PowerShell Requires Chilkat v11.0.0+

Decrypt S/MIME and Verify S/MIME Signatures

See more MIME Examples

_LANGUAGE_ example to decrypt S/MIME and verify S/MIME signatures. The S/MIME is unwrapped to get the original MIME prior to signing/encrypting. 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.

$mime = New-Object Chilkat.Mime

#  Load an S/MIME message from a file:
$success = $mime.LoadMimeFile("signedMime.txt")
if ($success -eq $false) {
    $($mime.LastErrorText)
    exit
}

#  The ContainsEncryptedParts/ContainsSignedParts methods
#  can be called to determine if the MIME is encrypted and/or signed:
$isEncrypted = $mime.ContainsEncryptedParts()
$isSigned = $mime.ContainsSignedParts()

#  We don't want the "unwrap extras".  You'll see what those
#  are in a few moments...
$mime.UnwrapExtras = $false

#  To verify the signature, call UnwrapSecurity.  This will
#  verify the signature(s) and decrypt the S/MIME and restore
#  the MIME to the unsigned/unencrypted state.
#  The results of what was found are present in the MIME object's
#  properties, as well as extra header fields that are added
#  to the unwrapped MIME.
$success = $mime.UnwrapSecurity()
if ($success -ne $true) {
    #  UnwrapSecurity returns $true if all signatures were
    #  verified and all parts decrypted.
    $($mime.LastErrorText)
    exit
}

#  The mime.UnwrapExtras property controls whether or not
#  these additional fields are added to the unwrapped MIME:
#  
#  X-NumPartsSigned: 1
#  X-SignaturesValid: yes
#  X-NumPartsEncrypted: 1
#  X-Decrypted: no
#  
#  The X-NumPartsSigned/X-SignaturesValid headers are added
#  if the MIME was signed.  
#  
#  The X-NumPartsEncrypted/X-Decrypted headers are added
#  if the MIME was encrypted.
#  

#  If the MIME was signed, get the certificate used for signing.
if ($isSigned -eq $true) {
    $signerCert = New-Object Chilkat.Cert

    #  The NumSignerCerts property indicates how many certificates
    #  were used for signing.  This example will assume the value is 1.
    #  To get the 1st signer cert, call LastSignerCert with an index of 0:
    $success = $mime.LastSignerCert(0,$signerCert)
    if ($success -eq $true) {
        $("**** Signer Cert: " + $signerCert.SubjectCN)
    }

}

#  If the MIME was encrypted, get the certificate used for decryption
if ($isEncrypted -eq $true) {
    #  The NumDecryptCerts property indicates how many certificates
    #  were used for decrypting.  This example will assume the value is 1.
    #  To get the 1st decrypt cert, call LastDecryptCert with an index of 0:
    $decryptCert = New-Object Chilkat.Cert
    $success = $mime.LastDecryptCert(0,$decryptCert)
    if ($success -eq $true) {
        $("**** Decrypt Cert: " + $decryptCert.SubjectCN)
    }

}

#  Display the unwrapped MIME:
$($mime.GetMime())

#  Save the unwrapped MIME to a file:
$success = $mime.SaveMime("unwrappedMime.txt")