Cryptographic protocol for secure communications

Details Cryptographic protocol for secure communications Cryptographic protocol for secure communications

1991-10-02

1993-08-31

Cain, David

Cryptography

Particular algorithmic function encoding

Nbs/des algorithm

380 30, 380 44, 380 28, H04L 900

Patent

active

052415996

ABSTRACT:
A cryptographic communication system. The system, which employs a novel combination of public and private key cryptography, allows two parties, who share only a relatively insecure password, to bootstrap a computationally secure cryptographic system over an insecure network. The system is secure against active and passive attacks, and has the property that the password is protected against offline "dictionary" attacks. If Alice and Bob are two parties who share the password P one embodiment of the system involves the following steps: (1) Alice generates a random public key E, encrypts it with P and sends P(E) to Bob; (2) Bob decrypts to get E, encrypts a random secret key R with E and sends E(R) to Alice; (3) Alice decrypts to get R, generates a random challenge C.sub.A and sends R(C.sub.A) to Bob; (4) Bob decrypts to get C.sub.A, generates a random challenge C.sub.B and sends R(C.sub.A, C.sub.B) to Alice; (5) Alice decrypts to get (C.sub.A, C.sub.B), compares the first against the challenge and sends R(C.sub.B) to Bob if they are equal; (6) Bob decrypts and compares with the earlier challenge; and (7) Alice and Bob can use R as a shared secret key to protect the session.

REFERENCES:
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