openssl smime in ruby/rails - ruby

Question

So, i have this application that creates a zip file with images and stuff
and i want to sign it using smime.
if i use the terminal command:
openssl smime -binary -sign -passin "pass:MYPASS" -signer ./MyCertificate.pem -inkey ./MyKey.pem -in ./manifest.in -out ./signature.out -outform DER
Formated:
openssl smime -binary -sign -passin "pass:MYPASS" \
-signer ./MyCertificate.pem -inkey ./MyKey.pem \
-in ./manifest.in -out ./signature.out -outform DER
the manifest.in is the file witch contains the text to be signed and signature.out is the output file.
i don't know a lot about signing but i believe this code is signing my file using PKCS7
how can i recreate the same result with ruby/rails?
i have tried to look in the documentation of OpenSSL but i couldn't find anything usefull for me
EDIT
if this helps someone,
this is what the documentation says
i need to build a:
A detached PKCS#7 signature of the manifest

Answer 1

Found a way.
like this:
require 'secure_digest'
def sign_manifest(manifest = {})
manifest_str = manifest.to_json
key4_pem = File.read Rails.root.join("lib", "keys", "key.pem")
pass_phrase = "supera"
key = OpenSSL::PKey::RSA.new key4_pem, pass_phrase
cert = OpenSSL::X509::Certificate.new File.read Rails.root.join("lib", "keys", "certificate.pem")
sign = OpenSSL::PKCS7.sign(cert, key, manifest_str, nil, OpenSSL::PKCS7::BINARY | OpenSSL::PKCS7::NOATTR | OpenSSL::PKCS7::DETACHED).to_der
sign
end
Just to clarify my code, manifest param is a hash witch i want to sign it using this code. if i want another item, like a image, string or file i just need do read it as string