From 0fbb5a9e127fe19a12bc79b7820b511c5a451ccc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Florian=20=22flowdy=22=20He=C3=9F?=
 <flowdy@users.noreply.github.com>
Date: Sat, 3 Sep 2016 14:31:10 +0200
Subject: [PATCH] Added pseudonymizr.sh so that real financial transfer data
 can be disclosed pseudonymized, in accordance with privacy laws, for a
 non-member of board or even the club to test treasuredb.

---
 pseudonymizr.pl | 107 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 107 insertions(+)
 create mode 100755 pseudonymizr.pl

diff --git a/pseudonymizr.pl b/pseudonymizr.pl
new file mode 100755
index 0000000..681e004
--- /dev/null
+++ b/pseudonymizr.pl
@@ -0,0 +1,107 @@
+#!/usr/bin/perl
+
+=head1 NAME
+
+pseudonymizr.pl - Unambiguous substitution of marked strings by randomized ones
+
+=head1 USE CASE
+
+Societies that consider to use treasuredb for their finances are
+strongly advised to test it in advance. The board members may do that
+themselves, but they might want to delegate that to competent regular
+members. However, in the latter case, privacy laws are to be observed that
+can prohibit disclosure of real data for this purpose.
+
+To conduct tests with real data without infringement of privacy laws,
+this script has been developped. It replaces all names and other sensible
+information that is specially marked, by a random string. It is guaranteed
+that repeatedly occurring strings are replaced by the same pseudonym,
+of course.
+
+=head1 HOW IT WORKS
+
+This script pseudonymizes lines from standard input and writes them to
+standard output. All strings that need to be replaced must be wrapped into
+a special marker, namely X{...}, where X can be any upper- or lowercase letter of the alphabet, denoting a certain category of information, e.g. "M" for
+member names.
+
+Caution with natural member names! Slightly differing content of M{...} clauses lead to completely different pseudonyms. In order not to render the tests
+irreversible and in disaccord with actual states, because the association of members and accounts is wrong, you should prefer using it for the unique and standard member ID, say the number in the member table. Where proper names in financial transfer information, use a different letter. 
+
+=head1 COMMAND
+
+ pseudonymizr.pl [-r] secret_registry.txt < in_file.csv > out_file.csv
+
+=head1 FLAGS
+
+=over 4
+
+=item -r
+
+reverse mode, i.e. de-pseudonymize
+
+=back
+
+=cut
+
+use strict;
+use utf8;
+
+my $LENGTH = 5;
+my @CHARS = ( 'A' .. 'Z', 'a' .. 'z', 0 .. 9 );
+
+my (%subst, %known, $registry_fh);
+my $reverse_mode = $ARGV[0] eq q{-r} && shift;
+my $registry_file = shift;
+open $registry_fh, '<:utf8', $registry_file
+    or die "Cannot read $registry_file: $!"
+    if -e $registry_file;
+
+if ( $registry_fh ) {
+    
+    my ($orig, $random);
+    my ($h1, $h2, $assign) = $reverse_mode
+        ? (\%subst => \%known, sub { ($random, $orig) = @_ })
+        : (\%known => \%known, sub { ($orig, $random) = @_ })
+        ;
+
+    while ( $_ = <$registry_fh> ) {
+        chomp;
+        $assign->( split /\t/ );
+        $h1->{ $random } = $orig;
+    }
+    %$h2 = reverse %$h1;
+
+}
+
+binmode STDIN, ':utf8';
+binmode STDOUT, ':utf8';
+while ( $_ = <STDIN> ) {
+    s/ (?<=\w\{) (.+?) (?=\}) / pseudonymize($1) /gexms;
+    print;
+}
+
+unless ( $reverse_mode ) {
+   # Rewrite the registry we could have expanded with new names (sorted)
+
+   open $registry_fh, '|-', qq{sort > $registry_file}
+       or die "Cannot pipe to sort: $!";
+
+   while ( my ($random, $orig) = each %known ) {
+       printf $registry_fh "%s\t%s\n", $random, $orig;
+   }
+
+}
+
+sub pseudonymize { my $orig = shift; $subst{ $orig } //= do {{
+
+    # Zufallsstring der Länge $LENGTH erzeugen
+    my $random = join q{}, map { $CHARS[ rand 62 ] } 1 .. $LENGTH;
+
+    # If known, try anew (p = 1 : 62 ^ $LENGTH, i.e. p > 0)
+    $_ = $_ ? redo : $orig for $known{ $random };
+
+    # in $subst speichern
+    $random;
+
+}}; }