User Identification
in
Speech
and
Cipher
Synchronization
Infomation
Hiding
Geng
Zhao,Ping
Xu
Communication Engineering Department
Beijing Electronic Science
&
Technology institute
Beijing, China,
100070
zgk2besti.edu.m
,
xp@besti,edu.cn
Absimcf-User identification must be done
in
speech
information hiding.
To
shorten the time
of
building link
and
exchanging protocol, this paper presents
a
technology for
fast
cross-identification.
To
enhance the security of communication,
encryption should be done before hiding information. After
encryption, secure info
is
hidden
in the
host
info which has
been recorded.
Bccause
speech communications arc
on
thc
full-duplex synchronization link
and
have
burst
of
communications,
,so
we
use
the
same encryption nnd
decryption algorithms on both sides to
avoid
increasing
operation spending which will
bc
caused
if
using different
encryption and decryption algorithms.
A
strict
synchronization algorithm
is
requested,
50
the
cycle buffcr
synchronization algorithm is presented.
I.
INTRODUCTION
Information hiding
is
a new and important research field
in info security.
Its
main researches are the methods of
hiding
special
info into digital
info,
such
as
text, digital
voice
and
video. Secure info
is
embedded .into host info
which seems
to
be
natural
and
public. Attacker can't judge
directly that whether the info he
is
monitoring contain secure
info
or
not. Secure info can't be seen if without special
treatment. Only when secure info
is
separated from the info
on host, then. it can entirely be recovered without any
loss.
Using info hiding technology, we can hide the secure info in
the host info which
is
public,
so
the
technology
can
be
broadly used
in
many important occasion,
such
as
secret-
keeping
of
info, encryption-hiding
of
info, even copyright
protect and digital watermark in user identification.
The
algorithm ofhiding info
is
reported in many literal,
such
as
LSB
algorithm['], Patchwork
algorithmt'I,spread-spectium
hiding algorithm[31. Although
info
hiding isn't easy
to
be
detected, security
of
info can't be guaranteed
if
detected.
So
speech hiding communication must use user identification
before formal communication and the secure info that
is
hidden should be pre-encrypted. Speech communication
is
on
the full-duplex synchronization link.
So
we must spend
1
Yi-Xin Liu
Information Engineering School
University
of
Science
and
Technology of Beijing
Beijing, China.
100083
long.time
to
build link and exchange protocol.
To
shorten
the time,
the
paper presents two methods
of
fast cross-
identification. Since the communication
is
duplex and the
request for communication is sudden, cryptogram should be
synchronized.
In
the traditional methodstwe
use
one chip for
encryption and decryption respectively.
To
lessen
spending
and
cost,
we
only
use
a symmetrical
key
encryption
and
,
decryption chip and present cycle-buffer synchronization
algorithm.
11.
INFO
HIDING
When sending speech info that
is
to be hidden,
it
is
converted with
AID
in coder
by
214
transition and-echo
counteract
loop,
and compressed and encoded
by
speech
processor, then the info
is
encrypted
by
encryption
,.algorithm with DSPand hidden on the recorded
host
info by
':he least
bit
(LSB
info hiding algorithm). Then
if
is
sent
to
PSTN
network
by
Modem
and
412
transition loop.
When
receiving the hidden speech
info
from
PSTN,
we
will
transit
it by
4/2
transition loop and then send it
to
modem. The
extraction and decryption
of
hidden info
are
controlled
by
DSP,
Then the hidden info
is
sent to speech processor and
decompressed. It
is
converted with
D/A
in decoder. The
speech info
is
recovered and
sent
to
phone by
2/4
transition
circuit. It is illustrated in
fig.1.
To
insure validity on both
communication sides, user identification should
be
done
before calling.
At
the
same time, the
info
to
be
hidden
is
encrypted before hiding. For speech communication on the
full-duplex
synchronization link, traditional encryption and
decryption are realized in
a
encryption and decryption chip
respectively at
both
sides.
We
only
use
a
encryption and
decryption chip
at
both
sides
to
simplify circuit. Due to the
characteristic
of
full-duples synchronization link, an
algorithm must
be
designed
to
synchronize encryption and
decryption in info-hiding
so
that
useful info
can
be
extracted
from
the hidden info.
This
work
was
financially
suppolfed
by
the
National
Science
Foundation
ofChina
(No70371068.
No70431002)
and
the
Key
Lab
Found
(YCHI)
of
Beijing Electronic Science
&
Technology
Institute
0-7803-901 5-6/05/$20.00
Q200.5
IEEE.
865