Ruby

Get the S/MIME Signer's Certificate

Demonstrates the Chilkat Mime.LastSignerCert method, which loads the signer certificate at a zero-based index from the most recent successful verification (or security-unwrapping) into a Cert. The first argument is the signer index and the second is the receiving Cert.

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: Verifying tells you the signature is mathematically valid, but you usually also need to know who signed — the subject, the issuer, the validity dates — to decide whether to trust it. This retrieves each signer's certificate after verification so your code can inspect and apply its own trust rules. A message can have multiple signers, so iterate from 0 to NumSignerCerts - 1.

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Ruby

require 'chilkat'

success = false

mime = Chilkat::CkMime.new()
success = mime.LoadMimeFile("qa_data/signed.eml")
if (success == false)
    print mime.lastErrorText() + "\n";
    exit
end

#  After a successful verification, load each signer's certificate to inspect it.  The 1st argument
#  is the zero-based signer index and the 2nd is a Cert object that receives the certificate.
success = mime.Verify()
if (success != true)
    print mime.lastErrorText() + "\n";
    exit
end

n = mime.get_NumSignerCerts()
cert = Chilkat::CkCert.new()

for i in 0 .. n - 1
    success = mime.LastSignerCert(i,cert)
    if (success == false)
        print mime.lastErrorText() + "\n";
        exit
    end

    print "Signer " + i.to_s() + ": " + cert.subjectCN() + " (issued by " + cert.issuerCN() + ")" + "\n";
end