I still disagree. Even if all the crypto operations were done in the dongle, it wouldn't be a "turnkey" device that could operate totally
Maybe not "totally" (there are no absolutes) but if well designed, it could come VERY close.
automatically. You'd still need a way for your host computer to turn it off and on, to select a public key for encryption or signature ... ... I.e., you'd have to run special driver software on the host anyway.
The way I envision it, the host must NOT have the ability to turn it on or off or do any of the other things you mentioned. The assumption is that you DON't trust the host. All these commands to the dongle will be given through the keypad and/or commands you type in from the terminal. So if the host does not even need to know the dongle exists, it is automatically independent of what type of computer, operating system, communications program or terminal you are using.
process. If I want to decrypt a file, I'd send the dongle the IDEA (or DES) key that had been encrypted with my public key. Once the dongle responds with the decrypted IDEA key, I can perform the actual IDEA decryption on my host computer with no further dongle interaction.
Again, you are trusting the host. What if the decryption program on the host has been modified to quietly write the plaintext to a hidden file.
speed, not the speed of the port that's talking to the dongle.
Once the host decrypts the file (at a high speed, as you say), you want to view the file, right? That means the plaintext is transmitted from the host to you. Anywhere in the link (which could be a simple RS-232 connection, or a chain of network links, modem connections, etc., someone may be watching. With my design, the decryption takes place at the very last step, just before showing up on your screen.
A palmtop ... would make a good platform for a prototype dongle. Most have serial ports (standard or optional)
I have thought of that too. I would need one with two serial ports though. If you know of a good, cheap (can something have these two properties simultaneously? :-) notebook computer with (option of?) two serial ports, please let me know.
Since it is a sensitive step, RSA key generation could also be done on the palmtop (although it would probably take hours) or it could be
Since that is not something you do every day, I think you can tolerate it taking a while. How long it takes also depends on how much security you want (i.e. key length)
main reason for using the dongle is to limit the trust you have to place in a borrowed PC (as opposed to protecting against your own home
That is just one of the reasons. The others are convenience, lack of trust in the host or the network, use of a terminal (which can't run any software locally), use of various computers/terminals (at home, at work, any other place you happen to be) use of an environment for which no PGP implementation exists or on which you do not have the access to install any software, and I'm sure you (any of you) can think of other reasons if you take some time. -- Yanek Martinson mthvax.cs.miami.edu!safe0!yanek uunet!medexam!yanek this address preferred -->> yanek@novavax.nova.edu <<-- this address preferred Phone (305) 765-6300 daytime FAX: (305) 765-6708 1321 N 65 Way/Hollywood (305) 963-1931 evenings (305) 981-9812 Florida, 33024-5819