我想计算一些内容的MD5校验和。如何在PowerShell中做到这一点?
当前回答
这是我用来获得一致哈希值的方法:
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 https://www.w3.org/TR/PNG/#D-CRCAppendix
Author: Øyvind Kallstad
Date: 06.02.2017
Version: 1.0
.INPUTS
byte[]
.OUTPUTS
uint32
.LINK
https://communary.net/
.LINK
https://www.w3.org/TR/PNG/#D-CRCAppendix
#>
[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 $hex.Substring(0, 8).ToLower()
}
其他回答
这是我用来获得一致哈希值的方法:
function New-CrcTable {
[uint32]$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 https://www.w3.org/TR/PNG/#D-CRCAppendix
Author: Øyvind Kallstad
Date: 06.02.2017
Version: 1.0
.INPUTS
byte[]
.OUTPUTS
uint32
.LINK
https://communary.net/
.LINK
https://www.w3.org/TR/PNG/#D-CRCAppendix
#>
[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()
}
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{$_.ToString("x2")})
下面是我使用的处理相对路径和绝对路径的函数:
function md5hash($path)
{
$fullPath = Resolve-Path $path
$md5 = new-object -TypeName System.Security.Cryptography.MD5CryptoServiceProvider
$file = [System.IO.File]::Open($fullPath,[System.IO.Filemode]::Open, [System.IO.FileAccess]::Read)
try {
[System.BitConverter]::ToString($md5.ComputeHash($file))
} finally {
$file.Dispose()
}
}
感谢@davor上面建议使用Open()而不是ReadAllBytes()，并感谢@jpmc26建议使用finally块。
另一个早在2003年就默认安装在Windows中的内置命令是Certutil，当然也可以从PowerShell调用它。
CertUtil -hashfile file.foo MD5
(注意:MD5应该全部大写以获得最大的健壮性)
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
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