How to decode CSR (PKCS #10) using Ruby

Question

I have the file:

-----BEGIN NEW CERTIFICATE REQUEST-----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-----END NEW CERTIFICATE REQUEST-----

How can I decode it in Ruby to obtain the following information that is part of the request subject?

Common name: www.somedomain.com
Organization:someorg.com
Organizational unit:someunit.com
City/locality:bj
State/province:bj
Country:CN

Luckily, Ruby comes with an [`OpenSSL`](http://ruby-doc.org/stdlib-2.4.2/libdoc/openssl/rdoc/OpenSSL.html) module which wraps the [OpenSSL](https://www.openssl.org/) library. — Stefan, Dec 11 '17 at 08:30
RubyOpenSSL can [generate](https://github.com/ruby/openssl/blob/4eda40878fc42ac5bad6dd7b1ebc8f0eac796b94/sample/gen_csr.rb) CSR, but there is no decoding method there. — Igor Polyakov, Dec 11 '17 at 09:08
Thank you very much! This solved my problem. P.S. `OpenSSL::X509::Request.new(File.open("/my/file.csr").read)` — Igor Polyakov, Dec 11 '17 at 09:27
That will leave you with an open file handle, use `File.read('/my/file.csr')` instead. — Stefan, Dec 11 '17 at 09:47
And feel free to provide an answer to your question (it's okay to answer your own question). I'd like to know how you managed to extract the information. — Stefan, Dec 11 '17 at 09:55

score 2 · Accepted Answer · answered Dec 11 '17 at 11:00

  def parse_csr(file_path)
    csr = OpenSSL::X509::Request.new(File.read(file_path))
    # puts csr.subject.to_a
    # => [["C", "RU", 19], ["ST", "State", 12], ["L", "City", 12], ["O", "CompanyName", 12], ["OU", "Unit", 12], ["CN", "App 1.0", 12], ["emailAddress", "user@company.com", 22]]
    csr.subject.to_a.inject({}) do |r, s|
      r.merge!(s[0] => s[1])
    end
  end

Output:

=> {"C"=>"RU", "ST"=>"State", "L"=>"City", "O"=>"Company Name", "OU"=>"Unit", "CN"=>"App v1.0", "emailAddress"=>"user@company.com"}

Slightly shorter: `subject.to_a.each(&:pop).to_h` – Stefan Dec 11 '17 at 12:32 — Stefan, Dec 11 '17 at 12:32

How to decode CSR (PKCS #10) using Ruby

1 Answers1