Mycelium HD Seed Word-Length and Entropy

BusyBeaverHP

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Quote from: apetersson on February 24, 2015, 04:29:09 AM

Quote from: BusyBeaverHP on February 23, 2015, 10:09:57 PM

I noticed while setting up a new Mycelium HD wallet, that I'm able to choose 12, 18, or 24 words as backup.

As far as I know from Electrum, 12 words is 128 bits of entropy. Does this mean that in Mycelium, I'm able to decide if my master private key is 128, 192, or 256 bits?

The master private key is always 256 bits. A 12 word backup has 128 bits of entropy. https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki

Right, I overlooked the part where Electrum seeds are hashed with 100,000 rounds of SHA2, which makes the master public key output 256 bits. Source:

https://bitcointalksearch.org/topic/m.1641145

It's nice that Mycelium allows me the option to utilize 256 bits of entropy, while keeping it simple at 128 bits by default.

apetersson

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Activity: 668

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Quote from: BusyBeaverHP on February 23, 2015, 10:09:57 PM

I noticed while setting up a new Mycelium HD wallet, that I'm able to choose 12, 18, or 24 words as backup.

As far as I know from Electrum, 12 words is 128 bits of entropy. Does this mean that in Mycelium, I'm able to decide if my master private key is 128, 192, or 256 bits?

The master private key is always 256 bits. A 12 word backup has 128 bits of entropy. https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki

The strength of ECDSA inversion from pubkey is 2^128. So some people (including me) think 12 words / 128 bit is sufficient, and longer wordlists may otherwise lead to people not doing backups.

The default for mycelium is 12 Words. At the first startup, If you import a wordlist from an external source you can chose 18 or 24 words also, with optional password.

BusyBeaverHP

full member

Activity: 209

Merit: 100

I noticed while setting up a new Mycelium HD wallet, that I'm able to choose 12, 18, or 24 words as backup.

As far as I know from Electrum, 12 words is 128 bits of entropy. Does this mean that in Mycelium, I'm able to decide if my master private key is 128, 192, or 256 bits?

Topic: Mycelium HD Seed Word-Length and Entropy (Read 3333 times)