Abstract: An image forming apparatus comprises: an output part that outputs variable information varying in a time-dependent manner in the image forming apparatus; a first encrypt part that encrypts the variable information outputted from the output part using a first encrypt key read out from a memory; a second encrypt key create part that creates a second encrypt key according to the variable information outputted from the output part; a second encrypt part that encrypts inherent information for specifying the image forming apparatus using the second encrypt key created by the second encrypt key create part; a generate part that generates code data according to the variable information encrypted in the first encrypt part and the inherent information encrypted in the second encrypt part; and an image form part that forms on a recording member a code image based on the code data generated in the generate part.

Abstract: An image forming apparatus comprises: an output part that outputs variable information varying in a time-dependent manner in the image forming apparatus; a first encrypt part that encrypts the variable information outputted from the output part using a first encrypt key read out from a memory; a second encrypt key create part that creates a second encrypt key according to the variable information outputted from the output part; a second encrypt part that encrypts inherent information for specifying the image forming apparatus using the second encrypt key created by the second encrypt key create part; a generate part that generates code data according to the variable information encrypted in the first encrypt part and the inherent information encrypted in the second encrypt part; and an image form part that forms on a recording member a code image based on the code data generated in the generate part.

Abstract: When a communication control section of an image forming apparatus receives image information, an administration information acquiring section detects administration information from GPS information or the like received through an antenna. An administration information generating section generates the detected administration information in the form of an image. An administration information adding section adds the image indicating the administration information to the image information. An image forming section forms an image added with the administration information.

Abstract: An article 1 to be prevented from forgery previously contains an optical semiconductor, the mixing ratio of which is predetermined. Under the condition that a light source 6 is turned off, microwaves are emitted to the article 1 to be prevented from forgery through a feed phone 5. These microwaves are reflected on the article 1 to be prevented from forgery and supplied to a receiving section 8 through a feed phone 7, so that the receiving level of the microwaves can be measured. Next, the light source 6 is turned on, and the receiving level of the microwaves is measured in the same manner. When an optical semiconductor is irradiated with rays of light, it is excited, so that the microwave reflection factor is enhanced. Accordingly, the receiving level in the case where the light source 6 is turned on is higher than the receiving level in the case where the light source 6 is turned off.

Abstract: Metal fibers are mixed, at a predetermined mixing ratio, into a document for which forgery should be prevented. In reading a document, microwaves are applied to the document via a transmission antenna and reflected microwaves are received via a reception antenna. The document includes a portion in which the microwave reception level falls within a predetermined range and which portion is longer than a predetermined length, the document is regarded as a forgery preventive document and the copying operation is stopped. Further, a registration guide is so formed as to reflect microwaves at a certain reflectance. Influences of variations due to a temperature change and aging are compensated by measuring a reception level corresponding to the registration guide.

Abstract: An image forming device, such as a color copying machine or a color printer, which processes an input image signal, thereby obtains an output image signal, and forms an output image on the basis of the output image signal. In the image forming device, an information input unit writes some information identifying the copying machine to an area in an information storing unit at the time when a power source is turned on for the copying machine for the first time after the assembly thereof. When the power source is turned on for a second and any subsequent times for the copying machine, the copying machine copies an original sheet in such a state of the machine that the information stored in the area of the information storing unit is added to the output image in the form of a pursuit image which it is hard or impossible to recognize with the human eyes.