The iisui.dll module serves as a client certificate mapper for the Microsoft Internet Information Services (IIS) which is a family of internet based services for servers running Windows. Client certificates issued for the IIS provide user authentication functionality. This client certificate will have information that identifies the user either individually or as part of a group.
The client will send the public portion of the certificate to the server then the server will check to make sure that the certificate is valid using the iisui.dll.
Through the use of the iisui.dll one can authenticate users that log in with an IIS client certificate by mapping the certificates to Windows user accounts. The mapped certificates are used to grant rights and permissions for the mapped user account or deny access to web resources.
The two types of mapping used by iisui.dll are one to one mapping and many to one mapping. One to one mapping simply maps one client certificate to one user account. This allows servers to compare a copy of its certificate with the client certificate that is sent by the web browser. The two certificates must be identical for the mapping to proceed.
Many to one mapping enables the iisui.dll to map multiple certificates to a single user account. Iisui.dll uses wildcard matching principles to define the criteria for the mapping. Though this type of matching does not do a comparison to the actual client certificate it accepts all client certificates that meet the specified criteria. Certificates will then be mapped to the appropriate user account if the certificates match the rule set.
What is a DLL?
DLL (Dynamic Link Library) files contain computer code and resources that can be used by multiple programs at the same time. This uses less system memory and helps your computer system run more efficiently. DLL files give program developers the ability to reuse code to add features to several programs without the need to write new code for each program.
There are many programs that require DLL files to function properly so when one of them is damaged or missing it will cause program crashes and poor system performance.
Suggested fix if you are receiving iisui.dll error messages:
DLL files are important parts of your operating system and many programs require them to function. When these files become damaged or are missing it causes poor system performance and system crashes. To fix these problems the user must replace the damaged file with a valid working version. If a working version cannot be found the user may perform a reinstallation of their operating system.
Iisui.dll is created by:
Known file path:
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