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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Post-quantum Key Exchange Protocol Using High Dimensional Matrix</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Richard Megrelishvili</string-name>
          <email>richard.megrelishvili@tsu.ge</email>
          <xref ref-type="aff" rid="aff3">3</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Avtandil Gagnidze</string-name>
          <email>gagnidzeavto@yahoo.com</email>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Melkisadeg Jinjikhadze</string-name>
          <email>mjinji@yahoo.com</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Giorgi Iashvili</string-name>
          <email>g.iashvili@scsa.ge</email>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Maksim Iavich</string-name>
          <email>m.iavich@scsa.ge</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Akaki Tsereteli State University</institution>
          ,
          <addr-line>Kutaisi</addr-line>
          ,
          <country country="GE">Georgia</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Caucasus University</institution>
          ,
          <addr-line>Tbilisi</addr-line>
          ,
          <country country="GE">Georgia</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Georia University</institution>
          ,
          <addr-line>Tbilisi</addr-line>
          ,
          <country country="GE">Georgia</country>
        </aff>
        <aff id="aff3">
          <label>3</label>
          <institution>I. J. Tbilisi State University</institution>
          ,
          <addr-line>Tbilisi</addr-line>
          ,
          <country country="GE">Georgia</country>
        </aff>
      </contrib-group>
      <fpage>83</fpage>
      <lpage>87</lpage>
      <abstract>
        <p>- Active work is being done to create and develop quantum computers. Google Corporation, NASA and the Universities Space Research Association (USRA) have teamed up with DWAFE, the manufacturer of quantum processors. D-Wave 2X is a quantum processor that contains 2,048 physical qubits. 1152 qubits from the whole number of qubits are used to perform the calculations. As we see, quantum computers can easily solve the problem of calculating the discrete logarithm used in DiffieHellman algorithm. So it can break Diffie-Hellman algorithm. When quantum computers are released all existing crypto systems will be useless, because there will be no way to transfer the key securely. In the article is proposed the new key exchange method using high dimensional matrix, this method is safe against attacks implemented using quantum computers. The case concerns the matrix function and algorithm for cryptographic keys exchange with open channel. For the algorithm is offered the method of building a high dimensional matrix multiplicative group. The arising of this goal is that traditional key exchange methods are vulnerable to quantum computer attacks.</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>But this problem can easily be solved by quantum computers
using Shor algorithm [1,2].</p>
      <p>The security of RSA algorithm relies on factorization problem,
but this problem can be easily solved using quantum computers
[3].</p>
      <p>Active work is being done to create and develop quantum
computers. Google Corporation, NASA and the Universities
Space Research Association (USRA) have teamed up with
DWAFE, the manufacturer of quantum processors. D-Wave 2X
is a quantum processor that contains 2,048 physical qubits. 1152
qubits from the whole number of qubits are used to perform the
calculations. As we see, quantum computers can easily solve the
problem of calculating the discrete logarithm used in
DiffieHellman algorithm. So it can break Diffie-Hellman algorithm.
When quantum computers are released all existing crypto
systems will be useless, because there will be no way to transfer
the key securely [4,5].</p>
      <p>In the article is proposed the new key exchange algorithm using
high dimensional matrix. This algorithm is safe against
quantum computer attacks.</p>
      <p>The case concerns the matrix function and algorithm for
cryptographic keys exchange with open channel.</p>
    </sec>
    <sec id="sec-2">
      <title>For this is offered the method building a high dimensional matrix multiplicative group.</title>
    </sec>
    <sec id="sec-3">
      <title>The arising of this goal is that traditional key exchange</title>
      <p>methods are vulnerable to quantum computer attacks.</p>
    </sec>
    <sec id="sec-4">
      <title>One-way function (OWF) is a function whose value is easy</title>
      <p>to calculate for any argument, but it is “difficult” to find an
argument for the given value of the function. The word
"difficult" is to understand the complexity of the computation.
In other words, finding the relevant argument of the given
function in real time is difficult even with the modern
computing techniques. The irreversibility of function does not
mean that the function is one-way [6,7].</p>
      <p>The existence of one-way functions is the basis for the idea
of asymmetric cryptography. It (one-way function) is the
foundation of asymmetric cryptography, personal
identification, authentication, and other fields of information
protection. Although there is no theoretical proof of the
existence of one-way functions in general, there are several
“possible pretendents” (eg, multiplication and factorization,
squaring and module rooting, discreet exponent and
logarithmization), whose one-wayity (ie the difficulty of
finding the argument for the value of function) at this time real
and is actively used in information exchange protocols.</p>
    </sec>
    <sec id="sec-5">
      <title>As we have mentioned, one-way functions are actively used</title>
      <p>in the algorithms for developing a cryptographic open key. The
initial idea (1976) belongs to Whitfield Duffie and Martin
Helman. Based of their idea was established the first practical
wel-known Diffie-Helman-Merkel method, which enabled the
development of a common cryptographic key using the open
(unprotected) channel. A year later, the first RSA algorithm of
asymmetric encryption was formed. The RSA in fact, resolved
the problem of exchange information with open channel. Both
algorithms are not safe against quantum computers attacks. Are
proposed quantum key exchange protocols, but quantum
computers are needed to implement them [8,9].</p>
    </sec>
    <sec id="sec-6">
      <title>II. ONE-WAY MATRIX FUNCTION</title>
      <p>
        The new one-way function for the development of common
cryptographic keys is based on high order cyclic matrix groups,
with the power  = 2 − 1 , where the n is row dimension of
the square matrix. Let's assume that "A" is the above matrix
group, while A is the initial  ×  matrix, then "A" = A={ ,  2,
 3, … ,  2 −1 =  } (
        <xref ref-type="bibr" rid="ref1">1</xref>
        )
where I represents an identity matrix.
      </p>
      <p>One-way function and algorithm for common key development
are as follows:
 The sender chooses  1 ∈ A secret matrix to send to the
receiving party via open channel the</p>
      <p>
        u 1 =   1 (
        <xref ref-type="bibr" rid="ref2">2</xref>
        )
vector where  ∈   vector is known (  – is a vector
space on GF field);
 The receiving party shall, on the other hand, choose
 2 ∈ A secret matrix and send to the sender
      </p>
      <p>
        2 =   2 (
        <xref ref-type="bibr" rid="ref3">3</xref>
        )
vector;
 Sender calculates  1 =  2 1 (
        <xref ref-type="bibr" rid="ref4">4</xref>
        )
vector;
 Receivier calculates  2 =  1 2 (
        <xref ref-type="bibr" rid="ref5">5</xref>
        )
where  1and  2 – are secret keys;
 Obviously,  1 =  2 =  , because
      </p>
      <p>
        =   1 2 =   2 1 (
        <xref ref-type="bibr" rid="ref6">6</xref>
        )
because of the commutativeness of the "A" group. The
   =  (
        <xref ref-type="bibr" rid="ref7">7</xref>
        )
is one-way fast function.
      </p>
      <p>
        Let  = ( 1,  2,  3, ⋯ ,   )∈   (
        <xref ref-type="bibr" rid="ref8">8</xref>
        )
and
 = ( 1,  2,  3, ⋯ ,   )∈   are non-secret vectors from
the above algorithm and
 11 ⋯  1
 1 = ( ⋮ ⋱ ⋮ ) ∈ A (
        <xref ref-type="bibr" rid="ref9">9</xref>
        )
  1 …  
is a secret matrix. Then, according to algorithm the following
system is formed:
(
        <xref ref-type="bibr" rid="ref10">10</xref>
        )
 1  1 +  2  2 + ⋯ +  3  3  
The number of unknowns in the system of linear equations is
the square of number of equations. Obviously, the system can
not be solved in limited time, if the size of the matrix is large
enough. Size of the matrix must be chosen considering Grover’s
algorithm. Classically, searching requires a linear search, which
is O(N) in time. Grover's algorithm needs O(N1/2) time, it is
considered as fastest quantum algorithm for searching an
unsorted information. This algorithm provides a quadratic
speedup [10,11].
      </p>
      <p>One fact must be taken into consideration if the  1 matrix
contains the internal recurrence, or if each of its rows are in a
certain recurrence with the previous row, then the task of
solving the system will be replaced by a simpler task that is easy
to solve. It is so important that it puts itself in doubt the
oneway character of our function and requires the existence of
Abelian multiplicative matrix group with a high order, that is
free from the recurrence of the inside.</p>
    </sec>
    <sec id="sec-7">
      <title>III. FINITE MATRIX GROUPS CONSTRUCTION</title>
      <p>Let's consider (1 +  ) , where j = 0,1,2, ⋯, and α represents
the root of primitive polynomial in the  (2 ) field odule with
the module p (x).</p>
      <p>(1 +  )0 = 1 1
(1 +  )1 = 1 +  11
(1 +  )2 = 1 +  2 101
(1 +  )3 = 1 +  +  2 +  3 1111
(1 +  )4 = 1 +  4 10001
(1 +  )5 = 1 +  +  4 +  5 110011
The polynomial coefficients generated the structure known as
Serpinsky Triangle. The derived structure contains a number of
sub-structures that can be used as a generator (generating
matrix) for multiplicative groups, ie primitive elements. Such
is, for example,
Lets keep the structure of  3 matrix and extend it by elements
 32( , )= ( 3</p>
      <p>0 ) =
Fore example, when  = 5 and  = 6, we have
0 ), where i,j=0..6. (13)
0
 36  36 0
take
into
consideration
that
the
set
each sub-matrix of the</p>
      <p>
        matrix is in the the same set:
0, 30, 31, 32, 33, 34, 35, 36 is a field, it is easy to assure that
 1,1 =  35 ×  35 +  36 ×  36 +  36 ×  36 =  33,
 1,2 =  35 ×  36 +  36 × 0+  36 ×  36 =  32,
 1,3 =  35 ×  36 +  36 × 0+  36 × 0 =  34,
 2,1 =  36 ×  35 + 0×  36 + 0×  36 =  34,
 2,2 =  36 ×  36 + 0× 0+ 0×  36 =  35,
 2,3 =  36 ×  36 + 0× 0+ 0× 0 =  35,
 3,1 =  36 ×  35 +  36 ×  36 + 0×  36 =  32,
 3,2 =  36 ×  36 +  36 × 0+ 0×  36 =  35,
365, 438, 511 are diagonal matrices (see pic. 3):
0 0  33
0
0
0 ),( 0
0 ),( 0
0
 30
0
0
0
 30
0  36
0  30
0
0 ),
0
0 )
Pic.3 : [ 32(
        <xref ref-type="bibr" rid="ref5 ref6">5,6</xref>
        )] , = 73,146,219,292,365,438,511
511, are diagonal matrices(pic 4):
      </p>
      <p>
        Also  32(
        <xref ref-type="bibr" rid="ref1">0,1</xref>
        )matrix is a primitive element, and elements
of the set [ 32(
        <xref ref-type="bibr" rid="ref1">0,1</xref>
        )] , when k=73, 146, 219, 292, 365, 438,
0 0  34
      </p>
      <p>
        0
0
 30
0 )
0
0 )
0  30
pic.4: [ 32(
        <xref ref-type="bibr" rid="ref5 ref6">5,6</xref>
        )] ,  = 73,146,219,292,365,438,511
primary group) and one of the elements is  30
.
      </p>
      <p>Set of non-zero elements of the diagonal matrices represents the
perturbation of the group  30,  31,  32,  33,  34,  35,  36 (called as
Finally, we can conclude that empirically we proved the
following fact:</p>
      <sec id="sec-7-1">
        <title>The second order ( ,  + 1)expansion  3</title>
        <p>
          of the matrix  3 is a primitive element and creates the Abelian
multiplicative finite group  ( 32( ,  + 1)), with the power
Below we can see other primitive elements that are results of
0 ),
0 ),
0 )
0
0 )
0 )
0 )
0
 32(
          <xref ref-type="bibr" rid="ref6">6,0</xref>
          )= ( 30
0 ) (17)
group  ( 3
order expansion).
        </p>
      </sec>
    </sec>
    <sec id="sec-8">
      <title>In order to get higher order primitive elements, we still</title>
      <p>retain the structure of  3 matrix and put into the elements of the
2( ,  + 1)). We get 33 order matrix (call it a third
following matrix (pic. 5):</p>
      <p>
        For example, if we use the elements of group  ( 32(
        <xref ref-type="bibr" rid="ref1">0,1</xref>
        ))
for the first and second expansions of the matrix of  3 ,
respectively [ 32(
        <xref ref-type="bibr" rid="ref1">0,1</xref>
        )]0 [ 32(
        <xref ref-type="bibr" rid="ref1">0,1</xref>
        )]1 matrices, we get the
pic.5.  33(
        <xref ref-type="bibr" rid="ref1">0,1</xref>
        )
      </p>
      <p>0 ) =
0 )
0 )
0 )
0</p>
      <p>0
( 31
0 )
0
0 )
0
( 31
 31
0
 31
0
0
0 )
0
)
(18)</p>
      <p>
        Let's consider [ 33(
        <xref ref-type="bibr" rid="ref1">0,1</xref>
        )] set. It has the same basic
structure  3 as the primary group, as well as the first and second
expansion matrices taken from the primary group. It is expected
that this set is characterized by the same properties as the
primary group has. Indeed, experimentally, it also has diagonal
matrices, whose diagonal elements represent one of the
perturbations of the primary group.
      </p>
      <p>For
the
set</p>
      <p>32 − 1, we get the final element of the set</p>
      <sec id="sec-8-1">
        <title>We see that this is an Identity matrix. Therefore  33(0,1)</title>
        <p>finite group with power 233 − 1.</p>
        <p>Definition: We call the following matrix
 3 ( ,  + 1)= ( 3+1
 −1
)</p>
        <p>(20)
 3 −1
 3+−11
 3+−11</p>
        <p>0
 3+−11
 3+−11
0
0
where</p>
        <p>3 −1 ∈  ( 3 −1( ,  + 1)), as the kth order ( ,  + 1)
expansion of the  3 matrix.</p>
        <p>Theorem:  3 ( ,  + 1)is a primitive element and creates the
multiplicative finite group  ( 3 ( ,  + 1))
with
abelian
power 2
elements are one of the permutations of the elements of the
 (22∙3 −1+23 −1+1)=
[ 3 ( ,  + 1)]
= [ 3 ( ,  + 1)]
= [ 3 ( ,  + 1)]</p>
        <p>[ 3 –1( ,  + 1)]
=
(
(21)</p>
      </sec>
    </sec>
    <sec id="sec-9">
      <title>This means that (3) the structure is a primitive matrix. The</title>
      <p>
        primitive matrices obtained have an interesting fractal structure
(see pic. 6). Abelian multiplicative groups adopted by the above
mentioned method represent sufficient sets for realizing our
one-way matrix functions
pic.6.  34(
        <xref ref-type="bibr" rid="ref1">0,1</xref>
        )
      </p>
    </sec>
    <sec id="sec-10">
      <title>IV. CONCLUSION</title>
      <sec id="sec-10-1">
        <title>Basic  3 matrix  3 ( ,  + 1) expansions are primitive</title>
        <p>matrices they generate abelian multiplicative matrix groups.</p>
        <p>An interesting trend of research results in the idea: use the
elements of the primary field as the first and second expanding
matrices with the same characteristic polynom. It is also
important the use of other baseline matrices, which enlarges a
new type of primitive structures. Elements of abelian
multiplicative matrix groups can be used in implementation of
one way function, that we offer. So the key exchange method is
got and it is secure against quantum computers attacks.</p>
      </sec>
    </sec>
    <sec id="sec-11">
      <title>ACKNOWLEDGEMENT The Work Was Conducted as a Part of Research Grant of Joint Project of Shota Rustaveli National Science Foundation and Science &amp; Technology Center in Ukraine [№ STCU-2016-08]</title>
    </sec>
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