- calculate file fingerprint

[ option... ][ filename... ]

-Help

-VERSion

The program is used to calculate the fingerprints of files. A fingerprint is a hash of the contents of a file. The default fingerprint is cryptographically strong, so the probability of two different files having the same fingerprint is less than 1 in 2**200.

The fingerprint is based on Dan Berstien <djb@silverton.berkeley.edu> public domain fingerprint 0.50 beta package 930809, posted to the alt.sources newsgroup. This program produces identical results; the expected test results were generated using Dan's package.

The fingerprint is a base-64-sanely-encoded fingerprint of the input. Imagine this fingerprint as something universal and permanent. A fingerprint is 76 characters long, containing the following:

1.

A Snefru-8 (version 2.5, 8 passes, 512->256) hash. (Derived from the Xerox Secure Hash Function.)

2.

An MD5 hash, as per RFC 1321. (Derived from the RSADSI MD5 Message-Digest Algorithm.)

3.

A CRC checksum, as in the new cksum utility.

4.

Length modulo 2^40.

The output format is not expected to be compatible with anything. However, options are available to produce the purported output of Merkle's snefru program, the purported output of RSADSI's mddriver -x, or the purported output of the POSIX cksum program.

If no files are named as input, the standard input will be used. The special file name ``-'' is understood to mean the standard input.

The following options are understood:

-Checksum

Print the CRC32 checksum and length of the named file(s).

-Identifier

Print a condensed form of the fingerprint (obtained by performing a CRC32 checksum on the full fingerprint described above - a definite overkill). This is an 8-digit hexadecimal number, useful for generating unique short identifiers out of long names. The first character is forced to be a letter (g-p), so there is no problem in using the output as a variable name.

-Help

Provide some help with using the program.

-Message_Digest

Print the RSA Data Security, Inc. MD5 Message-Digest Algorithm hash of the named file(s).

-Snefru

Print the Snefru hash of the named file(s), derived from the Xerox Secure Hash Function.

-VERSion

Print the version of the program being executed.

All other options will produce a diagnostic error.

All options may be abbreviated; the abbreviation is documented as the upper case letters, all lower case letters and underscores (_) are optional. You must use consecutive sequences of optional letters.

All options are case insensitive, you may type them in upper case or lower case or a combination of both, case is not important.

For example: the arguments "-help", "-HEL" and "-h" are all interpreted to mean the -Help option. The argument "-hlp" will not be understood, because consecutive optional characters were not supplied.

Options and other command line arguments may be mixed arbitrarily on the command line.

The GNU long option names are understood. Since all option names for are long, this means ignoring the extra leading '-'. The "--option=value" convention is also understood.

The command will exit with a status of 1 on any error. The command will only exit with a status of 0 if there are no errors.

version

Copyright Peter Miller; All rights reserved.

The program comes with ABSOLUTELY NO WARRANTY; for details use the ' -VERSion License' command. This is free software and you are welcome to redistribute it under certain conditions; for details use the ' -VERSion License' command.

tab(;); l r l. Peter Miller;E-Mail:;millerp@canb.auug.org.au /\/\*;WWW:;http://www.canb.auug.org.au/~millerp/

Portions of this program are derived from sources from other people, sometimes with liberal copyrights, and sometimes in the public domain. These include:

Dan Bernstien

See common/fp/README for details.

Gary S Brown.

See common/fp/crc32.c for details.

RSA Data Security, Inc.

See common/fp/md5.c for details.

Xerox Corporation

See common/fp/snefru.c for details.

In addition to the above copyright holders, there have been numerous authors and contributors, see the named files for details. Files names are relative to the root of the cook distribution.