how long in bytes the private key is
32 bytes, or 256 bits
then how many combinations of numbers it will contain
There are 2^256 different private keys. That's a little larger than a 1 followed by 77 zeroes.
what is the fastest computer or network of supercomputers
At its peak around August 2011, the Bitcoin network was checking 15 trillion sha256 ...
It gets it from the keypool, which has 100 pre-generated addresses by default. The next time you enter your passphrase, it will refill the pool with new addresses.
Here's an example that shows the pool running out, and refilling when the password is supplied. The following commands were performed by a trained professional. Please don't try this at home (...
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 encryption unnecessarily encourages treating them as a long-lived identity.
There may be ugly and dangerous interactions when keys are used for multiple protocols ...
Another way to look at it is to take a look at a recent block that was mined, for example, block 388368. Looking at this block on blockchain.info, you can see that the hash for this block is:
It took roughly 10 minutes for all of the miners (doing a combined 700,000,000 giga-hashes per ...
A Bitcoin private key is a random 256-bit number. However, the public key reveals some information about the private key. The best known algorithms for breaking ECDSA require O(sqrt(n)) operations. That means 2^128 operations would be needed to break a Bitcoin account.
The largest ECDSA key broken to date of the type that Bitcoin uses was 112 bits long. A ...
Private keys are 256 bit numbers
Public keys are a pair of X,Y coordinates. Each coordinate is a 256 bit number. BUT for every X coordinate there are only two possible Y coordinates (one positive, one negative) so you can store a public key as just the X coordinate (256 bits) and the sign of the Y coordinate (1 bit) and the proper Y coordinate can be ...
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, you will generate the same private keys. Those private keys are what are actually used in your wallet. Their public keys are generated and the addressees ...
All of Bitcoin's public-key cryptography is done with secp256k1. Every sane transaction has at least one secp256k1 signature and at least one secp256k1 public key or public key hash (address). A complete overnight failure of ECDSA/secp256k1 is the only technical failure I can think of which could destroy Bitcoin. This is very unlikely, though.
Bitcoin is ...
Revalin made available a sript that you can try running:
There may not yet be anything else, but you'ld probably find someone willing to write one if you offered to send your wallet along with what you think the pass phrase might be and ask only for a fraction of the wallet's bitcoins back ...
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 Grover's algorithm.
Which components of the bitcoin blockchain would be exposed to quantum attacks?
The security of SHA256 would be halved, ECDSA would be ...
Below extract should answer your question.
public class ECKeyPair implements Key
private static final SecureRandom secureRandom = new SecureRandom ();
private static final X9ECParameters curve = SECNamedCurves.getByName ("secp256k1");
private static final ECDomainParameters domain = new ECDomainParameters (curve.getCurve (), curve.getG (), ...
If the key pool is empty and the wallet is locked it will use an old key instead of generating a new key. When wallet encryption was implemented the block creation code was changed to make sure different coinbase transactions are generated in that case.
Besides storing your current private keys, bitcoin wallet file also contains some pool of unused private keys. When encrypting wallet, this pool is flushed.
If you make some transaction using new (encrypted) wallet then change is sent to one of addresses from the pool, which is not present in old (unencrypted) wallet.
For example, you had 1BTC incoming ...
No. Note that that the software's encryption encrypts only the private keys, not transaction and address book information, so to protect your privacy you may want to add encrypting the file itself.
1) Sybil attack (this is actually a huge one and has been for decades and decades in all kinds of applications). Other answers already mentioned this too. What is a majority if one attacker can easily pretend to be 10 million nodes?
Bitcoin makes (mining) nodes do Proof of Work and it's the amount of (unfakeable) work done that counts, not the ...
The traditional answer for Bitcoin to this question is "pseudonymity, not anonymity".
All the data published on the blockchain is necessary for the world to validate that transactions are valid, no theft occurs, no money is being printed, ... but not more. In particular, there are no identities on the chain, and reuse of (otherwise visible) addresses is ...
bitaddress.org allows you to recreate your public key from a private key. Go to the "Wallet Details" tab, paste in the private key and click 'view details'.
If you really don't trust ...
Since 0.6.0, key import/export are available in the client itself, though only through RPC. The commands are called dumpprivkey and importprivkey. For example (on testnet):
$ ./bitcoind getnewaddress
$ ./bitcoind dumpprivkey n2JjZgLeCUgfubswxDm9zAaBGSLLHSLdNv
Another alternative is btcrecover, available on GitHub here. From the Tutorial:
btcrecover is a free and open source multithreaded wallet password recovery tool with support for Armory, Bitcoin Core (a.k.a. Bitcoin-Qt), MultiBit (Classic and HD), Electrum (1.x and 2.x), mSIGNA (CoinVault), Hive for OS X, Blockchain.info (v1 and v2 wallet formats, both ...
See the following links for an overview and for details.
Note: In short, if you do not have a strong understanding of the BIP38 encryption and decryption workflow, do not BIP38-encrypt your paper wallet. Just print your paper wallet out without encryption, and keep it safe the same way you would jewels or cash.
Just encrypting with AES provides excellent ...
The requirement for a one time pad to be secure is that it consists of uniformly random data, only known to the participants that should be able to encrypt/decrypt.
The blockchain is not random (it's created by miners and users creating transactions), certainly not uniformly random (blocks and transactions have a very strict syntactic structure), and worst ...
The password must be at least 1 character long. I've not been able to find a maximum length. I set the passphrase to be a 100,000 character string, and that worked fine. Missing the last character off the end of the long string didn't work, so the 100,000th character is significant.
When first setting a passphrase the satoshi client requests that your ...
There is a script provided by a forum user Revalin which can be used to attempt variations. There is a forum user Rix who may be available for hire to provide assistance with this type of problem.
You can also try out this script:
You only need the passphrase to do certain things like send bitcoins or change the passphrase.
The encryption itself is attached to the wallet.dat file which contains
keypairs for each of your addresses
transactions done from/to your addresses
a version number
and if you ever want to switch ...
It will take significant resources (probably more electricity than can be generated by all fossil fuels on Earth) and time (orders of magnitude greater than the age of the universe) to generate a complete Bitcoin address "rainbow table".
See these answers for more details.
The files with the .cipher suffix are the regular wallets encrypted with 256 bit AES.
The password used is the one you use to first encrypt your wallet. MultiBit goes through all the unencrypted wallets, creates an encrypted copy and secure deletes the unencrypted one.
You can open the .cipher wallets using File | Open wallet and it asks you for the ...