On your computer enter the following in the command bar: certutil -hashfile FILENAMEHERE SHA256
Then you can compare the output with the image hash under ‘SHA256SUMS’ on the Mynode website.
To verify the Raspberry Pi4 image run the follwing commands:
wget https://raw.githubusercontent.com/mynodebtc/pubkey/master/mynode_release.pub
wget https://mynodebtc.com/device/mynode_images/mynode_raspi4_0-2-48.img.gz.sha256
openssl dgst -sha256 -verify mynode_release.pub -signature mynode_raspi4_0-2-48.img.gz.sha256 mynode_raspi4_0-2-48.img.gz
OR
wget https://raw.githubusercontent.com/mynodebtc/pubkey/master/mynode_release.pub
wget https://mynodebtc.com/device/mynode_images/mynode_raspi4_arm64_0-2-48.img.gz.sha256
openssl dgst -sha256 -verify mynode_release.pub -signature mynode_raspi4_arm64_0-2-48.img.gz.sha256 mynode_raspi4_arm64_0-2-48.img.gz