40
votes
51% attack - apparently very easy? refering to CZ's "rollback btc chain" - How to make sure such corruptible scenario can never happen so easily?
Disclaimer: I believe this question may be primarily opinion-based and not very appropriate for this site, but there are a number of technical misunderstandings that can be clarified along with it, so ...
- 110k
26
votes
Accepted
How do you derive the private key from two signatures that share the same k value?
ECDSA signatures are pairs (r,s) where r=(kG).x mod n, and s = (m + rx)/k mod n, where x is the secret key, k is the random nonce, and m is the message.
If you have two s values s1 and s2 for the same ...
- 110k
26
votes
Accepted
Is a bitcoin address collision possible if generating 90 million addresses every 4 hours?
Because of the Birthday paradox, you only need 280 addresses (despite there existing 2160 different address combinations) before a collision becomes probable.
Thankfully, that is still an enormous ...
- 110k
23
votes
How can Bitcoin.org be hacked?
How is this possible? What happened to allow for this?
The same way that any website can be hacked. Bitcoin.org isn't hosted in some special way that makes it unhackable, it's a website, like every ...
- 72.1k
22
votes
Is there something about Bitcoin that prevents us from implementing the same privacy protocols of Monero and Zcash?
I'm curious as to why Bitcoin has not perused a similar path to privacy.
I want to start by commenting on the phrasing of this question. Bitcoin is defined by the consensus of its users, and isn't a ...
- 110k
20
votes
Accepted
Bitcoin automatically diverted to bech32 address
I'm sorry to be the bearer of bad news: It looks like your funds are gone and the security of your computer is compromised. A quick google suggests that is one of the electrum phishing destination ...
- 7,727
17
votes
Accepted
What is the origin of insecure 64-bit nonces in signatures in the Bitcoin chain?
Based on the time-frame and my impression of the capabilities of the various groups developing wallet software during that period my initial guess was that the Bitpay copay software might be the ...
- 7,727
17
votes
How can government "seize" bitcoins?
It is not necessarily true that no amount of force or authority can cause or prevent any transfer of Bitcoin. The protocol does not allow arbitrary seizures or blocking, but there are still human ...
- 72.1k
15
votes
Accepted
Schnorr's batch validation
You're right that the elliptic curve multiplication is indeed the most expensive operation in the validation algorithm. And as both single signature validation and batch validation require two EC ...
- 110k
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 ...
- 1,344
14
votes
Accepted
Why is no security lost by using 32-byte public keys in Schnorr signatures instead of 33?
From the (very recently updated) bip-schnorr draft:
Implicit Y coordinates are not a reduction in security when expressed as the number of elliptic curve operations an attacker is expected to perform ...
- 110k
14
votes
Is bitcoin.org or bitcoincore.org the one to trust?
It looks like https://bitcoincore.org/ is the one run by the people who run the Github bitcoin/bitcoin project (the actual core developers) since it is the one listed on their Github page: https://...
- 2,078
13
votes
Accepted
Miner modifies unconfirmed transactions and put it into the block
Is is possible that a miner modified a unconfirmed transaction (like changing the output of transaction to the miner himself) and put it into the local block, and after 10 mins the miner luckily ...
- 72.1k
13
votes
Why is increasing block size in the Bitcoin network considered to decrease security?
Generally speaking, a larger block leads to more computational resources (tx validation, bandwidth, storage, memory) required for each person who wishes to validate newly confirmed transactions.
...
- 2,521
13
votes
Long term BTC investing
Recommendations for how or where to buy Bitcoin are generally off-topic here, but long-term storage is a fair question.
First, understand what owning Bitcoin really boils down to: having knowledge ...
- 18.4k
12
votes
Accepted
Are lightweight LN wallets vulnerable to transaction withholding?
There is no substitute in terms of security and trust for running a full node.
There are different "lightweight client" concepts. Some of them are...
BIP37 (bloom filter):
[minus] With current used ...
- 6,072
12
votes
Accepted
Does assumevalid lower the security of Bitcoin?
which, as I understand it, makes some data (until 2017?) real without verification.
You understand incorrectly. Firstly, the assumevalid blocks is updated at every major release, so it is at most a ...
- 72.1k
12
votes
How can government "seize" bitcoins?
A lot of bitcoins reside in a trading platforms or online wallets. These bitcoins are (in the particular bitcoin sense) controlled by the platform. The government (provided the platform/wallet is in a ...
- 301
11
votes
Why does the TXID have 256 bits when Bitcoin's address security is 160-bit?
Security levels
First of all, the relation between security level and the number of bits involved is non-trivial, and depends on the sort of attack we're talking about. For what follows, there are ...
- 110k
11
votes
How can Bitcoin.org be hacked?
There are no websites that represent bitcoin, as bitcoin is decentralised.
bitcoin.org is owned by a person and is a site that gives information about bitcoin, as many other sites do, and there is no ...
- 372
10
votes
How to make totally secure Bitcoin transactions?
If your machine connects to the internet at all, it should be considered potentially compromised. Consider what happens to it if you visit GMail, which happens to deliver an ad with compromised ...
- 1,566
10
votes
Accepted
Why is the length of the transport messages on the lightning network encrypted?
TCP and other stream based protocols do not have a 1-to-1 correlation of application level messages and IP packets. If you call send() 3 times, it might result in sending a single IP packet over the ...
- 3,349
10
votes
51% attack - apparently very easy? refering to CZ's "rollback btc chain" - How to make sure such corruptible scenario can never happen so easily?
(adding some color) Some discussion I saw suggested that people promoting this believed they only needed to achieve >50% hashpower, which caused them to overestimate the feasibility. Reorging with ...
- 7,727
10
votes
How to transfer bitcoin? No third party, no exchange, no hard wallet, no mobile wallet
If you want to avoid all third parties, you need to run a node yourself. Download bitcoin-core and let it sync might take a day or two depending on your machine.
You can import your paper wallet by ...
- 5,676
10
votes
How can Bitcoin.org be hacked?
I'm immediately removing every single instance of "bitcoin.org" in my code, in particular the scripts that check for new updates of Bitcoin Core and AUTO DOWNLOAD/INSTALL them after ...
- 15.5k
10
votes
Accepted
How much entropy is lost alphabetising your mnemonics?
TL;DR: you get around a factor 500 million attack speedup for 12 words, bringing it not quite in the realm of feasible attacks, but it's getting close. For 24 words, the speedup is around a factor ...
- 110k
9
votes
What are checkpoints?
Update on this as of time of writing, just to clarify more specifically upon the other answer: dependence on checkpoints in the security model has been significantly reduced, they are only used in one ...
- 11.9k
9
votes
Accepted
How to make totally secure Bitcoin transactions?
The primary concern with Bitcoin security is where your private keys are stored.
In your scenario the private keys are stored on a Linux laptop which is not unreasonable if you follow good internet ...
- 849
9
votes
Accepted
Why was an insecure merkle tree implementation chosen?
As with many things in Bitcoin, it is likely simply because it worked well enough, and such an attack was not immediately obvious.
Several of the choices made in the early days of Bitcoin don't have ...
- 17.3k
9
votes
Should I be worried that bitcoincore.org now suddenly only provides an "unsigned" Bitcoin Core installer?
Beginning with Taproot? Hmm... Something about this feels scary to me.
Your mistrust is misguided.
So, they are no longer making "signed" installers?
The releases are still signed with ...
- 15.5k
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