expand_hexstring

# File ext/openssl/lib/openssl/x509.rb, line 97
        def expand_hexstring(str)
          return nil unless str
          der = str.gsub(HexPair){$&.to_i(16).chr }
          a1 = OpenSSL::ASN1.decode(der)
          return a1.value, a1.tag
        end