Download A Secure File System Based on

sfs_rename Old_File_Name New_File_Name (with suffix .sfs.)
User_Password: *** (Users input directly)
System checks if both file names have suffix ‘.sfs’
If no, exit abnormally.
If yes, continue.
Decrypted_Key/Data_Pair =
Blowfish ( CipherText: Encrypted Absolute_File_Path /
hash_value2 + Encrypted_File_Password
Key: Encrypted User’s Login Password +
CPUID PSN (8byte) +
Hard disk Serial Number (20bytes) )
Retrieve the Encrypted
Key / Data pair from the
SGDBM database
SGDBM
new_hash_value2 = sha1( the key containing the User Password )
System compares the new_hash_value2 with the hash_value2
If new is not equal to old, exit abnormally.
If new is equal to old, continue.
Add a new Key/Data Pair for the new file name into the
SGDBM database
Add a new Key / Data pair
in the SGDBM database
SGDBM
Rename the file
on disk
Rename the Encrypted_File on disk to the new name
Disk
Delete the Key/Data Pair for the old file name from the SGDBM
database
SGDBM
Delete the Key / Data pair corresponding to
the old file name from the SGDBM database
Figure 4 command sfs_rename flow chart
87