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.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.\" References consulted:
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.\" Linux libc source code
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.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
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.\" 386BSD man pages
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.\" Modified Sat Jul 24 18:54:45 1993 by Rik Faith (faith@cs.unc.edu)
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.TH MEMFROB 3 2017-03-13 "GNU" "Linux Programmer's Manual"
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.SH NAME
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memfrob \- frobnicate (encrypt) a memory area
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.SH SYNOPSIS
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.nf
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.BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */"
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.B #include <string.h>
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.PP
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.BI "void *memfrob(void *" s ", size_t " n );
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.fi
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.SH DESCRIPTION
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The
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.BR memfrob ()
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function encrypts the first \fIn\fP bytes of the
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memory area \fIs\fP by exclusive-ORing each character with the number
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42.
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The effect can be reversed by using
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.BR memfrob ()
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on the
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encrypted memory area.
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.PP
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Note that this function is not a proper encryption routine as the XOR
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constant is fixed, and is suitable only for hiding strings.
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.SH RETURN VALUE
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The
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.BR memfrob ()
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function returns a pointer to the encrypted memory
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area.
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.SH ATTRIBUTES
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For an explanation of the terms used in this section, see
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.BR attributes (7).
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.TS
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allbox;
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lb lb lb
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l l l.
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Interface Attribute Value
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T{
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.BR memfrob ()
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T} Thread safety MT-Safe
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.TE
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.SH CONFORMING TO
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The
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.BR memfrob ()
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function is unique to the
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GNU C Library.
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.SH SEE ALSO
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.BR bstring (3),
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.BR strfry (3)
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.SH COLOPHON
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This page is part of release 4.15 of the Linux
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.I man-pages
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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\%https://www.kernel.org/doc/man\-pages/.
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