Extract and test PKCS7 signature

lib/rubrik.rb

@@ -12,4 +12,5 @@ class Error < StandardError; end
 require_relative "rubrik/document/increment"
 require_relative "rubrik/document/serialize_object"
 require_relative "rubrik/fill_signature"
+require_relative "rubrik/pkcs7_signature"
 require_relative "rubrik/sign"

lib/rubrik/fill_signature.rb

@@ -1,8 +1,6 @@
 # typed: true
 # frozen_string_literal: true
 
-require "openssl"
-
 module Rubrik
   module FillSignature
     extend T::Sig
@@ -55,8 +53,7 @@ def call(io, signature_value_ref:, private_key:, public_key:, certificate_chain:
       io.pos = second_offset
       data_to_sign += T.must(io.read(second_length))
 
-      signature = OpenSSL::PKCS7.sign(public_key, private_key, data_to_sign, certificate_chain,
-                                      OpenSSL::PKCS7::DETACHED | OpenSSL::PKCS7::BINARY).to_der
+      signature = PKCS7Signature.call(data_to_sign, private_key:, certificate: public_key)
       hex_signature = T.let(signature, String).unpack1("H*")
 
       padded_contents_field = "<#{hex_signature.ljust(Document::SIGNATURE_SIZE, "0")}>"

lib/rubrik/pkcs7_signature.rb

@@ -0,0 +1,24 @@
+# typed: true
+# frozen_string_literal: true
+
+require "openssl"
+
+module Rubrik
+  module PKCS7Signature
+    extend T::Sig
+    extend self
+
+    OPEN_SSL_FLAGS = OpenSSL::PKCS7::DETACHED | OpenSSL::PKCS7::BINARY
+
+    sig {params(
+        data: String,
+        private_key: OpenSSL::PKey::RSA,
+        certificate: OpenSSL::X509::Certificate,
+        certificate_chain: T::Array[OpenSSL::X509::Certificate]
+      ).returns(String)
+    }
+    def call(data, private_key:, certificate:, certificate_chain: [])
+      OpenSSL::PKCS7.sign(certificate, private_key, data, certificate_chain, OPEN_SSL_FLAGS).to_der
+    end
+  end
+end

test/pkcs7_signature_test.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+# typed: true
+
+require "test_helper"
+
+class Rubrik::PKCS7SignatureTest < Rubrik::Test
+  def test_signature_generation
+    # Arrange
+    certificate_file = File.open("test/support/demo_cert.pem", "rb")
+
+    private_key = OpenSSL::PKey::RSA.new(certificate_file, "")
+    certificate_file.rewind
+    certificate = OpenSSL::X509::Certificate.new(certificate_file)
+
+    # Act
+    raw_result = Rubrik::PKCS7Signature.call("test", private_key:, certificate:)
+
+    # Assert
+    result = OpenSSL::ASN1.decode(raw_result)
+
+    assert_kind_of(OpenSSL::ASN1::Sequence, result)
+
+    content_type = result.value.first
+    assert_equal("pkcs7-signedData", content_type.value)
+
+  ensure
+    certificate_file&.close
+  end
+end