Simson Garfinkel, Ph.D. (U.S. Census Bureau)
Alex Nelson, Ph.D. (NIST)
Douglas White (NIST)
Vassil Roussev, Ph.D. (University of New Orleans)


This paper explores the use of purpose-built functions and cryptographic hashes of small data blocks for identifying data in sectors, file fragments, and entire files. It introduces and defines the concept of a “distinct” disk sectorda sector that is unlikely to exist elsewhere except as a copy of the original. Techniques are presented for improved detection of JPEG, MPEG and compressed data; for rapidly classifying the forensic contents of a drive using random sampling; and for carving data based on sector hashes.