I want to generate an Ethereum private key from a single word mnemonic. For example,
(1) I could use keccack256 online tool to transform a word to a private key. Would this be a valid key? Are there any other ways this could have been done?
(2) In the case of a 12-24 word mnemonic it is possible to generate a 512-seed from the mnemonic sentence which is used to generate a private key. How might this be done with only one word as seed ‘’phrase’’? I know this is possible since it has been done but I do not understand how. Would it be done in the exact same way the seed from the 12 word mnemonic is derived from?
So how is it possible to generate a private key from a single word. Is it possible only using case (1) or also case (2) and other?
Best Answer
Any 256-bit number is a valid private key, so yes, it would be a valid key. But this isn't enough entropy to generate a secure private key. I could just run every word in the dictionary through
keccak256()(and every other widely used hash function that generates 256-bit numbers) and check whether there are any funds associated with each private key until I find yours.The whole idea behind using 12-24 dictionary words as the seed is to make the entropy sufficient to make it secure.
https://xkcd.com/936/
You can't have both the seed and the hash function known or easy-to-guess. (
keccak256()is known, dictionary words are easy to guess.)You have 2 choices:
For the first option, you could use a password manager to generate a secure password, then run that through
keccak256()or any other hash function that can give you a 256-bit number. However, your secure password (high entropy) doesn't come under your definition of "mnemonic".For the second option, you would need to run your chosen dictionary word (low entropy) through a hash function you had written yourself (or, alternatively, a series of known hash functions in an order only you know).