Get-HashValues.ps1

# Setup CRC32 function
Set-Alias crc32 Get-Crc32
 
   <#
    .NOTES
        Author: greg zakharov
   #>

$asm = Add-Type -Mem @'
   [DllImport("ntdll.dll")]
   internal static extern UInt32 RtlComputeCrc32(
       UInt32 InitialCrc,
       Byte[] Buffer,
       Int32 Length
   );
   
   public static String ComputeCrc32(String file) {
     UInt32 crc32 = 0;
     Int32  read;
     Byte[] buf = new Byte[4096];
     
     using (FileStream fs = File.OpenRead(file)) {
       while ((read = fs.Read(buf, 0, buf.Length)) != 0)
         crc32 = RtlComputeCrc32(crc32, buf, read);
     }
           
     return ((crc32.ToString("X", CultureInfo.CurrentCulture)).PadLeft(8,'0'));
   }
'@ -Name Check -NameSpace Crc32 -Using System.IO, System.Globalization -PassThru
 


# Start Hash value function
Function Get-HashValues {
[CmdletBinding()]
Param(
      [Parameter(Mandatory=$True,ValueFromPipeline=$True,ParameterSetName='File')]
      [ValidateScript({If ((-Not (Test-Path -Path "$_")) -and ((Get-Item -Path "$_").Length -ne 0)) {  } return $true })]
      [String]$FilePath
      )


$Script:HashValues = $NULL
$Script:HashValues = [ordered]@{"Name"="$($FilePath | Split-Path -Leaf)";"Size"="$((Get-Item $FilePath).Length)";"CRC32"="";"MD5"="";"SHA1"=""}  # Removed: ;"SHA256"=""


If ([int32]$HashValues.Size -gt "99000000") {

Foreach ($i in $HashValues.Keys.Clone()) {

Switch ($i) {
"CRC32" {
         If ($InputObject1 -eq $NULL) {} Else { $InputObject1.Dispose() }  # Destroys the object if present
         Try {
              # $CRC = $asm::ComputeCrc32($($FilePath))
              $HashValues[$i] = [string]$asm::ComputeCrc32($($FilePath))
              } Catch {
                       $HashValues[$i] = "Error"
                       }
         }
 "MD5" {
        $MD5               = New-Object -TypeName System.Security.Cryptography.MD5CryptoServiceProvider
        $InputObject1   = [System.IO.File]::Open("$($FilePath)",[System.IO.Filemode]::Open, [System.IO.FileAccess]::Read)
        $HashValues[$i] = ([System.BitConverter]::ToString($MD5.ComputeHash($InputObject1))).Replace("-","")
        $InputObject1.Dispose()
        }
 "SHA1" {
         $SHA1              = New-Object -TypeName System.Security.Cryptography.SHA1CryptoServiceProvider
         $InputObject1   = [System.IO.File]::Open("$($FilePath)",[System.IO.Filemode]::Open, [System.IO.FileAccess]::Read)
         $HashValues[$i] = ([System.BitConverter]::ToString($SHA1.ComputeHash($InputObject1))).Replace("-","")
         $InputObject1.Dispose()
         }
 "SHA256" {
           $SHA256            = New-Object -TypeName System.Security.Cryptography.SHA256CryptoServiceProvider
           $InputObject1   = [System.IO.File]::Open("$($FilePath)",[System.IO.Filemode]::Open, [System.IO.FileAccess]::Read)
           $HashValues[$i] = ([System.BitConverter]::ToString($SHA256.ComputeHash($InputObject1))).Replace("-","")
           $InputObject1.Dispose()
           }
}

}

} Else {


$InputObject2      = [System.IO.File]::ReadAllBytes("$($FilePath)")


Foreach ($i in $HashValues.Keys.Clone()) {

Switch ($i) {

"CRC32" {
         Try {
         # If ($InputObject2 -eq $NULL) {} Else { $InputObject2.Dispose() }  # Destroys the object if present
         # $CRC = $asm::ComputeCrc32($($FilePath))
         $HashValues[$i] = [string]$asm::ComputeCrc32($($FilePath))
         } Catch {
                  $HashValues[$i] = "Error"
                  }
         }

 "MD5" {
        $Hasher = [System.Security.Cryptography.HashAlgorithm]::Create("$($i)")
        [Byte[]]$ComputedHash = $Hasher.ComputeHash($InputObject2)
        $HashValues[$i] = [string][System.BitConverter]::ToString($ComputedHash).Replace("-","")
        }
"SHA1" {
        $Hasher = [System.Security.Cryptography.HashAlgorithm]::Create("$($i)")
        [Byte[]]$ComputedHash = $Hasher.ComputeHash($InputObject2)
        $HashValues[$i] = [string][System.BitConverter]::ToString($ComputedHash).Replace("-","")
        }
"SHA256" {
          $Hasher = [System.Security.Cryptography.HashAlgorithm]::Create("$($i)")
          [Byte[]]$ComputedHash = $Hasher.ComputeHash($InputObject2)
          $HashValues[$i] = [string][System.BitConverter]::ToString($ComputedHash).Replace("-","")
          }
}

}

}

}
# End Hash value function