Logo/Ensure-RealBitLockerKey.ps1

function Ensure-RealBitLockerKey {
    [CmdletBinding(SupportsShouldProcess=$true, ConfirmImpact='Medium')]
    param(
        [Parameter(ParameterSetName='Single', Position=0)]
        [ValidatePattern('^[A-Z]:$')]
        [string]$MountPoint  = $env:SystemDrive,

        [Parameter(ParameterSetName='All')]
        [switch]$AllDisks,

        [switch]$FullReencrypt,
        [switch]$PersistToRegistry,

        [Parameter(Mandatory=$true, ParameterSetName='Persist')]
        [int]$UDFNumber,

        [string]$RegistryBasePath = 'HKLM:\SOFTWARE\CentraStage'
    )

    # Determine target drives
    if ($AllDisks) {
        $targets = Get-WmiObject -Query "SELECT DeviceID FROM Win32_LogicalDisk WHERE DriveType=3" |
                   Select-Object -ExpandProperty DeviceID
    }
    else {
        $targets = @($MountPoint)
    }

    $results = @()
    foreach ($d in $targets) {
        if (-not $PSCmdlet.ShouldProcess("Volume $d","Ensure recovery key")) {
            continue
        }

        # Key regex
        $keyPattern = '^\d{6}(-\d{6}){7}$'
        $vol = Get-BitLockerVolume -MountPoint $d
        $curKey = $vol.KeyProtector |
                  Where-Object KeyProtectorType -eq 'RecoveryPassword' |
                  Select-Object -Last 1 -ExpandProperty RecoveryPassword

        if ($curKey -match $keyPattern) {
            $results += [PSCustomObject]@{
                MountPoint  = $d
                Action      = 'None'
                RecoveryKey = $curKey
                AuditString = $null
            }
            continue
        }

        # Provision new key
        if ($FullReencrypt) {
            Disable-BitLocker -MountPoint $d -ErrorAction Stop
            while ((Get-BitLockerVolume -MountPoint $d).VolumeStatus -ne 'FullyDecrypted') {
                Start-Sleep 15
            }
            Enable-BitLocker `
                -MountPoint $d `
                -UsedSpaceOnly `
                -SkipHardwareTest `
                -TpmProtector `
                -RecoveryPasswordProtector `
                -ErrorAction Stop
            $action = 'FullReencrypt'
        }
        else {
            $vol.KeyProtector |
              Where-Object KeyProtectorType -eq 'RecoveryPassword' |
              ForEach-Object { Remove-BitLockerKeyProtector -MountPoint $d -KeyProtectorId $_.KeyProtectorId }
            Add-BitLockerKeyProtector -MountPoint $d -RecoveryPasswordProtector -ErrorAction Stop
            $action = 'AddProtector'
        }

        # Grab the newly provisioned key
        $newKey = (Get-BitLockerVolume -MountPoint $d).KeyProtector |
                  Where-Object KeyProtectorType -eq 'RecoveryPassword' |
                  Select-Object -Last 1 -ExpandProperty RecoveryPassword

        $auditString = $null
        if ($PersistToRegistry) {

            # -- Replace PowerShell 7 ternary with if/else --
            if ($env:usrAlert -match 'true') {
                $alert = 'Notice'
            }
            else {
                $alert = 'Status'
            }

            # -- Build TPM mask --
            $t    = Get-Tpm
            $mask = (if ($t.TpmPresent) { 1 } else { 0 }) + `
                    (if ($t.TpmReady)   { 6 } else { 0 })

            # Capture and discard the switch output
            switch ($mask) {
                0 { $state = 'Absent';      break }
                1 { $state = 'Disabled';    break }
                3 { $state = 'Deactivated'; break }
                7 { $state = 'Active';      break }
                Default { $state = 'Error' }
            }
            $null = $state

            # -- Replace PowerShell 7 “? :” for drives list --
            if ($AllDisks) {
                $drives = $targets
            }
            else {
                $drives = ,$d
            }

            # Build disk-status string
            $diskStatus = ''
            foreach ($x in $drives) {
                $stat = (Get-BitLockerVolume -MountPoint $x).VolumeStatus
                switch ($stat) {
                    'FullyEncrypted'          { $code = 'ENCPASS'; break }
                    'EncryptionInProgress'     { $code = 'ENCPASS'; break }
                    'DecryptionInProgress'     { $code = 'ENCFAIL'; break }
                    'EncryptionSuspended'      { $code = 'ENCFAIL'; break }
                    'DecryptionSuspended'      { $code = 'ENCFAIL'; break }
                    'EncryptingWipeInProgress' { $code = 'ENCFAIL'; break }
                    Default                    { $code = 'ENCFAIL' }
                }
                $diskStatus += "/$x`$$code"
            }
            $diskStatus  = $diskStatus.TrimStart('/')
            $auditString = "TPM: $mask | DISKS: $diskStatus | RECOVERY: $newKey"

            # Persist to registry/UDF
            New-ItemProperty `
                -Path  $RegistryBasePath `
                -Name  "Custom$UDFNumber" `
                -Value $auditString `
                -Force | Out-Null
        }

        $results += [PSCustomObject]@{
            MountPoint  = $d
            Action      = $action
            RecoveryKey = $newKey
            AuditString = $auditString
        }
    }

    return $results
}