PowerShell Requires Chilkat v11.0.0+

RSASSA-PSS Sign String to Create Base64 PCKS7 Signature

See more Digital Signatures Examples

Signs a string to create a PKCS7 signature in the base64 encoding. The signature algorithm is RSASSA-PSS with SHA256. PowerShell

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

$success = $false

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

$crypt = New-Object Chilkat.Crypt2

#  Get a digital certificate with private key from a .pfx
#  (Chilkat has many different ways to provide a cert + private key for siging.
#  Using a PFX is just one possible option.)
$pfx = New-Object Chilkat.Pfx
$success = $pfx.LoadPfxFile("qa_data/rsassa-pss/privatekey.pfx","PFX_PASSWORD")
if ($success -eq $false) {
    $($pfx.LastErrorText)
    exit
}

#  Get the certificate to be used for signing.
#  (The typical case for a PFX is that it contains a cert with an associated private key,
#  as well as other certificates in the chain of authentication.  The cert with the private
#  key should be in the first position at index 0.)

$cert = New-Object Chilkat.Cert
$success = $pfx.CertAt(0,$cert)
if ($success -eq $false) {
    $($pfx.LastErrorText)
    exit
}

$crypt.SetSigningCert($cert)

#  Indicate that RSASSA-PSS with SHA256 should be used.
$crypt.SigningAlg = "pss"
$crypt.HashAlgorithm = "sha256"

$crypt.EncodingMode = "base64"

#  Sign a string and return the base64 PKCS7 detached signature
$originalText = "This is a test"
$pkcs7sig = $crypt.SignStringENC($originalText)
$("Detached Signature:")
$($pkcs7sig)

#  This signature looks like this:
#  MIIG5wYJKoZIhvcNAQcCoIIG2DCCBtQCAQExDzANBgl .. YToLqEwTdU87ox5g7rvw==

#  The ASN.1 of the signature can be examined by browsing to https://lapo.it/asn1js/ ,
#  then copy-and-paste the Base64 signature into the form and decode..

#  The signature can be verified against the original data like this:
$success = $crypt.VerifyStringENC($originalText,$pkcs7sig)
$("Signature verified: " + $success)
$success = $crypt.VerifyStringENC("Not the original text",$pkcs7sig)
$("Signature verified: " + $success)

#  Now we'll create an opaque signature (the opposite of a detached signature). 
#  An opaque signature is a PKCS7 message that contains both the original data and
#  the signature.  The verification process extracts the original data.
$opaqueSig = $crypt.OpaqueSignStringENC($originalText)
$("Opaque Signature:")
$($opaqueSig)

#  The ASN.1 of the signature can be examined by browsing to https://lapo.it/asn1js/ ,
#  then copy-and-paste the Base64 signature into the form and decode..

#  We can verify and extract the original data:
$origTxt = $crypt.OpaqueVerifyStringENC($opaqueSig)
if ($crypt.LastMethodSuccess -ne $true) {
    $("Signature verification failed.")
    $($crypt.LastErrorText)
    exit
}

$("Signature verified.")
$("Extracted text:" + $origTxt)