v1.2.1 — API_LEVEL 26 revival (Nano S+)

Kadena app v1.2.1 — API_LEVEL 26 revival (Nano S+)

First installable Kadena app build for current Ledger Nano S+ firmware (OS 1.6.x = API_LEVEL 26).
The last upstream release (v1.2.0) targets API_LEVEL 24 and is rejected by today's OS.

What changed vs v1.2.0

• Rebuilt from source against the current Ledger SDK (API_LEVEL 26) for all five supported
  devices (Nano S+, Nano X, Stax, Flex, Apex/Gen5).
• Memory-safety hardening in the transaction-display renderers and the JSON parser (issues
  present in the old official binaries; found in an independent review of the signing/display
  path and fixed here).
• Full Zemu test matrix green across all five device targets; end-to-end proven on hardware
  (install → derivation → clear-sign + hash-sign → transaction mined).
• All Ledger CI gates green on this repository, including the mandatory guidelines_enforcer.

Assets (Nano S+ sideload — advanced users)

File	SHA-256
installer_s2.sh	428a9ccc5da865b94c4aef91accbfb7650d5368b9c63e662bad751db53d7c223
app.hex	65701676ae571e3f5f905159e67d3880e3a2e64611e00e2b9f69314f3a1f06fc

Expected device-reported application full hash (printed by the loader at install — verify it):

d11a7d4976bebc8448429e54ae09f1c5d2f2a8abaa9da3b142d110ed6e883c05

Reproducible build: ghcr.io/ledgerhq/ledger-app-builder/ledger-app-builder:latest
(SDK v26.5.0), PRODUCTION_BUILD=1 TARGET=nanos2, from this tag. Building twice yields a
byte-identical hash — verify independently.

Install (Nano S+ only)

chmod +x ./installer_s2.sh
./installer_s2.sh load

Approve the unsigned-app prompts on the device; the app reports v1.2.1. Hash-mode signing
requires the "Blind sign" toggle in the app settings (a separate item from "Expert mode").
Sideloading never touches the device OS/Secure Element; ./installer_s2.sh delete removes the app.

Nano X, Stax, Flex and Gen 5 have no sideload path — those devices get the app when it returns to
official availability via the Ledger submission (in preparation).

Originally developed by Zondax (Apache-2.0 — license and copyright preserved). Maintained
continuation by Smart Pacts.