(Swift 2) Send a Signed Email using RSASSA-PSS with SHA256

Demonstrates how to sign and send an email using the RSASSA-PSS signing algorithm with the SHA256 hash algorithm.

Note: This example requires Chilkat v9.5.0.67 or greater.

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

    // Get a digital certificate with private key from a .pfx
    // (Chilkat has many different ways to provide a cert + private key for siging.
    // Using a PFX is just one possible option.)
    let pfx = CkoPfx()
    var success: Bool = pfx.LoadPfxFile("qa_data/rsassa-pss/privatekey.pfx", password: "PFX_PASSWORD")
    if success != true {
        print("\(pfx.LastErrorText)")
        return
    }

    let email = CkoEmail()

    // Create a simple email.
    email.Subject = "Sample RSASSA-PSS Signed Email"
    email.Body = "Sample RSASSA-PSS Signed Email"
    email.From = "from_name@mydomain.com"
    // Add one ore more recipients..
    email.AddTo("Chilkat Support", emailAddress: "support@chilkatsoft.com")
    email.AddTo("Chilkat GMail", emailAddress: "chilkat.support@gmail.com")

    // Indicate that the email is to be signed, and that we want to use RSASSA-PSS.
    email.SendSigned = true
    email.SigningAlg = "pss"
    email.SigningHashAlg = "sha256"

    // Get the certificate to be used for signing.
    // (The typical case for a PFX is that it contains a cert with an associated private key,
    // as well as other certificates in the chain of authentication.  The cert with the private
    // key should be in the first position at index 0.)
    var cert: CkoCert? = pfx.GetCert(0)
    if pfx.LastMethodSuccess != true {
        print("\(pfx.LastErrorText)")
        return
    }

    // Tell the email object to use this cert (and private key) for signing.
    email.SetSigningCert(cert)
    cert = nil

    let mailman = CkoMailMan()

    // Set the SMTP settings for your email account on your mail server.
    mailman.SmtpUsername = "SMTP_LOGIN"
    mailman.SmtpPassword = "SMTP_PASSWORD"
    mailman.SmtpHost = "MY_SMTP_DOMAIN_OR_IP"
    mailman.SmtpPort = 587
    mailman.StartTLS = true

    // Signed email can be sent in two different ways.  
    // In a multipart/signed email, the signature is attached as a separate MIME part.
    // In an opaque email (signedData) the content of the email is encapsulated within the signature
    // and the email is sent as "application/pkcs7-mime". 
    // Either should be fine, but some receiving systems might require one or the other..
    mailman.OpaqueSigning = false

    // Send the email.  The mailman will sign the email as directed by the 
    // property settings of the email object.
    success = mailman.SendEmail(email)
    if success != true {
        print("\(mailman.LastErrorText)")
        return
    }

    success = mailman.CloseSmtpConnection()
    if success != true {
        print("Connection to SMTP server not closed cleanly.")
    }

    print("Mail Sent!")

    // -----------------------------------------------------------
    // This is the MIME of the RSASSA-PSS signed email that was sent

    // 	MIME-Version: 1.0
    // 	Date: Thu, 20 Apr 2017 10:14:58 -0500
    // 	Message-ID: <3682A87344CB3A4FB5EB5BC9908C0C4DA01DA461@CHILKAT13>
    // 	Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha256;
    // 	 boundary="------------050103020705000601010800"
    // 	X-Priority: 3 (Normal)
    // 	Subject: Sample RSASSA-PSS Signed Email
    // 	From: support@chilkatsoft.com
    // 	To: "Chilkat Support" <support@chilkatsoft.com>,
    // 	 "Chilkat GMail" <chilkat.support@gmail.com>
    // 
    // 	--------------050103020705000601010800
    // 	Content-Type: text/plain; format=flowed
    // 	Content-Transfer-Encoding: 7bit
    // 
    // 	Sample RSASSA-PSS Signed Email
    // 	--------------050103020705000601010800
    // 	Content-Transfer-Encoding: base64
    // 	Content-Type: application/pkcs7-signature; name="smime.p7s"
    // 	Content-Disposition: attachment; filename="smime.p7s"
    // 
    // 	MIIG5wYJKoZIhvcNAQcCoIIG2DCCBtQCAQExDzANBglghkgBZQMEAgEFADALBgkqhkiG9w0BBwGg
    // 	ggL4MIIC9DCCAl2gAwIBAgIJAMPsJCT11cniMA0GCSqGSIb3DQEBCwUAMIGSMQswCQYDVQQGEwJB
    // 	VTERMA8GA1UECAwIVmljdG9yaWExEjAQBgNVBAcMCU1lbGJvdXJuZTEhMB8GA1UECgwYSW50ZXJu
    // 	ZXQgV2lkZ2l0cyBQdHkgTHRkMQ8wDQYDVQQDDAZXaWRnZXQxKDAmBgkqhkiG9w0BCQEWGWFkbWlu
    // 	QGludGVybmV0d2lkZ2V0cy5jb20wHhcNMTYxMTAxMTY1MjMyWhcNMjExMDMxMTY1MjMyWjCBkjEL
    // 	MAkGA1UEBhMCQVUxETAPBgNVBAgMCFZpY3RvcmlhMRIwEAYDVQQHDAlNZWxib3VybmUxITAfBgNV
    // 	BAoMGEludGVybmV0IFdpZGdpdHMgUHR5IEx0ZDEPMA0GA1UEAwwGV2lkZ2V0MSgwJgYJKoZIhvcN
    // 	AQkBFhlhZG1pbkBpbnRlcm5ldHdpZGdldHMuY29tMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKB
    // 	gQDGIdoCjyavs+F/Rm0VIB4m6O7VL1j+1IqieoR9NEX2GQvu2VCdceyxf9qaw1bxipEvjLwUkw7M
    // 	e+BTlLpWQbBMH87s6KpsC8MVyXhMLpP0oM8NFix/vLz2wdLhUh7CZvJA0plqkJk9bj57QIu+EO1k
    // 	tUHM2DFb6sckvCL2yybD1wIDAQABo1AwTjAdBgNVHQ4EFgQUONKKu2zsXIrinWxIGT654vrcQwsw
    // 	HwYDVR0jBBgwFoAUONKKu2zsXIrinWxIGT654vrcQwswDAYDVR0TBAUwAwEB/zANBgkqhkiG9w0B
    // 	AQsFAAOBgQArFvdi5u9i2QF1Qw+cdC1l7w2Y3+q6RIkln2W8rWJFje00644o8hXy7v46giJCedmF
    // 	ULlhm1n7XIsZGy2W3lJ77v5agn9gFwXu1h3cqkGXkoteE6SQJQXWgsW3GWPveObvTL8LF4y57fgM
    // 	9ZWS+V9MJajeu44Rf/tU17TLYKjvEjGCA7MwggOvAgEBMIGgMIGSMQswCQYDVQQGEwJBVTERMA8G
    // 	A1UECAwIVmljdG9yaWExEjAQBgNVBAcMCU1lbGJvdXJuZTEhMB8GA1UECgwYSW50ZXJuZXQgV2lk
    // 	Z2l0cyBQdHkgTHRkMQ8wDQYDVQQDDAZXaWRnZXQxKDAmBgkqhkiG9w0BCQEWGWFkbWluQGludGVy
    // 	bmV0d2lkZ2V0cy5jb20CCQDD7CQk9dXJ4jANBglghkgBZQMEAgEFAKCCAjQwGAYJKoZIhvcNAQkD
    // 	MQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcNMTcwNDIwMTUxNDU4WjAvBgkqhkiG9w0BCQQx
    // 	IgQgoHOtpFiAgti0cwDw46C8wyYSZbhx2yJqJZ/qRE8WPSQwXwYJKoZIhvcNAQkPMVIwUDALBglg
    // 	hkgBZQMEAQIwCgYIKoZIhvcNAwcwDgYIKoZIhvcNAwICAgCAMA0GCCqGSIb3DQMCAgFAMAcGBSsO
    // 	AwIHMA0GCCqGSIb3DQMCAgEoMIGxBgkrBgEEAYI3EAQxgaMwgaAwgZIxCzAJBgNVBAYTAkFVMREw
    // 	DwYDVQQIDAhWaWN0b3JpYTESMBAGA1UEBwwJTWVsYm91cm5lMSEwHwYDVQQKDBhJbnRlcm5ldCBX
    // 	aWRnaXRzIFB0eSBMdGQxDzANBgNVBAMMBldpZGdldDEoMCYGCSqGSIb3DQEJARYZYWRtaW5AaW50
    // 	ZXJuZXR3aWRnZXRzLmNvbQIJAMPsJCT11cniMIGzBgsqhkiG9w0BCRACCzGBo6CBoDCBkjELMAkG
    // 	A1UEBhMCQVUxETAPBgNVBAgMCFZpY3RvcmlhMRIwEAYDVQQHDAlNZWxib3VybmUxITAfBgNVBAoM
    // 	GEludGVybmV0IFdpZGdpdHMgUHR5IEx0ZDEPMA0GA1UEAwwGV2lkZ2V0MSgwJgYJKoZIhvcNAQkB
    // 	FhlhZG1pbkBpbnRlcm5ldHdpZGdldHMuY29tAgkAw+wkJPXVyeIwPQYJKoZIhvcNAQEKMDCgDTAL
    // 	BglghkgBZQMEAgGhGjAYBgkqhkiG9w0BAQgwCwYJYIZIAWUDBAIBogMCASAEgYCDQpT6vJZ9zERJ
    // 	JVX69PGUfCN5Eq9pKzoOTQSrIBe1YgNDSPd5pyOPP2MN1RpI0T/GTQZw4iWy5LZq0T5sjmk3fFVB
    // 	+VZjKtkTuhGaCdzMQXomVLBbI2fN4UaA4v1/Ayrqr8SY9Rsa20TpKv/bufK7oYs083UOtlcA1EHY
    // 	41wQ5A==
    // 
    // 	--------------050103020705000601010800--

}