下面是我用来获取给定字符串的MD5的代码片段:

$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")}) 

如果你正在使用PowerShell社区扩展，有一个Get-Hash命令可以很容易地做到这一点:

C:\PS> "hello world" | Get-Hash -Algorithm MD5


Algorithm: MD5


Path       :
HashString : E42B054623B3799CB71F0883900F2764

右击菜单选项示例:

[HKEY_CLASSES_ROOT\*\shell\SHA1 PS check\command]
@="C:\\Windows\\system32\\WindowsPowerShell\\v1.0\\powershell.exe -NoExit -Command Get-FileHash -Algorithm SHA1 '%1'"

PowerShell One-Liners(字符串到散列)

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("-","")

正如已接受的答案中所述，Get-FileHash很容易用于文件，但也可以用于字符串:

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

下面是一个尝试验证SHA256指纹的漂亮打印示例。我使用PowerShell v4下载了gpg4win v3.0.3(需要Get-FileHash)。

从https://www.gpg4win.org/download.html下载包，打开PowerShell，从下载页面抓取散列，然后运行:

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)) 
}

输出:

Hash matches for file gpg4win-3.0.3.exe