A clear text security method has a table of secure prompts stored in memory of a transaction terminal, such as memory of a PIN entry device, that is connected to a remote device. A data entry prompt in a display command is received by the transaction terminal followed by a command for entry of data into the transaction terminal to be transmitted as clear text data. Before accepting the data entry command, the transaction terminal compares the data entry prompt to prompts stored in a table of secured prompts. The transaction terminal accepts the data entry command only if the prompt included in the most recent display command received by the transaction terminal is a secure prompt. The transaction terminal determines that the data entry prompt is a secure prompt if it matches a prompt in the secure prompt table, matches only a portion of any secure prompt in the secure prompt table, or a any prompt in the secure prompt table matches only a portion of the data entry prompt.