METHOD AND APPARATUS FOR ENABLING PHYSICAL LAYER SECRET KEY GENERATION

• US 20090141900A1
• Filed: 11/06/2008
• Published: 06/04/2009
• Est. Priority Date: 11/06/2007
• Status: Active Grant

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Inventors: Truco, Frederic H., Closs, Julien, Reznik, Alexander, Shah, Yogendra C., Ye, Chunxuan
• Granted Patent: US 9,490,977 B2
• Time in Patent Office: Days
• US Class Current: 380/270
• CPC Class Codes: H04K 1/00 Secret communication
• CPC Class Codes: H04L 2209/80 Wireless network architectures or network communication protocols for wireless network security H04W12/00
• CPC Class Codes: H04L 9/0875 based on channel impulse response [CIR]
• CPC Class Codes: H04W 12/02 Protecting privacy or anonymity, e.g. protecting personally identifiable information [PII]
• CPC Class Codes: H04W 12/04 Key management, e.g. using generic bootstrapping architecture [GBA]
• CPC Class Codes: H04W 12/61 Time-dependent

Abstract

A method and apparatus for generating physical layer security keys is provided. Channel impulse response (CIR) measurements are recorded. Each CIR measurement is associated with a time-stamp. Where possible, the time-stamps are paired with time-stamps that are associated with another plurality of CIR measurements. The CIR data associated with the paired time-stamps is aggregated. Each of the aggregated CIR measurements is aligned, and at least one CIR measurement is selected for use in secret key generation.

Claims

1. A method for generating a physical layer security key, the method comprising:

pairing a first time-stamp associated with a first CIR measurement with a second time-stamp, wherein the first time-stamp is associated with a first CIR measurement in a first plurality of CIR measurements, and the second time-stamp is associated with a second CIR measurement in a second plurality of CIR measurements;

post-processing each CIR measurement of the first plurality of CIR measurements;

selecting at least one sample from the post-processed CIR measurements; and

generating a physical layer secret key from the at least one selected sample.

2. The method of claim 1, wherein each CIR measurement of the first plurality of CIR measurements includes 64 complex samples.

3. The method of claim 1, further comprising:

validating the first plurality of CIR measurements.

4. The method of claim 1 wherein the pairing includes:

determining whether the first time stamp is older than a stopping time; and

deleting the first time stamp and the associated CIR measurement in response to a first time-stamp that is older than a stopping time.

5. The method of claim 1, wherein the post-processing includes:

pruning each CIR measurement of the first plurality of CIR measurements;

upsampling the pruned CIR measurements; and

shifting the upsampled CIR measurements.

6. The method of claim 5, wherein the pruning includes:

for each CIR measurement, selecting a sequential plurality of samples, wherein the selected sequential plurality of samples has a largest magnitude sample in the middle.

7. The method of claim 5, wherein the upsampling includes:

inserting a zero value sample between each sample in each CIR measurement;

constructing a resampling finite impulse response (FIR) filter;

convolving the resampling FIR filter with each CIR measurement; and

selecting a plurality of samples from the middle of the samples in each CIR measurement.

8. The method of claim 1, wherein the selecting includes:

determining a plurality of samples from the post-processed CIR measurements;

whitening the determined plurality of samples; and

sorting the whitened plurality of samples.

9. A wireless transmit/receive unit (WTRU) for generating physical layer security keys, the WTRU comprising:

a channel impulse response (CIR) measurement unit configured to generate a first plurality of CIR measurements, wherein each CIR measurement is associated with a time-stamp;

a time-stamp pairing unit configured to identify a plurality of paired time-stamps, wherein a first time-stamp is associated with a first CIR measurement in the first plurality of CIR measurements, and a second time-stamp is associated with a second CIR measurement in a second plurality of CIR measurements;

a CIR post-processing unit configured to align the first plurality of CIR measurements;

a data selection unit configured to select at least one sample from the post-processed CIR measurements; and

a secret key generation unit configured to generate a physical layer secret key from the at least one selected sample.

10. The WTRU of claim 9, wherein the CIR post-processing unit includes:

a CIR pruning unit configured to reduce the number of samples in each CIR measurement;

a CIR upsampling unit configured to interpolate each pruned CIR measurement to a higher sampling rate;

a first CIR shift unit configured to align each upsampled CIR measurement;

a signal power calculation unit configured to calculate a signal power of each CIR measurement; and

a CIR normalization unit configured to normalize each shifted CIR measurement.

11. The WTRU of claim 9, further comprising:

a second CIR shift unit configured to further align each CIR measurement.

12. A method of generating a list of paired time-stamps, the method comprising:

comparing a first list of time-stamp pairing candidates with a second list of time-stamp pairing candidates;

reporting an acknowledgement (ACK) message including the list of paired time-stamps.

13. The method of claim 12, wherein the comparing includes:

selecting a first time-stamp from a first plurality of time-stamps;

selecting a second time-stamp from a second plurality of time-stamps; and

comparing the first time-stamp and the second time-stamp if the first time-stamp is not an impossible time-stamp value and the second time-stamp is not an impossible time-stamp value;

selecting the next time-stamp in the first plurality of time-stamps as the first time-stamp if the first time-stamp is less than the second time stamp and the difference between the selected time-stamps is greater than a threshold;

selecting the next time-stamp in the second plurality of time-stamps as the second time-stamp if the first time-stamp is greater than or equal to the second time stamp and the difference between the selected time-stamps is greater than a threshold;

marking the selected time-stamps as paired if the difference between the selected time-stamps is less than or equal to a threshold, wherein marking includes selecting the next time-stamp in the first plurality of time-stamps as the first time-stamp, and selecting the next time-stamp in the second plurality of time-stamps; and

iteratively repeating the selecting a first time-stamp, the selecting a second time-stamp, the comparing, the selecting the next time-stamp in the first plurality, the selecting the next time-stamp in the second plurality, and the marking, for each time-stamp in the first plurality of time-stamps, and for each time-stamp in the second plurality of time-stamps.

14. The method of claim 12, wherein the comparing includes:

selecting a first time-stamp from a first plurality of time-stamps;

selecting a second time-stamp from a second plurality of time-stamps; and

comparing the first time-stamp and the second time-stamp if the first time-stamp is not an impossible time-stamp value and the second time-stamp is not an impossible time-stamp value;

selecting the next time-stamp in the first plurality of time-stamps as the first time-stamp if the first time-stamp is less than the second time stamp, the difference between the selected time-stamps is greater than a threshold, and the difference between the selected time-stamps is less than or equal to a time-stamp wrapping point;

selecting the next time-stamp in the second plurality of time-stamps as the second time-stamp if the first time-stamp is less than the second time stamp, the difference between the selected time-stamps is greater than a threshold, the difference between the selected time-stamps is greater than a time-stamp wrapping point, and the difference between the selected time stamps less than or equal to the difference between a maximum time-stamp value and a threshold;

selecting the next time-stamp in the second plurality of time-stamps as the second time-stamp if the first time-stamp is greater than or equal to the second time stamp, the difference between the selected time-stamps is greater than a threshold, and the difference between the selected time-stamps is less than or equal to a time-stamp wrapping point;

selecting the next time-stamp in the first plurality of time-stamps as the first time-stamp if the first time-stamp is greater than or equal to the second time stamp, the difference between the selected time-stamps is greater than a threshold, the difference between the selected time-stamps is greater than a time-stamp wrapping point, and the difference between the selected time stamps less than or equal to the difference between a maximum time-stamp value and a threshold;

marking the selected time-stamps as paired if the difference between the selected time-stamps is less than or equal to a threshold, wherein marking includes selecting the next time-stamp in the first plurality of time-stamps as the first time-stamp, and selecting the next time-stamp in the second plurality of time-stamps; and

marking the selected time-stamps as paired if the difference between the selected time-stamps is greater than a threshold, the difference between the selected time-stamps is greater than a time-stamp wrapping point, and the difference between the selected time stamps less than or equal to the difference between a maximum time-stamp value and a threshold, wherein marking includes selecting the next time-stamp in the first plurality of time-stamps as the first time-stamp, and selecting the next time-stamp in the second plurality of time-stamps; and

iteratively repeating the selecting a first time-stamp, the selecting a second time-stamp, the comparing, the selecting the next time-stamp in the first plurality, the selecting the next time-stamp in the second plurality, and the marking, for each time-stamp in the first plurality of time-stamps, and for each time-stamp in the second plurality of time-stamps.

15. The method of claim 12, wherein the comparing includes:

selecting a first time-stamp from a first plurality of time-stamps;

selecting a second time-stamp from a second plurality of time-stamps; and

comparing the first time-stamp and the second time-stamp if the first time-stamp is not an impossible time-stamp value and the second time-stamp is not an impossible time-stamp value;

selecting the next time-stamp in the first plurality of time-stamps as the first time-stamp if the first time-stamp is less than the second time stamp, the first time-stamp is greater than or equal to a previous time-stamp in the first plurality of time-stamps, the second time-stamp is less than or equal to a previous time stamp in the second plurality of time-stamps, and the difference between the selected time-stamps is greater than a threshold;

selecting the next time-stamp in the second plurality of time-stamps as the second time-stamp if the first time-stamp is less than the second time stamp, the first time-stamp is less than to a previous time-stamp in the first plurality of time-stamps, the second time-stamp is greater than a previous time stamp in the second plurality of time-stamps, the difference between the selected time stamps less than the difference between a maximum time-stamp value and a threshold;

selecting the next time-stamp in the second plurality of time-stamps as the second time-stamp if the first time-stamp is greater than or equal to the second time stamp, the first time-stamp is greater than a previous time-stamp in the first plurality of time-stamps, the second time-stamp is less than a previous time stamp in the second plurality of time-stamps, and the difference between the selected time-stamps is greater than a threshold;

selecting the next time-stamp in the first plurality of time-stamps as the first time-stamp if the first time-stamp is greater than or equal to the second time stamp, the first time-stamp is greater than a previous time-stamp in the first plurality of time-stamps, the second time-stamp is less than a previous time stamp in the second plurality of time-stamps, the difference between the selected time stamps less than the difference between a maximum time-stamp value and a threshold;

marking the selected time-stamps as paired if the first time-stamp is less than the second time stamp, the first time-stamp is greater than or equal to a previous time-stamp in the first plurality of time-stamps, the second time-stamp is less than or equal to a previous time stamp in the second plurality of time-stamps, and the difference between the selected time-stamps is less than or equal to a threshold, wherein marking includes selecting the next time-stamp in the first plurality of time-stamps as the first time-stamp, and selecting the next time-stamp in the second plurality of time-stamps; and

marking the selected time-stamps as paired if the first time-stamp is less than the second time stamp, the first time-stamp is less than to a previous time-stamp in the first plurality of time-stamps, the second time-stamp is greater than a previous time stamp in the second plurality of time-stamps, the difference between the selected time stamps greater than or equal to the difference between a maximum time-stamp value and a threshold, wherein marking includes selecting the next time-stamp in the first plurality of time-stamps as the first time-stamp, and selecting the next time-stamp in the second plurality of time-stamps; and

iteratively repeating the selecting a first time-stamp, the selecting a second time-stamp, the comparing, the selecting the next time-stamp in the first plurality, the selecting the next time-stamp in the second plurality, and the marking, for each time-stamp in the first plurality of time-stamps, and for each time-stamp in the second plurality of time-stamps.