(PureBasic) 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.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkCert.pb"
IncludeFile "CkEmail.pb"
IncludeFile "CkPfx.pb"
IncludeFile "CkMailMan.pb"

Procedure ChilkatExample()

    ; 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.)
    pfx.i = CkPfx::ckCreate()
    If pfx.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success.i = CkPfx::ckLoadPfxFile(pfx,"qa_data/rsassa-pss/privatekey.pfx","PFX_PASSWORD")
    If success <> 1
        Debug CkPfx::ckLastErrorText(pfx)
        CkPfx::ckDispose(pfx)
        ProcedureReturn
    EndIf

    email.i = CkEmail::ckCreate()
    If email.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Create a simple email.
    CkEmail::setCkSubject(email, "Sample RSASSA-PSS Signed Email")
    CkEmail::setCkBody(email, "Sample RSASSA-PSS Signed Email")
    CkEmail::setCkFrom(email, "from_name@mydomain.com")
    ; Add one ore more recipients..
    CkEmail::ckAddTo(email,"Chilkat Support","support@chilkatsoft.com")
    CkEmail::ckAddTo(email,"Chilkat GMail","chilkat.support@gmail.com")

    ; Indicate that the email is to be signed, and that we want to use RSASSA-PSS.
    CkEmail::setCkSendSigned(email, 1)
    CkEmail::setCkSigningAlg(email, "pss")
    CkEmail::setCkSigningHashAlg(email, "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.)
    cert.i = CkPfx::ckGetCert(pfx,0)
    If CkPfx::ckLastMethodSuccess(pfx) <> 1
        Debug CkPfx::ckLastErrorText(pfx)
        CkPfx::ckDispose(pfx)
        CkEmail::ckDispose(email)
        ProcedureReturn
    EndIf

    ; Tell the email object to use this cert (and private key) for signing.
    CkEmail::ckSetSigningCert(email,cert)
    CkCert::ckDispose(cert)

    mailman.i = CkMailMan::ckCreate()
    If mailman.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Set the SMTP settings for your email account on your mail server.
    CkMailMan::setCkSmtpUsername(mailman, "SMTP_LOGIN")
    CkMailMan::setCkSmtpPassword(mailman, "SMTP_PASSWORD")
    CkMailMan::setCkSmtpHost(mailman, "MY_SMTP_DOMAIN_OR_IP")
    CkMailMan::setCkSmtpPort(mailman, 587)
    CkMailMan::setCkStartTLS(mailman, 1)

    ; 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..
    CkMailMan::setCkOpaqueSigning(mailman, 0)

    ; Send the email.  The mailman will sign the email as directed by the 
    ; property settings of the email object.
    success = CkMailMan::ckSendEmail(mailman,email)
    If success <> 1
        Debug CkMailMan::ckLastErrorText(mailman)
        CkPfx::ckDispose(pfx)
        CkEmail::ckDispose(email)
        CkMailMan::ckDispose(mailman)
        ProcedureReturn
    EndIf

    success = CkMailMan::ckCloseSmtpConnection(mailman)
    If success <> 1
        Debug "Connection to SMTP server not closed cleanly."
    EndIf

    Debug "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--


    CkPfx::ckDispose(pfx)
    CkEmail::ckDispose(email)
    CkMailMan::ckDispose(mailman)


    ProcedureReturn
EndProcedure