1. A secret key encryption and restoration device, comprising:a communication module;

a memory that stores a secret key encryption and restoration program; and

a processor that executes the program,

wherein when a request for restoration of a secret key is received from a user, the processor restores the secret key of which restoration is requested on the basis of restoration information received from each of a key management server and one or more trusted devices according to execution of the program,

the secret key of the user is generated and encrypted by the processor in response to the request from the user, and

the restoration information is generated corresponding to the secret key and then transmitted to each of the key management server and the one or more trusted devices through the communication module,

wherein the restoration information includes one or more restoration coordinate information and parameters generated on the basis of the secret key, and

the processor transmits the one or more restoration coordinate information to the trusted devices and transmits the parameters to the key management server,

wherein a number of the trusted devices is equal to or higher than a minimum number of the one or more restoration coordinate information,

wherein the parameters include a prime number (p) used in a restoration coordinate generation process, a number (n) of coordinates (x, f(x)) for restoration, a number (k) of the trusted devices, and a coefficient (i) that has the same value as the secret key in a secret key restoration polynomial, and the one or more restoration coordinate information are k number of coordinates (x, f?(x), m) selected among n number coordinates and defined by the equation below:

(x0,f?(x0),m0),(x1,f?(x1),m1), . . . ,(xk?1,f?(xk?1),mk?1),

wherein (m) is a quotient added to each of the coordinates for restoration, and

f?(x) is derived from the equation f?(x)=f(x)(mod p).