All Questions
Tagged with ethereum or cryptocurrency
32 questions
3
votes
2
answers
2k
views
Can you tell me why doing scalar multiplication of a point on a Elliptic curve over a finite field gets to a point at infinity?
I am reading Programming Bitcoin. The author said:
Another property of scalar multiplication is that at a certain multiple, we get to the point at infinity (remember, the point at infinity is the ...
- 139
11
votes
3
answers
6k
views
Is double SHA-256 the best choice for Bitcoin?
So I was just curious.
I really look up to Blockchain technology and I have read that Bitcoin uses double SHA-256 for hashing.
( from what I understood, double sha256 is essentially $\operatorname{SHA-...
8
votes
1
answer
3k
views
How can uniformity of hash functions (e.g. SHA-256) be proved?
In reading about the Bitcoin protocol I noticed how much its proofs-of-work apparently depend on uniformity of the SHA-256 hash function. And so presumably do many other applications.
How do ...
- 243
61
votes
3
answers
13k
views
Hashing or encrypting twice to increase security?
Over on the bitcoin forums I asked why the bitcoin client computes SHA-256(SHA-256(x)) as its cryptographic hash for a variety of purposes. The leading theory--since the bitcoin author has disappeared-...
- 711
2
votes
5
answers
4k
views
Optimized modular multiplicative inverse for Bitcoin (secp256k1)
I have written an application to brute-force attack Bitcoin addresses for OpenCL. It implements a simple exhaustive search starting from public key G (private key 1) and point increment (addition of G)...
- 623
57
votes
4
answers
58k
views
Is secp256r1 more secure than secp256k1?
Curves secp256r1 and secp256k1 are both examples of two elliptic curves used in various asymmetric cryptography.
Googling for these shows most of the top results are Bitcoin related. I've heard the ...
- 1,047
19
votes
2
answers
9k
views
SHA-256: (Probabilistic?) partial preimage possible?
Currently busying myself with the Bitcoin "mining" algorithm, I am wondering if the process really cannot be simplified.
For reference, the algorithm is basically SHA-256d:
$$\mathit{success} := \...
- 312
20
votes
1
answer
6k
views
Will IBM's Condor quantum processor run Shor's Algorithm to crack a 256-bit Elliptic Curve key?
Yesterday IBM announced that they have a 433 bit quantum computer, called Osprey. There is nothing in the press releases I can find that says whether it can or cannot run Shor's Algorithm.
They also ...
- 353
13
votes
2
answers
8k
views
Does secp256k1 have any known weaknesses?
I am wondering whether there are any properties of the curve which would technically make it easier to attack than any other curves of 256 bits in size.
I have heard that being a Koblitz curve, it ...
- 245
7
votes
1
answer
2k
views
Elliptic curve cryptography related key attacks [closed]
This question is an extension of Families of public/private keys in elliptic curve cryptography
As described above, bitcoin "type 2" deterministic wallets use a root private/public key pair, where ...
- 95
3
votes
1
answer
1k
views
Has a SHA256 output ever been found consisting entirely of the same character?
Is it possible to have an output consisting purely of one character and does this change the entropy of that output? (If that's even possible to ascertain.)
As an example, the Bitcoin cryptocurrency ...
- 149
3
votes
1
answer
1k
views
ECC partially blind signature scheme verification
Continued from Is there a flaw in this ECC blind signature scheme?
The problem
I needed a partially blind signature scheme for one of my projects, but couldn't find one on the internet, so I've made ...
- 185
3
votes
2
answers
3k
views
Would SHA-256(SHA-256(x)) produce collisions?
Was reviewing some Bitcoin public-key hash literature and the use of RIPEMD-160 and the SHA-256 as below:
RIPEMD160(SHA256(ECDSA_publicKey))
The Proof-of-work ...
3
votes
1
answer
748
views
Is AES a group?
The question I'm wondering is whether the AES cipher is a closed cipher (which is equivalent to AES being a group). And this question interests me due to the lack of understanding of whether it is ...
- 53
-2
votes
2
answers
1k
views
How to find at least one private key from a large list of compressed public keys secp256k1
Not long ago I saw a discussion on the Bitcoin Talk forum:
https://bitcointalk.org/index.php?topic=5060735.msg50736695#msg50736695
Please give advice and working methods? Is it possible to find at ...
11
votes
1
answer
1k
views
HD (Hierarchical Deterministic) Keys using Safe Curves?
Bitcoin's HD (Hierarchical Deterministic) Keys as described in BIP32 allow for a master key to be created (a private key and a chain code) such that a tree of both public and private keys can be ...
9
votes
2
answers
895
views
Is there a guarantee that for each possible hash y there exists a number x such that with hash function H, H(x) = y?
Specifically talking about SHA-256 here and its involvement in Bitcoin, this was a question someone asked me which I didn't know the answer to. Yes, I am aware that SHA-256 can only have a hash from $...
- 93
9
votes
1
answer
2k
views
Simple digital signature example that one could compute without a computer?
I am working on a document to explain Bitcoin to students. But I am having a hard time translating the principle described in §2 of the Bitcoin whitepaper in layman's terms.
There is a great question ...
- 207
6
votes
1
answer
864
views
Can a digital money system exist, that's secure, anonymous and allows offline transactions?
I just read Offline anonymous electronic money systems and their cryptographical base , which asks for anonymous offline systems. The OP claims eCash is such a system, and the answer claims that ...
- 25.1k
5
votes
1
answer
892
views
Is there a flaw in this ECC blind signature scheme?
Recently I've found the following work on the internet: An ECC-Based Blind Signature Scheme
The paper claims to be an ECDSA blind signature however it seems that their scheme has a flaw in it.
The ...
- 185
5
votes
3
answers
18k
views
How can i check if a public key match with a private key
Is there a way to check, (with openssl command for example), if a given public key match with a private key ?
Thanks
- 151
5
votes
1
answer
2k
views
In Bitcoin, given half the 52-character private key in WIF format, is it possible to reconstruct the whole private key?
Given the following two preconditions:
It is almost impossible to reconstruct a bitcoin private key if an attacker only has one half of the private key as well as the public key.
It is almost ...
- 151
4
votes
1
answer
590
views
Can keys from Bitcoin's Hierarchical Deterministic Wallets be correlated (reducing privacy)?
I'm trying to understand if the feature "Hierarchical Deterministic Wallets" in Bitcoin allows for complete privacy of all derived keys, and if any of those keys can be associated with each other ...
- 2,631
3
votes
0
answers
354
views
Are digital signatures a type of zero-knowledge proof?
Are the digital signatures used in cryptocurrencies such as Bitcoin a type of zero-knowledge proof?
3
votes
1
answer
853
views
Is it possible to combine digital signature to provide message addition?
Let's assume we are using the textbook RSA where $Sig(x)=x^d$. Alice has public key $(e,N)$, and private key $(d,p,q)$.
Now, if Alice sends $Sig(5)$ and $Sig(10)$ to Bob, where $5$ and $10$ is just ...
- 452
3
votes
2
answers
404
views
Cryptocurrency for quantum computers that is physically impossible to double-spend?
Could a cryptocurrency running (at least partially) on a quantum computer (and/or on a quantum network) be developed in which it is physically impossible to double-spend? In other words, a coin in ...
- 33
2
votes
1
answer
226
views
How to implement a "viewing key" for secrets proved by zero knowledge proofs?
In ZCash, Monero etc, the sender/receiver addresses as well as transaction details are hidden. However, with a viewing key, a third party can see the exact details of the transaction or all ...
- 21
2
votes
2
answers
641
views
How Secure Is Splitting A Bitcoin Private Key?
NOTE: This question cannot be posted to Bitcoin SE because it will not render there due to the mathematical notation. Since the mathematical notation is part of the question, this is the more ...
2
votes
1
answer
1k
views
Offline anonymous electronic money systems and their cryptographical base
What anonymous offline electronic money systems exist and what are they based on? I know only one currently - eCash, based on RSA blind signatures.
2
votes
1
answer
3k
views
Can someone give me an example of a Merkle–Damgård transformation?
I started reading "Bitcoin and Cryptocurrency Technologies - Princeton University" (coursera) and in the first chapter it talks about Merkle–Damgård transformations for SHA-256. I was trying to ...
1
vote
1
answer
2k
views
anonymous signature implementation and usage?
This is one of the question asked in my class. Implement a anonymous digital signature. So it means hiding signers information. i could not find any article in anonymous digital signing. Also another ...
- 111
1
vote
2
answers
427
views
How does this formula work $(aG + bG) = (a + b) G$ in ECDSA?
Please explain how does this formula $(aG + bG) = (a + b) G$ work in ECDSA?
According to the source:
$a$ and $b$ are different private keys
Suppose
$a = 3$
$b = 4$
then the public key is $Q = aG$...
- 19