New York University

Anandabrata Pal

Nasir D Memon

Kulesh Shanmugasundaram

File carving is a technique whereby data files are extracted from a digital device without the assistance of file tables or other disk meta-data, and can therefore be used to recover files that are fragmented. Sequential hypothesis testing procedures are used to detect a fragmentation point of a file by sequentially comparing adjacent pairs of blocks from the starting block of a file until the fragmentation point is reached. The detected fragmentation point can be used to help recover the fragmented file. Such a serial analysis helps to minimize errors and improve performance.

Detecting a file fragmentation point for reconstructing fragmented files using sequential hypothesis testing

Files can be reassembled from fragments by (a) accepting (or determining) adjacency scores for each pair of fragments from a set of fragments, (b) identifying header fragments from among the fragments of the set of fragments, and (c) for each of the header fragments identified, reconstructing a corresponding one of two or more files from the fragments of the set of fragments such that the sum of the adjacency scores are optimized. Any of the fragments, other than the identified header fragments, are permitted to belong, at least provisionally, to more than one of the at least two files when reconstructing the file(s).

Reassembling fragmented files or documents in a file order-independent manner

Files can be reassembled from fragments by (a) accepting adjacency scores for each pair of fragments from the set of fragments, (b) identifying header fragments from among the fragments of the set of fragments, and (c) for each of the header fragments identified, reconstructing a corresponding one of the two or more files from the fragments of the set of fragments such that the sum of the adjacency scores are optimized, wherein each of the fragments is permitted to belong to only one of the at least two files, and wherein at least two files are reconstructed such that the results are independent of the order in which the files are reconstructed.

Reassembling fragmented files or documents in an order-independent manner that ensures each of the fragments belongs to only one reassembled file

Files can be reassembled from fragments by (a) accepting adjacency scores for each pair of fragments from a set of fragments, (b) identifying header fragments from the set of fragments, and (c) for each of the header fragments, (i) setting a current fragment to the identified header fragment, (ii) selecting, from any of the fragments not identified as a header fragment, a fragment with a best adjacency score with the current fragment, (iii) determining if the selected fragment has a better adjacency score with any of the other fragments not identified as a header than with the current fragment, (iv) if so, then (A) selecting another fragment, from any of the fragments not identified as a header fragment, a fragment with a next best adjacency score with the current fragment, and continuing, and otherwise (A) adding the selected fragment to a reassembly path started with the identified header fragment, and (B) setting the current fragment to the selected fragment, and continuing until the file is reconstructed.

Growing community of inventors

Brooklyn, NY, United States of America

Anandabrata Pal