All Questions
Tagged with z-cash or cryptocurrency
291 questions
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
1
vote
2
answers
344
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 ...
- 113
1
vote
1
answer
494
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 ...
- 113
0
votes
1
answer
115
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 ...
- 232
4
votes
3
answers
498
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 ...
- 101
1
vote
2
answers
135
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 ...
- 113
0
votes
1
answer
105
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 ...
- 11
2
votes
3
answers
293
views
Broadcast encryption not using symmetric keys
Is there a common scheme for broadcast encryption that doesn't involve an exchange of a shared key? I'm aware that traditionally a common symmetrical key would be given to all parties and exchanged ...
- 21
2
votes
3
answers
272
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 ...
- 21
1
vote
1
answer
137
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 ...
- 11
0
votes
2
answers
2k
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 ...
- 3
0
votes
1
answer
573
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
...
- 133
4
votes
2
answers
19k
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:
...
- 151
0
votes
1
answer
631
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 ...
- 151
0
votes
1
answer
142
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, ...
- 103
1
vote
1
answer
218
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 ...
- 11
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
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
-5
votes
1
answer
234
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
1
vote
0
answers
121
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 ...
- 589
2
votes
2
answers
417
views
Is there a way to bruteforce the private key of this cryptocurrency altcoin?
In the end of 2013 or the beginning of 2014, I bought 80 000 Applecoins (APC) for 0.1 Bitcoins and got another ten by an airdrop, so I had a total of 80 010. I never spent the coins, and when a ...
3
votes
2
answers
223
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 ...
- 274
2
votes
0
answers
92
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 ...
- 29
0
votes
2
answers
265
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
2
votes
1
answer
1k
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 ...
- 41
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 ...
2
votes
4
answers
644
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 ...
- 313
2
votes
1
answer
457
views
Hash function and Digital Encryption 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 ...
- 21
0
votes
2
answers
307
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 ...
- 41
-2
votes
1
answer
224
views
are all elements of ZpxZp in ECC definite over Zp
are all elements of ZpxZp in ECC (elliptic curve) definite over Zp ?
otherwise: assume G a base point of ECC and n the order of G.
why n is equal or nother to p*p ? (p a prime number).
(Think to a ...
- 1
1
vote
0
answers
332
views
Can Bitcoin mining solve Graph Isomorphism-related problems?
Given a cryptographic hash $H:\{0,1\}^*\mapsto\{0,1\}^N$ and data $D\in\{0,1\}^*$, the Hashcash/Bitcoin Proof-of-Work entails finding a nonce $x$ such that $H(x\Vert D)$ begins with $d$ leading zeros, ...
- 289
2
votes
1
answer
7k
views
Best method of converting a private key string into a 12 word mnemonic?
Is there a method of converting a Bitcoin private key into a 12 word mnemonic seed out of a 1000-2000 word dictionary? I couldn't think of a good way of solving this.
- 157
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
27
votes
1
answer
10k
views
Why hashing twice?
I'm trying to understand the Bitcoin protocol, and sometimes see instructions like this:
The TransactionId is defined by SHA256(SHA256(txbytes))
or
The hash of the public key is generated by ...
- 373
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
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
4
votes
1
answer
1k
views
SECP256K1 Jacobian algorithms
I am working on a bitcoin related project and I am trying to speedup the ecc calculation. I started with double-and-add and sliding window.
I would like to go move over to the jacobian coordinates. ...
- 395
2
votes
1
answer
547
views
Trouble understanding range proof of Greg Maxwell's Confidential Transaction
i've some trouble understanding the base of the range proof presented at
https://elementsproject.org/elements/confidential-transactions/investigation.html
I've understand the base of the Pedersen ...
- 21
1
vote
0
answers
262
views
How are attributes encoded in private keys in Attribute-Based Encryption?
I understand how private keys are generated from public keys in a setup like Bitcoin (using ECDSA).
I understand that anyone can verify they have the 'correct' private key using a digital signature ...
3
votes
2
answers
2k
views
Brute forcing an elliptic curve encrypted key
I've been reading about ECC, and what I've established so far (correct me if I'm wrong) is that:
pubKey = privKey * G
where G is some special point on the secp256k1 curve.
Doesn't this mean we ...
- 31
3
votes
1
answer
170
views
Piggyback on Bitcoin for independent data verification?
The recent threats to EPA data integrity have me wondering if it's possible to archive data in a way such that one can later check whether the data have been tampered with since the original archival.
...
- 133
40
votes
2
answers
13k
views
How does hashing twice protect against birthday attacks?
The bitcoin wiki says:
Bitcoin is using two hash iterations (denoted SHA256^2 ie "SHA256 function squared") and the reason for this relates to a partial attack on the smaller but related SHA1 hash. ...
- 503
6
votes
2
answers
191
views
Is there a signature scheme which doesn't rely on the difficulty of factoring/dlp which generates short signatures?
The Lamport signature scheme, for example, doesn't rely on the difficulty of any problem and it only depends on the existence of one-way functions.
Is there an alternative scheme which also doesn't ...
- 1,365
10
votes
3
answers
3k
views
Why don't crypto-currencies use the Lamport signature scheme?
The Lamport signature scheme is faster, less complex and considerably safer than ECDSA. It's only downside - being only usable once - isn't really a downside when signing transactions, since you could ...
- 1,365
3
votes
1
answer
910
views
Blockchain use in record management
From my understanding of blockchain, I feel the main use of blockchain is to do something in a decentralised way as compared to the traditional centralised way which involves a middle man. Usually, ...
- 2,266
-1
votes
1
answer
146
views
Signing operation with public key in bitcoin protocol (video lecture)
At 5:26 in this princeton coursera course video the presenter says that the public key is used (by the recipient) to generate the signature to redeem the coins.
I'm a little confused here. If the ...
1
vote
0
answers
98
views
Digital cash and blind signiture: coherence between signature and serial number
My question is about the basics of the topic "creating digital cash".
At the very beginning of that topic the amount of the banknote and a serial number are the requirements for generating a ...
- 111
8
votes
1
answer
467
views
What are the characteristics of a quantum secure protocol?
What are the characteristics of quantum secure protocol, and does it always need to be information theoretic to be called as quantum secure? Are the current techniques used in bitcoins quantum secure?
- 573
3
votes
1
answer
2k
views
GoofyCoin question -- why pk, why not sk?
At 45:43 in this video (from the Princeton Coursera Bitcoin and CryptoCurrency Course), they talk about GoofyCoin and show the image below.
My question is, why does it say "signed by pk"... isn't the ...
4
votes
1
answer
351
views
Could the multisignature scheme in bitcoin alternatively also be implemented by means of a Shamir Secret Sharing Scheme?
When I first came across the Bitcoin multisignature scheme, I wondered that it remarkably looked similar to what Shamir Secret Sharing does (SSS), but then by using facilities in the bitcoin scripting ...
- 111