1cookfp(1) General Commands Manual cookfp(1)
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6 cookfp - calculate file fingerprint
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9 cookfp [ option... ][ filename... ]
10 cookfp -Help
11 cookfp -VERSion
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14 The cookfp program is used to calculate the fingerprints of files. A
15 fingerprint is a hash of the contents of a file. The default finger‐
16 print is cryptographically strong, so the probability of two different
17 files having the same fingerprint is less than 1 in 2**200.
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19 The fingerprint is based on Dan Berstien <djb@silverton.berkeley.edu>
20 public domain fingerprint 0.50 beta package 930809, posted to the
21 alt.sources newsgroup. This program produces identical results; the
22 expected test results were generated using Dan's package.
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24 The fingerprint is a base-64-sanely-encoded fingerprint of the input.
25 Imagine this fingerprint as something universal and permanent. A fin‐
26 gerprint is 76 characters long, containing the following:
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28 1. A Snefru-8 (version 2.5, 8 passes, 512->256) hash. (Derived from
29 the Xerox Secure Hash Function.)
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31 2. An MD5 hash, as per RFC 1321. (Derived from the RSADSI MD5 Mes‐
32 sage-Digest Algorithm.)
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34 3. A CRC checksum, as in the new cksum utility.
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36 4. Length modulo 2^40.
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38 The output format is not expected to be compatible with anything. How‐
39 ever, options are available to produce the purported output of Merkle's
40 snefru program, the purported output of RSADSI's mddriver -x, or the
41 purported output of the POSIX cksum program.
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43 If no files are named as input, the standard input will be used. The
44 special file name ``-'' is understood to mean the standard input.
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47 The following options are understood:
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49 -Checksum
50 Print the CRC32 checksum and length of the named file(s).
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52 -Identifier
53 Print a condensed form of the fingerprint (obtained by perform‐
54 ing a CRC32 checksum on the full fingerprint described above -
55 a definite overkill). This is an 8-digit hexadecimal number,
56 useful for generating unique short identifiers out of long
57 names. The first character is forced to be a letter (g-p), so
58 there is no problem in using the output as a variable name.
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60 -Help
61 Provide some help with using the cookfp program.
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63 -Message_Digest
64 Print the RSA Data Security, Inc. MD5 Message-Digest Algorithm
65 hash of the named file(s).
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67 -Snefru Print the Snefru hash of the named file(s), derived from the
68 Xerox Secure Hash Function.
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70 -VERSion
71 Print the version of the cookfp program being executed.
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73 All other options will produce a diagnostic error.
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75 Portions of this program are derived from sources from other people,
76 sometimes with liberal copyrights, and sometimes in the public domain.
77 These include:
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79 Dan Bernstien
80 See common/fp/README for details.
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82 Gary S Brown.
83 See common/fp/crc32.c for details.
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85 RSA Data Security, Inc.
86 See common/fp/md5.c for details.
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88 Xerox Corporation
89 See common/fp/snefru.c for details.
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91 In addition to the above copyright holders, there have been numerous
92 authors and contributors, see the named files for details. Files names
93 are relative to the root of the cook distribution.
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97Reference Manual Cook cookfp(1)