PowerShell

Add a Detached Signature with a Separate Private Key

Demonstrates the Chilkat Mime.AddDetachedSignaturePk method, which creates a detached signature using a signer certificate and its separately supplied private key. The first argument is the Cert and the second is the PrivateKey.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: Sometimes the certificate and its private key live apart — a .cer alongside a PEM key file, for instance — rather than bundled in a single PFX. This method pairs them explicitly for signing, whereas AddDetachedSignature expects a Cert that already provides its key. The result is the same multipart/signed message.

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

$success = $false

$mime = New-Object Chilkat.Mime
$success = $mime.SetBodyFromPlainText("This message will be signed.")
if ($success -eq $false) {
    $($mime.LastErrorText)
    exit
}

#  Load the certificate and its private key separately.
$cert = New-Object Chilkat.Cert
$success = $cert.LoadFromFile("qa_data/signer.cer")
if ($success -eq $false) {
    $($cert.LastErrorText)
    exit
}

$privKey = New-Object Chilkat.PrivateKey
$success = $privKey.LoadPemFile("qa_data/signer_privkey.pem")
if ($success -eq $false) {
    $($privKey.LastErrorText)
    exit
}

#  Create a detached signature when the certificate and private key are supplied separately.  The
#  1st argument is the signer certificate and the 2nd is its private key.
$success = $mime.AddDetachedSignaturePk($cert,$privKey)
if ($success -eq $false) {
    $($mime.LastErrorText)
    exit
}

$success = $mime.SaveMime("qa_output/signed.eml")
if ($success -eq $false) {
    $($mime.LastErrorText)
    exit
}

$("Detached signature added.")