Ruby PKCS#7 Certificate Only Degenerate (application/x-x509-ca-ra-cert)

pkcs7_degenerate.rb

# Creates a degenerate PKCS#7 certificate only in ruby (SCEP application/x-x509-ca-ra-cert)
# Inspiration: https://github.com/AppBlade/TestHub/blob/master/app/controllers/scep_controller.rb#L92-L112
#
# Tested Ruby 2.2.0 OSX 10.10, OpenSSL 1.0.1l
require 'openssl'

cert = OpenSSL::X509::Certificate.new File.read('some_cert.crt')

# Fails ruby 2.2, OpenSSL 1.0.1l!!
p7certs = OpenSSL::PKCS7.new
p7certs.type = 'signed'
p7certs.certificates = [cert, cert, ..., cert]  # Obviously you would use different certs
der = p7certs.to_der

OpenSSL::PKCS7.new(der) # Fail!

# Working equivalent
include OpenSSL::ASN1
degenerate = Sequence.new([  
  OpenSSL::ASN1::ObjectId.new('1.2.840.113549.1.7.2'),
  ASN1Data.new([
    Sequence.new([
      OpenSSL::ASN1::Integer.new(1),
      OpenSSL::ASN1::Set.new([
      ]),
      Sequence.new([
        OpenSSL::ASN1::ObjectId.new('1.2.840.113549.1.7.1')
      ]),
      ASN1Data.new([
        decode(cert.to_der),   # OpenSSL::PKCS7.certificates[0]
        decode(cert.to_der),   # OpenSSL::PKCS7.certificates[1],
        # ...
        decode(cert.to_der)    # OpenSSL::PKCS7.certificates[n-1]
      ], 0, :CONTEXT_SPECIFIC),
      
      
      ASN1Data.new([
      ], 1, :CONTEXT_SPECIFIC),
      OpenSSL::ASN1::Set.new([
      ])
    ])
  ], 0, :CONTEXT_SPECIFIC)
])

der = degenerate.to_der

decoded_p7certs = OpenSSL::PKCS7.new(der)
puts decoded_p7certs.certificates

Note: it seems like OpenSSL::PKCS7.new(der) line has issues, I think with OSX enrollment. I think you'll need to manually build the entire pkcs7 wrapper as shown in this code here