04200770 is referenced by 891 patents.

A cryptographic system transmits a computationally secure cryptogram over an insecure communication channel without prearrangement of a cipher key. A secure cipher key is generated by the conversers from transformations of exchanged transformed signals. The conversers each possess a secret signal and exchange an initial transformation of the secret signal with the other converser. The received transformation of the other converser's secret signal is again transformed with the receiving converser's secret signal to generate a secure cipher key. The transformations use non-secret operations that are easily performed but extremely difficult to invert. It is infeasible for an eavesdropper to invert the initial transformation to obtain either conversers' secret signal, or duplicate the latter transformation to obtain the secure cipher key.

Title
Cryptographic apparatus and method
Application Number
5/830754
Publication Number
4200770
Application Date
September 6, 1977
Publication Date
April 29, 1980
Inventor
Ralph C Merkle
Palo Alto
CA, US
Bailey W Diffie
Berkeley
CA, US
Martin E Hellman
Stanford
CA, US
Agent
Flehr Hohbach Test
Assignee
Stanford University
CA, US
IPC
H04L 9/04
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