What are the odds of getting same address or private-key or 12/24 set of mnemonic to 2 different people

Question

Questions!!

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1. What are the chances that 2 people get the same set of those 12 or 24-word mnemonic??

2. In web3.js, there is a function ' web3.eth.accounts.wallet '... It spits out a set of accounts and private keys... What are the odds of getting the wallet or address ?? (I think its related to the question above)

3. (Noobie question) Let's say I generated a wallet. now,

   • is it possible to create 12/24 mnemonic from that wallet (mostly no but still I need your point of view)
   • If I want to create my own wallet using javascript, how can I get that functionality to generate that set of mnemonic (a feature used by Metamask)

Answer 1

What are the chances that 2 people get the same set of those 12 or 24-word mnemonic?

Mnemonic phrases are generated from 128 bits (12 words) to 256 bits (24 words) of entropy. The probability to guess a mnemonic phrase is 2^-128 to 2^-256, which is very small. The longer the mnemonic phrase, the smaller the chance to guess it though.

Is it possible to create 12/24 mnemonic from that wallet?

Mnemonic phrases only go one way. You generate a mnemonic phrase, and derive a private key from that. You cannot "import" a private key into the mnemonic phrase, without brute forcing the mnemonic phrase. As explained above, that would be near impossible.

Here is a more detailed explanation of mnemonic phrases.

If I want to create my own wallet using javascript, how can I get that functionality to generate that set of mnemonic

You can use Ethers.js to generate a random mnemonic phrase:

import { utils } from 'ethers';

const entropy = utils.randomBytes(16);
const mnemonicPhrase = utils.entropyToMnemonic(entropy);

This will generate a random 12 word mnemonic phrase. If you want to generate a 24 word mnemonic phrase, change utils.randomBytes(16) to utils.randomBytes(32) instead.