PowerBuilder

Create an Opaque (Attached) S/MIME Signature

Demonstrates the Chilkat Mime.ConvertToSigned method, which creates an opaque (attached) S/MIME signature. The only argument is the signing Cert. On success the entity is replaced by a CMS/PKCS #7 signed-data structure that wraps the content inside the signature.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: An opaque signature bundles the content inside the CMS structure, so the message is a single application/pkcs7-mime blob that only S/MIME-aware software can read. It is more tamper-resistant in transit — nothing can alter the content without breaking the wrapper — at the cost of the backward compatibility a detached signature offers. Use it when every recipient is known to support S/MIME.

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PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Mime
string ls_PfxPassword
oleobject loo_Cert

li_Success = 0

loo_Mime = create oleobject
li_rc = loo_Mime.ConnectToNewObject("Chilkat.Mime")
if li_rc < 0 then
    destroy loo_Mime
    MessageBox("Error","Connecting to COM object failed")
    return
end if
li_Success = loo_Mime.SetBodyFromPlainText("This message will be signed.")
if li_Success = 0 then
    Write-Debug loo_Mime.LastErrorText
    destroy loo_Mime
    return
end if

//  Load the signing certificate (which must have access to its private key) from a PFX file.
//  The PFX password should come from a secure source rather than being hard-coded.
ls_PfxPassword = "myPfxPassword"
loo_Cert = create oleobject
li_rc = loo_Cert.ConnectToNewObject("Chilkat.Cert")

li_Success = loo_Cert.LoadPfxFile("qa_data/signer.pfx",ls_PfxPassword)
if li_Success = 0 then
    Write-Debug loo_Cert.LastErrorText
    destroy loo_Mime
    destroy loo_Cert
    return
end if

//  Create an OPAQUE (attached) S/MIME signature.  The entity is replaced by a CMS/PKCS #7
//  signed-data structure that wraps the content inside the signature.
li_Success = loo_Mime.ConvertToSigned(loo_Cert)
if li_Success = 0 then
    Write-Debug loo_Mime.LastErrorText
    destroy loo_Mime
    destroy loo_Cert
    return
end if

li_Success = loo_Mime.SaveMime("qa_output/signed_opaque.eml")
if li_Success = 0 then
    Write-Debug loo_Mime.LastErrorText
    destroy loo_Mime
    destroy loo_Cert
    return
end if

Write-Debug "Message converted to an opaque signed message."


destroy loo_Mime
destroy loo_Cert