udisksctl unlock -b /dev/sdb
Passphrase: 
Error unlocking /dev/sdb: GDBus.Error:org.freedesktop.UDisks2.Error.Failed: Error unlocking /dev/sdb: Error spawning command-line `cryptsetup luksOpen "/dev/sdb" "luks-42248d91-72d0-4ba3-8e32-ec50213698de" ': Failed to execute child process "cryptsetup" (No such file or directory) (g-exec-error-quark, 8)