.\" zip_fopen_encrypted.mdoc -- open encrypted file in zip archive for reading
.\" Copyright (C) 2011-2020 Dieter Baron and Thomas Klausner
.\"
.\" This file is part of libzip, a library to manipulate ZIP archives.
.\" The authors can be contacted at <libzip@nih.at>
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in
.\"    the documentation and/or other materials provided with the
.\"    distribution.
.\" 3. The names of the authors may not be used to endorse or promote
.\"    products derived from this software without specific prior
.\"    written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS
.\" OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
.\" GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
.\" IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
.\" OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
.\" IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd September 15, 2020
.Dt ZIP_FOPEN_ENCRYPTED 3
.Os
.Sh NAME
.Nm zip_fopen_encrypted ,
.Nm zip_fopen_index_encrypted
.Nd open encrypted file in zip archive for reading
.Sh LIBRARY
libzip (-lzip)
.Sh SYNOPSIS
.In zip.h
.Ft zip_file_t *
.Fn zip_fopen_encrypted "zip_t *archive" "const char *fname" "zip_flags_t flags" "const char *password"
.Ft zip_file_t *
.Fn zip_fopen_index_encrypted "zip_t *archive" "zip_uint64_t index" "zip_flags_t flags" "const char *password"
.Sh DESCRIPTION
The
.Fn zip_fopen_encrypted
function opens the encrypted file name
.Ar fname
in
.Ar archive
using the password given in the
.Ar password
argument.
If
.Ar password
is
.Dv NULL
or the empty string, the default password is used (see
.Xr zip_set_default_password 3 ) .
The
.Ar flags
argument are the same as for
.Xr zip_fopen 3 .
.Pp
The
.Fn zip_fopen_index_encrypted
function opens the file at position
.Ar index ,
see
.Xr zip_fopen_index 3 .
These functions are called automatically by
.Xr zip_fopen 3 ;
you only need to call them if you want to specify a non-default password
(see
.Xr zip_set_default_password 3 ) .
.Sh RETURN VALUES
Upon successful completion, a
.Ft struct zip_file
pointer is returned.
Otherwise,
.Dv NULL
is returned and the error code in
.Ar archive
is set to indicate the error.
.Sh ERRORS
.Bl -tag -width ZIP_ER_ENCRNOTSUPPXX
.It Bq Er ZIP_ER_NOPASSWD
No password was provided.
.El
.Pp
The function
.Fn zip_fopen_encrypted
may also fail and set
.Va zip_err
for any of the errors specified for the routine
.Xr zip_fopen 3 .
.Pp
The function
.Fn zip_fopen_index_encrypted
may also fail and set
.Va zip_err
for any of the errors specified for the routine
.Xr zip_fopen_index 3 .
.Sh SEE ALSO
.Xr libzip 3 ,
.Xr zip_fclose 3 ,
.Xr zip_fopen 3 ,
.Xr zip_fread 3 ,
.Xr zip_get_num_entries 3 ,
.Xr zip_name_locate 3
.Sh HISTORY
.Fn zip_fopen_encrypted
and
.Fn zip_fopen_index_encrypted
were added in libzip 1.0.
.Sh AUTHORS
.An -nosplit
.An Dieter Baron Aq Mt dillo@nih.at
and
.An Thomas Klausner Aq Mt tk@giga.or.at
.Sh CAVEATS
The zip file format provides very limited possibility for password
verification (a short hash of is compared against one byte in the zip
archive).
For this reason, reading a file while using an incorrect password may
immediately fail with
.Er ZIP_ER_WRONGPASSWD ,
but if the mismatch is not detected, a zlib error may be returned
later instead.
Since zlib errors can also be caused by broken compressed data, there
is no way to make sure if the password was incorrect or if it was
correct, but the compressed data was invalid.