Detect valid or invalid certificate

detect_invalid_certificate.rb

require "openssl"

pem = DATA.read

begin
  OpenSSL::X509::Certificate.new(pem)
  puts "Valid!"
rescue
  puts "Invalid!"
end

pem << "-----END CERTIFICATE-----"

begin
  OpenSSL::X509::Certificate.new(pem)
  puts "Valid!"
rescue
  puts "Invalid!"
end

__END__
-----BEGIN CERTIFICATE-----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