.\" This file is part of GNUnet.
.\" Copyright (C) 2001-2019 GNUnet e.V.
.\"
.\" Permission is granted to copy, distribute and/or modify this document
.\" under the terms of the GNU Free Documentation License, Version 1.3 or
.\" any later version published by the Free Software Foundation; with no
.\" Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.  A
.\" copy of the license is included in the file
.\" FDL-1.3.
.\"
.\" A copy of the license is also available from the Free Software
.\" Foundation Web site at http://www.gnu.org/licenses/fdl.html}.
.\"
.\" Alternately, this document is also available under the General
.\" Public License, version 3 or later, as published by the Free Software
.\" Foundation.  A copy of the license is included in the file
.\" GPL3.
.\"
.\" A copy of the license is also available from the Free Software
.\" Foundation Web site at http://www.gnu.org/licenses/gpl.html
.\"
.\" SPDX-License-Identifier: GPL3.0-or-later OR FDL1.3-or-later
.\"
.Dd August 8, 2013
.Dt GNUNET-SCALARPRODUCT 1
.Os
.Sh NAME
.Nm gnunet-scalarproduct
.Nd compute a vectorproduct
.Sh SYNOPSIS
.Nm
.Op Fl e Ar ELEMENTS | Fl -elements= Ns Ar ELEMENTS
.Op Fl m Ar MASK | Fl -mask= Ns Ar MASK
.Op Fl k Ar KEY | Fl -key= Ns Ar KEY
.Op Fl c Ar FILENAME | -config= Ns Ar FILENAME
.Op Fl p Ar PEERID | Fl -peer= Ns Ar PEERID
.Op Fl h | -help
.Op Fl L Ar LOGLEVEL | Fl -loglevel= Ns Ar LOGLEVEL
.Op Fl v | -version
.Sh DESCRIPTION
.Nm
enables you to compute a vectorproduct across two peers
.Sy Alice
and
.Sy Bob .
.Pp
A client can issue one of two messages to its service:
.Bl -enum -width 3n -offset indent
.It
A request to compute a vectorproduct with another peer (Alice)
.It
Elements to support a peer in computing a vectorproduct (Bob)
.El
.Pp
Both requests must share the same SID, which can be an arbitrary
string identifying the session. SIDs should be unique, however it is
sufficient to guarantee the uniqueness of the tuple element count and
session ID.
.Pp
Alice's client must supply the ASCII encoded peer ID of bob's
service, it will internally be checked by the client for
validity. Invalid values here result in the client or the service
failing the session.
.Pp
Elements are handed over as signed decimal integers, the element count
supplied by Alice and Bob must match. Alice can also
supply a mask for these values to her service, which allows partial
vector products to be computed across the vector. Elements can be
masked by setting their the corresponding mask element to zero, any
other value means the element will not be masked. Alice's
client will also mask all 0-values to avoid information leakage to
Bob.
.Pp
The protocol by definition relies on Alice and Bob being
benign, thus Bob can arbitrarily falsify his information. Both
peers collaborate to achieve a correct result.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl e Ar ELEMENTS | Fl -elements= Ns Ar ELEMENTS
The element-vector the vectorproduct should be computed over in
signed decimal form, eg: "42,1,-3,3,7".
Zero value elements will be automatically masked.
.It Fl m Ar MASK | Fl -mask= Ns Ar MASK
Elements in the vector can be masked.
There must be at least two elements left in the vector to
compute a vectorproduct.
Non-Zero values indicate an element is not maskes.
.It Fl k Ar KEY | Fl -key= Ns Ar KEY
The session key, a shared string of arbitrary length from which
the SID will be generated.
.It Fl c Ar FILENAME | Fl -config= Ns Ar FILENAME
Use the configuration file FILENAME.
.It Fl p Ar PEERID | Fl -peer= Ns Ar PEERID
The remote peer's ASCII-armored gnunet-peer ID as output by
.Xr gnunet-peerinfo 1 .
If this option is not given, the peer will take the Bob's role.
.It Fl h | -help
Print short help on options.
.It Fl L Ar LOGLEVEL | Fl -loglevel= Ns Ar LOGLEVEL
Use LOGLEVEL for logging.
Valid values are DEBUG, INFO, WARNING and ERROR.
.It Fl v | -version
Print GNUnet version number.
.El
.Sh SEE ALSO
.Xr gnunet-peerinfo 1
.sp
The full documentation for gnunet is maintained as a Texinfo manual.
If the
.Xr info 1
and gnunet programs are properly installed at your site, the command
.Pp
.Dl info gnunet
.Pp
should give you access to the complete handbook,
.Pp
.Dl info gnunet-c-tutorial
.Pp
will give you access to a tutorial for developers.
.sp
Depending on your installation, this information is also available in
.Xr gnunet 7 and
.Xr gnunet-c-tutorial 7 .
.\".Sh HISTORY
.\".Sh AUTHORS
.Sh BUGS
Report bugs by using
.Lk https://bugs.gnunet.org
or by sending electronic mail to
.Aq Mt gnunet-developers@gnu.org .