btsync PaperSecret Converter

This little tool turns BitTorrent Sync Secrets into 15 words you can write down and copy more easily.

The idea and the wordlist is from the BIP 0039 reference implementation: trezor/python-mnemonic

Try it right here!

TODO

• Autocompletion for the words to input them more easily
• Design improvements (Sorry, first time i'm using bootstrap)

How does it work:

btsync uses 33 characters for displaying the secret to the user. The secret only contains characters [A-Z] and [2-7].

This results in 26 + 6 = 32 = 2⁵ different characters, which can be stored in 5 bits.

With 33 of this characters the secret has 33 · 5 = 165 bits of data.

With a wordlist of 2048 = 2¹¹ words the data can now be splitted into 165/11 = 15 words. And a single word then represents its number in the list as data.