.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified Sat Jul 24 18:54:45 1993 by Rik Faith (faith@cs.unc.edu)
.TH MEMFROB 3  2021-03-22 "GNU" "Linux Programmer's Manual"
.SH NAME
memfrob \- frobnicate (encrypt) a memory area
.SH SYNOPSIS
.nf
.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
.B #include <string.h>
.PP
.BI "void *memfrob(void *" s ", size_t " n );
.fi
.SH DESCRIPTION
The
.BR memfrob ()
function encrypts the first \fIn\fP bytes of the
memory area \fIs\fP by exclusive-ORing each character with the number
42.
The effect can be reversed by using
.BR memfrob ()
on the
encrypted memory area.
.PP
Note that this function is not a proper encryption routine as the XOR
constant is fixed, and is suitable only for hiding strings.
.SH RETURN VALUE
The
.BR memfrob ()
function returns a pointer to the encrypted memory
area.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR memfrob ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH CONFORMING TO
The
.BR memfrob ()
function is unique to the
GNU C Library.
.SH SEE ALSO
.BR bstring (3),
.BR strfry (3)