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Biometric subject verification based on electrocardiographic signals

  • US 8,924,736 B1
  • Filed: 03/11/2013
  • Issued: 12/30/2014
  • Est. Priority Date: 03/11/2013
  • Status: Active Grant
First Claim
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1. A method of authenticating or declining to authenticate an asserted identity of a candidate person (c-p), the method comprising:

  • (i) initializing a count index c (c(initial)=0);

    (ii) providing or receiving a sequence of N reference heart electrical action cycles, numbered n=1, . . . , N, of a known reference person, and forming a graph v(t;

    n) representing each provided heart cycle for the reference person;

    (iii) randomly choosing K heart cycle graphs, numbered k=1, 2, . . . , K (3≦

    K≦

    N) of the provided reference heart cycles, comparing each chosen heart cycle graph v(t;

    k) with each of the other chosen heart cycle graphs, and identifying a pair of graphs, v(t;

    k1) and v(t;

    k2), for which ρ

    1(k1;

    k2) is a maximum value, where ρ

    1 is a first numerical-valued, graph comparison metric that compares two heart cycle graphs, v(t;

    k′

    ) and v(t;

    k″

    ), and provides a first numerical metric value ρ

    1(k′

    ;

    k″

    ) that is a measure of how closely the two graphs resemble each other;

    (iv) forming a composite heart cycle graph, denoted v(t;

    k12), using graph values associated with the graphs v(t;

    k1) and v(t;

    k2);

    (v) determining when at least a first selected fraction f1 (0.5≦

    f1<

    1) of the N heart cycle graphs resemble the composite graph, according to a first condition ρ

    1(k12;

    n)−

    (thr1)=D1, with D1 being always non-negative or always non-positive, where (thr1) is a selected first metric threshold value;

    (vi) when at least the selected fraction f1 of the N heart cycle graphs resemble each other according to the first condition, creating or providing a reference heart cycle graph v(t;

    ref)=v(t;

    k12);

    for the reference person;

    (vii) when at least the fraction f1 of the N heart cycle graphs do not resemble each other, incrementing the count index (c→

    c+1) to provide an incremented count index;

    (viii) when the incremented count index c is not greater than a selected maximum index value c(max), returning to step (iii) and repeating steps (iii)-(viii) at least once; and

    (ix) when the incremented count index satisfies c>

    c(max), interpreting this condition as indicating that it is not possible to create a reference heart cycle graph for the reference person.

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