# Identify Files in a NIST RDS Hash Set

The `NistRdsFilter` task calculates the checksum of the file associated with a document. If the checksum is present in a NIST RDS hash set, the function adds the fields `AUTN_NIST_RDS_LIST`, `AUTN_NO_FILTER`, and `AUTN_NO_EXTRACT` to the document.

The NIST RDS hash sets contain the checksums of millions of files that originate from operating systems and application software, so you can use this task to filter out documents that represent those files.

NOTE: Before using this task you must populate a datastore with the NIST RDS hash set(s). For information about how to do this, see the following procedure.

To configure a NIST RDS Filter task

1. Configure the NIST RDS filter task in the CFS configuration file. For example:

       [ImportTasks]
       Pre0=NistRdsFilter:NistRdsFilterSettings

       [NistRdsFilterSettings]
       NistRdsStoreType=BTREE

2. Download the NIST RDS hash sets that you want to use.

3. Use the NIST RDS tool, provided in the `tools` directory of your CFS installation, to populate the datastore that you have configured.

       NistRdsTool.exe CFS.cfg NistRdsFilterSettings NistRdsFile.zip

   where,

   `CFS.cfg` | is the path to the CFS configuration file.
   `NistRdsFilterSettings` | is the section in the configuration file that contains the NIST RDS Filter task settings.
   `NistRdsFile.zip` | is the list of NIST RDS hash sets that you downloaded. If you want to use multiple hash sets, include all of the file names separated by spaces.

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