BitLocker Key Storage Checker

<#
.TITLE
    BitLocker Key Storage Checker

.SYNOPSIS
    Monitor and verify that BitLocker recovery keys for Windows devices are properly stored in Entra ID.

.DESCRIPTION
    This script connects to Microsoft Graph API, retrieves all Windows devices from Intune,
    and checks if each device has BitLocker recovery keys stored in Entra ID. The script
    provides detailed reporting on compliance status, identifies devices without stored keys,
    and exports comprehensive results to CSV format for further analysis. This helps ensure
    proper BitLocker key escrow for data recovery scenarios.

.TAGS
    Monitoring,Security

.MINROLE
    Intune Administrator

.PERMISSIONS
    DeviceManagementManagedDevices.Read.All,BitlockerKey.ReadBasic.All

.AUTHOR
    Ugur Koc

.VERSION
    1.4

.CHANGELOG
    1.4 - Added Azure Automation contract validation, portal-safe boolean parameters, beta Graph endpoints, and terminating paging errors
    1.3 - Azure Automation now records script progress, outcomes, and summaries in job history
    1.2 - Summary now reuses collected results instead of re-querying every device; key checks get a per-device delay and 429 retry; guarded last sync date parsing; device list selects only needed fields (isEncrypted replaces the invalid encryptionState property); pagination helper keeps single-item results as arrays
    1.1 - Local runs now use MgGraphCommunity for WAM-free interactive sign-in (auto-installed if missing)
    1.0 - Initial release

.LASTUPDATE
    2026-07-30

.EXAMPLE
    .\check-bitlocker-keys.ps1
    Generates BitLocker key storage report for all Windows devices in Intune

.EXAMPLE
    .\check-bitlocker-keys.ps1 -OutputPath "C:\Reports" -OnlyShowMissing "true"
    Saves report to specified directory and shows only devices missing BitLocker keys

.EXAMPLE
    .\check-bitlocker-keys.ps1 -IncludeLastSync "true" -ExportJson "true"
    Includes last sync information and exports results in JSON format as well

.NOTES
    - Requires Microsoft.Graph.Authentication module: Install-Module Microsoft.Graph.Authentication
    - BitLocker keys are automatically escrowed to Entra ID when properly configured
    - Devices must be Azure AD joined or Hybrid Azure AD joined for key escrow
    - Consider configuring BitLocker policies to enforce key escrow
    - Regular monitoring helps ensure compliance with data protection requirements
    - Local interactive sign-in uses the MgGraphCommunity module to avoid the Graph SDK's mandatory WAM broker on Windows
#>

[CmdletBinding()]
param(
    [Parameter(Mandatory = $false, HelpMessage = "Directory path to save reports")]
    [ValidateNotNullOrEmpty()]
    [string]$OutputPath = ".",

    [Parameter(Mandatory = $false, HelpMessage = "Only show devices missing BitLocker keys")]
    [ValidateSet("true", "false", "1", "0", '$true', '$false')]
    [string]$OnlyShowMissing,

    [Parameter(Mandatory = $false, HelpMessage = "Include last sync date information")]
    [ValidateSet("true", "false", "1", "0", '$true', '$false')]
    [string]$IncludeLastSync,

    [Parameter(Mandatory = $false, HelpMessage = "Export results in JSON format as well")]
    [ValidateSet("true", "false", "1", "0", '$true', '$false')]
    [string]$ExportJson,

    [Parameter(Mandatory = $false, HelpMessage = "Show progress during processing")]
    [ValidateSet("true", "false", "1", "0", '$true', '$false')]
    [string]$ShowProgress,

    [Parameter(Mandatory = $false, HelpMessage = "Force module installation without prompting")]
    [ValidateSet("true", "false", "1", "0", '$true', '$false')]
    [string]$ForceModuleInstall
)

# Normalize the local module-install override for Azure Automation parameter binding.
$forceModuleInstallRaw = [string]$ForceModuleInstall
Remove-Variable -Name ForceModuleInstall
if ([string]::IsNullOrWhiteSpace($forceModuleInstallRaw)) {
    $ForceModuleInstall = $false
}
elseif ($forceModuleInstallRaw.Trim().ToLowerInvariant() -in @("true", "1", '$true')) {
    $ForceModuleInstall = $true
}
elseif ($forceModuleInstallRaw.Trim().ToLowerInvariant() -in @("false", "0", '$false')) {
    $ForceModuleInstall = $false
}
else {
    throw "Parameter 'ForceModuleInstall' accepts only true, false, 1, 0, $true, or $false."
}

# Azure Automation supplies portal parameter values as strings. Normalize the
# public boolean parameters once so local and runbook execution use real booleans.
foreach ($runbookBooleanParameter in @('OnlyShowMissing', 'IncludeLastSync', 'ExportJson', 'ShowProgress')) {
    $runbookBooleanRaw = [string](Get-Variable -Name $runbookBooleanParameter -ValueOnly)
    Remove-Variable -Name $runbookBooleanParameter

    if ([string]::IsNullOrWhiteSpace($runbookBooleanRaw)) {
        Set-Variable -Name $runbookBooleanParameter -Value $false
        continue
    }

    switch ($runbookBooleanRaw.Trim().ToLowerInvariant()) {
        { $_ -in @("true", "1", '$true') } {
            Set-Variable -Name $runbookBooleanParameter -Value $true
        }
        { $_ -in @("false", "0", '$false') } {
            Set-Variable -Name $runbookBooleanParameter -Value $false
        }
        default {
            throw "Parameter '$runbookBooleanParameter' accepts only true, false, 1, 0, $true, or $false."
        }
    }
}

# ============================================================================
# ENVIRONMENT DETECTION AND SETUP
# ============================================================================

function Initialize-RequiredModule {
    <#
    .SYNOPSIS
    Ensures required modules are available and loaded
    #>
    param(
        [string[]]$ModuleNames,
        [bool]$IsAutomationEnvironment,
        [bool]$ForceInstall = $false
    )

    foreach ($ModuleName in $ModuleNames) {
        Write-Verbose "Checking module: $ModuleName"

        # Check if module is available
        $module = Get-Module -ListAvailable -Name $ModuleName | Select-Object -First 1

        if (-not $module) {
            if ($IsAutomationEnvironment) {
                $errorMessage = @"
Module '$ModuleName' is not available in this Azure Automation Account.

To resolve this issue:
1. Go to Azure Portal
2. Navigate to your Automation Account
3. Go to 'Modules' > 'Browse Gallery'
4. Search for '$ModuleName'
5. Click 'Import' and wait for installation to complete

Alternative: Use PowerShell to import the module:
Import-Module Az.Automation
Import-AzAutomationModule -AutomationAccountName "YourAccount" -ResourceGroupName "YourRG" -Name "$ModuleName"
"@
                throw $errorMessage
            }
            else {
                # Local environment - attempt to install
                Write-Information "Module '$ModuleName' not found. Attempting to install..." -InformationAction Continue

                if (-not $ForceInstall) {
                    $response = Read-Host "Install module '$ModuleName'? (Y/N)"
                    if ($response -notmatch '^[Yy]') {
                        throw "Module '$ModuleName' is required but installation was declined."
                    }
                }

                try {
                    # Check if running as administrator for AllUsers scope
                    $isAdmin = ([Security.Principal.WindowsPrincipal] [Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole] "Administrator")
                    $scope = if ($isAdmin) { "AllUsers" } else { "CurrentUser" }

                    Write-Information "Installing '$ModuleName' in scope '$scope'..." -InformationAction Continue
                    Install-Module -Name $ModuleName -Scope $scope -Force -AllowClobber -Repository PSGallery
                    Write-Information "✓ Successfully installed '$ModuleName'" -InformationAction Continue
                }
                catch {
                    throw "Failed to install module '$ModuleName': $($_.Exception.Message)"
                }
            }
        }

        # Import the module
        try {
            Write-Verbose "Importing module: $ModuleName"
            Import-Module -Name $ModuleName -Force -ErrorAction Stop
            Write-Verbose "✓ Successfully imported '$ModuleName'"
        }
        catch {
            throw "Failed to import module '$ModuleName': $($_.Exception.Message)"
        }
    }
}

# Detect execution environment
if ($PSPrivateMetadata.JobId.Guid) {
    Write-Output "Running inside Azure Automation Runbook"
    $IsAzureAutomation = $true
}
else {
    Write-Output "Running locally in IDE or terminal"
    $IsAzureAutomation = $false
}

# Initialize required modules
$RequiredModuleList = @(
    "Microsoft.Graph.Authentication"
)

# MgGraphCommunity gives WAM-free interactive sign-in for local runs
if (-not $IsAzureAutomation) {
    $RequiredModuleList += "MgGraphCommunity"
}

try {
    Initialize-RequiredModule -ModuleNames $RequiredModuleList -IsAutomationEnvironment $IsAzureAutomation -ForceInstall $ForceModuleInstall
    Write-Verbose "✓ All required modules are available"
}
catch {
    Write-Error "Module initialization failed: $_"
    exit 1
}

# ============================================================================
# AUTHENTICATION
# ============================================================================

try {
    if ($IsAzureAutomation) {
        # Azure Automation - Use Managed Identity
        Write-Output "Connecting to Microsoft Graph using Managed Identity..."
        Connect-MgGraph -Identity -NoWelcome -ErrorAction Stop
        Write-Output "✓ Successfully connected to Microsoft Graph using Managed Identity"
    }
    else {
        # Local execution - WAM-free interactive sign-in via MgGraphCommunity
        Write-Output "Connecting to Microsoft Graph with interactive authentication..."
        $Scopes = @(
            "DeviceManagementManagedDevices.Read.All",
            "BitlockerKey.ReadBasic.All"
        )
        Connect-MgGraphCommunity -Scopes $Scopes -NoWelcome -ErrorAction Stop
        Write-Output "✓ Successfully connected to Microsoft Graph"
    }
}
catch {
    Write-Error "Failed to connect to Microsoft Graph: $($_.Exception.Message)"
    exit 1
}

# ============================================================================
# HELPER FUNCTIONS
# ============================================================================

# Function to get all pages of results from Graph API
function Get-MgGraphPaginatedData {
    param(
        [Parameter(Mandatory = $true)]
        [string]$Uri,
        [int]$DelayMs = 100
    )

    $AllResult = @()
    $NextLink = $Uri
    $RequestCount = 0

    do {
        try {
            # Add delay to respect rate limits
            if ($RequestCount -gt 0) {
                Start-Sleep -Milliseconds $DelayMs
            }

            $Response = Invoke-MgGraphRequest -Uri $NextLink -Method GET
            $RequestCount++

            if ($null -ne $Response.value) {
                $AllResult += $Response.value
            }
            else {
                $AllResult += $Response
            }

            $NextLink = $Response.'@odata.nextLink'
        }
        catch {
            if ($_.Exception.Message -like "*429*" -or $_.Exception.Message -like "*throttled*") {
                Write-Information "`nRate limit hit, waiting 60 seconds..." -InformationAction Continue
                Start-Sleep -Seconds 60
                continue
            }
            throw "Error fetching data from $NextLink : $($_.Exception.Message)"
        }
    } while ($NextLink)

    # Comma prevents unrolling so single-element results stay arrays
    return , $AllResult
}

# Function to check BitLocker key availability for a device
function Test-BitLockerKeyAvailability {
    param (
        [Parameter(Mandatory = $true)]
        [string]$AzureADDeviceId,
        [Parameter(Mandatory = $false)]
        [string]$DeviceName = "Unknown"
    )

    if ([string]::IsNullOrWhiteSpace($AzureADDeviceId)) {
        Write-Verbose "Device $DeviceName has no Azure AD Device ID"
        return @{
            HasKey   = $false
            KeyCount = 0
            Status   = "No Azure AD Device ID"
        }
    }

    $maxRetries = 2
    $retryCount = 0
    while ($true) {
        try {
            $keyIdUri = "https://graph.microsoft.com/beta/informationProtection/bitlocker/recoveryKeys?`$filter=deviceId eq '$AzureADDeviceId'"
            $keyIdResponse = Invoke-MgGraphRequest -Uri $keyIdUri -Method GET

            $keyCount = $keyIdResponse.value.Count
            $hasKey = $keyCount -gt 0

            return @{
                HasKey   = $hasKey
                KeyCount = $keyCount
                Status   = if ($hasKey) { "Key Available" } else { "No Key Found" }
            }
        }
        catch {
            # Retry on throttling instead of reporting a false "Error Checking"
            if (($_.Exception.Message -like "*429*" -or $_.Exception.Message -like "*throttled*") -and $retryCount -lt $maxRetries) {
                $retryCount++
                Write-Information "Rate limit hit checking device $DeviceName, waiting 60 seconds (retry $retryCount of $maxRetries)..." -InformationAction Continue
                Start-Sleep -Seconds 60
                continue
            }
            Write-Warning "Error checking BitLocker key for device $DeviceName : $($_.Exception.Message)"
            return @{
                HasKey   = $false
                KeyCount = 0
                Status   = "Error Checking"
            }
        }
    }
}

# Function to format device last sync date
function Format-LastSyncDate {
    param([datetime]$LastSyncDateTime)

    if ($LastSyncDateTime -eq [datetime]::MinValue) {
        return "Never"
    }

    $daysSinceSync = (Get-Date) - $LastSyncDateTime

    if ($daysSinceSync.TotalDays -lt 1) {
        return "Today"
    }
    elseif ($daysSinceSync.TotalDays -lt 2) {
        return "Yesterday"
    }
    else {
        return "$([math]::Round($daysSinceSync.TotalDays)) days ago"
    }
}

# ============================================================================
# MAIN SCRIPT LOGIC
# ============================================================================

try {
    Write-Output "Starting BitLocker key storage check..."

    # Validate output path
    if (-not (Test-Path $OutputPath)) {
        New-Item -Path $OutputPath -ItemType Directory -Force | Out-Null
        Write-Output "Created output directory: $OutputPath"
    }

    # Get all Windows devices from Intune
    Write-Output "Retrieving Windows devices from Intune..."
    $devicesUri = "https://graph.microsoft.com/beta/deviceManagement/managedDevices?`$filter=operatingSystem eq 'Windows'&`$select=id,deviceName,serialNumber,model,manufacturer,osVersion,azureADDeviceId,complianceState,isEncrypted,lastSyncDateTime"
    $devices = Get-MgGraphPaginatedData -Uri $devicesUri

    if ($devices.Count -eq 0) {
        Write-Warning "No Windows devices found in Intune"
        return
    }

    Write-Output "Found $($devices.Count) Windows devices. Checking BitLocker key status..."

    $results = @()
    $processedCount = 0
    $devicesWithKeys = 0

    foreach ($device in $devices) {
        $processedCount++

        if ($ShowProgress) {
            $percentComplete = [math]::Round(($processedCount / $devices.Count) * 100, 1)
            Write-Progress -Activity "Checking BitLocker Keys" -Status "Processing device: $($device.deviceName)" -PercentComplete $percentComplete
        }

        # Delay between per-device key checks to respect rate limits
        if ($processedCount -gt 1) {
            Start-Sleep -Milliseconds 100
        }

        # Check BitLocker key availability
        $bitlockerCheck = Test-BitLockerKeyAvailability -AzureADDeviceId $device.azureADDeviceId -DeviceName $device.deviceName

        if ($bitlockerCheck.HasKey) {
            $devicesWithKeys++
        }

        # Prepare result object
        $deviceResult = [PSCustomObject]@{
            DeviceName                  = $device.deviceName
            SerialNumber                = $device.serialNumber
            Model                       = $device.model
            Manufacturer                = $device.manufacturer
            OSVersion                   = $device.osVersion
            AzureADDeviceId             = $device.azureADDeviceId
            "BitLocker Key in Entra ID" = if ($bitlockerCheck.HasKey) { "Yes" } else { "No" }
            "Key Count"                 = $bitlockerCheck.KeyCount
            Status                      = $bitlockerCheck.Status
            ComplianceState             = $device.complianceState
            EncryptionState             = $device.isEncrypted
        }

        # Add last sync information if requested
        if ($IncludeLastSync) {
            # lastSyncDateTime arrives as a string from Graph; cast with a guard
            if (-not [string]::IsNullOrEmpty($device.lastSyncDateTime)) {
                $lastSyncDate = [datetime]$device.lastSyncDateTime
                $lastSyncDisplay = $lastSyncDate.ToString("yyyy-MM-dd HH:mm")
                $syncStatusDisplay = Format-LastSyncDate -LastSyncDateTime $lastSyncDate
            }
            else {
                $lastSyncDisplay = "Unknown"
                $syncStatusDisplay = "Unknown"
            }
            $deviceResult | Add-Member -MemberType NoteProperty -Name "Last Sync" -Value $lastSyncDisplay
            $deviceResult | Add-Member -MemberType NoteProperty -Name "Sync Status" -Value $syncStatusDisplay
        }

        # Add to results (filter if only showing missing keys)
        if (-not $OnlyShowMissing -or -not $bitlockerCheck.HasKey) {
            $results += $deviceResult
        }
    }

    if ($ShowProgress) {
        Write-Progress -Activity "Checking BitLocker Keys" -Completed
    }

    # Display results
    Write-Output "`nBitLocker Key Storage Results:"
    $results | Format-Table -AutoSize

    # Calculate and display summary statistics from the results collected above
    $totalDevices = $devices.Count
    $devicesWithoutKeys = $totalDevices - $devicesWithKeys
    $compliancePercentage = [math]::Round(($devicesWithKeys / $totalDevices) * 100, 1)

    Write-Output "`n========================================"
    Write-Output "BitLocker Key Storage Summary"
    Write-Output "========================================"
    Write-Output "Total Windows devices in Intune: $totalDevices"
    Write-Output "Devices with BitLocker keys in Entra ID: $devicesWithKeys"
    Write-Output "Devices without BitLocker keys: $devicesWithoutKeys"
    Write-Output "Compliance percentage: $compliancePercentage%"
    Write-Output "========================================"

    # Export results to CSV
    $timestamp = Get-Date -Format "yyyyMMdd-HHmmss"
    $csvPath = Join-Path $OutputPath "BitLocker-Key-Storage-Report-$timestamp.csv"
    $results | Export-Csv -Path $csvPath -NoTypeInformation -Encoding utf8
    Write-Output "✓ Results exported to: $csvPath"

    # Export to JSON if requested
    if ($ExportJson) {
        $jsonPath = Join-Path $OutputPath "BitLocker-Key-Storage-Report-$timestamp.json"
        $jsonData = @{
            GeneratedDate = Get-Date -Format "yyyy-MM-dd HH:mm:ss"
            Summary       = @{
                TotalDevices         = $totalDevices
                DevicesWithKeys      = $devicesWithKeys
                DevicesWithoutKeys   = $devicesWithoutKeys
                CompliancePercentage = $compliancePercentage
            }
            Devices       = $results
        }
        $jsonData | ConvertTo-Json -Depth 3 | Set-Content -Path $jsonPath
        Write-Output "✓ Results exported to JSON: $jsonPath"
    }

    # Show devices without keys if any exist and not in OnlyShowMissing mode
    if ($devicesWithoutKeys -gt 0 -and -not $OnlyShowMissing) {
        Write-Output "`nDevices without BitLocker keys in Entra ID:"
        $devicesWithoutKeysList = $results | Where-Object { $_."BitLocker Key in Entra ID" -eq "No" } | Select-Object DeviceName, SerialNumber, Status
        $devicesWithoutKeysList | Format-Table -AutoSize
    }

    Write-Output "✓ BitLocker key storage check completed successfully"
}
catch {
    Write-Error "Script failed: $($_.Exception.Message)"
    exit 1
}
finally {
    # Cleanup operations
    try {
        Disconnect-MgGraph -ErrorAction SilentlyContinue | Out-Null
        Write-Output "Disconnected from Microsoft Graph"
    }
    catch {
        Write-Verbose "Unable to disconnect from Microsoft Graph: $($_.Exception.Message)"
    }
}

# ============================================================================
# SCRIPT SUMMARY
# ============================================================================

Write-Output "
========================================
Script Execution Summary
========================================
Script: BitLocker Key Storage Checker
Total Devices Processed: $($devices.Count)
Devices with Keys: $devicesWithKeys
Compliance Rate: $compliancePercentage%
Report Location: $OutputPath
Status: Completed
========================================
"