Needham-Schroeder

The term Needham–Schroeder protocol can refer to one of the two key transport protocols intended for use over an insecure network, both proposed by Roger Needham and Michael Schroeder. These are:

Here, Alice (A) initiates the communication to Bob (B). S is a server trusted by both parties. In the communication:

The protocol can be specified as follows in :

${\displaystyle A\rightarrow S:\left.A,B,N_{A}\right.}$

${\displaystyle S\rightarrow A:\{N_{A},K_{AB},B,\{K_{AB},A\}_{K_{BS}}\}_{K_{AS}}}$

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