Simply Series: Seeds and Private Keys Part 2, BIP 39 Explained


Knowing your BIP32 seed is important.

You want to "back it up" (meaning physically writing it down somewhere)

It can be entered into any another BIP32 hierarchical deterministic (or HD) wallet and restore every private key, public key, and public address generated from your BIP32 seed. In other words, it can restore all of your coins you used with that wallet.

A BIP32 seed could look like this:

xprv9s21ZrQH143K2yLqS7wJa3h5cegqGq5mu2k2NXoEgSPnc36FW6XTKJgraFthHf3U6BvGUELsKDjM1acNAcvdKrTj6UcReNhrBXTk2gpx3Zj

Pretty unreadable right?

Whether you try to memorize it or write it down somewhere, you're prone to make a mistake.

One false letter, number, sequence of characters, upper case, lower case, etc. can lead to losing your coins forever.

But what if there was a way to transform it into something more friendly?

BIP39 does just that.

BIP39: Mnemonic code for generating mnemonic keys

BIP39 basically says that long string of numbers and letters that is your BIP32 seed is unreadable (to any normal human anyway).

So instead (through some complicated math), BIP39 states a seed can be generated from friendly mnemonic phrase - a group of easy to remember words - consisting of 12-24 words in a SPECIFIC order.

We'll continue to refer to this as a "mnemonic phrase" but it can be referred to as a wallet recovery seed, mnemonic seed, backup phrase, or any other variation of the words: seed, recovery, back up, phrase, mnemonic.

A mnemonic phrase looks something like this:

cheese upset pudding inmate flavor crush hard same element index laugh supreme

A mnemonic phrase aren't just any words. They come from a specific BIP39 wordlist consisting of 2048 specific words.

Being actual words, a mnemonic phrase allows easier memorization, is more readable, and lessens the chance of human error when copying it down.

A cryptocurrency wallet using both BIP32 and BIP39 will provide you with these 12-24 words in a specific order and advise/warn you to write it down.

Like a BIP32 seed, a mnemonic phrase can be entered into a wallet utilizing BIP39 and BIP32 to restore and recover all of your coins.

To summarize:

A BIP32 seed:

xprv9s21ZrQH143K2yLqS7wJa3h5cegqGq5mu2k2NXoEgSPnc36FW6XTKJgraFthHf3U6BvGUELsKDjM1acNAcvdKrTj6UcReNhrBXTk2gpx3Zj 

Can be generated from a BIP39 mnemonic phrase:

cheese upset pudding inmate flavor crush hard same element index laugh supreme 

Which can be entered in any wallet utilizing BIP32 and BIP39 to recover your coins.