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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Is it possible to hack an ethereum account? [duplicate]

I want to know if is it possible to hack an Ethereum account?
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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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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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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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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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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 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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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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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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159 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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Gas limit exceeded despite function not being complex

I am writing a function which takes in a bytes32 message and validates it against a signature (this is done without hashing to save gas). I am able to call the recover function and have it execute but ...
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551 views

R,S,V ECDSA packet signatures

I am using BouncyCastle to generate .NET core packet signatures. I want to be able to get the v value for the Ethereum signature. To these ends, and with my understanding of the meaning of the v ...
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How to call Internal functions ? or how to protect Withdraw and kill functions?

I had some function like withdraw and self-destruct functions set as internal, but I can't call them from "Mist", then I turned them to public but I set the modifier : modifier isOwner() { if (msg....
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Private ledgers on a Ethereum Blockchain Network

We are exploring one use case to connect a million customers with a bank. Since customers' transactions should be private to them, we want to understand whether we can have concept of private ledger ...
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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 ...
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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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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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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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3answers
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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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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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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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37 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 ...
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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 ...
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Correct way to easily call function with web3j from deployed contract

I am trying to call a function from a modified ERC20 contract and I can't manage to make it work. I am doing this with web3j from Android. I can connect to Infura. The contract is already deployed on ...
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110 views

How to prevent tampering of contract call from the web?

I have a project where users will be calling my contract from the web. I want to ensure they call the contract with exactly the parameters I give them. My strategy was to hash the combo of parameters, ...
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483 views

Create hash in c# and validate in solidity

I'm trying to build an app that will call a contract from javascript. I want the contract to validate that the parameters weren't tampered with. In order to do that, my plan was to figure out the ...
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1answer
414 views

Mist Wallet Stuck on “Connected to Node”

It got about 80% of the way through the blockchain download, then it just stopped and went to "finding peers" So I closed the wallet, restarted the PC, and now it just gets stuck on "connected to node"...
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Should investors add token address to their account to receive the ICO rewards?

I just created a token in blockchain and when I test it on Rikenby network but no tokens appear on my wallet until I added the Token address to watch list. 1- Is that normal that investors should add ...
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How to calculate an Ethereum Contract's address during its creation using the Solidity language?

Now I know and have read the other thread saying that a contract's address is created deterministically via RLP encoding the creator's address and his nonce and then hashed with Keccak-256 but the ...
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230 views

Encryption of keystore, keys and cryptographic library usage locations

I understand that another question posted has mentioned that the keystore has aes-128-ctr encryption: What is the strength of Mist wallet encryption? Key Derivation Function uses scrypt (where the ...