CommonUtils.ps1

# This script contains common utility functions used in different functions

Function Convert-ByteArrayToB64
{

    [cmdletbinding()]

    param(
        [parameter(Mandatory=$true,ValueFromPipeline)]
        [Byte[]]$Bytes,
        [Switch]$UrlEncode,
        [Switch]$NoPadding
    )

    $b64 = [convert]::ToBase64String($Bytes);

    if($UrlEncode)
    {
        $b64 = $b64.Replace("/","_").Replace("+","-")
    }

    if($NoPadding)
    {
        $b64 = $b64.Replace("=","")
    }

    return $b64
}

Function Convert-B64ToByteArray
{

    [cmdletbinding()]

    param(
        [parameter(Mandatory=$true,ValueFromPipeline)]
        [String]
        $B64
    )
    $B64 = $B64.Replace("_","/").Replace("-","+")

    # Fill the header with padding for Base 64 decoding
    while ($B64.Length % 4)
    {
        $B64 += "="
    }

    return [convert]::FromBase64String($B64)
}

Function Convert-B64ToText
{

    [cmdletbinding()]

    param(
        [parameter(Mandatory=$true)]
        [String]
        $B64
    )

    return [text.encoding]::UTF8.GetString(([byte[]](Convert-B64ToByteArray -B64 $B64)))
}

Function Convert-TextToB64
{

    [cmdletbinding()]

    param(
        [parameter(Mandatory=$true)]
        [String]
        $Text
    )

    return Convert-ByteArrayToB64 -Bytes  ([text.encoding]::UTF8.GetBytes($text))
}

Function Convert-ByteArrayToHex
{

    [cmdletbinding()]

    param(
        [parameter(Mandatory=$true,ValueFromPipeline)]
        [Byte[]]
        $Bytes
    )

    $HexString = [System.Text.StringBuilder]::new($Bytes.Length * 2)

    ForEach($byte in $Bytes){
        $HexString.AppendFormat("{0:x2}", $byte) | Out-Null
    }

    $HexString.ToString()
}


Function Convert-HexToByteArray
{

    [cmdletbinding()]

    param(
        [parameter(Mandatory=$true,ValueFromPipeline)]
        [String]
        $HexString
    )

    $Bytes = [byte[]]::new($HexString.Length / 2)

    For($i=0; $i -lt $HexString.Length; $i+=2){
        $Bytes[$i/2] = [convert]::ToByte($HexString.Substring($i, 2), 16)
    }

    $Bytes
}


# Converts OID string to bytes
function Convert-OidToBytes
{

    [cmdletbinding()]
    Param(
        [Parameter(Mandatory=$True,ValueFromPipeline)]
        [String]$Oid
    )
    Process
    {
        $digits = $oid.Split(".")
        $bytes =  @()

        # Encode the first byte
        $bytes += ([byte]$digits[0]) * 40 + ([byte]$digits[1])

        # Calculate the rest
        for($pos = 2; $pos -lt $Digits.Count; $pos++)
        {
            [int]$digit = $digits[$pos]

            # Double byte integer needed
            if($digit -gt 127)
            {
                # Move $b1 seven bits to right and switch the first bit on
                $b1 = (($digit -shr 7) -bor 0x80)
                # Keep only the "first" 8 bits by nullifying others
                $b2 = ($digit -band 0xFF)

                $bytes += [byte]$b1
                $bytes += [byte]$b2
            }
            else
            {
                $bytes += [byte]$digit
            }

        }

        # Return
        return [byte[]]$bytes

    }
}

# Converts byte array to oid string
function Convert-BytesToOid
{

    [cmdletbinding()]
    Param(
        [Parameter(Mandatory=$True,ValueFromPipeline)]
        [byte[]]$Bytes
    )
    Process
    {
        $pos = 0

        # Check whether we have DER tag. If so, skip the first 2 bytes
        if($Bytes[0] -eq 0x06) 
        {
            $pos=2
        }
        
        # Calculate the first two digits
        $oid="$([byte]($Bytes[$pos]/40)).$([byte]$Bytes[$pos]%40)"

        # Calculate the rest
        for($pos+=1; $pos -lt $Bytes.Count; $pos++)
        {
            # Double byte integer if first bit is set
            if(($Bytes[$pos] -band 0x80) -gt 0)
            {
                $b1 = $Bytes[$pos]
                $b2 = $Bytes[$pos+1]

                # Add the last bit of $b1 to the first bit of $b2 (shift bits one step to right)
                $b2 = $b2 -bor (($b1 -band 1) -shl 7)
                # Switch the first bit of $b1 to 0 and one bit left
                $b1 = ($b1 -band 0x7F) -shr 1

                # Calculate the digit
                $digit = [int]($b1 * 256  + $b2)
                $pos++
            }
            else
            {
                $digit = $Bytes[$pos]
            }
            $oid += ".$digit"
        }

        # Return
        $oid
    }
}

# Load .pfx certificate
function Load-Certificate
{
<#
    .SYNOPSIS
    Loads X509 certificate from the given .pfx file
 
    .DESCRIPTION
    Loads X509 certificate from the given .pfx file
 
    .Parameter FileName
    The full path to .pfx file from where to load the certificate
 
    .Parameter Password
    The password of the .pfx file
     
    .Example
    PS C:\>Get-AADIntCertificate -FileName "MyCert.pfx" -Password -Password "mypassword"
 
#>

    [cmdletbinding()]
    Param(
        [Parameter(Mandatory=$True,ValueFromPipeline)]
        [String]$FileName,
        [Parameter(Mandatory=$False)]
        [String]$Password="",
        [Switch]$Exportable
    )
    Process
    {
        if(!(Test-Path $FileName))
        {
            throw "Certificate file $FileName not found!"
        }
        
        # Load the certificate
        try
        {
            if($Exportable)
            {
                $Certificate = New-Object System.Security.Cryptography.X509Certificates.X509Certificate2((Get-Item $FileName).FullName, $Password, [System.Security.Cryptography.X509Certificates.X509KeyStorageFlags]::Exportable) -ErrorAction SilentlyContinue
            }
            else
            {
                $Certificate = New-Object System.Security.Cryptography.X509Certificates.X509Certificate2((Get-Item $FileName).FullName, $Password, [System.Security.Cryptography.X509Certificates.X509KeyStorageFlags]::PersistKeySet) -ErrorAction SilentlyContinue
            }
            
        }
        catch
        {
            throw "Error opening certificate: $($_.Exception.InnerException.Message)"""
        }
        
        return $Certificate
    }
}


# Loads the private key from the given Certificate
function Load-PrivateKey
{
<#
    .SYNOPSIS
    Loads the private key from the given x509 certificate
 
    .DESCRIPTION
    Loads the private key from the given x509 certificate
         
    .Example
    $Certificate = Load-Certificate -Filename "mycert.pfx" -Password "myverysecretpassword"
    PS C:\>$PrivateKey = Load-AADIntPrivateKey -Certificate $Certificate
 
#>

    [cmdletbinding()]
    Param(
        [Parameter(Mandatory=$True,ValueFromPipeline)]
        [System.Security.Cryptography.X509Certificates.X509Certificate2]$Certificate
    )
    Process
    {
        # Store the private key to so that it can be exported
        $cspParameters = [System.Security.Cryptography.CspParameters]::new()
        $cspParameters.ProviderName = "Microsoft Enhanced RSA and AES Cryptographic Provider"
        $cspParameters.ProviderType = 24
        $cspParameters.KeyContainerName ="AADInternals"
            
        # Get the private key from the certificate
        $privateKey = [System.Security.Cryptography.RSACryptoServiceProvider]::new(2048,$cspParameters)
        $privateKey.ImportParameters([System.Security.Cryptography.X509Certificates.RSACertificateExtensions]::GetRSAPrivateKey($Certificate).ExportParameters($true))
        
        Write-Verbose "Private Key from $($Certificate.Subject) loaded to the certificate store."
        Write-Debug   "PK: $( Convert-ByteArrayToB64 -Bytes (([System.Security.Cryptography.RSA]::Create($privateKey.ExportParameters($true))).key.Export([System.Security.Cryptography.CngKeyBlobFormat]::GenericPublicBlob)) )"

        return $privateKey
    }
}

# Unloads the private key from the store
function Unload-PrivateKey
{
<#
    .SYNOPSIS
    Unloads the private key from the store
 
    .DESCRIPTION
    Unloads the private key from the store
         
    .Example
    $Certificate = Load-Certificate -Filename "mycert.pfx" -Password "myverysecretpassword"
    PS C:\>$privateKey = Load-AADIntPrivateKey -Certificate $Certificate
    PS C:\>Unload-AADIntPrivateKey -PrivateKey $privateKey
 
#>

    [cmdletbinding()]
    Param(
        [Parameter(Mandatory=$True,ValueFromPipeline)]
        [System.Security.Cryptography.RSA]$PrivateKey
    )
    Process
    {
        try
        {
            # Remove the private key from the store
            $privateKey.PersistKeyInCsp=$false
            $privateKey.Clear()

            Write-Verbose "Private Key unloaded from the certificate store."
        }
        catch
        {
            Write-Verbose "Could not unload Private Key from the certificate store. That's probably just okay: ""$($_.Exception.InnerException.Message)"""
        }
        
    }
}


function Get-CompressedByteArray {

    [CmdletBinding()]
    Param (
    [Parameter(Mandatory,ValueFromPipeline,ValueFromPipelineByPropertyName)]
        [byte[]] $byteArray = $(Throw("-byteArray is required"))
    )
    Process {
        Write-Verbose "Get-CompressedByteArray"
           [System.IO.MemoryStream] $output = New-Object System.IO.MemoryStream
        $gzipStream = New-Object System.IO.Compression.GzipStream $output, ([IO.Compression.CompressionMode]::Compress)
          $gzipStream.Write( $byteArray, 0, $byteArray.Length )
        $gzipStream.Close()
        $output.Close()
        $tmp = $output.ToArray()
        Write-Output $tmp
    }
}


function Get-DecompressedByteArray {

    [CmdletBinding()]
    Param (
        [Parameter(Mandatory,ValueFromPipeline,ValueFromPipelineByPropertyName)]
        [byte[]] $byteArray = $(Throw("-byteArray is required"))
    )
    Process {
        Write-Verbose "Get-DecompressedByteArray"
        $input = New-Object System.IO.MemoryStream( , $byteArray )
        $output = New-Object System.IO.MemoryStream
        $gzipStream = New-Object System.IO.Compression.GzipStream $input, ([IO.Compression.CompressionMode]::Decompress)
        $gzipStream.CopyTo( $output )
        $gzipStream.Close()
        $input.Close()
        [byte[]] $byteOutArray = $output.ToArray()
        Write-Output $byteOutArray
    }
}

# Parses the given RSA Key BLOB and returns RSAParameters
Function Parse-KeyBLOB
{

    [cmdletbinding()]

    param(
        [parameter(Mandatory=$true,ValueFromPipeline)]
        [Byte[]]$Key
    )
    process
    {
        # https://docs.microsoft.com/en-us/windows/win32/api/bcrypt/ns-bcrypt-bcrypt_rsakey_blob
        # https://docs.microsoft.com/en-us/windows/win32/seccrypto/base-provider-key-blobs

        # RSAPUBKEY
        # DWORD magic ("RSA1" = public, or "RSA2" = private)
        # DWORD bitlen
        # ORD pubex
        $magic  = [text.encoding]::ASCII.GetString($Key[0..3])
        $bitlen = [bitconverter]::ToUInt16($Key,4)
        $publen = [bitconverter]::ToUInt16($Key,8)
        $modlen = [bitconverter]::ToUInt16($Key,12)
        $pri1len = [bitconverter]::ToUInt16($Key,16)
        $pri2len = [bitconverter]::ToUInt16($Key,20)

        $pubex  = $Key[24..(24+$publen-1)]

        $p=24+$publen

        $modulus = $key[($p)..($bitlen/8 + $p)]
        $p += $modlen

        # Private key
        if($magic -eq "RSA2") 
        {
            # RSAPUBKEY rsapubkey;

            # BYTE modulus[rsapubkey.bitlen/8];
            # BYTE prime1[rsapubkey.bitlen/16];
            # BYTE prime2[rsapubkey.bitlen/16];
            # BYTE exponent1[rsapubkey.bitlen/16];
            # BYTE exponent2[rsapubkey.bitlen/16];
            # BYTE coefficient[rsapubkey.bitlen/16];
            # BYTE privateExponent[rsapubkey.bitlen/8];

            $prime1 =           $key[($p)..($p + $bitlen/16)] ; $p += $bitlen/16
            $prime2 =           $key[($p)..($p + $bitlen/16)] ; $p += $bitlen/16
            $exponent1 =        $key[($p)..($p + $bitlen/16)] ; $p += $bitlen/16
            $exponent2 =        $key[($p)..($p + $bitlen/16)] ; $p += $bitlen/16
            $coefficient =      $key[($p)..($p + $bitlen/16)] ; $p += $bitlen/16
            $privateExponent =  $key[($p)..($p + $bitlen/8)] 
            
        }
        
        $attributes=@{
            "D" =        $privateExponent
            "DP" =       $exponent1
            "DQ" =       $exponent2
            "Exponent" = $pubex
            "InverseQ" = $coefficient
            "Modulus" =  $modulus
            "P" =        $prime1
            "Q"=         $prime2
        }

        [System.Security.Cryptography.RSAParameters]$RSAp = New-Object psobject -Property $attributes

        return $RSAp

    }
}

# Converts the given RSAParameters to DER
Function Convert-RSAToDER
{

    [cmdletbinding()]

    param(
        [parameter(Mandatory=$true,ValueFromPipeline)]
        [System.Security.Cryptography.RSAParameters]$RSAParameters,
        [Switch]$PEM
    )
    process
    {
        # Reverse bytes

        $modulus =  $RSAParameters.Modulus[($RSAParameters.Modulus.Length)..0]
        $exponent = $RSAParameters.Exponent[($RSAParameters.Exponent.Length)..0]

        $der = Add-DERSequence -Data @(
                    Add-DERSequence -Data @(
                        # OID
                        Add-DERTag -Tag 0x06 -Data @( 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x01 )
                    
                        0x05 # Null
                        0x00
                    ) # Sequence
                    Add-DERTag -Tag 0x03 -Data @(
                        0x00 # Number of unused bits

                        Add-DERSequence -Data @(
                            Add-DERInteger -Data $modulus
                            Add-DERInteger -Data $exponent
                        
                        ) # Sequence
                    ) # Tag 0x03
                    
                ) # Sequence

        if($PEM)
        {
            return @"
-----BEGIN PUBLIC KEY-----
$(Convert-ByteArrayToB64 -Bytes $der)
-----END PUBLIC KEY-----
"@

        }                
        else
        {
            return $der
        }

    }
}


# Gets the error description from AzureAD
# Aug 2nd 2020
Function Get-Error
{
    <#
    .SYNOPSIS
    Gets a error description for the given error code.
 
    .DESCRIPTION
    Gets a error description for the given error code.
 
    .Parameter ErrorCode
    Azure AD error code
 
    .Example
    Get-AADIntError -ErrorCode AADST700019
 
    700019: Application ID {identifier} cannot be used or is not authorized.
 
    .Example
    Get-AADIntError -ErrorCode 700019
 
    700019: Application ID {identifier} cannot be used or is not authorized.
#>

    [cmdletbinding()]

    param(
        [parameter(Mandatory=$true,ValueFromPipeline)]
        [String]$ErrorCode
    )
    Process
    {
        # Get the error message
        $response=Invoke-RestMethod -Method Get -Uri "https://login.microsoftonline.com/error?code=$ErrorCode"

        if($response.IndexOf("<table>") -gt 0)
        {
            $s=$response.IndexOf("<td>Error Code</td>")+23
            $e=$response.IndexOf("</td>",$s)
            $code=$response.Substring($s,$e-$s)

            $s=$response.IndexOf("<td>Message</td>")+20
            $e=$response.IndexOf("</td>",$s)
            $message=$response.Substring($s,$e-$s)

            Write-Host "$code`: $message"
        }
        else
        {
            Write-Host "Error $ErrorCode not found!"
        }

    }
}