(Swift 3,4,5...) Add DKIM-Signature Header to MIME / Email

Demonstrates how to add a DKIM-Signature header field to a MIME message.

Note: The DKIM / DomainKey functionality is included with the Chilkat MIME license.

Chilkat Downloads for the Swift Programming Language MAC OS X (Cocoa) Objective-C/Swift Libs iOS Objective-C/Swift Libs

func chilkatTest() {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // Important: It is helpful to send the contents of the
    // dkim.LastErrorText property when requesting support.

    let dkim = CkoDkim()!

    // To create a DKIM signature for email (i.e. MIME),
    // you'll need to provide the following:
    // (1) An RSA private key in any common file format.
    // (2) The domain name (typically the same domain
    // as the sender of an email).
    // (3) A selector for the domain name -- an arbitrary string
    // to identify the matching public key in DNS.

    // To allow an email recipient to verify the DKIM signature via an
    // external email client supporting DKIM or using other software,
    // you will need to create a DNS record with the selector
    // and matching public key.  This example does not provide
    // information about DKIM DNS record creation.  
    // (Chilkat does not provide an API for creating DNS records.  
    // Creating the DKIM DNS record is something you would do
    // manually.)

    // Set the domain and selector:
    // You'll need to provide your own values here..
    dkim.dkimDomain = "chilkatsoft.com"
    dkim.dkimSelector = "tuna"

    // Load a private key from any common RSA private key
    // format, such as DER, PKCS8, PEM, XML, etc.
    // The LoadDkimPkFile method automatically detects
    // the file format and reads it appropriately.
    // If a password is not required, you'll still need to provide
    // a password string argument, but it is ignored.
    var password: String? = "optionalPassword"
    let privKey = CkoPrivateKey()!
    var success: Bool = privKey.loadAnyFormatFile("myPrivateKey.pem", password: password)
    if success != true {
        print("\(privKey.lastErrorText!)")
        return
    }

    success = dkim.setDkimPrivateKey(privKey)
    if success != true {
        print("\(dkim.lastErrorText!)")
        return
    }

    // Load a MIME file into a byte array.
    let fac = CkoFileAccess()!
    var mimeData: NSData
    mimeData = fac.readEntireFile("testMessage.eml")
    if fac.lastMethodSuccess != true {
        print("\(fac.lastErrorText!)")
        return
    }

    // Sign it.  This adds the DKIM-Signature header and
    // returns the new MIME with DKIM-Signature added.
    var dkimSignedMime: NSData
    dkimSignedMime = dkim.addSignature(mimeData)
    if dkim.lastMethodSuccess != true {
        print("\(dkim.lastErrorText!)")
        return
    }

    success = fac.writeEntireFile("dkimSigned.eml", fileData: dkimSignedMime)
    if success != true {
        print("\(fac.lastErrorText!)")
        return
    }

    print("Success.")

}