Checksum.ps1
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<#PSScriptInfo
.VERSION 1.0 .GUID 9a0e19f8-99d8-453b-82c7-d939fa414adb .AUTHOR William A. Keyon .PROJECTURI https://github.com/WilliamKeyon/Powershell-Checksum .COMPANYNAME .COPYRIGHT .TAGS checksum file-integrity commandline .LICENSEURI https://github.com/WilliamKeyon/Powershell-Checksum/blob/main/LICENSE .ICONURI .EXTERNALMODULEDEPENDENCIES .REQUIREDSCRIPTS .EXTERNALSCRIPTDEPENDENCIES .RELEASENOTES #> <# .SYNOPSIS Checksum - Calculate, compares and display the checksum of the specified file with the known provided hash. .DESCRIPTION Calculates, compares and display the checksum of the specified file with the known provided hash. Note that the checksum relies on Get-FileHash. .PARAMETER FilePath The path to the file for which the checksum will be calculated. .PARAMETER Hash The hash value for which the checksum will be compared. .PARAMETER Alg The checksum algorithm to use. [MD5, SHA1, SHA256, SHA384, SHA512] By default the algorithm is chosen by the hash length, with a fallback on SHA256. .EXAMPLE Checksum -FilePath .\Example.txt -Hash ED076287532E86365E841E92BFC50D8C -Alg MD5 .EXAMPLE Checksum .\Example.txt 2EF7BDE608CE5404E97D5F042F95F89F1C232871 .NOTES Author: William A. Keyon Version: 1.0 Date: 2025-05-01 #> [CmdletBinding()] param ( [string]$FilePath, [string]$Hash, [string]$Alg ) $Version = '1.0' $Hash = $Hash.Trim() if ($($FilePath).Length -eq 0 -Or $FilePath -ieq 'Help' -Or $Hash.Length -eq 0) { Write-Host 'Checksum - Calculates, compares and display the checksum of the specified file with the known provided hash.' Write-Host '' Write-Host "Usage:`t`tChecksum -FilePath .\Example.txt -Hash ED076287532E86365E841E92BFC50D8C -Alg MD5" Write-Host "Or simply:`tChecksum .\Example.txt ED076287532E86365E841E92BFC50D8C" Write-Host '' Write-Host 'Parameters:' Write-Host " -FilePath`tThe path to the file for which the checksum will be calculated." Write-Host " -Hash`t`tThe known hash value for which the checksum will be compared." Write-Host " -Alg`t`tThe checksum algorithm to use. [MD5, SHA1, SHA256, SHA384, SHA512]" Write-Host "`t`tBy default the algorithm is chosen by the hash length, with a fallback on SHA256." Write-Host '' Write-Host 'Options:' Write-Host " Help`t`tShows this help message." Write-Host " Version or V`tShows the current version, which is $Version." Write-Host '' Write-Host 'Note that the checksum relies on Get-FileHash.' Write-Host '' Write-Host 'Author: William A. Keyon' return } if ($FilePath -ieq 'Version' -Or $FilePath -ieq 'V') { Write-Host $Version return } if (!(Test-Path $FilePath)) { Write-Host "Cannot find path '$FilePath' because it does not exist." -ForegroundColor Red return } if ($Hash.Length -eq 0) { Write-Host 'Missing hash value. Please provide the known hash value.' -ForegroundColor Red return } if ($Alg.Length -eq 0) { switch ($Hash.Length) { 32 { $Alg = 'MD5' } 40 { $Alg = 'SHA1' } 64 { $Alg = 'SHA256' } 96 { $Alg = 'SHA384' } 128 { $Alg = 'SHA512' } Default { $Alg = 'SHA256' } } } Write-Host 'Calculating hash, please wait...' Write-Host '' [string]$CalculatedHash = [string]::Empty try { $CalculatedHash = (Get-FileHash -Path $FilePath -Algorithm $Alg).Hash } catch { Write-Host "An error occurred: $($_.ErrorInformation)" -BackgroundColor Red throw $_.Exception return } [string]$FileName = Split-Path $FilePath -Leaf [bool]$IsMatch = $CalculatedHash -ieq $Hash Write-Host "The checksum of the provided file ""$FileName"" " -NoNewline if ($IsMatch) { Write-Host "matches the expected hash ""$CalculatedHash""." Write-Host 'The file is authentic and unaltered.' -ForegroundColor Green } else { "does NOT match the expected hash ""$CalculatedHash""." Write-Host 'The file has been altered or corrupted since the last known authentic checksum was recorded.' -ForegroundColor Red } |