trustedpath

Trusted path is a security concept that provides a dedicated, verifiably secure channel for handling sensitive user input and output. It is intended to protect actions such as authentication prompts, password entry, and PIN entry from being intercepted or manipulated by untrusted software running in the normal user space.

The core idea of a trusted path is isolation and verification. By routing critical interactions through a trusted, restricted component, the system aims to prevent malware, compromised applications, or other untrusted code from spoofing prompts or capturing keystrokes during sensitive operations. Achieving this often involves a combination of design elements, such as a secure attention sequence, a minimal trusted code base, restricted user interfaces, and strong access controls.

Mechanisms commonly associated with trusted paths include a secure attention sequence that forces the system to switch from the regular user interface to the trusted subsystem, a protected or minimized input/output path, and a trusted process or daemon that handles authentication or other high-sensitivity tasks. Some implementations rely on hardware or firmware support, dedicated console paths, or separate session environments to reduce exposure to untrusted software.

Examples and scope of trusted path concepts vary by platform. In some UNIX-like and mainframe environments, trusted path facilities were implemented to guard console login and key entry. In modern Windows environments, secure desktop modes and attention-sequence mechanisms provide analogous protections for credential prompts and user account control prompts. The exact composition and enforcement of a trusted path depend on hardware, operating system design, and security requirements.

Limitations include the fact that trusted path protections can be bypassed through hardware compromises, supply-chain risks, or attacks that exploit the trusted subsystem itself. As a design goal, trusted path remains one layer of defense within broader authentication and system integrity strategies.