Author: Tobias Kaupat 2021-05-09 07:24:28
Published on: 2021-05-09T07:24:28+00:00
A user named Tobias responded to a message from Chris Johnston on the bitcoin-dev mailing list. Chris had suggested an optional method of producing a BIP39 passphrase using only BIP39 'mnemonic' seed words, and called it a 'quantum' passphrase. The idea was for two-factor authentication to protect a Bitcoin wallet using only 24 seed words, providing plausible deniability about the existence of this separate second layer passphrase. Tobias questioned whether this suggestion was necessary since there is no restriction in how users choose their passphrase, but acknowledged that it could be a helpful way to choose a password. Tobias also raised the issue that a hardware wallet needs the passphrase to generate the complete mnemonic, creating a chicken-egg problem for some implementations. He suggested that the restore feature could be used to work around this. Chris's proposal aimed to provide an extremely safe and secure 'low-tech' option that required minimal adjustments to the seed words, and offered several advantages over existing methods of multi-factor protection. These included discouraging user-created words or sentences and providing plausible deniability in case of coercion. The large amount of data required to produce a 'quantum' passphrase encouraged physical backup, and the use of BIP39-only words provided a higher degree of standardization. A two-wallet configuration provides the user with an opportunity to safely split the two factors of protection. Finally, following four non-destructive BIP39-compatible rules, the 24 seed words can also function as a 'quantum' passphrase. The rules were: only BIP39 words, only the first four letters of each word, only upper case letters, and no spaces between words.
Updated on: 2023-06-14T21:46:58.911465+00:00