def parse(field)
        case @format
        when :delimited
          field.split(field_delimiter)
        when :json
          parsed = JSON.parse(field)
          [parsed['iv'], parsed['key'], parsed['message']]
        end
      end
def parse(field)
        case @format
        when :delimited
          field.split(field_delimiter)
        when :json
          parsed = JSON.parse(field)
          [parsed['iv'], parsed['key'], parsed['message']]
        end
      end
Extracts the initialization vector, encrypted key, and
 cipher text according to the specified format.

 delimited:
 * Expected format: iv::encrypted-key::ciphertext

 json:
 * Expected keys: iv, key, message