The .zip-file that contains the offline version of kn Secrets can be downloaded here.
To verify that the .zip-file is genuine, use any appropriate tool to compute its SHA256 hash value. The SHA256 hash value should come out to be
67469c8e503572c8188862b54d75cf850de8dc546e41987adcf7cc8e6fcff6ba.
Once successfully verified, unzip the file into a directory on your disk, find the file "index.html" in that directory, and double-click that file to start kn Secrets in offline mode. Please follow the security guidelines whenever using kn Secrets in offline mode.