PowerShell v3 Function Get ObjectHash

The following function is based on Lee Holmes Get-FileHash:

http://poshcode.org/2154

I simply added a switch for strings to accompany the current file option when calculating hashes.  So, this is really Lees function with a little extra cut-and-paste code.

function Get-ObjectHash

{

    ##############################################################################

    ##

    ## Get-ObjectHash

    ##

    ## Adapted From Windows PowerShell Cookbook (OReilly)

    ## by Lee Holmes (http://www.leeholmes.com/guide)

    ##

    ##############################################################################

    <#

        .SYNOPSIS

            Get the hash of an input file or string.

        .EXAMPLE

        Get-FileHash myFile.txt

        Gets the hash of a specific file

        .EXAMPLE

        dir | Get-FileHash

        Gets the hash of files from the pipeline

        .EXAMPLE

        Get-FileHash myFile.txt -Hash SHA1

        Gets the has of myFile.txt, using the SHA1 hashing algorithm

           

            .EXAMPLE

           

            Get-ObjectHash string

            Gets the MD5 hash of the string string.

     

            .EXAMPLE

           

            Get-ObjectHash -String @(test,string,MD5) -HashAlgorithm SHA256

            Gets the SHA256 hash of an array of strings.

    #>

      [CmdletBinding(

            DefaultParameterSetName = String

      )]

    param(

        ## The string to check

            [Parameter(

                  ParameterSetName = String

            )]

            [String[]]

            $String,

           

            ## The path of the file to check

            [Parameter(

                  ParameterSetName = Path

            )]

            [String[]]       

        $Path,

        ## The algorithm to use for hash computation

        [ValidateSet("MD5", "SHA1", "SHA256", "SHA384", "SHA512")]

        $HashAlgorithm = "MD5"

    )

    Set-StrictMode -Version Latest

    ## Create the hash object that calculates the hash of our file.

    $hashType = [Type] "System.Security.Cryptography.$HashAlgorithm"

    $hasher = $hashType::Create()

class="MsoNormal">    if($PSBoundParameters.ContainsKey(Path))

      {

            ## Create an array to hold the list of files

          $files = @()

          ## If they specified the file name as a parameter, add that to the list

          ## of files to process

          if($path)

          {

              $files += $path

          }

          ## Otherwise, take the files that they piped in to the script.

          ## For each input file, put its full name into the file list

          else

          {

              $files += @($input | Foreach-Object { $_.FullName })

          }

          ## Go through each of the items in the list of input files

          foreach($file in $files)

          {

              ## Skip the item if it is not a file

              if(-not (Test-Path $file -Type Leaf)) { continue }

              ## Convert it to a fully-qualified path

              $filename = (Resolve-Path $file).Path

              ## Use the ComputeHash method from the hash object to calculate

              ## the hash

              $inputStream = New-Object IO.StreamReader $filename

              $hashBytes = $hasher.ComputeHash($inputStream.BaseStream)

              $inputStream.Close()

              ## Convert the result to hexadecimal

              $builder = New-Object System.Text.StringBuilder

              $hashBytes | Foreach-Object { [void] $builder.Append($_.ToString("X2")) }

              ## Return a custom object with the important details from the

              ## hashing

              $output = New-Object PsObject -Property @{

                  Path