Get-Hash2.ps1

1. <# 
2. .SYNOPSIS 
3.    Creates a Hash of a file and returns the hash   
4. .DESCRIPTION 
5.     Uses System.Security.Cryptography.HashAlgorithm and members to create
6.     the hash. This script improves on:
7.     http://pshscripts.blogspot.com/2009/01/get-hashpsm1.html by using 
8. .NOTES 
9.     File Name  : Get-Hash1.PSM1 
10.     Author     : Thomas Lee - tfl@psp.co.uk 
11.     Requires   : PowerShell V2 CTP3 
12.     Thanks to the #PowerShell Twitter Posse (PTP) for help figuring out
13.     the –verbose parameter. And thanks to the PTP for comments on the
14.     earlier version of this script, which now uses a file stream as 
15.     input to the hash alghorithm. 
16. .LINK 
17.     Posted to         :  http://pshscripts.blogspot.com/2009/01/get-hash2ps1.html
18.     Based on          :  http://tinyurl.com/aycszb written by Bart De Smet 
19.     An improvement of :  http://pshscripts.blogspot.com/2009/01/get-hashpsm1.html 
20. .PARAMETER Algorithm 
21.     The name of one of the hash Algorithms defined at 
22.     http://msdn.microsoft.com/en-us/library/system.security.cryptography.hashalgorithm.aspx 
23. .PARAMETER File 
24.     The name of a file to provide a hash for. 
25. .PARAMETER Verbose 
26.     if specified, this script will produce chattier output. 
27. .EXAMPLE 
28.     PS C:\foo> ls *.txt | where {!$_.psiscontainer}| c:\foo\Get-Hash2.ps1 sha1 -verbose 
29.     OK, I'll be chatty 
30.     The sha1 hash of file C:\foo\asciifile.txt is: "55055a5c8eeb3af7fa6d426314578ee1d56df016" 
31.  
32.     The sha1 hash of file C:\foo\log.txt is: "575f4b35e3cadb9b273095fc463bd43e9a3f5774" 
33.  
34.     The sha1 hash of file C:\foo\sites.txt is: "8ce6663cd2b64a513cf18a831843afd98e190764" 
35.  
36.     The sha1 hash of file C:\foo\test.txt is: "a2f26abbeeb4e6846e159ba506e07cae5496d458" 
37.  
38.     The sha1 hash of file C:\foo\test2.txt is: "9b1baaa9077a3691f8e2685d81ffa24cdd73f71d" 
39.  
40.     The sha1 hash of file C:\foo\unicodefile.txt is: "094ef2696d9eb3374e657eb7c227ff4c36cd0cb9" 
41. .EXAMPLE 
42.     PS C:\foo> ls *.txt | where {!$_.psiscontainer}| c:\foo\Get-Hash2.ps1 sha1 
43.     55055a5c8eeb3af7fa6d426314578ee1d56df016 
44.     575f4b35e3cadb9b273095fc463bd43e9a3f5774 
45.     8ce6663cd2b64a513cf18a831843afd98e190764 
46.     a2f26abbeeb4e6846e159ba506e07cae5496d458 
47.     9b1baaa9077a3691f8e2685d81ffa24cdd73f71d 
48.     094ef2696d9eb3374e657eb7c227ff4c36cd0cb9 
49. .EXAMPLE 
50.     PS C:\foo> Get-Hash  md5 asciifile.txt -verbose 
51.     OK, I'll be chatty 
52.     The md5 hash of file c:\foo\asciifile.txt is: "06f51e7bfced5c0623eec5f72e0999d6" 
53. .EXAMPLE 
54.     PS C:\foo> .\get-hash2 md5 c:\foo\asciifile.txt 
55.     06f51e7bfced5c0623eec5f72e0999d6 
56. #> 
57. #[CmdletBinding()] 
58. param ( 
59. [Parameter(Position=0, mandatory=$true)] 
60. [string] $Algorithm, 
61. [Parameter(Position=1, mandatory=$true, valuefrompipeline=$true)] 
62. [string] $File 
63. ) 
64.  
65. Begin {  
66. if ($VerbosePreference.Value__ -eq 0) {$verbose=$false} else {$verbose=$true} 
67. if ($Verbose) {"OK, I'll be chatty"} 
68. } 
69.  
70. Process { 
71.  
72. if ($VerbosePreference.Value__ -eq 0) {$verbose=$false} else {$verbose=$true} 
73.  
74.     # Get the alghorthm object 
75.     $Algo=[System.Security.Cryptography.HashAlgorithm]::Create($algorithm) 
76.     if ($Algo){ 
77.         # Open the file 
78.         $Filemode = [System.IO.FileMode]::Open 
79.         $Fs = New-Object System.Io.Filestream $File, $Filemode 
80.         if ($fs.length -gt 0) { 
81.             # Now compute hash 
82.             $Hash = $Algo.ComputeHash($Fs)    
83.             $Hashstring ="" 
84.             foreach ($byte in $hash) {$hashstring += $byte.tostring("x2")} 
85.             # pass hash string on 
86.             if ($verbose){ 
87.               "The {0} hash of file {1} is: `"{2}`"" -f $algorithm, $file, $hashstring 
88.               "" 
89.             } 
90.             else { 
91.              $Hashstring 
92.             } 
93.         } 
94.         else { 
95.              if ($verbose) {"File {0} can not be hashed" -f $file ; ""}      
96.         } 
97.         $fs.close() 
98.         } 
99.     else {"Algorithm {0} not found" -f $algorithm} 
100. } 

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