Lianja

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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llSuccess = .F.

loMime = createobject("CkMime")
llSuccess = loMime.LoadMimeFile("qa_data/signed.eml")
if (llSuccess = .F.) then
    ? loMime.LastErrorText
    release loMime
    return
endif

//  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.
llSuccess = loMime.Verify()
if (llSuccess <> .T.) then
    ? loMime.LastErrorText
    release loMime
    return
endif

n = loMime.NumSignerCerts
loCert = createobject("CkCert")

for i = 0 to n - 1
    llSuccess = loMime.LastSignerCert(i,loCert)
    if (llSuccess = .F.) then
        ? loMime.LastErrorText
        release loMime
        release loCert
        return
    endif

    ? "Signer " + str(i) + ": " + loCert.SubjectCN + " (issued by " + loCert.IssuerCN + ")"
next


release loMime
release loCert