What are "crl-set" and "manifest.fingerprint" Temporary Files on my Windows 7 computer? Can I remove them?

"crl-set", "manifest.json", and "manifest.fingerprint" Temporary Files are created by Chrome and Chromium browsers. They are located repeatedly in multiple sub-folders like "5856_28038" in the \Users\<userid>\AppData\Local\Temp folder.

By default, Chrome (and Chromium) browser runs a background process, even after you have closed the browser. The process visits all CA (Certificate Authority) Websites to download the CRL (Certificate Revocation List) and stores the information in those temporary folders.

In every one or two days, the Chrome background process will create a new temporary folders with two random numbers as the folder name like "5856_28038". The folder contains 3 files like:

04/01/2017  05:32 AM             1,481 crl-set
04/01/2017  05:32 AM                66 manifest.fingerprint
04/01/2017  05:32 AM                34 manifest.json

"manifest.json" and "manifest.fingerprint" files contains little information. But the "crl-set" file contains a set of CRL entries in JSON format:

{
   "Version": 0,
   "ContentType": "CRLSetDelta",
   "Sequence": 3642,
   "DeltaFrom": 3641,
   "NumParents": 58,
   "BlockedSPKIs": [
      "GvVsmP8EPvkr6\/9UzrtN1nolupVsgX8+bdPB5S61hME=",
      "PtvZrOY5uhotStBHGHEf2iPoWbL79dE31CQEXnkZ37k=",
      ...
      "MO\/kE4JHbDOA8C9+I+ZrovhnsFnuHqaHlrRBuFtdElY="
   ],
   "NotAfter": 1491378849
}

CRL entries are important to be updated to allow Chrome to stop visiting Websites whos security certificates have been revoked for some reason.

But Chrome should have done a better job to use a single temporary file/folder and update it repeatedly, instead of creating hundreds and thousands temporary files.

No. You should not remove those "crl-set" temporary files. One day, Chrome will be enhanced to stop creating so many of them.

⇒ ~DF*.TMP Temporary Files

⇐ TCD*.tmp Temporary Folders

⇑ Files in %TEMP% and %TMP% Folders

⇑⇑ Windows 7 Tutorials