This step is to verify a downloaded firmware binary against a reference checksum to avoid download errors.
Obtaining the reference checksum from the download page is currently a little inconvenient, as the reference checksums of the firmware binaries are currently not listed on the LEDE device tech data pages.
To get the reference checksum, recall the URL path of firmware binary you just downloaded, e.g. if your firmware download-URL was
then open the web page https://downloads.lede-project.org/releases/version/targets/chipset/modell/
There you will find a list of firmware images, one of it being the file you just downloaded. Now note the additional checksum string on the right side of the download link (in the table column “sha256sum”).
We will now calculate a checksum of the downloaded file and compare it with that string. If that check fails, the firmware file was not properly downloaded and if you proceed flashing such a file, you will probably brick the device permanently or requiring annoying procedures to recover.
To use the built-in “certutil:
certutil -hashfile "%USERPROFILE%/Downloads/LEDE-file-name-here" sha256
SHA256-Hash of file C:\Users\USERNAME\Downloads\lede-17.01.1-...-factory.bin: 79 f9 4e fa d3 2c 14 8f f1 95 3f 09 6d 98 c7 41 c0 ff 8f 7e b4 68 8c 9d 5b f9 fb 01 c0 90 fb ab
Mac has an integrated tool to check sha256sums, but it has no graphical user interface so we will have to use the Terminal to interact with it.
shasum -a 256 ./Desktop/file-name-here
Linux has an integrated tool that is accessible from command line, similar to Mac.
Command line verification: