Questions tagged [cryptography]

Discipline or techniques employed in protecting integrity or secrecy of electronic messages by converting them into unreadable (cipher text) form.

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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 * (...
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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 ...
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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 ...
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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 ?
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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 // ...
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67 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 { ...
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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 ...
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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 ...
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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 ...
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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 ) => { ...
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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 ...
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Encryption with Ethereum Keys for all Clients (iOS,Android,Web)

I was trying to encrypt data with Ethereum Key pairs. So far, I have managed to encrypt and decrypt data with these keys using ECIES schema on eth-crypto. Eth-crypto is a package which is built on top ...
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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 ...
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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.
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197 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 ...
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1answer
403 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 ...
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1answer
3k 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?
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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 ...
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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 ...
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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. ...
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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.
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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 ...
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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 ...
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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 ...
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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 ...
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299 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 ...
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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 ...
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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 ...
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2answers
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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 ...
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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 ...
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247 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 ...
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Can private keys change once created?

Can private keys change once the public key (address) is created?
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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 ...
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190 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]); * // ...
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405 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 ...
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“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 ...
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1answer
150 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 ...
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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 ...
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2answers
473 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 ...
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955 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....
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Would it be profitable enough to do a Master's degree in blockchain technologies (focused on ethereum above all)?

The end of my university studies is getting closer and closer. I'm sure I want to do a Masters degree, but I have some doubts. About a month ago my university released a Masters degree completely on ...
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37 views

Is there a privacy token implementation in the works for Ethereum like Monero's Tari system?

With the recent announcement of being able to have privacy type tokens on the Monero blockchain. Is there a proposal on ethereum for something similar? The usecase of having a private ERC20 would be ...
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cryptography algorithm used in ethereum [duplicate]

what algorithm does ethereum use to generate public and private key pair. If i have both the keys how can i verify the match of the key in solidity, and how much gas does it cost? is it an expensive ...
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Any understandable cryptography book/article/lecture to introduce to signatures, hashes, ECDSA etc..? [closed]

It's a long time I'm searching for cryptography lectures related to ethereum inside mechanisms, and everything I found has a high mathematical level. I'm an engineer, not a mathematics, so any article ...
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3answers
652 views

Will be a ring signature scheme possible to implement at Ethereum?

It's been quite a few days I'm wondering if a Ring Signature Scheme (like Monero (XMR) has) can be implemented on Ethereum blockchains. As far as I know, that will be so nice in order to increase ...
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141 views

How to decrypt using Public Key

Can anyone decrypts cipher-text using Public Key? as I know we can only decrypt using private key, but in this RLPx documentation what this line means? Receiver receives the initiator handshake and ...
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Why does a signed transaction include a “hash” field?

When signing a transaction using the go-ethereum library, the resulting object looks something like this: "tx": { "nonce": "0x7", "gasPrice": "0x77359400", "gas": "0x5208", ...
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Which is cryptographically harder (higher cost to break), sha256 or secp256k1?

Which has a higher computational cost, to find the private key associated with a signature, or, a pre-image of a sha256 hash?
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I to want introduce myself to learn new and advanced technologies like AI, blockchain [closed]

I have completed 2days blockchain executive program two weeks back. Course covers high-level concept on blockchain, ethereum I have around 12+ yrs of IT experience and worked on different tools and ...
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Generate Public Key

I use the command: > eth.getTransaction("0xac844bd1107761fec3abe2f55bf739f0e7cc6dd1cd169a60176bfb22 9826b5a8") Where the brackets contain the hash of the successful transaction. This is what I ...