02-09-2010, 09:03 PM
FILE CARVER
File carver is a data recovery projct based on block detection algoritham in linux specificaly on EXT3 file system with journelling machanism. In the case of a file which has been releted completely from a filesystem thats by pressing shift-Del/ rm -f command.The directory structure which contains the inode valude of the file has been modified and the block of mammory that has been used for inserting the content of the file has been assighned as unallocated.So there is a chance for overwring of the blocks the software hadles the unallocated blocks of the filesytem and matches with the deleted files properties to find the correct blocks which hols the data,The blocks group has been considered for the recovery process there can be allocated block in the block groups we use so we have to find the appropriate block for the file,
Since the location is traced we have to take the data back assighn a memmory extra prefered to be in othe disk to keep our unallocated place unallocated. The statring and ending position of the file must be calculated and the data is recoverd to a temporary raw data first. Then wa can convert it to the specific file type we need.
All process will get complicated when the file is large or the filesystem is highly fragmented.The blocks which stores the data with de direct ,indirect doubly directed .....The pointing mechanism is used in ext3 filesytem for storing files when the file is large or filesytem is fragmented that continuous allocation of memmory in memmory is not possible the pointers will get complicated so that the recovery mechanism will become slower.
If the blocks get allocated to any other data we can only use the resting memmory for recovery so the efficiany of the recovery depends upon the time taken for the recovery from the deletion.