Abstract: A moisture content measurement method that calculates moisture content of dehydrated sludge using a calibration curve for calculating the moisture content of the dehydrated sludge, the calibration curve being obtained by performing multivariate regression analysis after first-order differential processing or an offset correction is performed on absorbance for reflected light or reflectance for infrared rays from dehydrated sludge, the absorbance or the reflectance being obtained by measuring the dehydrated sludge using an infrared measurement apparatus provided with a light-receiving unit that can receive at least infrared rays reflected from a target object to be measured and a light source that has a plurality of infrared LEDs that can emit infrared rays having respectively different wavelengths or a light source having an infrared-region tungsten lamp or halogen lamp.

Abstract: According to one embodiment, a processor of a storage device is configured: to receive an instruction of setting a portion of an area of a storage medium from a first state to a second state and receive first information defining a condition of setting the portion of the area from the second state to the first state again from a first host device among a plurality of host devices; to set the portion of the area to the second state in response to the instruction; and to set, after the portion of the area is set to the second state in response to the instruction, the portion of the area from the second state to first state again based on the first information.

Abstract: A storage device includes a non-volatile memory having a plurality of storage areas. Received data is encrypted with a first cryptographic key and stored in one of the storage areas. Upon receiving an request from a host, a key processor replaces the first cryptographic key used to encrypt data stored on a specified one of the non-volatile memories with a different cryptographic key not previously used for any of the storage areas by generating a second cryptographic key, converting the previously used keys into first value by an operation, converting the candidate key into a second value by the same operation. The first and second values are compared, and when the first information is not the same as the second information, the second cryptographic key replaces the first cryptographic key, and when not, the second cryptographic key is discarded and a new second cryptographic key generated.

Abstract: According to embodiments, a storage device includes a storage unit, a receiving unit, an authenticating unit, and a control unit. Prior to executing erasure processing of data that has been stored in the storage unit, the receiving unit receives, from an external device that clocks time, third information including first information and second information, the first information regarding time counted by the external device and the second information being information for authenticating the external device. The authenticating unit performs authentication processing of the external device by using the second information included in the third information. When the authentication of the external device has succeeded, the control unit generates an erasure log that contains erasure time when the erasure processing has been executed on the basis of the first information included in the third information. When the authentication of the external device has failed, the execution of the erasure processing is prohibited.

Abstract: According to one embodiment, a storage device comprises a cipher processing unit, a memory, and a key processing unit. The cipher processing unit encrypts data using a key. The memory stores the encrypted data. The key processing unit replaces a first key having been used by the cipher processing unit with a second key. The key processing unit comprises a generating unit, a history managing unit, a computing unit, and a comparing unit. The history managing unit converts the first key into first information by an operation and stores the first information. The computing unit converts a candidate key generated by the generating unit into second information by the operation. The comparing unit compares the first information and the second information, and, if the two do not coincide, determines the candidate key as the second key and, if the two coincide, discards the candidate key.