System and method of securely distributing keys for peer-to-peer usage
First Claim
1. A method of securely distributing keys to a plurality of mobile devices, wherein each of the plurality of mobile devices has a PIN associated therewith, the method comprising the steps of:
- a) defining a security parameter d associated with the plurality of mobile devices;
b) defining a function f of at most degree d associated with the plurality of mobile devices, the function f comprising a first variable x and a second variable y, wherein f(x,y)=f(y,x) over a finite field Fq of order q;
c) for a first mobile device of the plurality of mobile devices, evaluating f with one of x and y having the value of the PIN thereof to compute a first device-specific function f1; and
d) for a second mobile device of the plurality of mobile devices, evaluating f with one of x and y having the value of the PIN thereof to compute a second device-specific function f2;
wherein, in operation, at least one message is encrypted, using a shared key computed at the first mobile device by evaluating f1 with the other of x and y having the value of the PIN of the second mobile device, and is transmitted from the first mobile device to the second mobile device, the at least one message capable of being decrypted using a shared key computable at the second device by evaluating f2 with the other of x and y having the value of the PIN of the first mobile device.
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Abstract
A system and method for generating keys that can be used for encrypting and decrypting PIN messages transmitted between mobile devices. In one embodiment, the method comprises defining a function f, where f(x,y)=f(y,x), and for each of first and second mobile devices, evaluating f with one of x and y having the value of the PIN of the respective mobile device. Each one of the first and second mobile devices can then compute a shared messaging key by evaluating f with the other of x and y having the value of the PIN of the other mobile device. The shared key can then be used specifically to encrypt and decrypt PIN messages transmitted between those two mobile devices.
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Citations
13 Claims
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1. A method of securely distributing keys to a plurality of mobile devices, wherein each of the plurality of mobile devices has a PIN associated therewith, the method comprising the steps of:
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a) defining a security parameter d associated with the plurality of mobile devices;
b) defining a function f of at most degree d associated with the plurality of mobile devices, the function f comprising a first variable x and a second variable y, wherein f(x,y)=f(y,x) over a finite field Fq of order q;
c) for a first mobile device of the plurality of mobile devices, evaluating f with one of x and y having the value of the PIN thereof to compute a first device-specific function f1; and
d) for a second mobile device of the plurality of mobile devices, evaluating f with one of x and y having the value of the PIN thereof to compute a second device-specific function f2;
wherein, in operation, at least one message is encrypted, using a shared key computed at the first mobile device by evaluating f1 with the other of x and y having the value of the PIN of the second mobile device, and is transmitted from the first mobile device to the second mobile device, the at least one message capable of being decrypted using a shared key computable at the second device by evaluating f2 with the other of x and y having the value of the PIN of the first mobile device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for securely distributing keys to a plurality of mobile devices comprising:
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a plurality of mobile devices comprising at least first and second mobile devices, each of the plurality of mobile devices having a PIN associated therewith;
wherein at least the first and second mobile devices are communicatively coupled such that a message can be transmitted at least from the first mobile device to the second mobile device;
wherein a security parameter d associated with the plurality of mobile devices and a function f of at most degree d associated with the plurality of mobile devices are defined, the function f comprising a first variable x and a second variable y, wherein f(x,y)=f(y,x) over a finite field Fq of order q;
wherein for a first mobile device of the plurality of mobile devices, f is evaluated with one of x and y having the value of the PIN thereof to compute a first device-specific function f1; and
wherein for a second mobile device of the plurality of mobile devices, f is evaluated with one of x and y having the value of the PIN thereof to compute a second device-specific function f2;
wherein the first mobile device is adapted to encrypt at least one message using a shared key computed at the first mobile device by evaluating f1 with the other of x and y having the value of the PIN of the second mobile device, and to transmit the at least one message from the first mobile device to the second mobile device; and
wherein the second mobile device is adapted to receive the at least one message and decrypt the at least one message using a shared key computable at the second device by evaluating f2 with the other of x and y having the value of the PIN of the first mobile device. - View Dependent Claims (12, 13)
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Specification