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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. The latter kinds are unwelcome. Please note that Stackexchange has dedicated websites for Bitcoin, Ethereum, Monero, etc.

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Bitcoin Key Recovery Without Nonce Re-Use

There are a lot of questions in these forums regarding the recovery of private keys. But I'm here to postulate on something unique to a specific piece of research that I looked into recently. The ...
-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 ...
1 vote
2 answers
585 views

Can we retrieve his private key using his public key in ECC?

A paper wallet is the name given to an obsolete and unsafe method of storing bitcoin which was popular between 2011 and 2016. It works by having a single private key and bitcoin address, being printed ...
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i want to verify the following p2pkh transaction

I know to veify the p2pkh transaction we have to place the unlocking script and locking script in a stack and than evalute the stack. In such cases the the scriptpubkey_asm is of the form <OP_DUP ...
2 votes
1 answer
514 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 ...
1 vote
1 answer
67 views

How should I map E'(Fp6) --> E'(Fp) starting from Bitcoin public key coordinates(x,y)?

Let $p$ be the prime number 115792089237316195423570985008687907853269984665640564039457584007908834671663 and let $E$ and $E'$ be the curve equations $$E(\mathbb ...
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1 answer
60 views

Can I construct a incomplete Merkle Tree without denting its security?

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3 votes
1 answer
724 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 ...
4 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 ...
4 votes
1 answer
347 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 ...
13 votes
2 answers
7k 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 ...
-1 votes
2 answers
280 views

Formula for deriving the x-coordinate using the y-coordinate (decompressing a compress public key)

According to my understanding a public key is made up of x and y coordinate and a compress public key is made up of the y-coordinate since it's possible to directly calculate the uncompress public key ...
1 vote
1 answer
466 views

What if the hash code of the genesis block (first block in the block chain) is changed?

If so, what would happen? And if not, what are some limitations to it? The reason I am asking is because I just started getting into the cryptocurrency and am very interested in the cybersecurity ...
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1 answer
99 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 ...
-1 votes
2 answers
221 views

If it is proved that P=NP, what happens to crypto? [duplicate]

If various PKC is shown to be not NP=Hard, what happens to crypto? More importantly, what happens to crypto wallets? If it is shown that P=NP for many currently assumed to be hard problems, but ...
2 votes
1 answer
127 views

In NIZK, what is the difference between "transparent“ and “without trusted setup”?

When I study a zk-SNARK scheme, the scheme claims to be transparent. Does this mean that this scheme does not require a trusted setup? Furthermore, if a NIZK scheme includes a Common Reference String (...
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3 answers
234 views

bitcoin public address cryptography

I was learning about bitcoin cryptography and seen some strange bitcoin public addresses like this 1Lets1xxxx1use1xxxxxxxxxxxy2EaMkJ 1fuLL1xxxx1power1xxxxxxxxxxzatvCK ...
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Interacting with Zksync sometimes returns an "invalid value for value.blockHash" error

I've been sometimes getting this error while interacting with zksync "invalid value.blockHash" and have been unable to find information about it elsewhere. What's curious to me is that it ...
1 vote
1 answer
194 views

Deriving of the y-coordinate on secp256k1 elliptic curve

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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 ...
1 vote
0 answers
39 views

How can the validity of signatures in layer-2 transactions be proven in zk-rollup?

I have many questions about the details of using zk-SNARK technology in zk-rollup: How can the validity of signatures in layer-2 transactions be proven in zk-rollup? In zk-rollup, is a single large ...
1 vote
1 answer
170 views

What is the probability of decrypting AES-128-ECB if some of the information is available?

There is a JSON array like this: ...
0 votes
0 answers
47 views

Practical deployments of ECC with cofactor of elliptic curves $4$ or $8$?

Are cofactor $4$ and $8$ ECC schemes widely used in practical deployments such as those in cryptocurrencies? Can you name some practical settings where there curves are used and cryptocurrencies where ...
0 votes
2 answers
65 views

Proof generation in zk cryptocurrency

In a cryptocurrency with privacy e.g., zcash, where does proof generation take place? Can it happen in the client's device every time a transaction is performed? If it happens in client's device, are ...
-7 votes
1 answer
58 views

In the context of a blockchain-based digital currency, I have some questions regarding the functionality and operations of a particular system

Could you clarify where the stack object is typically generated? Is it created on the sender's device or the recipient's device? If I send funds to a multipay stack that was created on another device ...
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39 views

The specific nature of a 51% attack - in relation to a multiple choice question that I was marked as incorrect on

In a course I'm taking the following question came up: ...
3 votes
1 answer
234 views

Does PBKDF2 HMAC 512 really only produce a maximum of ~128 bits of entropy? Regardless of input?

Andreas Antonopoulos effectively states: an input of 256bits of entropy into PBKDF2-HMAC-SHA512 will ONLY output a 64 byte hash containing ~128 bits of entropy. He states the algorithm essentially ...
1 vote
0 answers
195 views

Quantum-safe algorithm for hiding cryptocurrency transaction amount [closed]

I have a decentralized coin system that I am trying to develop. Each coin can be split up into 1,000,000 units. I've been looking for a quantum-safe and practical (efficient) algorithm to send ...
3 votes
1 answer
220 views

Creating a private cryptocurrency without trusted setup

I am interested in creating a cryptocurrency that keeps the sender, the receiver and the amount private and does not require a trusted setup. I have already read the Zerocash protocol but It uses zk-...
1 vote
0 answers
92 views

Can we reduce the size of the XMSS signature?

As XMSS is post-quantum we can use it to secure blockchain. One of the main disadvantage of XMSS is its signature size. If we can reduce the size of the signature then we can use XMSS in the ...
1 vote
0 answers
36 views

Ethereum signature as xml-dsig11

This question was originally posted in https://ethereum.stackexchange.com/questions/151471/ethereum-signature-as-xml . I post it here aswell because I rarely get any response there. I am seeking to ...
4 votes
1 answer
200 views

Can you elaborate on pBFT for dBFT in relation to PoW and PoS consensus algorithms in layman's terms?

I've read all other related answers and googled this extensively. My intention and background in asking this question is that I am delving into cryptocurrency and blockchain technology in general. ...
4 votes
1 answer
182 views

ECDSA (ecrecover) - How an attacker can construct a hash and signature that look valid

I found information, that it is possible to construct a hash and signature that look valid if the hash is not computed within the contract itself (we are talking about ECDSA/ecrecover here). So, the ...
1 vote
1 answer
76 views

Can the last n bitcoin blocks (including transactions) be reliable enough to be used as a seed for a PRNG or an input to a crypto hash-function?

Suggested by u/HolgerBier on reddit Is it unpredictable enough or too difficult to manipulate (as in more than a few hundred million USD) to have a sequence of blocks?
2 votes
1 answer
178 views

How does hardware wallet recovery work?

I'm investigating hardware cryptocurrency wallets and am trying to understand how recovery works from a technical point of view. These wallets typically provide a 24-word "recovery seed" ...
2 votes
1 answer
166 views

Provably secure cryptography in blockchains

Do you know a blockchain that does not use at all cryptographic primitives standardized by USA or other countries? It is strange to me that the security of many cryptocurrencies is based on ciphers, ...
2 votes
0 answers
23 views

Which channel protocol should I use to broadcast the message between parties?

I am building the Threshold Signature Scheme (TSS) based wallet. I would like to run the each party's node separately with different host. And these nodes should be able to send the messages through ...
1 vote
1 answer
60 views

ZKP vs disposable addresses [closed]

In other words, what does ZKP brings on top of the practice of not reusing addresses? From my research, ZCash is currently a state of the art example of ZKP application, but what extra benefits does ...
1 vote
0 answers
63 views

Secure permutation of $E(\mathbb{F}_q)$ as a set for an elliptic curve $E$ over a finite field $\mathbb{F}_q$

Let $E$ be an elliptic curve over a finite field $\mathbb{F}_q$. For simplicity, let the group $E(\mathbb{F}_q)$ be of prime order. Assume that I know how to construct an efficiently computable ...
1 vote
0 answers
48 views

In Zcash, how does a recipient look up which transactions belong to him/her?

For Monero, the scheme for stealth addresses is pretty straightforward. (For example: https://monero.stackexchange.com/questions/1500/what-is-a-stealth-address) However, I haven't found any details on ...
2 votes
1 answer
1k views

Can Blake2 be a replacement for double SHA-256?

Is it a good choice to drop double SHA-256 and use straight Blake2 in a Bitcoin-like blockchain (more POS oriented so it's not a mining problem)? I'm talking about Blake2 because I've read more about ...
-1 votes
1 answer
52 views

Zero knowledge proof to validate/invalidate a claim

Have a look at the Twitter conversation below in the screenshots. @theveveshow asks if @trader1sz has sent ETH to the girl in question? @trader1sz responds that the girl in question has indeed sent ...
1 vote
0 answers
37 views

How does the Mongomery Algorithm work? [closed]

can someone please explain to me what's the role of montgomery reduction algorithm and how to implement it in python. I wrote the code below to calculate a*b mod m but it doesn't seem to work well. ...
3 votes
1 answer
386 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 ...
1 vote
1 answer
131 views

zkSNARKS: What prevents the prover from chosing a different polynomial than the one he is expected to know

I am reading this explanation of zkSnark written by Maksym Petkus - https://arxiv.org/pdf/1906.07221.pdf Here the Prover knows a polynomial of degree 3, 2 of the solutions of the polynomial are 3 &...
1 vote
1 answer
94 views

How to Ensure Security in a Gaming Peer to Peer Network

I've been recently thinking about building a c++ poker game that would let players to play over sockets in a peer to peer network. However I do not know how security would be ensured. I was thinking ...
1 vote
0 answers
322 views

Understanding seed phrase, private key, wallet addresses

I have a question about Cryptocurrency wallets like Metamask (soft) or Ledger (hard). How is a 12 or 24 word seed phrase enough to show the same crypto addresses in any crypto wallet that supports the ...
2 votes
1 answer
201 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 ...
2 votes
0 answers
717 views

ECDSA Common Nonce Reuse Attack

so I recently stumbled upon this video by @bertcmiller who created two transactions with the same nonce "k". That seen I researched quite a lot of pages explaining how to recover the private ...
19 votes
1 answer
5k 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 ...

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