Zkool - The successor to Ywallet

Zcash Apps
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Hi hanh,

I’m reaching out because you’re one of the few people who deeply understands both Zcash protocol internals and Ledger integration.

My situation:

  • Device: Original Ledger Nano S (functional, PIN known)

  • Amount: 100 ZEC (~€40,000)

  • Address: t1ZsfDa4kpk8aYjffUgv149suF2i54hLH4P

  • Transaction date: May 25, 2018 — one month BEFORE Overwinter activation (block 347500)

  • Problem: Pre-Overwinter UTXOs (v1 transaction format)

  • Critical issue: I lost my 24-word recovery phrase

What I’ve tried:

  1. Ledger Live + standard Zcash app → bad-tx-consensus-branch-id-mismatch

  2. Zondax ZecWallet + Zcash Shielded app → syncs but doesn’t find 2018 UTXOs

  3. Contacted Zondax → they confirmed no solution for pre-Overwinter format

  4. Contacted Ledger support → they confirmed Zkool solution requires Nano S Plus (Zcash Shielded app on Nano S doesn’t support NU6)

The core problem:

  • Zkool + Zcash Shielded can recover old UTXOs (v1, v2, v3), but only on Nano S Plus/X/Stax

  • Original Nano S has old Zcash Shielded version that doesn’t support NU6

  • Without seed, I can’t migrate to a newer device

  • The private key is locked inside the Secure Element

My question:

Is there ANY technical path to spend pre-Overwinter transparent UTXOs from an original Ledger Nano S without the seed phrase?

I’m thinking:

  • Modified Ledger app that supports v1 transaction signing on Nano S?

  • Some way to use the old Zcash app (not Shielded) with correct branch ID?

  • Any other approach I haven’t considered?

I am willing to fund development of a solution — up to €40,000 (the value of the locked funds). If you’re interested or know someone who could help, please let me know.

Thank you for your time.

Best regards, Andrey