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7.1.5 SF.CE_OPE_LOCK Service Mode Lock Function
The Service Mode Lock Function restricts use of the Maintenance 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 the Maintenance Functions. If it is set to "On", the TOE does not
allow the CE to use the Maintenance 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 data to be stored on the HDD.
Following are the explanations of each functional item in "SF.CIPHER Encryption
Function" and their corresponding security functional requirements.
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
Encryption
operations
Standar
d
Encryption
algorithm
Key size
Writing data to HDD Encrypt
Reading data from HDD Decrypt
FIPS197 AES 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.
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