128 one-bit rolls
SEED SECURITY
Create a Bitcoin seed phrase with dice
Learn how entropy, BIP39 words, checksums, and careful offline handling fit together. Review the workbook before using it with real funds.
WORKBOOK
Download the password-protected workbook
The download is a cleaned, blank copy of the supplied workbook. It retains the workbook layout and calculations, but the previously filled dice entries and cached outputs have been removed. The password is shared separately, not published on this page.
256 one-bit rolls
words in each standard list
What a seed phrase does
A wallet recovery phrase represents the secret material from which wallet keys and addresses are derived. Anyone who learns the phrase can usually take the bitcoin controlled by that wallet. There is no password reset or customer support that can restore a lost phrase.
Entropy is the source of security
Entropy means unpredictable information. A longer phrase is not automatically safer if its words were chosen by a person or generated by a compromised computer. Use fair, independent dice and keep every roll private. Do not choose, edit, or repeat rolls to make a phrase look memorable.
How this workbook turns rolls into bits
The workbook maps each fair six-sided roll to one bit: 1, 2, or 3 becomes 0; 4, 5, or 6 becomes 1. Each side of the split has three outcomes, so an ideal fair roll contributes one unbiased bit. It needs 128 such rolls for 128 bits of entropy, or 256 for 256 bits.
How BIP39 turns bits into words
BIP39 accepts 128–256 bits of entropy in steps of 32 bits. It hashes the entropy with SHA-256, appends the first ENT/32 checksum bits, then splits the result into 11-bit numbers. Each number selects one of 2,048 words. That gives 12 words from 128 bits or 24 words from 256 bits. The checksum helps catch mistakes; it adds no entropy and does not prove that a phrase was generated safely.
What the attached workbook calculates
This workbook asks for 256 seed rolls and uses them to show both a 24-word phrase and a 12-word phrase derived from the first 128 bits. It also has 50 rolls for Diceware passphrase words and displays QR encodings. The two phrases share part of their underlying entropy, so do not treat them as unrelated wallets. Every displayed phrase, QR code, screenshot, printout, or saved copy is sensitive.
A general spreadsheet is not an air-gapped signer
Entering rolls into Excel puts the resulting secret on a general-purpose computer. Being offline reduces some risks but does not rule out malware, backups, autosave, recovery files, printers, or later reconnection. For a wallet holding meaningful funds, prefer a reputable hardware wallet with a documented dice-entry workflow so the phrase is generated and kept on the signing device. Check the device maker’s instructions and independently verify recovery before depositing funds.
A SECOND SECRET
Optional BIP39 passphrase
A BIP39 passphrase is an additional secret, not one of the 12 or 24 words. Each different passphrase opens a different wallet, including a wallet that looks empty. The workbook’s Diceware section creates 6-, 7-, or 8-word options from 50 dice rolls. A forgotten passphrase cannot be recovered from the seed words.
WORKBOOK WALKTHROUGH
If you are studying the workbook
Prepare a private workspace
Use a new, fair, standard six-sided die on a flat surface. Work alone, with cameras and voice assistants away. Keep the computer disconnected from networks and cloud sync. Do not use an online seed generator or paste a real phrase into a website.
Enter seed rolls only in the marked cells
On “DICE ROLLS SEED,” enter the results in the blue dice-roll rows, left to right. The sheet maps 1–3 to 0 and 4–6 to 1. The workbook requires 256 rolls for the 24-word output; the 12-word output uses the first 128 bits. Do not edit the formula rows or the checksum area.
Check the workbook’s status cells
The workbook includes roll-count, invalid-roll, phrase-sync, and QR-length checks. Confirm they all show their expected “OK” or “In sync” state. These checks test spreadsheet consistency; they do not prove the computer or workbook is uncompromised.
Treat the output as a secret immediately
Do not photograph, email, message, cloud-save, or print the phrase or its QR unless you have a deliberate secure process. A QR is another readable form of the same secret. If the phrase has appeared on an internet-connected device, assume it may have been copied.
Verify recovery with the wallet
Use the exact recovery procedure for the wallet you intend to use. Confirm that it restores the same wallet and receiving address, then test recovery before moving a substantial balance. Keep a durable offline backup and store any optional passphrase separately and securely.