# File lib/net/ssh/key_factory.rb, line 50
      def load_data_private_key(data, passphrase=nil, ask_passphrase=true, filename="")
        if OpenSSL::PKey.respond_to?(:read)
          pkey_read = true
          error_class = ArgumentError
        else
          pkey_read = false
          if data.match(/-----BEGIN DSA PRIVATE KEY-----/)
            key_type = OpenSSL::PKey::DSA
            error_class = OpenSSL::PKey::DSAError
          elsif data.match(/-----BEGIN RSA PRIVATE KEY-----/)
            key_type = OpenSSL::PKey::RSA
            error_class = OpenSSL::PKey::RSAError
          elsif data.match(/-----BEGIN EC PRIVATE KEY-----/) && defined?(OpenSSL::PKey::EC)
            key_type = OpenSSL::PKey::EC
            error_class = OpenSSL::PKey::ECError
          elsif data.match(/-----BEGIN (.+) PRIVATE KEY-----/)
            raise OpenSSL::PKey::PKeyError, "not a supported key type '#{$1}'"
          else
            raise OpenSSL::PKey::PKeyError, "not a private key (#{filename})"
          end
        end

        encrypted_key = data.match(/ENCRYPTED/)
        tries = 0

        begin
          if pkey_read
            return OpenSSL::PKey.read(data, passphrase || 'invalid')
          else
            return key_type.new(data, passphrase || 'invalid')
          end
        rescue error_class
          if encrypted_key && ask_passphrase
            tries += 1
            if tries <= 3
              passphrase = prompt("Enter passphrase for #{filename}:", false)
              retry
            else
              raise
            end
          else
            raise
          end
        end
      end