(Swift 3,4,5...) Get Certificate Authority Information Access

Demonstrates how to get a certificate's Authority Information Access extension data (if it exists).

Note: This example requires Chilkat v9.5.0.76 or greater.

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func chilkatTest() {
    let cert = CkoCert()!

    var success: Bool = cert.load(fromFile: "qa_data/certs/test_haswdt.cer")
    if success != true {
        print("\(cert.lastErrorText!)")
        return
    }

    // Get the Authority Information Access extension, which is at OID 1.3.6.1.5.5.7.1.1
    var extensionXmlStr: String? = cert.getExtensionAsXml("1.3.6.1.5.5.7.1.1")
    if cert.lastMethodSuccess == false {
        print("Certificate does not have the AuthInfoAccess extension.")
        return
    }

    let xml = CkoXml()!
    xml.load(extensionXmlStr)

    // See what we have..
    print("\(xml.getXml()!)")

    // We should get XML like this:

    // <?xml version="1.0" encoding="utf-8" ?>
    // <sequence>
    //     <sequence>
    //         <oid>1.3.6.1.5.5.7.48.2</oid>
    //         <contextSpecific tag="6" constructed="0">aHR0cDovL2NydC5jb21vZG9jYS5jb20vQ09NT0RPUlNBQ2xpZW50QXV0aGVudGljYXRpb25hbmRTZWN1
    // cmVFbWFpbENBLmNydA==</contextSpecific>
    //     </sequence>
    //     <sequence>
    //         <oid>1.3.6.1.5.5.7.48.1</oid>
    //         <contextSpecific tag="6" constructed="0">aHR0cDovL29jc3AuY29tb2RvY2EuY29t</contextSpecific>
    //     </sequence>
    // </sequence>

    // Typically, a certificate AIA(Authority Information access) contains 2 parts:
    // 
    //     On-line Certificate Status Protocol (1.3.6.1.5.5.7.48.1)
    //     Certification Authority Issuer (1.3.6.1.5.5.7.48.2)
    // 
    // The base64 content for each OID (in this case) is just a string.  
    // The data can be accessed and decoded like this:

    let sbOcsp = CkoStringBuilder()!
    success = xml.getChildContentSb("/C/oid,1.3.6.1.5.5.7.48.1|++", sb: sbOcsp)
    if success == true {
        sbOcsp.decode("base64", charset: "utf-8")
        print("1.3.6.1.5.5.7.48.1:  \(sbOcsp.getAsString()!)")
    }

    let sbIssuer = CkoStringBuilder()!
    success = xml.getChildContentSb("/C/oid,1.3.6.1.5.5.7.48.2|++", sb: sbIssuer)
    if success == true {
        sbIssuer.decode("base64", charset: "utf-8")
        print("1.3.6.1.5.5.7.48.2:  \(sbIssuer.getAsString()!)")
    }

    // The output looks like this:

    // 1.3.6.1.5.5.7.48.1:  http://ocsp.comodoca.com
    // 1.3.6.1.5.5.7.48.2:  http://crt.comodoca.com/COMODORSAClientAuthenticationandSecureEmailCA.crt

    // -------------------------------------------------------------------------------
    // Note: The Chilkat path passed to GetChildContentSb is composed of two commands:
    // The first command is "/C/oid,1.3.6.1.5.5.7.48.1".   It says "traverse the XML tree from the caller
    // node and stop at the 1st node having tag = "oid" and content = "1.3.6.1.5.5.7.48.1".
    // The "|" char separates the 1st command from the 2nd.
    // The 2nd command is "++" and says "move to the next sibling".

}