Shamir Secret Sharing: Protecting Bitcoin from Single Point of Failure

Millions of dollars' worth of Bitcoin are lost due to one simple reason: a single seed phrase that can't be recovered. Chainalysis and Ledger Academy point to this as the root cause, with River Financial estimating that 1.6 million BTC is lost due to self-custody mismanagement alone.

This issue can be addressed using Shamir Secret Sharing (SSS), a threshold cryptography scheme that splits a seed into multiple shares, so no single share can recover or destroy the wallet on its own. The SLIP-39 specification adapts SSS specifically for backing up hierarchical deterministic wallets.

A study by Oobit found that 35% of US crypto holders have lost access to a wallet at least once, and 31% of those people never got their funds back. Losses tied to the 2022 LastPass breach topped $435 million, including $150 million lost by Ripple co-founder Chris Larsen.

SSS is designed to survive the loss of some shares and distribute recovery authority across people and places without giving any one of them full control. The standard BIP-39 recovery phrase is convenient but also a single point of failure, as anyone holding the phrase holds the funds.