How to get an MD5 checksum in PowerShell

Here is a pretty print example attempting to verify the SHA256 fingerprint. I downloaded gpg4win v3.0.3 using PowerShell v4 (requires `Get-FileHash`).

Download the package from

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, open PowerShell, grab the hash from the download page, and run:

cd ${env:USERPROFILE}\Downloads
$file = "gpg4win-3.0.3.exe"

# Set $hash to the hash reference from the download page:
$hash = "477f56212ee60cc74e0c5e5cc526cec52a069abff485c89c2d57d1b4b6a54971"

# If you have an MD5 hash: # $hashAlgo="MD5"
$hashAlgo = "SHA256"

$computed_hash = (Get-FileHash -Algorithm $hashAlgo $file).Hash.ToUpper()
if ($computed_hash.CompareTo($hash.ToUpper()) -eq 0 ) {
Write-Output "Hash matches for file $file"
}
else {
Write-Output ("Hash DOES NOT match for file {0}: `nOriginal hash: {1} `nComputed hash: {2}" -f ($file, $hash.ToUpper(), $computed_hash))
}

Output:

```lang-none
Hash matches for file gpg4win-3.0.3.exe
```

Another built-in command that's long been installed in Windows by default dating back to 2003 is [Certutil][1], which of course can be invoked from PowerShell, too.

CertUtil -hashfile file.foo MD5

(Caveat: MD5 should be in all caps for maximum robustness)

[1]:

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Here is a one-line-command example with both computing the proper checksum of the *file*, like you just downloaded, and comparing it with the published checksum of the original.

For instance, I wrote an example for [downloadings from the Apache JMeter project][1]. In this case you have:

1. downloaded binary file
2. checksum of the original which is published in *file.md5* as one string in the format:

> 3a84491f10fb7b147101cf3926c4a855 *apache-jmeter-4.0.zip

Then using this PowerShell command, you can verify the integrity of the downloaded file:

PS C:\Distr> (Get-FileHash .\apache-jmeter-4.0.zip -Algorithm MD5).Hash -eq (Get-Content .\apache-jmeter-4.0.zip.md5 | Convert-String -Example "hash path=hash")

Output:

True

Explanation:

The first operand of `-eq` operator is a result of computing the checksum for the file:

(Get-FileHash .\apache-jmeter-4.0.zip -Algorithm MD5).Hash

The second operand is the published checksum value. We firstly get content of the file.md5 which is one string and then we extract the hash value based on the string format:

Get-Content .\apache-jmeter-4.0.zip.md5 | Convert-String -Example "hash path=hash"

Both *file* and *file.md5* must be in the same folder for this command work.

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As stated in the accepted answer, [`Get-FileHash`][1] is easy to use with files, but it is also possible to use it with strings:

$s = "asdf"
Get-FileHash -InputStream ([System.IO.MemoryStream]::New([System.Text.Encoding]::ASCII.GetBytes($s)))

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This is what I use to get a consistent hash value:

``` powershell
function New-CrcTable {
[uint32]$c = $null
$crcTable = New-Object 'System.Uint32[]' 256

for ($n = 0; $n -lt 256; $n++) {
$c = [uint32]$n
for ($k = 0; $k -lt 8; $k++) {
if ($c -band 1) {
$c = (0xEDB88320 -bxor ($c -shr 1))
}
else {
$c = ($c -shr 1)
}
}
$crcTable[$n] = $c
}

Write-Output $crcTable
}

function Update-Crc ([uint32]$crc, [byte[]]$buffer, [int]$length, $crcTable) {
[uint32]$c = $crc

for ($n = 0; $n -lt $length; $n++) {
$c = ($crcTable[($c -bxor $buffer[$n]) -band 0xFF]) -bxor ($c -shr 8)
}

Write-Output $c
}

function Get-CRC32 {
<#
.SYNOPSIS
Calculate CRC.
.DESCRIPTION
This function calculates the CRC of the input data using the CRC32 algorithm.
.EXAMPLE
Get-CRC32 $data
.EXAMPLE
$data | Get-CRC32
.NOTES
C to PowerShell conversion based on code in

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Author: Øyvind Kallstad
Date: 06.02.2017
Version: 1.0
.INPUTS
byte[]
.OUTPUTS
uint32
.LINK

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.LINK

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#>
[CmdletBinding()]
param (
# Array of Bytes to use for CRC calculation
[Parameter(Position = 0, ValueFromPipeline = $true)]
[ValidateNotNullOrEmpty()]
[byte[]]$InputObject
)

$dataArray = @()
$crcTable = New-CrcTable
foreach ($item in $InputObject) {
$dataArray += $item
}
$inputLength = $dataArray.Length
Write-Output ((Update-Crc -crc 0xffffffffL -buffer $dataArray -length $inputLength -crcTable $crcTable) -bxor 0xffffffffL)
}

function GetHash() {
[CmdletBinding()]
param(
[Parameter(Position = 0, ValueFromPipeline = $true)]
[ValidateNotNullOrEmpty()]
[string]$InputString
)

$bytes = [System.Text.Encoding]::UTF8.GetBytes($InputString)
$hasCode = Get-CRC32 $bytes
$hex = "{0:x}" -f $hasCode
return $hex
}

function Get-FolderHash {
[CmdletBinding()]
param(
[Parameter(Position = 0, ValueFromPipeline = $true)]
[ValidateNotNullOrEmpty()]
[string]$FolderPath
)

$FolderContent = New-Object System.Collections.ArrayList
Get-ChildItem $FolderPath -Recurse | Where-Object {
if ([System.IO.File]::Exists($_)) {
$FolderContent.AddRange([System.IO.File]::ReadAllBytes($_)) | Out-Null
}
}

$hasCode = Get-CRC32 $FolderContent
$hex = "{0:x}" -f $hasCode
return $hex.Substring(0, 8).ToLower()
}
```

Here is the snippet that I am using to get the MD5 for a given string:

$text = "text goes here..."
$md5 = [Security.Cryptography.MD5CryptoServiceProvider]::new()
$utf8 = [Text.UTF8Encoding]::UTF8
$bytes= $md5.ComputeHash($utf8.GetBytes($text))
$hash = [string]::Concat($bytes.foreach{$_.ToString("x2")})

PowerShell One-Liners (string to hash)

MD5
```
([System.BitConverter]::ToString((New-Object -TypeName System.Security.Cryptography.MD5CryptoServiceProvider).ComputeHash((New-Object -TypeName System.Text.UTF8Encoding).GetBytes("Hello, World!")))).Replace("-","")
```
SHA1
```
([System.BitConverter]::ToString((New-Object -TypeName System.Security.Cryptography.SHA1CryptoServiceProvider).ComputeHash((New-Object -TypeName System.Text.UTF8Encoding).GetBytes("Hello, World!")))).Replace("-","")
```
SHA256
```
([System.BitConverter]::ToString((New-Object -TypeName System.Security.Cryptography.SHA256CryptoServiceProvider).ComputeHash((New-Object -TypeName System.Text.UTF8Encoding).GetBytes("Hello, World!")))).Replace("-","")
```
SHA384
```
([System.BitConverter]::ToString((New-Object -TypeName System.Security.Cryptography.SHA384CryptoServiceProvider).ComputeHash((New-Object -TypeName System.Text.UTF8Encoding).GetBytes("Hello, World!")))).Replace("-","")
```
SHA512
```
([System.BitConverter]::ToString((New-Object -TypeName System.Security.Cryptography.SHA512CryptoServiceProvider).ComputeHash((New-Object -TypeName System.Text.UTF8Encoding).GetBytes("Hello, World!")))).Replace("-","")
```

(
[System.Security.Cryptography.MD5CryptoServiceProvider]::new().ComputeHash(
[System.Text.UTF8Encoding]::new().GetBytes($yourText)
) `
| %{ [Convert]::ToString($_, 16) }
) -join ''

`$yourText = 'hello'` yields `5d41402abc4b2a76b9719d911017c592`

Team!
Look at my hash calculation function.
```powershell
Function Get-StringHash {
<#
.DESCRIPTION
Get string persistant hash.
#>
[OutputType([string])]
[CmdletBinding()]
Param(
[Parameter( Mandatory = $True, Position = 0, HelpMessage = "String to calculate hash." )]
[string] $String,
[Parameter( Mandatory = $false, Position = 0, HelpMessage = "String encoding." )]
[ValidateSet( 'UTF8' )]
[string] $StringEncoding = 'UTF8',
[Parameter( Mandatory = $false, Position = 2, HelpMessage = "Hash algoritm." )]
[ValidateSet( 'md5', 'sha256', 'sha512' )]
[string] $Algoritm = 'sha256'
)
try {
#region functions
#endregion

$Result = $null

switch ( $Algoritm ) {
'md5' {
$HashProvider = New-Object -TypeName System.Security.Cryptography.MD5CryptoServiceProvider
}
'sha256' {
$HashProvider = New-Object -TypeName System.Security.Cryptography.SHA256CryptoServiceProvider
}
'sha512' {
$HashProvider = New-Object -TypeName System.Security.Cryptography.SHA512CryptoServiceProvider
}
Default {}
}

switch ( $StringEncoding ) {
'UTF8' {
$Encoding = New-Object -TypeName System.Text.UTF8Encoding
}
Default {}
}


$Result = [System.BitConverter]::ToString( $HashProvider.ComputeHash( $Encoding.GetBytes( $String ) )).replace('-','')

}
catch {
Get-ErrorReporting -Trap $_
}

return $Result
}

$String = 'Some text'
$Algoritm = 'MD5'

$Hash = Get-StringHash -String $String -Algoritm $Algoritm

write-host "$String has $Algoritm hash $hash"

Starting in PowerShell version 4, this is easy to do for files out of the box with the [`Get-FileHash`][1] cmdlet:

Get-FileHash <filepath> -Algorithm MD5

This is certainly preferable since it avoids the problems the solution for older PowerShell offers as identified in the comments (uses a stream, closes it, and supports large files).

If the content is a string:

$someString = "Hello, World!"
$md5 = New-Object -TypeName System.Security.Cryptography.MD5CryptoServiceProvider
$utf8 = New-Object -TypeName System.Text.UTF8Encoding
$hash = [System.BitConverter]::ToString($md5.ComputeHash($utf8.GetBytes($someString)))


------

**For older PowerShell version**

If the content is a file:

$someFilePath = "C:\foo.txt"
$md5 = New-Object -TypeName System.Security.Cryptography.MD5CryptoServiceProvider
$hash = [System.BitConverter]::ToString($md5.ComputeHash([System.IO.File]::ReadAllBytes($someFilePath)))


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