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PRODID:-//pretalx//pretalx.bitfest.uk//bitfest-2026//talk//EKAY9N
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UID:pretalx-bitfest-2026-EKAY9N@pretalx.bitfest.uk
DTSTART:20261121T112500Z
DTEND:20261121T120500Z
DESCRIPTION:**TL\;DR:** Picture this: on an air-gapped device\, you create 
 a 3-of-5 backup of your BIP39 seed. Years later\, you recover it using jus
 t pen\, paper and a calculator. This is one of the many cool things DuraSh
 are can do. In this hands-on workshop\, you’ll see a live air-gapped cer
 emony in action\, perform an individual share audit\, and manually reconst
 ruct a toy model seed (3 words plus checksum) step-by-step to experience t
 rue software-independent recovery firsthand.\n\n## Abstract\n\nLong-horizo
 n cryptocurrency self-custody faces a dual failure model: exposing or losi
 ng a master BIP39 mnemonic\, or surviving decades only to find recovery so
 ftware\, operating systems\, or specialized hardware obsolete or unavailab
 le. Existing approaches may use custom share encodings\, alternative walle
 t-derivation models\, or high manual friction.\n\nThis workshop presents *
 *DuraShare**\, a BIP39-native _k_-of-_n_ threshold backup with full manual
  fallback and per-share audit capability. For everyday convenience we adop
 t a software-assisted model\, while ensuring that all the core math remain
 s feasible for recovery\, requiring nothing beyond paper\, a calculator\, 
 and specific instructions.\n\n**DuraShare** combines three existing\, well
 -established cryptographic techniques: (1) **Shamir Secret Sharing** over 
 _GF(2053)_\, the smallest prime field containing the 2048-word BIP39 list\
 ; (2) **2D error detection**\, applying row and column checksums to each s
 hare to protect the data against transcription errors and physical damage\
 ; and (3) an optional **affine inner-product MAC** over the same finite fi
 eld that\, when the corresponding key material is separately held and unco
 mpromised\, provides bounded detection of active share substitution before
  secret reconstruction.\n\nTo demonstrate recovery independence\, the work
 shop includes two live demos: the whole process using a **single-file HTML
  tool** (designed for air-gapped environments like Tails OS)\, followed by
  a **hands-on\, step-by-step paper-and-calculator recovery of a single row
 ** (3 words and a checksum) using printed templates.
DTSTAMP:20261108T155146Z
LOCATION:Momentum - Hack Zone Stage
SUMMARY:DuraShare: BIP39-Native Threshold Backup with Full Manual Fallback 
 and Per-Share Audit - Renato Schiavinato Lopez
URL:https://pretalx.bitfest.uk/bitfest-2026/talk/EKAY9N/
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