Questions tagged [cryptocurrency]
A cryptocurrency is a digital currency powered by cryptography. This tag is applicable only to Q&As about the cryptographic mechanisms used by a currency, not for questions about economy, usage, or acquisition of any particular currency. Please note that Stackexchange has dedicated websites for Bitcoin, Ethereum, Monero, etc.
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0answers
24 views
Public / ePub / Private Keys [closed]
I have googled a lot but I still didnt get the answer right about the following questions in terms of Crypto:
What is Public Address?
What is ePub Address?
What is Private Keys?
Is it Safe to give ...
0
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0answers
21 views
Time-locked deposit 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 ...
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votes
1answer
89 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 ...
3
votes
1answer
124 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....
1
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1answer
82 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
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1answer
76 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 ...
0
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1answer
95 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 ...
3
votes
2answers
77 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 ...
0
votes
1answer
38 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 ...
0
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2answers
73 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
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0answers
18 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 ...
3
votes
3answers
238 views
Why is it impossible to find the private key from the public key?
From what I understand, based on the article A Beginner’s Guide: Private and Public Key Cryptography Deciphered, the public key is generated by performing $n$ tangent plus mirroring operations from ...
0
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0answers
44 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 ...
2
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1answer
73 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 ??
1
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0answers
42 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 ...
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votes
1answer
83 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
1answer
175 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 ...
3
votes
1answer
61 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 :
...
0
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1answer
72 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?
1
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1answer
326 views
ECDSA vulnerability related to recovering private key using same r
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 ...
1
vote
2answers
200 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 ...
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votes
1answer
186 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]....
3
votes
1answer
48 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?
...
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2answers
139 views
Zencash uses your passphrase to identify AND unlock a wallet - how is this secure?
When looking into Zencash I stumbled into myzenwallet.io (by the Zencash creators), which gives you the option to enter a passphrase to generate a wallet (seems normal), but then after creating your ...
1
vote
1answer
153 views
Basic question on interaction with HSM using PKCS11
I am a beginner on cryptography, I've been reading about PKCS11 and usage of PKCS11 on HSM's
I understand the concept of HSM,
I read about the HD wallets in bitcoin how keys are hashed and combined ...
0
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1answer
41 views
A method to receive payments at obscured addresses [closed]
The background:
We assume that coin ownership and payments are recorded on a public ledger.
Suppose Alice wants to publish some information to let her receive coins from anyone.
But she does not want ...
3
votes
1answer
90 views
Why won't a BFT protocol using simple signing/voting work?
PBFT and most consensus algorithms are more complicated than a simple voting scheme. By simple voting I mean the following: we require all nodes to sign their local copy of the state and send this ...
1
vote
2answers
54 views
How does `d-KCA` help secure the zcash protocol?
I have been going back and forth between part 2 and part 4 of the Explaining SNARKs series.
In part 2, it is claimed that Bob has an idea about the polynomial and want to test whether Alice knows it ...
0
votes
1answer
49 views
Paper wallet QR codes
What is the purpose for and distinction between each of the following keys commonly used in cryptocurrencies?
Address
Tracking key
Passphrase
Private key
For context:
I got a bytecoin paper wallet ...
2
votes
3answers
141 views
Is that possible to prove that 'I do not know something' (i.e, the private key for a Bitcoin wallet) using cryptography?
Is that possible to prove that 'I do not know something' (i.e, the private key for a cryptocurrency wallet) using cryptography?
The problem might be nonsense at first glance. But the intuition for ...
1
vote
1answer
124 views
Revealing vote after time
Imagine we have 5 different parties, all of these parties test if a particular thing is true or false over the course of 24 hours. The network needs to come to a consensus about the majority outcome ...
0
votes
2answers
568 views
Probability last character sha256 hash
A quick question. I want to use the last character of a SHA256 hash (blockhash of a bitcoin block) as my random source. Is 100 /16(amount of different chars) = 6.25% true for all characters or are ...
0
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1answer
176 views
Signature Aggregation / Multi-Signature
I want to save the space signatures take up in a block of Bitcoin transactions. To simplify it, here is the general transaction structure in a block:
message
public key
signature of the message
...
2
votes
2answers
2k views
How insecure is AES-128-CTR to encrypt any kind of data using the Ethereum keystore file format?
I am using the Ethereum keystore file format to encrypt any other data such a plain text or JSON.
Here is an example of pseudocode of the implementation:
...
0
votes
1answer
268 views
Is my AES-128-CTR implementation secure enough to encrypt private keys and mnemonic seed? [closed]
I am building a cryptocurrency wallet online where everything is stored in the browser (No servers).
At this moment I am storing all private keys encrypted using AES-128-CTR I've chosen this method ...
0
votes
1answer
59 views
Do I need to use HMAC in this crypto wallet backup application?
I'm building an application for securely backing up cryptocurrency private keys or 12-word backup phrases that crypto wallets use as a seed to generate private keys. For the purpose of this question, ...
1
vote
1answer
97 views
Use of cryptographic hash for computing previous block hashes in blockchains
Why is the previous block hash computed using a cryptographic hash function instead of a regular hash function in Bitcoin and other blockchains?
What cryptographic hash properties (pre-image ...
2
votes
1answer
255 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 ...
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0answers
23 views
I lost my wallet seed. how i find seed of wallet [duplicate]
I recently lost the seed of coin purse that participated in ico. Is there a way to find Seed?
0
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4answers
922 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)...
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votes
1answer
142 views
Someone discover two pair privkey for one address
I have a question about bitcoin privkey:
If you have TWO pair privkey(compressed and uncompressed) I wrote again TWO pair, yes i know, many person say - it is not possible, but...
And this works ...
1
vote
0answers
94 views
Reconciling Multiple Blockchains?
I'm playing around with the idea of a blockchain where both the proof-of-work and verification steps are NP-hard. It seems the NP-hard verification step can be resolved if you allow for multiple ...
3
votes
2answers
191 views
Lack of usage of secrets in ZK Bitcoin ownership proof
I read the paper "Provisions: Privacy-preserving proofs of solvency
for Bitcoin exchanges" which is available for download on http://crypto.stanford.edu/~dabo/pubs/abstracts/provisions.html and have ...
3
votes
0answers
62 views
Ecash - Probability of catching a user using secret splitting who duplicates the coin
For detecting double spending, secret splitting is used. If a user duplicates the coin, then there will be two different transaction items in transaction list. What is the probability of catching a ...
0
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2answers
188 views
Bitcoin Private Key Question
If Bitcoin can be forked, and the same address can exist on both blockchains, what stops the re-generation of a privatekey on one blockchain that would also work on the other?
For that matter, what ...
1
vote
1answer
559 views
How difficult is it to crack sha256(sha256(pin)) with a 6 digit pin and no salt?
My friend forgot the password to his electrum wallet but knows that it's a 6 digit pin. I looked into it and from what I can find electrum uses the sha256(sha256(pin)) to generate the key used to ...
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1answer
473 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 ...
2
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4answers
328 views
How would I convert committed coordinates $x$ and $y$ to a commitment of the EC point without revealing the point (in Zero Knowledge) or vice versa?
I am working in the secp256k1 elliptical curve, though I suspect this would apply to any elliptical curve. I have a Pedersen Commitment of the $x$ and $y$ coordinates in some discrete log scheme with ...
1
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1answer
160 views
Hash function and Digital Excryption Algorithm
I am familiar with the fundamentals of cryptography as well as Digital Signatures. I understand how DSA like RSA works and the fundamentals of mathematics behind digital signing and verification. I ...
0
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2answers
155 views
Why can't you hijack someone's public key
Sorry, this might be a stupid question but the more questions are here the easier you can use the Internet.
To sign your message in Bitcoin network, Alice uses his private key and message content. Bob ...
