Method and apparatus for multi-distant weighted scoring system
View Patent ↗Methods of comparing a plurality of measurements to a template are described. Measurements are compared piecewise (element-by-element) and a proportion of successful comparisons at each of a plurality of distance scaling factors is calculated. The proportions are subjected to a nonlinear transformation, then normalized and combined into a weighted sum. The weighted sum is compared with a threshold value to establish the result of the comparison. Software and systems to implement embodiments of the invention are also described and claimed.
1. A method comprising:
collecting a vector S of n measurements of a characteristic of a user input on an input device;
computing a vector P as
P
j
=
∑
i
=
1
n
{
1
if
T
i
-
S
i
<
d
j
·
V
i
0
otherwise
n
wherein T is a vector of n template values, V is a corresponding vector of n variability values and d is a vector of m distance scaling factors;
computing a vector F as
F
j
=
-
1
d
j
log
(
1
-
P
j
)
computing a vector D as
D j =A·F j +B
wherein A and B are constants;
computing a scalar W as
W
=
∑
j
=
1
m
WF
j
·
D
j
∑
j
=
1
m
WF
j
wherein WF is a vector of m weight factors; and
comparing the scalar W to a predetermined value to authenticate the user of the input device.
2. The method of claim 1 wherein m is 6.
3. The method of claim 1 wherein A is 1 and B is 0.
4. The method of claim 1 wherein d is {0.5, 1.0, 1.5, 1.7, 1.9, 2.0}.
5. The method of claim 1 wherein WF is {0.1, 0.1, 0.2, 0.25, 0.3, 0.05}.
6. The method of claim 1 wherein
∑
i
=
1
m
WF
i
=
1.
7. The method of claim 1 wherein the input device is coupled to a computer system and comparing the scalar W to a predetermined value authorizes the user to access the computer system.
8. The method of claim 7 wherein authorizing the user to access the computer system comprises identifying the user if the scalar W exceeds the predetermined value, and distinguishing the user as an imposter if the scalar W does not exceed the predetermined value.
9. A method comprising:
collecting a plurality of measurements of a user input on an input device;
computing a proportion of the plurality of measurements that fall within a scaled range of a corresponding plurality of template measurements for a plurality of scale values;
applying a nonlinear transformation to each of the proportions;
normalizing the transformed proportions;
calculating a weighted sum of the normalized, transformed proportions; and
comparing the weighted sum to a threshold value to authenticate the user of the input device.
10. The method of claim 9 wherein the plurality of measurements includes a plurality of keystroke timing values.
11. The method of claim 9 wherein the nonlinear transformation is a logarithmic transformation.
12. The method of claim 9 wherein normalizing comprises converting the transformed proportions to truncated linear scale.
13. The method of claim 9 , further comprising:
granting access to a resource if the weighted sum exceeds the threshold value.
14. A machine-readable medium containing instructions to cause a programmable logic device to perform operations comprising:
collecting a plurality of sample measurements of a user input on an input device;
thresholding the sample measurements against a corresponding plurality of template measurements at a plurality of scales;
computing a proportion of successful measurements at each of the plurality of scales;
applying a nonlinear transformation to the plurality of proportions;
normalizing the transformed proportions;
calculating a weighted sum of the normalized, transformed proportions; and
comparing the weighted sum to a predetermined value to authenticate the user of the input device.
15. The machine-readable medium of claim 14 , containing additional instructions to cause the programmable logic device to perform further operations, including:
measuring at least one of a duration of a key press, a time between a key press and a subsequent key release, a time between a first key press and a second key press, or a pressure of a key press.
16. The machine-readable medium of claim 14 wherein thresholding comprises:
comparing a sample measurement against a template measurement to determine whether the sample measurement lies within a scaled variability range of the template measurement.
17. The machine-readable medium of claim 14 wherein the nonlinear transformation is a logarithmic transformation.
18. The machine-readable medium of claim 14 , containing additional instructions to cause the programmable logic device to perform further operations, including:
granting access to a resource if the weighted sum exceeds the predetermined value.
19. The machine-readable medium of claim 14 wherein the plurality of scales comprises scaling factors between about 0.5 and about 2.0.
20. A system comprising:
a user entry device;
sampling logic to collect measurements from the user entry device;
proportion logic to compute a proportion of the measurements that fall within a scaled range of corresponding measurements of a template for a plurality of scale values;
transformation logic to apply a non-linear transformation to each of the proportions;
normalizing logic to normalize the transformed portions;
comparison logic to prepare a weighted sum of normalized, transformed, proportions; and
access control logic to grant access to a resource if the weighted sum exceeds a predetermined value.
21. The system of claim 20 wherein the resource is use of the system.
22. The system of claim 20 , further comprising:
a communication interface to exchange data with a network, wherein
the resource is data to be obtained through the network.