Grid Generation
Border Wallets employ three key components in order to provide users with a reliable means to memorise their Bitcoin wallets:
- A Pattern
- An Entropy Grid
- A checksum
In order to provide users with a practical means for creating all three components, we made a tool - the Entropy Grid Generator (or ‘EGG’).
The EGG comes as a .html file which opens locally within the user’s browser.
The GENERATE tab of the EGG provides users with the ability to create:
- Pattern Grids - for creating and drawing a memorable ‘pattern’ which the user memorises (1)
- Entropy Grids - for transposing or ‘mapping’ the pattern onto in order to determine the seed words that will make up the first 11 or 23 words of a user’s wallet (2).
The Entropy Grids offer users the ability to work with up to four kinds of grid - a Word Grid (shortened BIP39 seedwords), Number Grids (using their corresponding numbers), Index Grids (the same as Word Grids, but the index is 0 instead of 1) and Hexadecimal Grids (base 16). Most people will want to use Word Grids.
The Entropy Grid Generator uses 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 BIP-39 seed words.
The option to reproduce Entropy Grids using 12 words as entropy uses Gibson Research Corporation’s Ultra-High Entropy Pseudo-Random Number Generator.
When populating the list of seed words in the Word Grids, only the first four letters of each word are produced in order to save space and time.
Both options produce a wallet of the same strength - that is set by how many cells your pattern selects (11 or 23 words), not by the grid.
The difference is how hard the grid itself is to reproduce. A Deterministic Grid is derived from a 12-word Recovery Phrase, so it is fixed by 128 bits of entropy - the same as a 12-word Bitcoin seed. A Maximum Entropy Grid is one of 2048! possible arrangements (about 19,580 bits) and cannot be derived from anything, which is why no Recovery Phrase can be offered for it.
Choose Deterministic if you want the option of a written 12-word backup of your grid. Choose Maximum Entropy if you would rather the grid exist in no other form.
Once the user has generated their Pattern and their Entropy Grid, and identified which words will form the first 11 or 23 words of their seedphrase, they then need to calculate the final - Checksum - word. The EGG provides a means to do this.