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Using Speculos

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Speculos emulates Ledger Nano S, Nano X and Blue apps on standard desktop computers, without any hardware device.

Usage example: ./ apps/btc.elf.


The emulator handles only a few syscalls made by common apps; for instance, syscalls related to app install, firmware update or OS info can’t be implemented.

There is absolutely no guarantee that apps will have the same behavior on hardware devices and Speculos:

  • Invalid syscall parameters might throw an exception on a real device while being ignored on Speculos.
  • Attempts to perform unaligned accesses when not allowed (eg. dereferencing a misaligned pointer) will cause an alignment fault on a hardware device.


Apps can make arbitrary Linux system calls (and use QEMU semihosting features), thus don’t run Speculos on untrusted apps.

It’s worth noting that the syscall implementation (src/) doesn’t expect malicious input. By the way, in Speculos, there is no privilege separation between the app and the syscalls. This doesn’t reflect the security of the firmware on hardware devices where app and OS isolation is enforced.

Linux installation
Getting Started
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