A repeatable cryptographic key is generated based on varying parameters which
represent
physical measurements. Locations within a share table, which locations store valid
and invalid cryptographic shares, are identified as a function of received varying
parameters. The share table is configured such that locations which are expected
to be identified by legitimate access attempts contain valid cryptographic shares,
and locations which are not expected to be identified by legitimate access attempts
contain invalid cryptographic shares. The share table configuration may be modified
based on prior history of legitimate access attempts. In various embodiments, the
stored shares may be encrypted or compressed. A keystroke feature authentication
embodiment uses the inventive techniques to implement an authentication system
which authenticates based on an entered password and the manner in which (e.g.
keystroke dynamics) the keystroke is entered. Another embodiment uses the inventive
techniques to protect sensitive database information which is accessible using
DNA measurements.
