However, the realization of PKI is faced with many complicated problems such as certification management, validity, revocation, cross certification etc.

然而PKI的实现却面临着诸如证书管理、验证、撤销、域间交叉认证等许多复杂问题。

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Rather, ACI-NA expected the FAA to issue letters to specific airports that have systems with known Year 2000 problems and require them to fix or replace the equipment or face revocation of their safety certification.

CNN: Airports resist new Y2K tests