Add DomainKey-Signature Header to MIME / Email

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

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

Downloads for Windows/Linux and Install Instructions

require 'rubygems'
require 'chilkat'

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

dkim = Chilkat::CkDkim.new()

#  Any string automatically begins a fully-functional 30-day trial.
success = dkim.UnlockComponent("Anything for 30-day trial")
if (success != true)
    print dkim.lastErrorText() + "\n"
    exit
end

#  To create a DomainKey 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 DomainKey signature via an
#  external email client supporting DomainKey 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 DomainKey DNS record creation.
#  (Chilkat does not provide an API for creating DNS records.
#  Creating the DomainKey DNS record is something you would do
#  manually.)

#  Set the domain and selector:
#  You'll need to provide your own values here..
dkim.put_DomainKeyDomain("chilkatsoft.com")
dkim.put_DomainKeySelector("salmon")

#  Load a private key from any common RSA private key
#  format, such as DER, PKCS8, PEM, XML, etc.
#  The LoadDomainKeyPkFile 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.

password = "optionalPassword"
success = dkim.LoadDomainKeyPkFile("myPrivateKey.pem",password)
if (success != true)
    print dkim.lastErrorText() + "\n"
    exit
end

#  Load a MIME file.
mimeData = Chilkat::CkByteData.new()

success = mimeData.loadFile("testMessage.eml")
if (success != true)
    print "Failed to load file." + "\n";
    exit
end

#  Sign it.  This adds the DomainKey-Signature header and
#  returns the new MIME with DomainKey-Signature added.
domainKeySignedMime = Chilkat::CkByteData.new()
success = dkim.AddDomainKeySignature(mimeData,domainKeySignedMime)
if (success != true)
    print dkim.lastErrorText() + "\n";
    exit
end

success = domainKeySignedMime.saveFile("domainKeySigned.eml")
if (success != true)
    print "Failed to save file." + "\n";
    exit
end

print "Success." + "\n"