ISENCRYPT(3G-SVR4)  RISC/os Reference Manual   ISENCRYPT(3G-SVR4)



NAME
     isencrypt - determine whether a character buffer is
          encrypted

SYNOPSIS
     cc [flag ...] file ...  -lgen [library ...]

     #include <libgen.h>

     int isencrypt (const char *fbuf, sizet ninbuf);

DESCRIPTION
     isencrypt 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 charac-
     ters in the buffer.

     isencrypt assumes that the file is not encrypted if all the
     characters in the first block are ASCII characters.  If
     there are non-ASCII characters in the first ninbuf charac-
     ters, isencrypt assumes that the buffer is encrypted if the
     setlocale LC_CTYPE category is set to C or ASCII.

     If the LC_CTYPE category is set to a value other than C or
     ASCII, then isencrypt uses a combination of heuristics to
     determine if the buffer is encrypted.  If ninbuf has at
     least 64 characters, a chi-square test is used to determine
     if the bytes in the buffer have a uniform distribution; and
     isencrypt assumes the buffer is encrypted if it does.  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.

DIAGNOSTICS
     If the buffer is encrypted, 1 is returned; otherwise zero is
     returned.

SEE ALSO
     setlocale(3C).
















                        Printed 11/19/92                   Page 1