Phoenix Technologies Ltd.

Integrity Sciences, Inc.

David P Jablon

Systems, methods and software that enable multiple servers to verify a password, without providing any single server, client or network attacker with the ability to validate guesses for the password off-line is disclosed. Password security is maintained in a very simple model, requiring no previously secured or server-authenticated channel between the client and any servers. Data may be protected by a small password, and no other keys, remains secret even against an enemy that compromises any, but not all, of two or more cooperating authenticating servers.

Systems, methods and software for remote password authentication using multiple servers

Methods are described for two parties to use a small shared secret (S) to mutually authenticate one another other over an insecure network. The methods are secure against off-line dictionary attack and incorporate an otherwise unauthenticated public key distribution system. One embodiment uses two computers Alice and Bob, and a Diffie-Hellman exponential key exchange in a large prime-order finite group. Both parties choose the same generator of the group (g) as a function of S. Alice chooses a random number R, and sends gto Bob. Bob chooses a random R, sends gto Alice. Both compute a shared key K=g. Each party insures that K is a generator of the group, verifies that the other knows K, and then uses K as an authenticated key. Constraints are described to prevent passive and active attacks. An extension is described where Alice proves knowledge of S to Bob who knows only a one-way transformation of S. These methods establish a secure, authenticated network session using only an easily memorized password.

Cryptographic methods for remote authentication

Methods are described for two parties to use a small shared secret (S) to mutually authenticate one another other over an insecure network. The methods are secure against off-line dictionary attack and incorporate an otherwise unauthenticated public key distribution system. One embodiment uses two computers Alice and Bob, and a Diffie-Hellman exponential key exchange in a large prime-order finite group. Both parties choose the same generator of the group (g) as a function of S. Alice chooses a random number R , and sends g to Bob. Bob chooses a random R , sends g to Alice. Both compute a shared key K&equals;g . Each party insures that K is a generator of the group, verifies that the other knows K, and then uses K as an authenticated key. Constraints are described to prevent passive and active attacks. An extension is described where Alice proves knowledge of S to Bob who knows only a one-way transformation of S. These methods establish a secure, authenticated network session using only an easily memorized password.

Methods are described for two parties to use a small shared secret (S) to mutually authenticate one another other over an insecure network. The methods are secure against off-line dictionary attack and incorporate an otherwise unauthenticated public key distribution system. One embodiment uses two computers Alice and Bob, and a Diffie-Hellman exponential key exchange in a large prime-order finite group. Both parties choose the same generator of the group (g) as a function of S. Alice chooses a random number R,, and sends g,to Bob. Bob chooses a random R,, sends g,to Alice. Both compute a shared key K&equals;g,. Each party insures that K is a generator of the group, verifies that the other knows K, and then uses K as an authenticated key. Constraints are described to prevent passive and active attacks. An extension is described where Alice proves knowledge of S to Bob who knows only a one-way transformation of S. These methods establish a secure, authenticated network session using only an easily memorized password.

Growing community of inventors

Westboro, MA, United States of America

David P Jablon