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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2
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2answers
528 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]....
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2answers
52 views

Doesn't d6 to binary for 256-bit bitcoin private key generation produce biased results?

If the mapping table looks like: 1: 000 2: 001 3: 010 4: 011 5: 100 6: 101 Then you are guaranteed that your key will never have a chain of 4 or more 1s, much fewer chains of 3 ones than would ...
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2answers
302 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 ...
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1answer
212 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 ...
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1answer
165 views

Large Volumes of Asymmetric Encryption

First of all, I apologize in advance if I use any incorrect terminology. I am just getting my feet wet when it comes to cryptography and there is a lot to learn. For the past 12 months, we have been ...
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22 views

Which application software can be used to simulate the Proof-of-work algorithm of a single node?

Which application software can be used to simulate the Proof-of-work algorithm of a single node, with parameters such as changing the size of the Nonce and inputting customised block created ...
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2answers
543 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 ...
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1answer
77 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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0answers
51 views

ZK Proof that a blinded message (for a blind signature) contains a certain value

I am toying with eCash systems and blind signatures, and I started with Chaum's original formulation. In particular, I'm using this formulation from this link: User ...
2
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2answers
49 views

How blockchain system manages it's memory limit for nodes?

As we know, in the blockchain system every node has historical data that contains all previous transactions to maintain the integrity and approve the future transaction. What if blockchain is ...
2
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1answer
839 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 ...
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1answer
1k views

How is the base64 encoded signature in Craig Wright's proof constructed?

Mr. Craig S. Wright might be Satoshi Nakamoto - the inventor of bitcoin. He is currently proving the case. But how is the base64 encoded proof, that is published by himself on his blog post ...
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2answers
134 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 ...
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2answers
106 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 $Q = aG$...
2
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1answer
168 views

Encoding a message to a point of curve y^2=x^3+7 and Bitcoin Core

Where should I look at in Bitcoin Core source code to figure out how the signature process transform a message in a curve point? To sign a transaction (message) in the Bitcoin system, you need to ...
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1answer
48 views

Cryptography in virtual currencies [closed]

Apart from bitcoins and altcoins, are there any other virtual currencies (like game currencies, gift cards or coupons) that include cryptography in their algorithm?
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1answer
46 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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0answers
38 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], [...
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0answers
70 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 ...
2
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0answers
66 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 ...
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0answers
45 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 ...
25
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1answer
7k 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 ...
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2answers
4k views

How to deal with collisions in Bitcoin addresses?

When creating a Bitcoin account, you need to issue a couple of private/public ECDSA keys. Then, you derive your account address by taking a 160-bit hash (through SHA-256 and RIPEMD) of the public key ...
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2answers
347 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 ...
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1answer
121 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 ...
2
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2answers
252 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 ...
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2answers
125 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 ...
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1answer
1k 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 ...
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1answer
115 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 ...
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2answers
449 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 ...
3
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1answer
116 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 ...
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1answer
83 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 ...
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1answer
97 views

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: ...
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1answer
233 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 ...
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2answers
6k 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} := \...
4
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3answers
216 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 ...
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0answers
28 views

What is the cryptography involved in the initial setup of a cryptocurrency?

I keep hearing that when a cryptocurrency is created it goes through an initial setup phase wherein cryptographic parameters are created that are used by the cryptocurrency network throughout its ...
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0answers
56 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 ...
0
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1answer
491 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 ...
4
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1answer
71 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. ...
0
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1answer
59 views

Is the following non-interactive zero-knowledge set membership protocol provable 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 -...
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2answers
75 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. ...
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1answer
41 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 ...
5
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1answer
570 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 ...
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1answer
64 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?
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0answers
43 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 ...
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0answers
29 views

How to forge a Proof-of-Stake blockchain?

Suppose a node in a proof-of-stake blockchain network wants to forge a blockchain. I'm wondering what should this node do to forge it? Assume this node has a certain amount/fraction of money (but no ...
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2answers
160 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 ...
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1answer
72 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 ...
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1answer
99 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 ...