All Questions
Tagged with z-cash or cryptocurrency
290 questions
4
votes
1
answer
289
views
Post-quantum aggregate / multi signatures
Are there any practical post-quantum aggregate / multi signatures?
Currently, the aggregate / multi signature schemes seem to be limited to pre-quantum elliptic curve assumptions only, e.g., [BDN18], [...
- 438
3
votes
1
answer
445
views
Proof of membership on a merkle tree
I read the zcash paper recently. But I have been puzzled by a question. How did the authors prove that the coin commitment appears as a leaf of a Merkle tree with root rt? Apparently, the authors ...
- 61
3
votes
1
answer
313
views
How does ZK-snark work in zcash?
For a public one-way function $f()$, we can use zero proof to prove I know some secret $x$, such that the output of $x$ is a specific number $y$.
However, in zcash, I need to prove that I have some ...
- 61
1
vote
0
answers
57
views
Is the 51% attack the only technical reason no country will ever adopt Bitcoin as a state currency? [closed]
Is the 51% attack the only technical reason no country will adopt Bitcoin as a state currency?
Let's suppose a country with a GDP size less than 300 Billion USD adopt the Bitcoin as an official ...
- 111
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 ...
1
vote
2
answers
711
views
How does ECDSA signature verify work in EOS and ETH/BTC, compare to standard (on text book I mean)
I have been studing ECDSA signature/verify for a while. By my understanding: the standard ECDSA signature/verify process (which we find on text book) are like below:
- A sender combines message and ...
- 111
0
votes
1
answer
842
views
would parallel crypto mining work
Hi everyone I was wondering would it be possible to mine a cryptocurrency like bitcoin in parallel. I have read a little about mining pools https://en.wikipedia.org/wiki/Mining_pool , But that's not ...
- 15
0
votes
1
answer
788
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Bitcoin mining nonce and birthday attack
Having read the basics of mining and this about SHA256 (probabilistic?) partial preimage possible? and SAT solving - An alternative to brute force bitcoin mining, I have the following question:
...
- 103
-1
votes
1
answer
144
views
Double hash question [closed]
I would like a valid Bitcoin address (derived from a private key created by rolling a pair of hexadecimal dice 32 times) to be the private key of any private / public cryptography. So if I encrypt a ...
1
vote
0
answers
223
views
Modifying Elliptic Curve Parameters
For context, I was watching this bit of the video: which goes over this source code. The piece is about elliptic curve cryptography and how it works. I want to use some of this knowledge to make my ...
- 173
4
votes
1
answer
131
views
Time locked cryptography using Bitcoin difficulty param and/or smart contract?
Outcome: Create a message with a count down timer. Once a top level password is entered, a countdown timer starts. Once timer expires, the message is decrypted.
Known methods: Proof of work. ...
- 151
1
vote
2
answers
204
views
Is the following non-interactive zero-knowledge set membership protocol provably secure?
Given the following Zero-knowledge set-membership protocol https://infoscience.epfl.ch/record/128718/files/CCS08.pdf]. That is given in the following steps (Please refer to page 9).
The Verifier
-...
- 223
2
votes
2
answers
529
views
Whats wrong with my El Gamal signature example
I'm trying to digitally sign a message m using El Gamal. So far I've been unable to verify the digital signature ive made using El Gamal.
I am using prime number, p = 8369. prime root g = 3031. ...
- 31
1
vote
1
answer
76
views
Monero Ring CT sj calculation
For a university project, I am currently implementing the RingCT Ring signatures as used in Monero (before the introduction of Bulletproofs) as laid out in this paper.
To close the ring we calculate ...
- 121
-1
votes
1
answer
982
views
Is it possible for a hash in SHA-256 to have more than 8 digits? [closed]
Is it ever possible for a hash to have more than 8 digits in SHA-256?
user69001
2
votes
3
answers
8k
views
19 out of 24 words of BIP39 passphrase (brute-force last 5?)
I have managed to lose 5 words of my 24 word Ledger Nano S recovery phrase. I have words 1-19 but I am missing words 20-24.
I have significant holdings on the wallet so would very much like to recover ...
- 21
0
votes
0
answers
56
views
Problem with e-cash system with multiple banks
Say that many banks issue electronic cash of a particular type.
If there is a malicious bank and user collusion, the malicious bank signs electronic cash for a particular user. This user then takes ...
- 1
-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 ...
0
votes
1
answer
300
views
Block chain and storage issues
On reading about block chain technology, it was observed that it leverages the distributed ledger technology through P2P, here integrity is ensured through hash computed by miners, and then is ...
- 247
1
vote
1
answer
871
views
Question on using endomorphism on secp256k1 and negative results
I have read section 3.5 (algorithm 3.7) in "Guide to Elliptic Curve Cryptography", and have been trying to implement endomorphism on secpt256k1 to speed up calculating $kP$ by changing it into 2 point ...
- 95
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
1
vote
1
answer
309
views
Why is ethereum not using threshold signatures like dfinity for randomness? What's the drawback?
So Ethereum goes for RANDAO. The disadvantage with RANDAO is that the last validator in the commit-reveal scheme is able to hold his contributed value back and thereby influence the random outcome. ...
- 11
0
votes
0
answers
48
views
Explanation of Gallant-Lambert-Vanstone method / Endomorphism speedups [duplicate]
Can someone explain how the Gallant-Lambert-Vanstone method works (or which literature explains it)?
It is also unclear to me how the Frobenius endomorphism can be used in some cases for a speedup.
...
- 163
13
votes
2
answers
8k
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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
0
votes
0
answers
148
views
Concrete examples / tutorials of how blockchain/bitcoin works
I want to understand the crypto details behind the blockchain (at least in the form that bitcoin implements it).
Can you point me to some page or documents that show the details with examples?
I ...
- 121
0
votes
1
answer
864
views
The Secp256k1 curve is used in cryptocurrency. Can someone generate a private key with a different curve?
Many cryptocurrencies use Secp256k1.
Every cryptocurrency library comes with its own redundant implementation of Secp256k1, ECDSA, RIPEMD160, and SHA256. So, there can be some inconsistencies across ...
0
votes
1
answer
70
views
Time and location locked vault protocol?
I am designing a protocol where a user A sends a time-locked deposit to user that if the user B within time t provide a proof that he exists in a location x (this may be obtained by third party like ...
- 223
1
vote
1
answer
2k
views
How does Diffie Hellman protocol work in Bitcoin Blockchain Transactions?
Greetings to all! Please explain how the Diffie-Hellman protocol works in Bitcoin?
That is, in Blockchain Transactions, there is also a total number of "K" recipient and sender?
"K" the recipient and ...
- 27
3
votes
1
answer
647
views
Do I need to provide entropy to secp256k1_ecdsa_sign() ?
using secp256k1_ecdsa_sign() I noticed the same data signed multiple times, coming back with the same signature. I always thought that signatures are different because random data is somehow involved....
- 203
1
vote
1
answer
320
views
Does the One-Time Hash-based Signature Scheme render Ring Signatures useless?
On the Bitcoin community, to maintain privacy, they recommend using one-time spend addresses. CryptoNote, Monero et al. prefer Ring Signatures to maintain that privacy. There are some issues regarding ...
1
vote
1
answer
425
views
Blockchain without cryptography
Because blockchain is decentralized, what would happen if there was no cryptography anymore to protect the blockchain? I know it would not be used anymore but why? "Hackers" could reverse transactions ...
- 11
0
votes
1
answer
192
views
How might one create a system of election by lot (sortition) that is both secure and verifiable?
I've been puzzling recently over sortition, a democratic method of selection for public office which I find very fascinating. Basically, instead of choosing candidates like Hillary Clinton or Donald ...
- 153
3
votes
2
answers
308
views
Post-quantum SNARGs with near-constant verification?
We're building a private computation platform similar to Zexe, where nested proofs are used to preserve the privacy of the programs being computed. We may use different proof systems for the inner and ...
- 417
1
vote
1
answer
446
views
Ethereum RLPx protocol for inter-node communication - flaws in the encryption
Ethereum uses RLPx/devp2p for inter-node communication. The protocol is encrypted using Elliptic Curve Integrated Encryption Scheme (see ref)
Under Known-Issues I found this paragraph:
The RLPx ...
- 113
0
votes
1
answer
52
views
Economically Rational as a security proof
Is it possible to prove the security of a cryptocurrency payment protocol by saying that the actors will seek to maximize their profits. Would I need to set this up as a game and prove it that way or ...
- 113
0
votes
2
answers
357
views
The use of Elliptic Curves as part of a blockchain transaction
As I understand it, Elliptic-Curve Cryptography is used in the verification step of a transaction (i.e. when creating a digital signature), but not in the creation and security of a 'block' (when ...
- 1
2
votes
0
answers
96
views
General Private/Public key generation [closed]
I wanted to get an idea on how the whole cold-storage private/public key generation works for different cryptocurrencies. So I was playing around with BIP32 deriviation path on:
https://iancoleman.io/...
1
vote
0
answers
28
views
Can the precompiles in Ethereum Byzantium for pairings be used for implementation of BBS group signature verification?
I'm currently implementing a group signature verification on Ethereum and it seems that the Pairing check can only return a boolean.
According to the BBS algorithm, to validate a signature $s$, you ...
- 11
1
vote
0
answers
202
views
ChaCha20 - How confidentiality is lost if reusing nonce? [duplicate]
I read that (key, nonce) pair should be used only once for encryption of a message. My question is how confidentiality can be lost if two peers using a shared key use same (key, nonce) pair to encrypt ...
- 11
3
votes
1
answer
153
views
POW with Linear time to solve it?
Any suggestions for A Proof-of-Work algorithm in literature so that the time required for solving it is linear with the puzzle difficulty ??
- 31
1
vote
0
answers
82
views
Can I use a blockchain to lock access to some information before a certain amount of time has passed, without relying on third-parties?
Picture the following (the example is very similar to the real scenario):
I have a physical item in possession in which I want to lock myself (don't ask [1]) from accessing it until a ...
- 111
0
votes
1
answer
374
views
How do I convert KECCAK-256 to FLOPS? (Ethereum)
I wanted to know how much one Ethereum KECCAK-256(hash) is in FLOPS. I know bitcoin is 12,697 flops per hash.
0
votes
1
answer
3k
views
Half of any bitcoin (crypto) public key - (public key half) is possible
I found a topic on bitcointalk
Public key x and y == Double(Half of the Public key x and y)
half any public key is possible how that possible , in crypto there is subtraction and multiplication ...
- 167
3
votes
1
answer
267
views
Are there known special cases where the first 160 bits of keccak256 can be null ? Or does finding a collision is required?
In the Tronix contract code (a large ICO listed on many exchanges) lies this modifier which is used for all token transfers :
...
- 343
0
votes
1
answer
258
views
Does an anonymous signature hide the sender's identity from the receiver?
Does an anonymous signature hide the sender's identity from the receiver, or simply just hide the sender's identity from an eavesdropper or third party?
- 437
1
vote
1
answer
1k
views
ECDSA vulnerability related to recovering private key using same r [closed]
I'm considering this for bitcoin transaction as it uses ECDSA so if the signer generates two signatures suppose s1 and s2.
where:
I get it that any attacker who have s1 and s2 can recover its private ...
3
votes
1
answer
309
views
How can I generate a deterministic evenly distributed random number in a blockchain
Here's the hypothetical. There's a blockchain, which for the sake of simplicity, is modelled around Bitcoin and proof-of-work.
My goal, is that for each mined block, rather than a set reward (12.5 ...
- 133
2
votes
2
answers
2k
views
Could RSA keypairs be used for cryptocurrency addresses?
A bitcoin address is created from an ECDSA keypair. It is common to use use a hashed version of the public key as the shared address, but the original bitcoin implementation also allowed for using the ...
- 21
2
votes
2
answers
2k
views
ECC private key generation collision
I am generating ECC private keys. however I noticed that since ECC private key is just a BigInteger. e.g. spec256k1 says private key is anywhere between [0~2^256-1]....
- 133
3
votes
1
answer
70
views
How to decrypt using public key?
Can anyone decrypt ciphertext using a public key? I always thought we can only decrypt using a private key. In that case, what does this line in the RLPx documentation mean?
...
- 131