Questions tagged [cryptography]
Discipline or techniques employed in protecting integrity or secrecy of electronic messages by converting them into unreadable (cipher text) form.
138
questions
2
votes
0answers
24 views
Azure Blockchain Service node properties [closed]
What exactly are Access key 1, Access key 2, Member account, Web socket, DNS, creater account, etc. of a node in Azure Blockchain Service? I am getting confused as to what are these. Also what are the ...
1
vote
1answer
15 views
Using `recoverPersonalSignature` from `eth-sig-util` to verify message signed with go-ethereum's `crypto` package
I am using https://godoc.org/github.com/ethereum/go-ethereum/crypto#Sign to sign an arbitrary message and trying to recover the signer address using sigUtil.recoverPersonalSignature(https://www.npmjs....
1
vote
1answer
27 views
Why is privateKey padded before secp256k1 signing?
I am checking how the Ethereum handles signing but I can't figure out why the math.PaddedBigBytes is necessary:
func Sign(digestHash []byte, prv *ecdsa.PrivateKey) (sig []byte, err error) {
if ...
0
votes
1answer
22 views
MITM attack in hosted wallets
i have a question:
in the web wallets(hosted wallets)when user want to make a transaction and send the information to the wallet server , can a one change the information(man in the middle attack)?
0
votes
1answer
31 views
Sharing an verifiable secret message in a contract
I would like to hear your opinion on my idea to share a proof of a secret message in a contract, that users can verify later in a second phase when the message will be revealed.
If the message is a ...
1
vote
1answer
55 views
How is multiparty computation (MPC) possible using Ethereum?
MPC involves running calculations on numbers, perhaps from different parties, and sharing the result without anyone seeing the underlying data. Even the person operating the computer cannot access the ...
1
vote
1answer
47 views
Is it possible to have multiple private keys for a single public address? [duplicate]
Since the ratio of all possible digits (please correct my math if I am wrong) of a public key versus private is:
1/79228162514264337593543950336
for public (40^16): 1 461 501 637 330 902 918 203 684 ...
1
vote
1answer
94 views
Validating RSA, Ed25519 and ECDSA signatures in solidity
I am writing a contract in solidity for verifying multiple signature schemes.I found that solidity supports ECDSA, but how do I add check for RSA and Ed25519. is there any existing method/library ...
0
votes
0answers
27 views
Does the use of Non-interactive zero-knowledge proof (zk-snark) will eliminate the use of (consensus algorithm e.g. work proof)?
The privacy of the blockchain transaction is a high-demand topic these days due to some application use case requiring strict privacy protection. Some of the techniques applied to blockchain ...
3
votes
0answers
50 views
Cheap EC Operations on Unsupported Curves
I want to be able to verify signatures created by smart meters. Unfortunately, their signature algorithm doesn't use curve ALT_BN_128 but BrainpoolP256r1. I wrote this verification algorithm that ...
2
votes
2answers
168 views
How to guarantee IPFS file access based on Non Fungible Token ownership (or security)?
The file is too big to be stored on the blockchain, so it is stored on IPFS.
Only the person who owns a unique Non Fungible Token (or a Security Token) can access it.
Of course I can encrypt the file ...
0
votes
1answer
57 views
ECC scalar multiplication
I'm now trying to use scalar multiplication to recover v, but I have questions with ECC scalar multiplication.
I'm wondering if the following equations are correct.
If scalar * P = Q, then scalar * (...
0
votes
1answer
25 views
How did cryotokitties create the image of the cats?
For cryptoKitties, the images of the cats are based on gene, for example, color, curve type etc. and the image of the cat will be created, how does the image created, it is by programming running ...
2
votes
1answer
97 views
Algorand: What is the purpose of VRF
In the paper describing Algorand,two reasons are given to use verifiable random functions/cryptographic Sortion:
Sortition provides two important properties: First, given a random seed, the VRF ...
0
votes
0answers
26 views
Genesis.json Change Name from ETH to Any other [duplicate]
I want to change the name of the currency while setting up my private ethereum node, is it possible ? and if possible how can we change it ?
0
votes
0answers
14 views
if RecoverCompact succeeds, does it prove that signature is right?
eth not use VerifySignature to ensure signature,but use recovecompact func,
does it means that signature is right if recoverPlain succeeds,
// Validate the transaction sender and it's sig. Throw
// ...
2
votes
1answer
139 views
Decrypt message on-chain
I want to store some data in smart contract and then decrypt it on chain. Pseudocode:
contract EncryptedData {
bytes data;
string public decryptedData;
constructor(bytes data_) public {
...
0
votes
1answer
43 views
Is S of the signature(R,S) invalid when it is larger than N/2 in Ethereum? [duplicate]
In ECDSA, both signature(r,s) and (r,-s) are valid. However, in Bitcoin, it seems that the signature fails to be verified when s-part in the signature is bigger than half of the group order from this ...
2
votes
1answer
82 views
How to get 0x0 from ecrecover?
I have a fair understanding of how ecrecover works, but I don't know how to enforce a parameter set that will deterministically return the 0x0 address. I need this in my contract tests.
Is this even ...
0
votes
1answer
230 views
How to sign a transaction using nodejs crypto?
I have a js client, web API
Js client send some data in JSON format, API prepare a transaction to be send to a smart contract, than it returns transaction raw to client to be signed locally,
and ...
1
vote
0answers
70 views
Ecrecover wrong address is returned
I'm trying to validate signed data with ecrecover.
The message is signed like this on the FE:
return this.web3.eth.personal.sign( `${nonce}`, publicAddress ).then( ( signature ) => {
...
1
vote
2answers
106 views
Why does ecrecover() take signature parameters (v,r,s) instead of the full signature?
Is there any reason ecrecover() takes the (v, r, s) signature parameters instead of the full signature, given that these can be easily computed inside the function itself?
I am asking because ...
2
votes
1answer
374 views
HD wallet public to public key derivation and non-hardened keys
This question is about hierarchical deterministic wallets and the bip32 standard which, as I understand it, allows you to deterministically derive child private/public key pairs from a master seed ...
0
votes
1answer
13 views
Is it possible to provide some manual data to create private key for the ethereum account?
We were trying to provide some manual data to create the private key if I want to create a new ethereum account using this private key.
0
votes
1answer
278 views
How to get private key with web3 v0.2.x?
web3 version 1.x has the decrypt method, which decrypts a keystore v3 JSON.
By using it the following way, I can get the private key easily:
web3.eth.accounts.decrypt(keystoreJsonV3, password);
But ...
2
votes
1answer
909 views
Understanding Ethereum signatures
I would like to understand exactly which signatures are used in the Ethereum. Here https://bitcoin.stackexchange.com/questions/12554/why-the-signature-is-always-65-13232-bytes-long it says that there ...
4
votes
2answers
6k views
How can I get a mnemonic phrase from a private key?
I have a private key for my wallet and also a keystore for it. I want to use it in MEWConnect. Is there a way to get a mnemonic phrase from a private key?
0
votes
1answer
89 views
How to define 2048-bit integers on smart contracts?
As we know solidity supports only 256-bit big integers. But for crypto primitives (sometimes) we need bigger integers, e.g. 2048-bit.
Question: how can we define 2048-bit integers on a smart contract ...
2
votes
0answers
42 views
Why is an ephemeral key used in creating a digital signature?
When creating the 'S' component of a digital signature, both the actual private key and an ephemeral private key are used.
The reasoning I've read is to ensure that the sender’s actual private key ...
4
votes
1answer
219 views
Zero Knowledge v Multi Party Computation (MPC)
I am struggling with understanding the difference between the two. From what I am putting together, they have different adversarial models, MPC adds the condition of collusion between parties i.e. ...
0
votes
3answers
294 views
how to generate mnemonics from randombytes
I am able to get the randombytes using react-native-crypto-js
const words = CryptoJS.lib.WordArray.random(32);
Is that possible to generate mnemonics using random bytes.
1
vote
1answer
55 views
Is it possible to create one-time addresses, like in monero?
In http://src.getmonero.org/library/Zero-to-Monero-1-0-0.pdf, chapter "5.2 One-time addresses", there is description of how to create them.
The problem is that Monero uses Ed25519 and Ethereum ...
2
votes
1answer
35 views
How to get two points (x, y) from an encoded pubkey?
this gives a valid address from two points;
address(uint256(keccak256(abi.encodePacked(point[0], point[1]))) & 0x00FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);
but does that mean that if you are ...
1
vote
0answers
73 views
Ethereum geth node sync problem
I have to ethereum geth node runing as testnet syncmode=full on aws both running on same hardware and bandwidth why one is syncing very slow and other one is syncing fast?
and if I will stop the ...
0
votes
1answer
83 views
Estimation of gas in web3js 0.20
Q:- While sending only Ether One wallet to another wallet(NO SMART CONTRACT),
do we need to define the default gas limit and price?
i.e. 21000 * 3 OR 21000 * 4 OR 21000 * 5 etc
Or
I've need to use ...
3
votes
1answer
526 views
Does Ethereum support pairing operations?
I need to build an application that uses bilinear pairing operations for generating signatures. If I send a message with its signature to Ethereum, can Ethereum verify this message? Does the EVM ...
1
vote
0answers
59 views
Using ECC Brainpool curves instead of Elliptic Curves
I am exploring the use of ECC Brainpool curves instead of elliptic curves for digital signatures in Ethereum.
Is this part of the roadmap and/or anyone has experimented with the use of ECC Brainpool ...
9
votes
1answer
1k views
Why are Ethereum addresses hashes of public keys?
I understand how Ethereum addresses are generated. This thread has a great explanation: How are ethereum addresses generated?
However, what this explanation is missing is why a hash is used.
There ...
1
vote
2answers
230 views
Is data stored in string form in smart contracts publicly readable?
As a beginner, I wrote the contract below for learning purposes, aiming to create a "Safe Messaging System":
pragma solidity ^0.4.24;
contract SafeMessage {
string message;
string password;
string ...
0
votes
1answer
33 views
discover if a binary data contains Ethereum address in it?
Is there a way to guess, with some level of probability , that a 20 byte array is an Ethereum address, besides doing a query against the current StateDB and its history ?
I want to discover hidden ...
6
votes
1answer
372 views
Why are the last 20 bytes of the public key used as the address?
According to this post regarding how to derive the Ethereum address from a public key:
Take the last 40 characters / 20 bytes of this public key
(Keccak-256). Or, in other words, drop the first ...
1
vote
2answers
327 views
Can private keys change once created?
Can private keys change once the public key (address) is created?
0
votes
0answers
164 views
Smart Contract - Storing 113+ byte buffer in solidity
So I am using the module (eth-ecies) in npm to perform encryption of a message offchain using the public key of my reciever, and in turn I get a 113+ byte buffer after the encryption is done. Now i ...
0
votes
1answer
240 views
Solidity - Shuffle address[] Index
Hello World !
I'm trying to find a way to shuffle an array of addresses in Solidity !
Looking at Underscore / Lodash source code _.shuffle() points out a few things.
_.shuffle([1, 2, 3, 4]);
* // ...
4
votes
1answer
614 views
How can we verify BGLS aggregate signatures in Solidity?
BGLS [1] is an aggregate signature scheme by Boneh et al., that allows aggregation of signatures on n different messages from n different signers. What I want to achieve is to verify such signatures ...
0
votes
2answers
38 views
“Signing” a Smart Contract after it has been deployed
I've been tasked with writing a Smart Contract to create NFT/digital collectibles. For the most part, I'm using a standard ERC721 contract.
I will be responsible for deploying the contract. Is there ...
0
votes
1answer
205 views
Store and retrieve audio files on blockchain using hashes and authenticity matching [closed]
I am looking to store and retrieve hashes of authentic audio files on the Ethereum blockchain with the purpose of checking authenticity of these audio files in the future with the hashes stored on the ...
12
votes
2answers
854 views
What are zkSNARKs? How do they work?
From my brief exposure to the concept, zkSNARKs seems to be a form of zero-knowledge cryptography.
What can zkSNARKs bring to the table for Ethereum?
I have looked at projects like this but still ...
1
vote
2answers
587 views
Creating a new wallet mobile application for newly created crypto currency
I am doing as a Intern in Apogee Tech Global in Bangalore on Blockchain for three months.
My commitments is to learn solidity language, build smart contracts, learn Ethereum and Hyperledger.
I learnt ...
10
votes
3answers
1k views
Can ZKSnarks be implemented on the Ethereum ecosystem?
Since Zcash seems to have it's ZKSnarks implementation finished (or almost at least).
And versions of JPMorgan's Quorum had appeared with ZKsnarks implementations included see: https://www.coindesk....
