones based on specific primitives, like RSA and ECDSA specifically. Symmetric algorithms are supposed to be safe. With approximately half the number of bits of security due to ...
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  • 15.1k
8 votes
Accepted

Is Sharding a Good Alternative to MultiSig?

Advantages of OP_CHECKMULTISIG over Shamir Secret Sharing for k-of-n: There is no need to reconstruct the actual secret key on one specific machine. With SSS, you're inherently relying on that one ...
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