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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1answer
440 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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2answers
244 views

Securely send symmetrically encrypted data to contract?

Hey there I was wondering what the best technique would be for sending encrypted data to a contract, which can later be decrypted, either by the initial user, or by the contract itself, but not anyone ...
3
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1answer
759 views

Unable to verify signature returned by JSON-RPC `eth_sign` method

I am attempting to verify a signature returned by the eth_sign JSON-RPC method. https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_sign The verification is done using the following python code and ...
3
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1answer
539 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 ...
3
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1answer
514 views

Is there any way to create an ethereum account from RSA key?

I have my very private RSA key: -----BEGIN PRIVATE KEY----- MIIJQQIBADANBgkqhkiG9w0BAQEFAASCCSswggknAgEAAoICAQDI0vCkxjyJQ7b7 MVJKKXVTFSH3yN5xWozV1pZ8grTTr6dL90bmeCHIw9PnsZRJWsAhstnSnLm1v7KE kkNqFi2s+...
3
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1answer
931 views

Brute-forcing private keys

In this post by an Ethereum engineer taken from the Ethereum wiki about brute-forcing private keys, he writes: "Public keys are sized so that, absent a breakthrough in solving the discrete ...
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0answers
44 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 ...
3
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0answers
468 views

OpenSSL error message when decrypting Ethereum encrypted private key

I'm trying to help a friend recover his password for an older format ethereum encrypted private key (EPK). My friend thinks he knows the password. My plan has been to use his best guess at the ...
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0answers
326 views

Can the precompiles in Byzantium for pairings be used for implementation of BLS verification?

I am looking into implementing some operations for the BLS signature scheme in Solidity, using the new precompiled contracts for pairing operations released with Byzantium. In BLS verification, to ...
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3answers
830 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 ...
2
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1answer
677 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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2answers
415 views

What will happen if 2 cold storage (Ether) generates a same private key

I am new to crypto world trying to understand the Ether wallet generation process with the private key. Let us say 2 person A and B are buying a cold storage device "Ledger Nano S" and setting it up ...
2
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1answer
121 views

Why Ethereum can't talk to other blockchains?

I've heard that Ethereum can't talk to other blockchains (if I understand it correctly). What does it mean and what is the reason behind this?
2
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2answers
101 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 ...
2
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1answer
110 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 { ...
2
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1answer
34 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 ...
2
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1answer
384 views

How do I split a signature into v, r, and s parts in python?

I've got a signature, as a python bytes object, and want to split it into the components v, r, and s. I understand the details of what needs to be done, by reading: What's the best way to ...
2
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1answer
51 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 ...
2
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1answer
617 views

EIP-198 and RSA verify use cases

I was reading this post: https://medium.com/@alexberegszaszi/lets-bring-the-70s-to-ethereum-48daa16a4b51 and i'm a bit unclear about some of the details. I was hoping someone can shed some more light ...
2
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1answer
310 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 ...
2
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1answer
52 views

Can I know an address on another blockchain that was generated with the same key as an ETH address?

Let's assume another blockchain (blockchain ATH) uses the same protocol to derive addresses from private keys as the one used by Ethereum. If I see an ETH address then I know for sure that the ...
2
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1answer
65 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 ...
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0answers
33 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 ...
2
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0answers
47 views

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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0answers
145 views

Ethereum public key recovery validation

I always thought that only the person(s) in possession of the private key to an address would be able to spend or change state for that account. But by using the recover technique rather than the ...
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0answers
821 views

Ethereum Dapp Account Login Protocol with Metamask

I'm building an Ethereum dapp for users to use with Metamask. We're going to have an account management system and I was trying to follow this post on how to achieve a "password-less" account system ...
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0answers
42 views

In ENS, what does the secret phrase encrypt?

The Ethereum Name Service uses a secret phrase to encrypt the bid. What is encrypted, to later be revealed during the reveal phase?
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2answers
280 views

Can private keys change once created?

Can private keys change once the public key (address) is created?
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1answer
42 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 ...
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2answers
619 views

Hiding an answer/vote on the blockchain

I understand that every transaction is visible on the blockchain but would it be possible to create a DApp that allows people to vote in disguise? not showcasing their vote till the votingprocess is ...
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2answers
2k views

Using Web3j to load a smart contract, how do i specify my credentials?

I am using the Web3j library to generate a Java wrapper for my solidity contract, i have already deployed the contract to the blockchain and it has been mined, i now want to load the contract in java ...
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1answer
169 views

Does the private and public keys determine each other uniquely?

I wonder whether for each private/public key there correspond a unique public/private key? Of course, it must be computationally infeasible to compute the private key from the public key, but does ...
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1answer
44 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 ...
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2answers
163 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 ...
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2answers
539 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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1answer
40 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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2answers
51 views

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?
1
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1answer
710 views

Is it possible to create an X.509 certificate from an Ethereum/Bitcoin private key?

We all love Ethereum/Bitcoin (i.e. EC secp256k1) private keys, because they let us sign transactions. However, browsers don't support those keys for authentication -- what they do (sort of) support is ...
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1answer
650 views

What happens on hash collisions for, e.g., transactions, blocks, and contracts?

What happens on hash collisions for, e.g., transactions, blocks, and contracts? What happens if, say, two transactions hash to the same value? In this case, we say that a hash-collision occured. I'...
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4answers
2k views

Decryption in a smart contract

I have a key pair: The data is encrypted off-chain: and it is saved into the following smart contract: contract Foo { string data; } Can I decrypt stored data on-chain, assuming I provide a ...
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1answer
14 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 ...
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0answers
63 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 ) => { ...
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2answers
92 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 ...
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1answer
54 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 ...
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0answers
68 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 ...
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0answers
45 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 ...
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1answer
147 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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0answers
24 views

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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0answers
357 views

keccak256 returns 0x000000000000000

I am using the keccak256 hashing algo to retrieve a message for a signature however I am getting the return value above. Here is the code: function adminAuthorizedSwap(string price, string quantity, ...
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1answer
443 views

ecrecover on bytes32 array elements

I am creating a contract which will allow an atomic transfer of a token with only the buyer needing to pay gas (instead of both parties). I am doing this by creating an agreement with price, quantity ...