(Swift) Verify Opaque Signature and Retrieve Signing Certificates

Demonstrates how to verify a PCKS7 opaque digital signature (signed data), extract the original file/data, and then extract the certificate(s) that were used to sign.

Note: This example requires Chilkat v11.0.0 or greater.

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func chilkatTest() {
    var success: Bool = false

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    let crypt = CkoCrypt2()!

    // Verify a PKCS7 signed-data (opaque signature) file and extract the original content to a file.
    success = crypt.verifyP7M("qa_data/p7m/opaqueSig.p7", destPath: "qa_output/originalData.dat")
    if success == false {
        print("\(crypt.lastErrorText!)")
        return
    }

    // Alternatively, we can do it in memory...
    let binData = CkoBinData()!
    success = binData.loadFile("qa_data/p7m/opaqueSig.p7")
    // Your app should check for success, but we'll skip the check for brevity..

    // If verified, the signature is unwrapped and binData is replaced with the original data that was signed.
    success = crypt.opaqueVerifyBd(binData)
    if success == false {
        print("\(crypt.lastErrorText!)")
        return
    }

    // For our testing, we signed some text, so we can get it from the binData..
    print("Original Data:")
    print("\(binData.getString("utf-8")!)")

    // After any method call that verifies a signature, the crypt object will contain the certificate(s)
    // that were used for signing (assuming the X.509 certs were available in the signature, which is typically the case).

    // Get each signing certificate, and build the certificate chain for each.
    let cert = CkoCert()!
    let certChain = CkoCertChain()!
    var numCerts: Int = crypt.numSignerCerts.intValue
    var i: Int = 0
    while i < numCerts {
        crypt.lastSignerCert(i, cert: cert)
        print("\(cert.subjectDN!)")

        success = cert.build(certChain)
        if success == false {
            print("\(cert.lastErrorText!)")
            return
        }

        i = i + 1
    }


}