Sidebar: About the SecureNet Key

The SecureNet Key (SNK) is a challenge/response personal identification token that resembles a small, pocket-size calculator. The SNK was originally designed for use with Digital Pathway's line of SecureNet access control devices, but it is now available as a separate product.

The SNK has an electronic chip that implements a public key cryptographic algorithm using DES as the encryption scheme. (Public-key cryptography was invented in 1976 by Whitfield Diffie and Martin Hellman [1] in order to solve the problem of key management.) Each participant gets a pair of keys, the public key and the private key. Each participant's public key is published while the private key is kept secret. The need for sender and receiver to share secret information is eliminated: all communications involve only public keys, and no private key is ever transmitted or shared.

Before the SNK can be used, the system administrator must prime the SNK with the public key. The public key is a 24-bit random number unique for each and every SNK. After the SNK has been primed with the public key, it is handed over to the user, who then finishes the programming of the SNK by entering the private key -- a four-digit personal identification number (PIN). The SNK cannot be used until this step has been completed. Once it is primed and ready, only the user to whom the SNK was issued can unlock the device for use, by using the PIN.

In use, the computer will calculate a challenge string based upon the public key. The calculated challenges are always unique. The user will "open" the SNK using the PIN and enter the challenge number. The SNK will use the challenge number and public key to calculate a response string. The computer also uses the challenge number and public key to calculate its expected response. If the response that the user enters to the challenge string matches the response calculated by the computer, the computer allows access.

For information on the SNK, contact

Digital Pathways Inc. 201 Ravendale Drive Mountain View, CA USA

Digital Pathways Inc. 5 Campbell Court Campbell Rd Bramley, Basingstoke Hants RG265EG (44)256-882191

References

W. Diffie and M.E. Hellman. New directions in cryptography. IEEE Transactions on Information Theory, IT-22:644-654, 1976.