Bitcoin Seed Phrases – Details on a Feature Letting You To Store Your Bitcoin in Your Brain
The best way to secure access to the fruits of your labor.
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Whether you're a beginner or an experienced person in the Bitcoin world, you all know what the golden rule is to really take power with Bitcoin. There's a famous saying that helps you remember this golden rule:
Not your Keys, Not your Bitcoin.
Your Bitcoin is only yours when you have the associated private keys. If you have Bitcoin that is deposited on a trading platform, then it is not really yours. You are trusting a third party to hold the fruits of your labor.
You are stuck with the same problem as with the current monetary and financial system.
Without private keys, you cannot regain full control over your life
The exchange platform can decide at any time to block your Bitcoin. The unconfiscatable nature of Bitcoin disappears completely. You no longer have the freedom to live your life on your own terms. It is therefore essential to transfer your Bitcoin to cold storage as soon as possible to really access the liberating power of Bitcoin.
Some will even tell you that all you need to store your Bitcoin is to memorize your seed phrase.
This is something that may sound amazing, but it is totally true. In what follows, I'll give you all the details about this essential Bitcoin feature: mnemonic seed phrases.
A private key associated with Bitcoin is really just a large secret number. You will use it to authorize the transfer of your Bitcoin funds from an address on the Blockchain.
The first time you started cold storage such as a hardware wallet, you were asked to write down several words, between 12 and 24, and keep them absolutely secret.
You may have wondered what these words represent?
A list of 12 or 24 words is enough to access your Bitcoin at any time
These words are a representation of your private key that allows you to use your Bitcoin if you lose your hardware wallet or if it stops working.
To understand how these words encode your private key, it is necessary to go back in time a bit. In 2013, the BIP39 was introduced. Its purpose was to implement a strategy to represent private keys from a list of words.
In this list, there are 2048 possible words. Each word is associated with a number. You can see the complete list here on GitHub:
These words were chosen so that no two words in the list were similar and they were all basic, easy-to-remember words. Each word corresponds to its position in the list, starting with 0:
abandon = 0
ability = 1
able = 2
about = 3
zebra = 2044
zero = 2045
zone = 2046
zoo = 2047
The words have also been chosen to be easily remembered by the human brain.
This list of words can be transformed to obtain your private key
Each word is associated with a number, so you can easily convert a seed phrase into a list of numbers:
concert bulk cool predict monitor bronze royal craft video next erode frequent example describe furnace few reveal choice pony express wolf deposit control elder
373, 240, 382, 1357, 1144, 229, 1509, 400, 1950, 1194, 612, 741, 627, 476, 754, 684, 1475, 321, 1343, 646, 2022, 472, 379, 570
These numbers are then combined through various hashing steps to produce an associated private key. All the details of these transformation steps can be found on the GitHub repository of BIP39.
The interesting thing to notice is that the last word in the list encodes what is commonly called a checksum. This is the first few bits of a data hash that is used to make sure you haven't typed the words wrong.
So, if you type some words wrong, the software will detect it directly because the checksum will be invalid.
After the theory, it's time to practice generating a Bitcoin seed phrase
Now that you have all the theoretical details at your disposal, we can move on to practice. For this, I advise you to use the online tool created by Ian Coleman: https://iancoleman.io/bip39/.
In this tool, you will select the number of words in your seed phrase and the language for the list of words you want to remember next:
To go a little further, you can click on "Show entropy details". You will have more details about the whole process. You will see the numbers associated with each randomly generated word in the "Word Indexes" section:
Where things get interesting is when you try to reverse the first two words of your seed phrase: bulk and concert.
The software will immediately detect that the mnemonic is invalid:
This is where the checksum plays its role by allowing to detection of the problem directly. This feature allows you to avoid a lot of input errors.
From a mnemonic seed phrase, you can obtain your BIP39 seed
By putting your words in the right order, you will be able to discover the private key derived from this list of words in the "BIP39 Seed" section:
Here, the associated private key is :
You notice that the seed is 512 bits long, while a private key is supposed to be 256 bits long. The little subtlety here is that the first 256 bits are your private key, while the second 256 bits can be called a "chain code" for an HD Wallet (Hierarchical Deterministic Wallet).
Retaining your seed phrase in your brain is enough to access the fruits of your labor stored within the Bitcoin network
Now let's imagine that you have your Bitcoin stored on a hardware wallet. Of course, you have taken care to remember the 24 words of your Bitcoin seed phrase. One day, suddenly, you have to leave your country without being able to take any luggage with you.
Once you arrive in your new home, you will be able to regain full access to your Bitcoin thanks to the 24 words you have stored in your brain.
You can restore your entire Bitcoin wallet to a new hardware wallet. This is why Bitcoin is such an incredible store of value. You don't need to remember anything other than 24 words to be able to carry all your wealth around the world without the risk of someone stealing it.
One last important point to mention here is that you should absolutely not use the BIP39 site I just showed you to generate your word list. When you go to generate your Bitcoin seed phrase, you should not be connected to the Internet.
You never know if someone is spying on your computer or web browser. So, as always, you should be careful to protect the fruits of your labor.
So now you know why Bitcoiners keep saying that you only need your brain to store all your wealth in the Bitcoin system.