Patent ID: 7933406

Claim:
An encryption device that encrypts information formed on a recording member on the basis of an encryption code, the device comprising: an irradiation portion configured to irradiate a surface of the recording member with laser light, the laser light emitted from the irradiation portion being reflected by irregularities in the irradiated surface of the recording member to produce scattering light of which waves are interfered with each other; an image taking portion configured to receive the produced scattering light to take a speckle pattern image of the irradiated surface of the recording member irradiated with the laser light; and a preparation portion configured to prepare the encryption code on the basis of the taken speckle pattern image of the irradiated surface with respect to the recording member; wherein the information is constituted by a sequence of characters including at least one character, wherein the device further comprises: a dividing portion configured to divide the taken speckle pattern image of the irradiated surface into a predetermined number of regions; an assignment portion configured to assign all the characters constituting the sequence of characters to the divided regions; and a computation portion configured to compute a predetermined unique value with respect to each of the divided regions, and wherein said preparation portion is configured to prepare the encryption code by replacing all the characters respectively assigned to the divided regions with the predetermined unique values computed with respect to the divided regions.