21 votes
Accepted

Won't ASIC miners eventually break SHA-256 encryption?

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: ...
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  • 687
21 votes
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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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11 votes
Accepted

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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  • 62.5k
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
6 votes

why is the blockchain necessary if bitcoins utilize cryptography

Problems: 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 ...
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  • 6,218
6 votes

data confidentiality on blockchain

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 ...
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5 votes

Are there Bitcoin password crackers I can use to recover forgotten passwords?

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 ...
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5 votes
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one time pad using blockchain

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 ...
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5 votes

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

If you want to encrypt messages, you should use a proper message/file encryption tool like PGP/GPG. Homebrewed cryptography using bitcoin things is prone to having poor security properties.
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  • 7,519
5 votes

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

Be sure to follow the warnings given previously in other answers, but for the record this was implemented in a project called Bitmessage. The main implementation is in Python at https://github.com/...
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  • 7,090
4 votes

BIP38 or Brain wallet?

BIP38 wallets are significantly more secure and are resistant to brute-force attacks when a decent passphrase is used. Generally the term "Brain Wallet" refers to one in which the private key is ...
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4 votes

How long would it take a large computer to crack a private key?

A Bitcoin private key (ECC key) is an integer between one and about 10^77. This may not seem like much of a selection, but for practical purposes it's essentially infinite. If you could process one ...
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  • 1,101
4 votes
Accepted

Could someone solve for your private keys by sending many transactions to the same address?

So there are attacks where if you sign enough times with the same private key, the attacker, with access to a side-channel can figure out your key. So if you were signing with your private key a lot ...
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  • 7,639
4 votes

How can I fix corrupted encrypted wallet.dat?

Found out that pywallet has recovery feature, and it worked: Created 1GB FAT32 partition on flash drive(/dev/sdb1 in my case), copied corrupted wallet.dat on it and run: nyaa@ubuntu:~/github/...
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  • 171
4 votes
Accepted

Is this how I should calculate a Double SHA256

Yes you should convert your first output before feeding it back in: A hash function is typically a function which takes in an array of bytes (of arbitrary size) and spits out an array of bytes (of ...
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4 votes
Accepted

Should I put my bitcoin wallet on an encrypted disk or not?

This only helps when someone malicious has physical access to you hard drive while your computer is not operational (shut down, account logged out, screen locked, etc.). When your operating system is ...
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  • 3,154
4 votes
Accepted

How do Ledger Backups get stored?

Using words to back up wallets is a process described in BIP 39. Basically, the mnemonic is converted into a seed. This seed is then used as the seed to a Heirarchical Deterministic (HD) wallet, as ...
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  • 11.4k
4 votes

Ironically, encryption is not an important part of bitcoin (?)

Cryptography and Encryption In the wider world, cryptography is used for a variety of security related purposes: Authentication (proof of identity, or proof of ownership) Non-repudiation (author ...
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4 votes
Accepted

Bitcoin and encryption

Bitcoin uses cryptography to create digital signatures and cryptographic hash functions for various purposes such as transaction ids, block ids, and to commit to specific transactions in blocks. The ...
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  • 64.7k
3 votes

How are transactions secured?

First of all, nothing is encrypted in Bitcoin, there is no "encryption" involved whatsoever. Cryptography: yes, but encryption: no. The main aspect of private vs public key signing, is dat you can ...
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3 votes
Accepted

API Authentication via Python

A closer look at their API page, you will find LakeBTC has provided a simple code for Python: https://github.com/LakeBTC/lakebtc_python And others Sample Code you can find here: https://www.lakebtc....
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3 votes

Won't ASIC miners eventually break SHA-256 encryption?

TL;DR: No, but if the hashes were collected, one might be able to better tell as to whether or not the SHA256^2 algorithm is broken. If one can find a way to produce desired outputs from specific ...
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  • 1,193
3 votes
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How should I encrypt a bip39 mnemonic with a password?

Bip39 has an optional "encryption" over PBKDF2 (passphrase-to-key) used as salt (this allows possible deniability). https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki#from-mnemonic-to-seed ...
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3 votes

Do all Cryptocurrencies uses same Public key Cryptography algorithm?

Not necessarily. A cryptocoin can use whatever asymmetric algorithm they choose, and I'm sure some have tried different things, but ECDSA has a big advantage: public keys are generated from private ...
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  • 8,734
3 votes

How do Ledger Backups get stored?

It is a common misconception that there are actual objects or chunks of data that are Bitcoin and that your wallet receives. That is actually not the case; your Bitcoin are just values attached to ...
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  • 62.5k
3 votes

Encrypting wallet manually instead of using hardware wallet

The benefit of hardware deterministic wallets is that your keys are permanently kept offline and secret, as long as you don't leak your seed words. To spend bitcoin, the transaction signing is ...
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3 votes

How does blockchain technology handle the actual transaction data?

how are these files stored, encrypted and sent to B on the blockchain? They aren't. Those files are not stored on the blockchain nor are they transmitted to B using the blockchain. Does blockchain ...
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  • 62.5k
3 votes

data confidentiality on blockchain

Most blockchains do not promise confidentiality. Those that do usually employ some form of zero knowledge or encryption, such as with ZCash. The exact specifics of the implementation will vary wildly ...
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  • 16.5k
3 votes
Accepted

Is encryption really needed for blockchain to work?

Bitcoin does not use encryption, and does not need to in order to secure ownership of coins. Ownership of coins is proven by digitally signing a transaction with the owner's private keys. The ...
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  • 7,090
3 votes

Ironically, encryption is not an important part of bitcoin (?)

Standard transactions are digitally signed using a private key. If a middle man tampers with the transaction, then the digital signature verification would fail, because the only way to produce a ...
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  • 7,090

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