(PowerShell) Verify the RSA Signature of a SHA256 Hash

See more RSA Examples

Note: This example requires Chilkat v11.0.0 or greater.

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

$success = $false

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

# Let's say you have a file containing the 32-bytes of a SHA256 hash,
# and a file that is an RSA signature of those 32 bytes.
# Here's how you verify using the RSA public key found in a PEM.

$pubKey = New-Object Chilkat.PublicKey
$success = $pubKey.LoadFromFile("rsaPubKey.pem")
if ($success -eq $false) {
    $($pubKey.LastErrorText)
    exit
}

$rsa = New-Object Chilkat.Rsa

# Get the public key.
$success = $rsa.UsePublicKey($pubKey)
if ($success -eq $false) {
    $($rsa.LastErrorText)
    exit
}

# Get the 32-byte SHA256 hash.
$bdHash = New-Object Chilkat.BinData
$success = $bdHash.LoadFile("myHash.sha256")
if ($success -eq $false) {
    $("Failed to load SHA256 hash.")
    exit
}

# Get the RSA signature to be validated.
$bdSig = New-Object Chilkat.BinData
$success = $bdSig.LoadFile("mySig.sig")
if ($success -eq $false) {
    $("Failed to load RSA signature.")
    exit
}

# Verify the signature against the SHA256 hash.
$enc = "base64"
$rsa.EncodingMode = $enc
$success = $rsa.VerifyHashENC($bdHash.GetEncoded($enc),"sha256",$bdSig.GetEncoded($enc))
if ($success -eq $false) {
    $($rsa.LastErrorText)
    exit
}

$("Signature validated.")