Patent ID: 8607341

Claim:
A method for preserving security of sensor data in a ubiquitous sensor network based on a time key, comprising automated computer-implemented steps of: encrypting the sensor data with an encryption key obtained using a time key based polynomial derived using random numbers and a secret key which is shared by a sensor node and an application system; sending the time key and the encrypted sensor data from the sensor node to a sink node, which does not have access to the secret key; sending the encrypted sensor data and the time key, via the sink node, to the application system; and decrypting the encrypted sensor data with a decryption key obtained by deriving the same polynomial as the time key based polynomial using the random numbers and the secret key, wherein the deriving of the time key based polynomial comprises: calculating two coordinates (p x , p y ) and (q x , q y ) which are roots of the following quadratic polynomial using the application random number p and the sink random number q; and deriving the following equation using the two coordinates and the secret key shared by the sensor node and the application, y=|ax 2 +bx+C| where y, which is an output value for a time key input, is the material value used to generate the encryption key, a and b are coefficients of the quadratic polynomial, x is a certain time key value, C is the secret key value as a constant value of the quadratic polynomial, and |x| denotes an absolute value of x.