Telcordia Technologies, Inc.

The Cooper Union for the Advancement of Science and Art

Sheldon Walfish

Giovanni Di Crescenzo

Richard J Lipton

John L Bove

Efficient secure password protocols are constructed that remain secure against offline dictionary attacks even when a large, but bounded, part of the storage of a server responsible for password verification is retrieved by an adversary through a remote or local connection. A registration algorithm and a verification algorithm accomplish the goal of defeating a dictionary attack. A password protocol where a server, on input of a login and a password, carefully selects several locations from the password files, properly combines their content according to some special function, and stores the result of this function as a tag that can be associated with this password and used in a verification phase to verify access by users. Two main instantiations of our method are given; in one, a combination of mathematical tools, called dispersers and pairwise-independent hash functions is used to achieve security against adaptive intrusions (dispersers make sure that the password of each user depends on randomly chosen locations in a large password file, and pairwise-independent hash functions help in making this dependency sufficiently random); in a second one, a combination of mathematical tools, called k-wise independent hash functions and locally-computable and strong extractors (k-wise independent hash functions make sure that the locations chosen in the large password file from each password are sufficiently random, and locally-computable and strong extractors are used to combine the contents of these locations to generate a single long random value, which makes verification harder for the adversary to foil).

Method and system for password protocols in the bounded retrieval mode with security dictionary attacks and intrusions

A method of identifying and unknown compound comprises: (a) obtaining an absorption spectrum of the compound; (b) obtaining an absorbance value A(&#x3bd;) wherein Ais the absorption value at a wavenumber &#x3bd;; (c) generating an array of values A'(&#x3bd;&#x2032;) wherein A&#x2032;(&#x3bd;&#x2032;)=A&#x2032;(&#x3bd;&#x2032;)&#x2212;A&#x2033; where A&#x2033; is an absorbance value which is modified from the measured absorbance, such as Awhere Ais the average of A(&#x3bd;); (d) generating an array of values I(&#x3bd;) by integrating A&#x2032;(&#x3bd;&#x2032;) over a region of the spectrum; (e) normalizing the array of values I(&#x3bd;) with values I&#x2032;(&#x3bd;&#x2032;) obtained for a known compound. The system of this invention employs the above-described method in cooperation with a computer capable of receiving the absorption spectrum data and calculating values from the data using algorithms provided to the computer. The method and system of this invention may be used to identify unknown compounds for quality control, process control and other purposes.

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Sheldon Walfish