(PowerShell) Duplicate openssl dgst -sha256 -verify pubKey.pem -signature signature.sig in.dat

Demonstrates how to duplicate this OpenSSL command:

openssl dgst -sha256 -verify pubKey.pem -signature signature.sig in.dat

1. Creates a SHA256 digest of the contents of the input file.
2. Verifies the SHA256 digest using the public key.

Chilkat .NET Downloads Chilkat .NET Assemblies

Add-Type -Path "C:\chilkat\ChilkatDotNet47-9.5.0-x64\ChilkatDotNet47.dll"

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

$pubKey = New-Object Chilkat.PublicKey

# Load the public key from an PEM file:
$success = $pubKey.LoadFromFile("pubKey.pem")
if ($success -ne $true) {
    $($pubKey.LastErrorText)
    exit
}

# Load the data of the original file that was signed.
$bdFileData = New-Object Chilkat.BinData
$success = $bdFileData.LoadFile("in.dat")

# Load the signature.
$bdSig = New-Object Chilkat.BinData
$success = $bdSig.LoadFile("signature.sig")

$rsa = New-Object Chilkat.Rsa

# Import the public key into the RSA component:
$success = $rsa.ImportPublicKeyObj($pubKey)
if ($success -ne $true) {
    $($rsa.LastErrorText)
    exit
}

# OpenSSL uses big-endian.
$rsa.LittleEndian = $false

$success = $rsa.VerifyBd($bdFileData,"sha256",$bdSig)
if ($success -ne $true) {
    $($rsa.LastErrorText)
    $("The signature was invalid.")
    exit
}

$("The signature was verified.")