Get SHA256 hash of a file.

get-hash.ps1

param(
    [string] $file = $(throw 'a filename is required'),
    [string] $algorithm = 'sha256'
)

$fileStream = [system.io.file]::openread((resolve-path $file))
$hasher = [System.Security.Cryptography.HashAlgorithm]::create($algorithm)
$hash = $hasher.ComputeHash($fileStream)
$fileStream.close()
$fileStream.dispose()

[system.bitconverter]::tostring($hash).Replace("-","").ToLower()