Patent ID: 11937078
Assignee: CRYPTO LAB INC.
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 4:
5. A route overlap detecting method of a mobile device, the method comprising:
calculating and storing location information of the mobile device;
performing homomorphic encryption on a plurality of pieces stored location information and generating movement path information of the mobile device;
transmitting the movement path information to a server apparatus;
based on operation result data obtained by operating based on the movement path information and comparison target path information being received from the server apparatus, decrypting the operation result data;
outputting a message notifying whether a route overlaps the comparison target path information based on a decrypted result; and
wherein the generating the movement path information comprises encoding the plurality of pieces of location information to each element in a plaintext space of a homomorphic ciphertext, calculating a polynomial configured with each encoded element, and performing homomorphic encryption on the calculated polynomial f A(x) to generate the movement path information,
the polynomial, f
      A
     
     (
     x
     )
    
    ⁢
       
    is
    ⁢
       
    
     
      f
      A
     
     (
     x
     )
    
   
   =
   
    
     
      
       ∏
        
      
      
        
       
        i
        =
        1
       
      
      
        
       n
      
     
     ⁢
     
      (
      
       x
       -
       
        a
        
         i
          
        
       
      
      )
     
    
    ∈
    
     
      Z
      p
     
     [
     x
     ]
    
   
  
  ,, and
wherein, x represents a variable, Zp[x] represents the plaintext space, and ai represents an i-th element in the plaintext space.