'\" te
.\"  Copyright 1989 AT&T  Copyright (c) 1997, Sun Microsystems, Inc.  All Rights Reserved
.TH isencrypt 3GEN "29 Dec 1996" "SunOS 5.11" "String Pattern-Matching Library Functions"
.SH NAME
isencrypt \- determine whether a buffer of characters is encrypted
.SH SYNOPSIS
.LP
.nf
\fBcc\fR  [\fIflag\fR]... [\fIfile\fR]... \fB-lgen\fR [\fIlibrary\fR]...
.fi

.LP
.nf
#include<libgen.h>

\fBint\fR \fBisencrypt\fR(\fBconst char *\fR\fIfbuf\fR, \fBsize_t\fR \fIninbuf\fR);
.fi

.SH DESCRIPTION
.sp
.LP
\fBisencrypt()\fR uses heuristics to determine whether a buffer of characters is encrypted. It requires two arguments: a pointer to an array of characters and the number of characters in the buffer.
.sp
.LP
\fBisencrypt()\fR assumes that the file is not encrypted if all the characters in the first block are \fBASCII\fR characters. If there are non-\fBASCII\fR characters in the first \fIninbuf\fR characters, and if the \fBsetlocale()\fR \fBLC_CTYPE\fR category is set to \fBC\fR or \fBascii\fR, \fBisencrypt()\fR assumes that the buffer is encrypted
.sp
.LP
If the \fBLC_CTYPE\fR category is set to a value other than \fBC\fR or \fBascii\fR, then \fBisencrypt()\fR uses a combination of heuristics to determine if the buffer is encrypted. If \fIninbuf\fR has at least 64 characters, a chi-square test is used to determine if the bytes in the buffer have a uniform distribution; if it does, then \fBisencrypt()\fR assumes the buffer is encrypted.  If the buffer has less than 64 characters, a check is made for null characters and a terminating  new-line to determine whether the buffer is encrypted.
.SH RETURN VALUES
.sp
.LP
If the buffer is encrypted,  \fB1\fR is returned; otherwise, zero is returned.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
tab() box;
cw(2.75i) |cw(2.75i) 
lw(2.75i) |lw(2.75i) 
.
ATTRIBUTE TYPEATTRIBUTE VALUE
_
MT-LevelMT-Safe
.TE

.SH SEE ALSO
.sp
.LP
\fBsetlocale\fR(3C), \fBattributes\fR(5)
.SH NOTES
.sp
.LP
When compiling multithreaded applications, the \fB_REENTRANT\fR flag must be defined on the compile line.  This flag should only be used in multithreaded applications.