可信计算基（英语：Trusted computing base, TCB）是指为实现计算机系统安全保护的所有安全保护机制的集合，机制可以硬件、固件和软件的形式出现。一旦可信计算机基的某个构件出现进程错误或者安全隐患，就对整个系统的安全造成危害。 与之相反，如果除可信计算基之外的系统的其他部分出现问题，也只是泄漏了系统安全策略赋予它们的相关权限而已，这些权限一般都是比较低的。

精心设计和实现的系统可信计算基对系统整体安全至关重要。现代操作系统努力降低TCB的大小，使得对其代码库彻底的检查成为可能（通过手工或电脑辅助软件审计(software audit)或形式化验证的方法）。

The trusted computing base (TCB) of a computer system is the set of all hardware, firmware, and/or software components that are critical to its security, in the sense that bugs or vulnerabilities occurring inside the TCB might jeopardize the security properties of the entire system. By contrast, parts of a computer system outside the TCB must not be able to misbehave in a way that would leak any more privileges than are granted to them in accordance to the security policy.