Image forgery prevention device and method thereof using hash function

An image forgery prevention method using a hash function, the method comprising:

• a privacy area image detection step of detecting a privacy area image from an original image by a privacy area detection processor;
• a hash value generation step of using the hash function to generate a hash value of the privacy area image by a hash value generation processor, wherein
• the hash value is generated only for the detected privacy area image, and
• the hash value is generated with the image forgery prevention purpose of the detected privacy area,
• the hash value is generated to have a larger number of bits in a case where the detected privacy area image comprises a person's face as a result of the detection of the privacy area detection processor than the number of bits of the hash value in a case where the detected privacy area image is an object comprising an address, a vehicle license plate number, a password and a bank account number as a result of the detection of the privacy area detection processor;
• an obfuscation step of obfuscating the privacy area image by an obfuscation processor;
• a verification hash value insertion step of inserting a verification hash value corresponding to the hash value into an obfuscated privacy area of the original image in a predetermined encrypted form by a verification hash value insertion processor, wherein
• the verification hash value is inserted only for the obfuscated privacy area of the original image,
• the verification hash value is inserted with the image forgery prevention purpose of the detected privacy area,
• the verification hash value comprises a predetermined correlation only with the hash value;
• an authenticity determination step of determining, by an authenticity determination processor, whether the privacy area image is authentic or not by comparing the hash value of the privacy area image with the verification hash value inserted into the obfuscated privacy area of the original image;
• and
• an image restoration step of restoring, by an image restoration processor, the privacy area image to the obfuscated privacy area in a case where the hash value and the verification hash value satisfy the predetermined correlation.