System and methods for entropy and statistical quality metrics in physical unclonable function generated bitstrings

Patent metadata

Field	Value
Publication number	US-11095461-B2
Application number	US-201716346772-A
Country	US
Kind code	B2
Filing date	Nov 3, 2017
Priority date	Nov 4, 2016
Publication date	Aug 17, 2021
Grant date	Aug 17, 2021

Abstract

The Distribution Effect is proposed for the HELP PUF that is based on purposely introducing biases in the mean and range parameters of path delay distributions to enhance entropy. The biased distributions are then used in the bitstring construction process to introduce differences in the bit values associated with path delays that would normally remain fixed. Offsets are computed to fine tune a token's digitized path delays as a means of maximizing entropy and reproducibility in the generated bitstrings: a first population-based offset method computes median values using data from multiple tokens (i.e., the population) and a second chip-specific technique is proposed which fine tunes path delays using enrollment data from the authenticating token.

First claim

The invention claimed is:

1. A Physically Unclonable Function (PUF)-based authentication method between a hardware token and verifier, comprising the steps:
storing, by the verifier, a set of path delays from a plurality of tokens in a secure database;
selecting, by the verifier, from the set a distribution of path delays;
computing, by the verifier, a median value of each path delay;
storing, by the verifier, the median value of each path delay in a set of median values;
selecting, by the verifier, a Modulus operation that computes a difference between each median path delay and a specified constant;
computing, by the verifier, the difference between each mean path delay and the specified constant to provide offset values;
encoding, by the verifier, the offset values;
sending, by the verifier, to the token the encoded offset values;
adding, by the verifier, the offset values to the path delays to shift the distribution of path delays; and
generating, by the verifier, a bitstring from the path delays, wherein a value of each bit of the bitstring depends on the shifted distribution.

2. The PUF-based authentication method according to claim 1 , wherein the enrollment phase occurs before the token is released for field use.

3. The PUF-based authentication method according to claim 1 , wherein the shifted distributions of the path delays maximizes entropy of each generated bit.

Assignees

• Stc Unm

Inventors

• Plusquellic James
• Che Wenjie

Classifications

• H04L9/3278 Primary

  using physically unclonable functions [PUF] · CPC title

• G06F17/10 Primary

  Complex mathematical operations {(function generation by table look-up G06F1/03; evaluation of elementary functions by calculation G06F7/544)} · CPC title

• G06F7/58

  Random or pseudo-random number generators · CPC title

• G09C1/00 Primary

  Apparatus or methods whereby a given sequence of signs, e.g. an intelligible text, is transformed into an unintelligible sequence of signs by transposing the signs or groups of signs or by replacing them by others according to a predetermined system (cryptographic typewriters G09C3/00) · CPC title

• G06F21/44

  Program or device authentication · CPC title