[个人翻译]什么是TCB
本文翻译自http://wiki.franklinheath.co.uk/index.php/Symbian_OS_Platform_Security/02._Platform_Security_Concepts#The_Trusted_Computing_Base_.28TCB.29The Trusted Computing Base, or TCB, is the most trusted part of Symbian OS, as it controls the lowest level of the security mechanisms and has the responsibility for maintaining the integrity of the system. The first protection mechanism design principle above states the design should be small and simple, and therefore our TCB is as small as possible, in order to support this level of trust.
被信任的计算层，也就是TCB，这是塞班系统最信任的一个模块，因为它控制着级别最低的安全机制，有责任维护系统的完整性.上述的这种机制应当不占用过多的内存而且十分精细以便于支持这个级别的信任。
The TCB includes the operating system kernel, which looks after the details of each process, including the set of privileges assigned to it. The file server (F32) is also included in this tier because it is used to load program code to make a process. The process’s privilege information is established in the kernel during this loading activity. Some Symbian OS phones are ‘closed’, that is they do not support installation of native add-on software; on such a closed phone, the kernel, including the kernel-side device drivers, and the file server are the only fully-trusted components. On an ‘open’ phone, the software installer (SWInstall) is also part of the most-trusted group. This is the program that runs when you install files from a Symbian OS Software Install Script (SIS) file package. It extracts the files from the package (for example, program binaries) and it has the important role of validating the privileges requested for the program binaries against a digital signature on the installation package. Note that most user libraries are not included in the TCB – only those few which need to be used by the file server or software installer are given the highest level of trust.
TCB包含了管理每一个进程的具体内容的系统的核心，和分配给他们的特权级。文件服务器（F32)也包含在内，因为它用于加载程序的代码以用于启用另一个进程。有些塞班系统的手机是”封闭的“，换句话来说就是他们不支持安装附加的软件。在这种手机上，手机的内核（包括那些内置内核的驱动和文件系统）是唯一被完全信任的组件。在那些”开放的“手机上，软件安装主程序（SWInstall）也是最被信任的一个模块。（这个程序会在你安装软件，也就是调用塞班系统软件安装脚本包（SIS））他会解压在包内的文件（比如说文件的二进制代码），并且根据安装包上的数字签名验证为二进制程序文件请求特权，这是它的重要作用。注意，大多数用户库都没有包含在TCB中——只有那些需要由文件服务器或软件安装程序使用的少数用户库具有最高的信任级别才包含在其中！
The kernel, the file server process and the software installer have been carefully checked to ensure they behave properly and are considered completely trustworthy. They therefore run with the highest level of privilege of any processes on the phone.We should note here that strictly speaking the TCB also includes the phone hardware, including the MMU and other security-related hardware features; however, we will not be dwelling on that in this book as the hardware is not supplied by Symbian.
如果已经仔细检查了内核、文件服务器进程和软件安装程序，以确保它们正常运行，并且被认为是完全值得信任的。因此，它们以电话上任何进程的最高级别特权运行。我们注意到，严格来说，TCB还包括电话硬件，包括MMU和其他与安全相关的硬件特性;然而，我们不会在本书中详细讨论它，因为塞班并不提供硬件。
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