Category: CRYPTO

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Double spending is a security vulnerability in the Ethereum network that allows an attacker to spend a token twice. In this article, we will explore what double spending looks like and provide examples of how it can happen.

What is double spending?

Simply put, double spending occurs when a user attempts to spend the same token (known as the “base” or “prime”) twice. This means that the attacker controls two separate transactions: one in which they send the original amount of the token, and another in which they attempt to spend it again. The goal is to exploit this vulnerability by creating new blocks on the chain without validating them, allowing the transaction to be included in a future block.

How ​​does double spending happen?

Double spending can occur when:

• A user can control multiple wallets with the same private key.

• An attacker creates multiple transactions with the same base token and attempts to spend it twice.

• The network is not properly validated or secured, allowing duplicate transactions to be included in the block.

Example on Blockchain.info

To illustrate what a double spend looks like, let’s look at an example from Ethereum’s blockchain.info: “0x1234567890abcdef”. Let’s assume this user has multiple wallets with different private keys and controls two separate accounts:

• Account 1: “0x9876543210fedcba”.

• Account 2: “0x1234567890fedcba”.

In this case, an attacker can create the following transactions:

Transaction 1 (initial spend):

• Use “0.1 ETH” from wallet “0x9876543210fedcba” for a public transaction.

Transaction 2 (overlapping spend):

• Spend 0.5 ETH from wallet 0x1234567890fedcba again, but this time the network will not confirm it because it is an invalid half of a double spend.

Half of a double spend remains invalid after 0 confirmations?

In most cases, a single block containing overlapping transactions may not be confirmed immediately. Instead, it is possible that the transaction may remain unconfirmed for several blocks or even become part of a future block if the network is properly secured.

However, in some rare cases, an incorrect half of a double spend can achieve 1 or 2 confirmations depending on several factors, including:

• Network congestion and latency

• Transaction confirmation rules (e.g. requiring multiple signatures)

• Number of transactions included in a block

It is important to note that the Ethereum team has implemented measures to mitigate double spend vulnerabilities, including a cryptographic proof that makes it more difficult for attackers to create duplicate transactions.

Conclusion

Double spend is a security risk on the Ethereum network that can be exploited by malicious actors. Understanding what double spend looks like and how it occurs is crucial when understanding the importance of maintaining secure networks and protecting against such vulnerabilities. By following best practices, using secure wallets, and staying up to date with network updates, we can minimize the risks associated with double spend.

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Demo

As cryptocurrencies like Bitcoin and Ethereum continue to grow in popularity, many users are looking for ways to confirm transactions without resorting to third-party exchange services. In this article, we’ll explore whether it’s possible to perform a mining operation to validate transactions to a target address.

Background

A miner is a computer program designed to solve complex mathematical problems to validate and verify transactions made on a blockchain network. When a user initiates a Bitcoin or Ethereum transaction, these transactions are broadcast across the network, where they are confirmed by specialized nodes called miners. The goal of mining is to find a “solution” to a mathematical problem that requires significant computing power, which helps secure the network and verify transactions.

Is it possible to use mining to confirm events?

Unfortunately, it’s highly unlikely that anyone would be able to build a mining rig to listen to events in real time. Here’s why:

1. Network delay: Transactions are broadcast to the entire network, but it takes time for them to propagate and be confirmed by miners. This means that it’s not possible to react quickly enough to events that occur.

2. Number of transactions: The number of transactions made is enormous, billions of transactions per day in Bitcoin alone. This makes it impractical for a miner to verify every transaction in real time.

3. Mining pool limitations: Most mining pools are designed to confirm a certain number of transactions per second or minute. Simply using a miner that can verify transactions incredibly quickly would likely require a huge amount of computing power and energy.

Is it possible to use mining to monitor events?

While it is not possible to set up a mining rig to verify transactions in real time, there are a few scenarios in which you can use a mining rig to monitor transactions:

1. Data aggregation: You can use mining hardware to collect data from multiple sources and create a dashboard or analytics platform that shows the number of events over time.

2. Event tracking: Some miners offer event tracking services that can alert users to new events added to the blockchain in real time.

Conclusion

In summary, while it is technically possible to use a mining rig to monitor transactions on a cryptocurrency network, it would require a huge amount of computing power and energy. If you need to confirm events quickly for personal use or as part of a small-scale project, there are better options available.

If you decide to build your own miner, please note that:

You will likely incur significant hardware, electricity, and maintenance costs.

You may not get the same scalability or security benefits as using an established mining pool.

Be aware of any local laws or regulations regarding cryptocurrency mining.

Additional Resources

If you are interested in learning more about cryptocurrency mining, I recommend checking out the following resources:

Bitcoin Stack Exchange: A Q&A forum for Bitcoin enthusiasts and developers.

Ethereum Developer Documentation: Official documentation for building applications on the Ethereum blockchain.

Cryptocurrency Mining Guides: Numerous guides and tutorials are available online to learn more about cryptocurrency mining.

56439ed9 As a developer working with Ethereum-based smart contracts, especially with the latest versions of Next.js, you might encounter an error that seems confusing at first glance. The above error message indicates that parameters are missing or invalid when calling a function on the contract. In this article, we will delve into the reasons behind such errors and provide guidance on how to troubleshoot and resolve them.

Why is the error occurring?

[*P*]

When writing a function to interact with an Ethereum smart contract using Next.js, several factors can contribute to the “Parameters are missing or invalid” error:

Invalid function signature: check that the `contractAddress` parameter matches the expected format specified in the contract ABI (Application Binary Interface). In most cases, it should be in the format `address:address`.

Invalid function call syntax: Make sure you are calling the correct function with the correct parameters and order. The Ethereum blockchain API follows a specific structure for calling functions on contracts.

Missing or incorrect contract interface: The contract’s ABI (Application Binary Interface) file defines the interfaces used by the contract. If your contract has changed since the last ABI update, you may need to update the function call parameters accordingly.

Contract provider library or SDK mismatch: Using an outdated or incompatible Ethereum library can lead to errors like this.

Troubleshooting steps:

To resolve the error, follow these step-by-step instructions:

### Step 1: Check the function signature

Make sure your contract’s ABI file (e.g. `abi.json`) is formatted correctly and matches the expected structure.

Check that the function signature in your code matches the ABI file.

Example:

json

// abi.json

{

"inputs": [],

"name": "mycontract",

"outputs": [],

"stateMutability": "",

"type": ""

}

### Step 2: Correct the function call syntax

Make sure you are calling the correct function with the correct parameters and order. Check the contract provider library or SDK documentation for instructions on how to use the `contractAddress` parameter.

Make sure the function name, return type, and input arguments match the ABI file of your contract.

Example:

jsx

// myContract.js

import { ethers } from 'ethers';

const MyContract = async () => {

// Function call with correct parameters

};

### Step 3: Update the contract interface

If your contract has changed, update the `abi.json` file to reflect the new ABI.

Make sure you are using the latest version of the contract provider library or SDK.

Example:

json

// abi.json

{

"inputs": [],

"name": "my contract",

"outputs": [],

"stateMutability": "",

"type": ""

}

### Step 4: Review and test your code

[*P*]

Run your application with the updated `abi.json` file to verify that the function call is successful.

Test your contract interactions using tools like Remix or Truffle Suite.

By following these steps, you should be able to resolve the “Parameters are missing or invalid” error when calling functions on Ethereum-based smart contracts in Next.js.

29844e48 The 24-word seed, also known as a mnemonic phrase, is a key component in Ethereum wallets that allows users to recover their private keys in case of an emergency. However, as you pointed out, this limited length can make it difficult for users to track when they later added or removed wallets.

The Problem with 24-Word Seeds

A typical 24-word seed consists of a combination of letters and numbers that represent the wallet’s private key. This is where things get complicated. When you add a new wallet, you are essentially creating a new unique identifier for that wallet. However, this new seed only covers the initial creation process.

The Problem with Renaming or Deleting Wallets

If you rename or delete a wallet, the new resource created at the time of the rename or deletion will still be valid. This means that if your 24-word source is used to restore your wallet after it has been renamed or deleted, it may no longer work.

To illustrate, consider the following scenario:

You create two identical wallets with different names.

When you add a second wallet, you use the same 24-word source to generate the private key.

Later, you rename one of the wallets and use the new 24-word source for that wallet.

If you need to restore your old wallet, using the original 24-word source may still work.

Workaround

To overcome this limitation, users can leverage Ethereum’s “key revocation” feature. When a private key is no longer valid due to changes in ownership or wallet name, it can be revoked and removed from the blockchain.

By using a different 24-word source for each new wallet, you can track when wallets were added or removed, even if their private keys were renamed or modified. This way, you will always know if your current wallet is the one that was created at a specific time.

Conclusion

While the 24-word base may not be able to cover all scenarios, it can still play a vital role in maintaining the integrity of Ethereum wallets. By understanding how to use a different source for each new wallet and utilizing the key revocation feature, users can ensure that their private keys remain valid even after changes are made.

If you are interested in learning more about Ethereum wallets or how to manage your private keys, we are happy to provide additional resources and advice.

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55 минут назад – [[Начать изучать]] – Quantum Field Capital: Курс по торговле криптовалютами и техническому анализу

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– **Форматы обучения:**
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