C++

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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C++

#include <CkMime.h>
#include <CkCert.h>

void ChilkatSample(void)
    {
    bool success = false;

    CkMime mime;
    success = mime.LoadMimeFile("qa_data/signed.eml");
    if (success == false) {
        std::cout << mime.lastErrorText() << "\r\n";
        return;
    }

    //  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) {
        std::cout << mime.lastErrorText() << "\r\n";
        return;
    }

    int n = mime.get_NumSignerCerts();
    CkCert cert;
    int i;
    for (i = 0; i <= n - 1; i++) {
        success = mime.LastSignerCert(i,cert);
        if (success == false) {
            std::cout << mime.lastErrorText() << "\r\n";
            return;
        }

        std::cout << "Signer " << i << ": " << cert.subjectCN() << " (issued by " << cert.issuerCN() << ")" << "\r\n";
    }
    }