> derek@cs.wisc.edu (Derek Zahn) > >* in broad terms, what would I have to do to develop an > > algorithm that works from a user's perspective like > > p.k.c. (ie public/private keys, the central functional > > point of all the wonderful schemes based on pkc) but > > doesn't violate patents? L. Detweiler writes: > others have well addressed how patent issues are involved in this. b ut > this appears to be a simple technical question on one level. What do es > it take to come up with a good public key system? How about a poor public key system? What is the simplest public key system you can invent, if you didn't care that it is trivial to break? If the NSA can crack RSA, does that change the fact that it is a pkc? message=99 public_key= 1/3 private_key= 3 encrypted_message= message * public_key message= encrypted_message * private_key Would PKP reading of their patent claims cover this pkc? Seems overbr oad! No, because of the language in the patent which requires that it be infeasible to find the deciphering key from the enciphering key. Here's the claim, from patent 4218582, that covers all of public key cryptography: 1. In a method of communicating securely over an insecure communication channel of the type which communicates a message from a transmitter to a receiver, the improvement characterized by: providing random numbers at the receiver; generating from said random numbers a public enciphering key at the receiver; generating from said random numbers a secret deciphering key at the receiver such that the secret deciphering key is directly related to and computationally infeasible to generate from the public enciphering key; communicating the public enciphering key from the receiver to the transmitter; processing the message and the public enciphering key at the transmitter and generating an enciphered message by an enciphering transformation, such that the enciphering transformation is easy to effect but computationally infeasible to invert without the secret deciphering key; transmitting the enciphered message from the transmitter to the receiver; and processing the enciphered message and the secret deciphering key at the receiver to transform the enciphered message with the secret deciphering key to generate the message.