osProfile = @{
                    computerName = "test"
                    adminUsername = $username
                   #adminPassword = "[parameters('adminPassword')]"
                    linuxConfiguration = @{
                        disablePasswordAuthentication = $useSSH
                        ssh = @{
                            publicKeys = @(
                                @{
                                    keyData = $sshPublicKey
                                }

                            )
                        }
                    }
                }

failed with message '{ "error": { "code": "InvalidParameter", "target": "linuxConfiguration", "message": "The value of parameter linuxConfiguration is invalid." } }

2048 37 213...XXX.....37 rsa-key-20180723

edit

ssh-rsa AAAAB3....XXX....YHhqCtuRw== rsa-key-20180724