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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. Please note that Stackexchange has dedicated websites for Bitcoin, Ethereum, Monero, etc.

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14 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][1]: User ...
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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 ...
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18 views

Decrypto the freqency cipher [closed]

ODZKG FHOXP FOEYL HZEZK UXTGY OAGTA OATAX UOAUO DDUPY DTNPU XXKGG YADRV YAUGO HSOXT FDZXY ERYRY XTFOA PYOHU PYWKT YUUOQ QTANZ LUPYH OTAON OTAXU UPYVT AGZVX UPYVT AGBYN TAXUZ NKXUO AGUPY HOTAB YFZEY ...
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0answers
36 views

Would it be possible to have a cryptocurrency that has multiple mining methods? [closed]

What I mean is could a single cryptocurrency have multiple different processes that give you coins. It could have a Delegated-Proof-of-Stake system can get you coins, a proof-of-work algorithm can get ...
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2answers
93 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 $Q = aG$...
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1answer
46 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
45 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 ...
2
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0answers
31 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
52 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
51 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 ...
2
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2answers
160 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
90 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
64 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
63 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
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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0answers
53 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 ...
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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 ...
3
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1answer
62 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
58 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 -...
2
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2answers
74 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
39 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 ...
-1
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1answer
50 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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2answers
285 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 ...
0
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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
28 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
128 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
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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 ...
0
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1answer
75 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 ...
2
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1answer
239 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 ...
1
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0answers
58 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. ...
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0answers
39 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. ...
8
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2answers
972 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 ...
0
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0answers
74 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 ...
0
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1answer
179 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
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0answers
27 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 ...
-1
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1answer
309 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
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1answer
187 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
138 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
93 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
119 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
127 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
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1answer
110 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 ...
0
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1answer
42 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
115 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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0answers
20 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 ...
1
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0answers
64 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 ...
3
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1answer
103 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 ??
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0answers
47 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 ...
-1
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1answer
111 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.