Ricoh Aficio MP 2851 Security Target - Page 74

7.1.5 SF.CE_OPE_LOCK Service Mode Lock Function Page 74 of 81 The Service Mode Lock Function restricts use of the M aintenance Functions to CEs only , based on the Service Mode Lock Function setting specified by the machine administrator. The TOE allows the machine administrator to set the Service Mode Lock Function from the Operation Panel, and allows all authorised users to view the value of the setting. If the Service Mode Lock Function is set to "Off", the TOE allows only the CE to use theM aintenance Functions. If it is set to "On", the TOE does not allow the CE to use the M aintenance Functions. By the above, FMT_MTD.1 (Management of TSF data) is satisfied. 7.1.6 SF.CIPHER Encryption Function The TOE encrypts the document datato be stored on the HDD. Following are explanations of each functional item in "SF.CIPHER their corresponding security functional requirements. Encryption Function" and 7.1.6.1 Encryption of Document Data The TOE encrypts data with the Ic Hdd before writing it to the HDD. The TOE decrypts data with the Ic Hdd after reading it from the HDD. This process is performed for all data written to and read from the HDD. Document data is encrypted and decrypted by the TOE in a similar way. The HDD encryption keys are generated by the machine administrator. If the logged-in user is the machine administrator, the TOE displays a screen on the Operation Panel that the administrator can use to generate the HDD encryption keys. When the machine administrator uses the Operation Panel to instruct the TOE to generate an HDD encryption key, the TOE generates a 256-bit HDD encryption key using the TRNG encryption key generation algorithm (compliant with the BSI-AIS31 standard). When the TOE writes to or reads from the HDD, it performs the encryption operations shown in Table 33. Table 33: List of encryption operations on data stored on the HDD Encryption-triggering operation Writing data to HDD Reading data from HDD Encryption operations Encrypt Decrypt Standard FIPS197 Encryption algorithm AES Key size 256 bits The HDD encryption keys can also be printed. If the logged-in user is the machine administrator, the TOE displays a screen on the Operation Panel that the administrator can use to print the HDD encryption keys. The printed encryption keys are used to restore the encryption keys in the event of the encryption keys in the TOE becoming unavailable. In addition, the TOE verifies that the encryption function of the Ic Hdd operates normally at start-up and verifies the integrity of the HDD encryption keys. If the TOE is not able to verify the integrity of the HDD encryption keys, it will show that the HDD encryption keys have changed. Copyright (c) 2010 RICOH COMPANY, LTD. All Rights Reserved.