Encrypting a conversation

The capability to create and maintain customized code page mappings in the TinyTERM Emulator allows the ultimate in flexibility. Consider the case of two UNIX users who feel their e-mail or on-line talk conversations are being monitored by someone who should not have access to their information.

These users could encrypt their e-mail and on-line conversations by creating two custom code page maps using the TinyTERM Emulator. For the purpose of this example, we will call these custom code pages foo and bar. Both code pages would include all of the characters in code page 437, but in a different order. For instance, the letter A, which has the value 65 in code page 437, might be given the value 227 in code page foo, and the value 143 in code page bar.

Now the first user would login to the UNIX system as normal, and establish the conversation with the second user using the talk utility. Once both users are ready to encrypt their conversation, the first user would switch his transmit code page to foo and receive code page to bar. The second user would configure the TinyTERM Emulator in the opposite manner, setting the transmit code page to bar and the receive code page to foo. From that point on, their conversation would appear to be gibberish to any observer that did not have access to the code page maps being used to encrypt the conversation.

Encrypting mail messages

The same two users could encrypt mail messages in a similar manner. Each would start his or her mail program with the TinyTERM Emulator configured normally, and then switch the code pages to the above settings to read or edit mail messages.

The translations performed in this simple encryption scheme are illustrated in Figure 4:

Figure 4. Encrypting a conversation with code page mapping