Technical Brief Architecture & Data Flow
Ledger Live is a client application (desktop/mobile) that acts as a stateless UI and transaction coordinator. Private keys are generated and stored exclusively inside the Ledger hardware secure element (SE). The app constructs transactions and sends them to the device via a transport layer (USB, BLE, or WebHID). The device signs transactions and returns signatures; Ledger Live aggregates these signatures, broadcasts to the network, and updates the local indexed state.
Transport & protocol
The primary transports are:
- USB / HID: Low-level, stable connection for desktop workflows.
- Bluetooth LE: Used by mobile; implements secure pairing and ephemeral keys.
- WebHID/WebUSB: Browser integrations for Ledger Live Web features.
Communication follows an APDU-style command-response protocol; complex operations are split across multiple APDUs. The device enforces length and format validation and requires explicit physical confirmation for every signing operation.
Signing model & UX guarantees
Ledger implements a deterministic signing model with multi-step validation:
- Transaction prepared in Ledger Live and serialized.
- Serialized payload sent to device; device validates structure and displays human-readable fields.
- User reviews details on device and presses buttons to confirm — this step provides end-to-end integrity against compromised hosts.
Security assumptions & hardening
Key assumptions developers must respect:
- Host applications are potentially compromised; device UI is the ultimate authority.
- Recovery phrase is single source of backup; never export it to hosts.
- Firmware integrity is enforced by the device bootloader — updates are signed and verified on-device.
Developer considerations
If building integrations, follow these practices:
- Use official Ledger SDKs and app specifications for APDU formatting.
- Display full transaction details on the host but rely on device confirmation for trust.
- Implement retry and error handling for transport interruptions (BLE timeouts, USB detach events).
Operational best practices
Operators running nodes or services with Ledger integrations should:
- Keep Ledger Live and device firmware updated via official channels.
- Use hardware in secure environments; avoid public or untrusted networks when performing critical operations.
- Perform small test transactions when integrating new flows.