Ruby

Check if an Email Was Received Digitally Signed

Demonstrates the read-only Chilkat Email.ReceivedSigned property, which is true if the email was originally received carrying one or more digital signatures. Knowing a message was signed is separate from knowing the signature checked out, so this example also reads SignaturesValid to report whether the signed content verified.

Background: A digital signature on an email (S/MIME) provides two things: authenticity (it was really sent by the holder of a particular certificate) and integrity (the content was not altered in transit). The sender signs a hash of the message with their private key; the recipient verifies it with the sender's public certificate. ReceivedSigned simply tells you a signature is present — verifying it is a separate step exposed through SignaturesValid.

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Ruby

require 'chilkat'

success = false

#  Demonstrates the read-only Email.ReceivedSigned property, which is true if this
#  email was originally received with a digital signature.  Use SignaturesValid to
#  determine whether the signed content actually verified.

email = Chilkat::CkEmail.new()

success = email.LoadEml("qa_data/eml/signed.eml")
if (success == false)
    print email.lastErrorText() + "\n";
    exit
end

if (email.get_ReceivedSigned() == true)
    print "This email was received with a digital signature." + "\n";
    if (email.get_SignaturesValid() == true)
        print "All signatures are valid." + "\n";
    else
        print "One or more signatures are NOT valid." + "\n";
    end

else
    print "This email was not signed." + "\n";
end

#  Note: Paths such as "qa_data/..." are relative local filesystem paths,
#  relative to the current working directory of the running application.