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+\input texinfo   @c -*-texinfo-*-
+
+@c %**start of header
+@setfilename passcheck.info
+@settitle passcheck
+@afourpaper
+@documentencoding UTF-8
+@documentlanguage en
+@finalout
+@c %**end of header
+
+
+@dircategory Security
+@direntry
+* passcheck: (passcheck).            Passphrase strength evaluator
+@end direntry
+
+
+@copying
+Copyright @copyright{} 2013, 2015 Mattias Andrée
+
+@quotation
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.3 or
+any later version published by the Free Software Foundation; with no
+Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
+Texts. A copy of the license is included in the section entitled
+``GNU Free Documentation License''.
+@end quotation
+@end copying
+
+@ifnottex
+@node Top
+@top passcheck -- Passphrase strength evaluator
+@insertcopying
+@end ifnottex
+
+@titlepage
+@title passcheck
+@subtitle Passphrase strength evaluator
+@author by Mattias Andrée (maandree)
+
+@page
+@vskip 0pt plus 1filll
+@insertcopying
+@page
+@end titlepage
+
+@contents
+
+
+
+@menu
+* Overview::                        Brief overview of @command{passcheck}.
+* Invoking::                        Executing @command{passcheck}.
+* Factors::                         Factors weighted in at evaulation.
+* GNU Free Documentation License::  Copying and sharing this manual.
+@end menu
+
+
+
+@node Overview
+@chapter Overview
+
+@command{passcheck} is a tool that rates passphrases based on the strengths,
+a highly rated passphrase is a string passphrase. You are recommended not to
+use any passphrases rated below 300.
+
+Passphrases are read from stdin and the rating followed by the passphrase
+for each passphrases is written to stdout, and stderr is quited unless the
+program files.
+
+
+
+@node Invoking
+@chapter Invoking
+
+@command{passcheck} parses each line (must end exactly with one UNIX line break)
+as a passphrase and puts the (positive integer) rating before the passphrase
+separated with one blankspace.
+
+You may want to pipe stdout to @command{sort -n} to get the strongest passphrase
+at the bottom.
+
+Use @option{--raw} or @option{-r} if the passphrase may contain a ESC character,
+otherwise it is parsed as an ANSI escape sequence which is ignored in the rating
+and allows you to use colours in the passphrases.
+
+Server with vast amount of RAM memory may want to load the entire blacklist
+into RAM and create a hash set of it. To do this, use @option{--waste-ram} or
+@option{-w}. It is unreasonable to do this unless you have the process running
+indefinitely and (somewhat) continuously feed passphrases.
+
+
+
+@node Factors
+@chapter Factors
+
+@command{passcheck} weights in the following factors when evaluating
+the strength of a passphrase:
+@itemize @bullet
+@item
+The passphrase is not a known real passphrase.
+Currently a list of 5189414 leaked passphrases is is used.
+This list is created from several password leaks, name
+lists, and dictionaries.
+@item
+The passphrase is not a word listed in a file
+inside either ofthe directory @file{/usr/share/dict/}
+abd @file{/usr/local/share/dict/}.
+@item
+The degree to which characters are mixed.
+@item
+The classes of used characters. For example non-ASCII
+characters are better than ASCII chracters.
+@item
+The distance, on a QWERTY-keyboard, of successive keys.
+@item
+The length of the passphrase.
+@end itemize
+
+It has been argued that passphrases should not form grammatically
+correct sentence, even if the sentence itself if nonsense. The argument
+is that the majority of possible choices of words can be eliminated for
+each word position, based on the previous word. However a counterargument
+for this concern is that number of possible combinations, assuming the
+sentence is nonsensical, large enough even if choices can be eliminated
+using grammar. Currently, evaluation based on grammar is not made, so if
+you believe grammatically correct sentence should be avoided, please
+manually check that the passphrase you choose does not form a grammatically
+correct sentence, and preferably, not even in part.
+
+
+
+@node GNU Free Documentation License
+@appendix GNU Free Documentation License
+@include fdl.texinfo
+
+@bye
+