As each unique entropy grid contains a complete list of all BIP39 seed words in randomized format, and the users’ patterns exist only in their heads, users will store their entropy grid (or its recovery phrase) physically or digitally. Since entropy grids comprise all 2048 Bitcoin seed words in a random format, any evil maid attacks are faced with an upward difficulty adjustment that is significantly higher than if plain text seed phrase backups were discovered. You can think of it as a firewall between your seed words and any potential attackers.
Other Features
Final Word Calculator And Final Word “Number”
The EGG allows users to import the relevant 11 or 23 words from their entropy grid in order to calculate the final checksum word. In addition to the user’s pattern, the checksum is the only thing that must be memorized.
However, in order to make this even easier, the EGG includes a unique “final word number” feature. With this, instead of needing to remember the word “pair,” users can just remember the number “5” — they could even write down this number on their entropy grid since, on its own, it is meaningless and provides no clues about the final word without the other words being known.
Users may also change the final word number to something more meaningful to them, although this also changes the final word itself. Therefore, if users do change the number, the new checksum shown must be used to set up your Border Wallet. We don’t advise users to change the number (since it is generated with entropy by the tool), but the option is there if desired.
The EGG’s “final word” feature provides automatic calculation of the checksum. This checksum, or its associated “final word number” — a unique feature within the tool — is the only word that must be remembered to recreate the Border Wallet.
Deterministic Grid Regeneration
When creating an entropy grid, the EGG provides the option to choose deterministic entropy. By using 128 bits of entropy in the creation of these grids, we have the ability to simultaneously generate 12-word recovery phrases that give a plain text backup. Recovery phrases are automatically added to the bottom of deterministic entropy grids during generation.
An example of a 12-word grid recovery phrase provided when you generate a deterministic entropy grid. This provides the option to save entropy grids in plain text format. It looks and behaves like a normal Bitcoin wallet and therefore could be used as a decoy/canary.
The provision of a 12-word recovery phrase may at first glance seem counterintuitive to the concept of Border Wallets — after all, we are giving users the ability to memorize seed words, not find new ways of writing new ones down! However, some users may find value in having the option to make handwritten or digital copies of regeneration words in some circumstances: for example, if they want to store a copy of an entropy grid with a third party (sibling, parent, child, etc.) for safekeeping.
Since all 12-word recovery phrases are valid BIP39 mnemonic phrases, this gives additional options for deploying decoy funds on the resulting wallet or just to have nothing at all on them. In the latter case, an attacker may spend money and resources trying to brute force a passphrase on a seed phrase that looks like it should have funds, but which only unlocks an entropy grid.
Gridception And The Art Of Obfuscation
As there is essentially zero cost for generating entropy grids, users may choose to generate dozens (or even hundreds) of individually numbered grids, storing their preferred grid among considerable “noise.” Imagine having 100 unique and individually numbered entropy grids, the user being the only person who knows which grid(s) might have been used to generate the Border Wallet.
Gridception offers users the ability to use words from one Entropy Grid to generate new grids — dramatically increasing attack difficulty!
In fact, there is no reason why a user cannot generate multiple patterns — or even multiple entropy grids — to create a multisig wallet that they can carry in their head. Deterministic grids also unlock the ability to introduce multigrid solutions whereby a primary entropy grid is encoded within other entropy grids. We call this gridception .
To do this, users would generate a grid and then construct a 12-word pattern to apply it onto that grid. They then take those 12 words and input them to the “grid regeneration” tab within the EGG, producing a second grid. This can then be repeated to create new grids ad infinitum.
“A dream within a dream. I’m impressed. But in my dream, you play by my rules” — Saito, Inception
Encryption
For entropy grids stored digitally, i.e., on one’s personal computer, USB thumb drive or secure online cloud storage, the EGG features an option for users to natively encrypt and decrypt their entropy grids all within the tool’s interface. Once users have created a secure password, they drag and drop their entropy grid into the tool for encryption, producing an encrypted .json file that they can then store more safely in digital format. To decrypt, the .json file is imported back into the tool and unlocked with the same secure password.
Handling Seed Word Randomization
For “maximum” entropy grids — which use a truly cosmic 19,580-bits of entropy — the EGG employs the Fisher-Yates shuffle algorithm and the browser’s cryptographically strong pseudo-random number generator seeded with truly random values for generating a random permutation of all BIP39 seed words.
The option to reproduce deterministic entropy grids using 12 words — created using 128-bits of entropy — uses Gibson Research Corporation’s ultra-high entropy pseudo-random number generator .
Applications For Bitcoin And Beyond
For Bitcoin, Border Wallets and entropy grids offer new applications and solutions for bitcoin cold storage and transportation, legacy planning, gifting, third-party custody assistance as well as, most obviously, border crossings.
Looking beyond Bitcoin, however, we envisage the idea being applicable to other decentralized protocols where seed words are used for user account backup, i.e., Nostr, Web5 and other decentralized identifier-type systems.
This is a guest post by Wartime Microchad. Opinions expressed are entirely their own and do not necessarily reflect those of BTC Inc. or Bitcoin Magazine.