How to create the bip39 mnemonic words?

Is it better to use a physical device for this purpose or creating mnemonic bip39 phrase by ourselves? Let's go deeper in this article

In this short article, we will take in consideration how to create a own mnemonic with the best possible entropy. This snippet is from robertobipunto, an italian Bitcoin contributor

It undoubtedly makes life a lot easier to have a hardware wallet that suggests you the last word given all the previous ones, to date BitBox 02, Jade and Coinkite Coldcard do this.

Using the device

If you have one of these devices use one of the following method to find the first 23 words:

• Bitbox's table (is probably the most straightforward to follow);

• Blockstream Jade's table with “special” dices;

• draw 256 bits of raw entropy (heads or tails = 1 or 0 times 256) and find the words with robertobipunto's table, where each bip39 word is mapped to index in binary format.

Then enter the fist 23 words in your device and draw the last one from those suggested.

Note: you are invited to check the table of your choice against the BIP39 official wordslist:

https://github.com/bitcoin/bips/blob/master/bip-0039/english.txt

Without the device

If you don't have and don't want to invest in such devices, things get quite more complicated: it is probably better to draw 256 bits of raw entropy (heads or tails = 1 or 0 times 256) and enter them into Ian Coleman's BIP39 tool, configuring it to use raw binary entropy.

Note: you have to use Ian Coleman's tool offline, on a sufficiently secure OS (for example Tails and potentially better using the software keyboard to enter the entropy).

Once you get the 24 words you'll make the physical backup and decide which software wallet to use it on, if you don't have a hardware wallet probably the quickest and safest thing is to use Electrum on Tails by importing the mnemonic as BIP39.

As additional note, there is a possibility to brute-force the last word by hand by trial and error without using Ian Coleman's tool, but it's not exactly trivial and fast as a process.

The reader is invited to comment and post additional tips and notes that may be useful for everyone.