HFIND(1)						      General Commands Manual							  HFIND(1)

NAME

       hfind - Lookup a hash value in a hash database

SYNOPSIS

       hfind [-i db_type ] [-f lookup_file ] [-eq] db_file [hashes]

DESCRIPTION

       hfind looks up hash values in a database using a binary search algorithm.  This allows one to easily create a hash database and identify if
       a file is known or not.	It works with the NIST National Software Reference Library (NSRL) and the output of 'md5sum'.

       Before the database can be used by 'hfind', an index file must be created with the '-i' option.

       This tool is needed for efficiency.  Most text-based databases do not have fixed length entries and are sometimes not  sorted.	The  hfind
       tool  will  create an index file that is sorted and has fixed-length entries.  This allows for fast lookups using a binary search algorithm
       instead of a linear search such as 'grep'.

ARGUMENTS

       -i db_type
	      Create an index file for the database.  This step must be done before a lookup can be performed. The  'db_type'  argument  specifies
	      the database type (i.e. nsrl-md5 or md5sum).  See section below.

       -f lookup_file
	      Specify the location of a file that contains one hash value per line.  These hashes will be looked up in the database.

       -e     Extended mode.  Additional information besides just the name is printed.	(Does not apply for all hash database types).

       -q     Quick mode.  Instead of displaying the corresponding information with the hash, just display 0 if the hash was not found and 1 if it
	      was.  If this flag is used, then only one hash can be given at a time.

       -V     Display version

       db_file
	      The location of the hash database file.

       [hashes]
	      The hashes to lookup.  If they are not supplied on the command line, STDIN is used.  If index files exist for  both  SHA-1  and  MD5
	      hashes, then both types of hashes can be given at runtime.

INDEX FILE

       hfind uses an index file to perform a binary search for a hash value. This is much faster than using 'grep', which will do a linear search.
       Before a hash database is used, a corresponding index file must be created.  This is done with the '-i' option to hfind.

       The resulting index file will be named based on the database file name.	The name will have the original name following by  the	hash  type
       (sha1 or md5) followed by '.idx'.  For example, creating an MD5 hash index of the NIST NSRL results in 'NSRLFile.txt-md5.idx' and the SHA-1
       index results in 'NSRLFile.txt-sha1.idx'.

       The file has two columns.  Each entry is sorted by the first column, which is the hash value.  The second column has the byte offset of the
       corresponding  entry  in  the  original	file.  So, when a hash is found in the index, the offset is recorded and then 'hfind' seeks to the
       entry in the original database.

       The following input types are valid.  For NSRL, 'nsrl-md5' and 'nsrl-sha1' can be used.	The difference is which hash value  the  index	is
       sorted by.  The 'md5sum' value can also be used to sort and index "home made" databases.  'hfind' can take data in both common formats:

	   MD5 (test.txt) = 76b1f4de1522c20b67acc132937cf82e

       and

	   76b1f4de1522c20b67acc132937cf82e	   test.txt

EXAMPLES

       To create an MD5 index file for NIST NSRL:

	   # hfind -i nsrl-md5 /usr/local/hash/nsrl/NSRLFile.txt

       To lookup a value in the NSRL:

	   # hfind /usr/local/hash/nsrl/NSRLFile.txt 76b1f4de1522c20b67acc132937cf82e

	   76b1f4de1522c20b67acc132937cf82e  Hash Not Found

       You can even do both SHA-1 and MD5 if you want:

	   # hfind -i nsrl-sha1 /usr/local/hash/nsrl/NSRLFile.txt

	   # hfind /usr/local/hash/nsrl/NSRLFile.txt
	   76b1f4de1522c20b67acc132937cf82e
	   80001A80B3F1B80076B297CEE8805AAA04E1B5BA

	   76b1f4de1522c20b67acc132937cf82e  Hash Not Found

	   80001A80B3F1B80076B297CEE8805AAA04E1B5BA  thrdcore.cpp

       To make a database of critical binaries of a trusted system, use 'md5sum':

	   # md5sum /bin/* /sbin/* /usr/bin/* /usr/bin/* /usr/local/bin/* /usr/local/sbin/* > system.md5

	   # hfind -i md5sum system.md5

       To look entries up, the following will work:

	   # hfind system.md5 76b1f4de1522c20b67acc132937cf82e

	   76b1f4de1522c20b67acc132937cf82e  Hash Not Found

       or

	   # md5sum -q /bin/* | hfind system.md5

	   928682269cd3edb1acdf9a7f7e606ff2  /bin/bash

	   <...>

       or

	   # md5sum -q /bin/* > bin.md5

	   # hfind -f bin.md5 system.md5

	   928682269cd3edb1acdf9a7f7e606ff2  /bin/bash

	   <...>

SEE ALSO

       sorter(1)

       The NIST National Software Reference Library (NSRL) can be found at www.nsrl.nist.gov.

LICENSE

       Distributed under the Common Public License, found in the cpl1.0.txt file in the The Sleuth Kit licenses directory.

AUTHOR

       Brian Carrier <carrier at sleuthkit dot org>

       Send documentation updates to <doc-updates at sleuthkit dot org>

																	  HFIND(1)