=Paper= {{Paper |id=Vol-3200/paper2 |storemode=property |title=Using the Sum of Real Type Functions to Encrypt Messages |pdfUrl=https://ceur-ws.org/Vol-3200/paper2.pdf |volume=Vol-3200 |authors=Viktor Avramenko,Mykyta Bondarenko }} ==Using the Sum of Real Type Functions to Encrypt Messages== https://ceur-ws.org/Vol-3200/paper2.pdf
Using the Sum of Real Type Functions to Encrypt Messages
Viktor Avramenko1, Mykyta Bondarenko2
1,2
   Sumy State University, Rymskogo-Korsakova st. 2., Sumy, 40007, Ukraine


                  Abstract
                  This paper presents a symmetric key cryptosystem using the sum of real type functions which
                  allows to increase the cryptographic strength. Both transmitter and receiver choose Key
                  Functions with the same argument, the interval for setting the argument, and the step for
                  changing it. The symbol of the transmitted message is encrypted in an array where each
                  element is the sum of Key Functions with random amplitudes. This sum includes those Key
                  Functions for which the corresponding bit is one. Decryption uses disproportion functions. The
                  system is suitable for encrypting both discrete and continuous messages.

                  Keywords 1
                  Cryptosystems, disproportion functions, function of real variable, key functions, encryption,
                  decryption, text messages

1. Introduction                                                                              systems, but it’s not promising due to the
                                                                                             intensive development of the quantum computers
                                                                                             [7], which will significantly affect the
    Widely used cryptosystems are based on the
                                                                                             cryptographic strength of existing cryptosystems
set of integers. They implement symmetric and
                                                                                             [8]. The ordinal brute force has complexity O(2k),
asymmetric encryption algorithms. In symmetric
                                                                                             meanwhile Grover's quantum algorithm [9]
systems, the same key is used for both encryption
                                                                                             reduces it to O(2k/2) [9].
and decryption. The most famous symmetric
                                                                                                 Implementing quantum algorithms will also
systems are AES [1] and GOST 28147-89 [2, 3].
                                                                                             reduce the robustness of asymmetric systems. The
To hack such a system, an enumeration of
                                                                                             RSA system uses the super polynomial
possible keys is required. The brute-force
                                                                                             computational complexity of the factorization of
complexity is O(2k), where k is the key length in
                                                                                             natural numbers. At the same time, there is a
bits. For symmetric systems, if the
                                                                                             quantum algorithm whose complexity is
communication channel is open, there is a
                                                                                             polynomial O(n3) [10]. It means the cryptographic
problem of secure key transmission. This problem
                                                                                             strength of asymmetric systems can be reduced as
does not exist for asymmetric open key systems.
                                                                                             a result of the implementation of Shor's quantum
In these systems, the most widely used algorithms
                                                                                             algorithm for computing the discrete logarithm. In
are RSA and El-Gamal [4, 5]. The RSA algorithm
                                                                                             [11], Shor's algorithm is given for the group of
is based on the computational complexity of the
                                                                                             points of an elliptic curve over the field GF(p)
integer factorization problem. El-Gamal's
                                                                                             with complexity O(n3). Implementing quantum
algorithm is based on the difficulty of computing
                                                                                             algorithms will also reduce the robustness of
the discrete logarithm, especially over a group of
                                                                                             asymmetric systems. A method for increasing the
points of an elliptic curve [6]. For breaking
                                                                                             crypto resistance of the system under these
asymmetric       cryptosystems,      there     are
                                                                                             conditions is proposed in [12]. Along with the
cryptanalysis methods which are faster than full
                                                                                             search for ways to hack cryptosystems, methods
search. This circumstance makes it necessary to
                                                                                             for detecting signals of means of secretly
use longer keys compared to keys in symmetric

III International Scientific And Practical Conference “Information
Security And Information Technologies”, September 13–19, 2021,
Odesa, Ukraine
EMAIL: vv.avramenko@cs.sumdu.edu.ua (A.1);
nikbond97@gmail.com (A. 2)
ORCID: 0000-0002-6317-6711 (A. 1); 0000-0002-8849-7378
(A. 2)
              © 2021 Copyright for this paper by its authors. Use permitted under Creative
              Commons License Attribution 4.0 International (CC BY 4.0).

              CEUR Workshop Proceedings (CEUR-WS.org)
obtaining information are also being developed             The cryptosystems [15-18] in the process of
[13].                                                   computer      modeling      have    shown      high
    The above analysis shows that one should look       cryptographic strength when trying to guess the
for other ways to create cryptosystems. In              parameters of keys functions, even if their form is
particular, to complicate the selection of keys         known. To further complicate the work of
using the simple enumeration method, one should         cryptanalysts, the task is to develop a
switch from using integers to real ones. It is          cryptosystem that could combine the advantages
known [14] the set of real numbers has a higher         of the systems considered in [15-17] and the
cardinality compared to the set of natural              system [18]. So, it’s necessary to develop the
numbers, so one can expect the cryptographic            algorithms for encryption and decryption of
strength of a cryptosystem based on real numbers        analog and discrete messages, using several
will be higher. The possibilities of creating           functions of a real variable as keys without the
cryptosystems using one or more functions of a          necessity to calculate derivatives.
real variable as keys are considered in [15-18].
    So, in [15], characters from the ASCII code         2. Mathematical formulation of the
table are encrypted by the sum of 10 functions of
a real variable, which are keys. Each key-function         problem
is preceded by a coefficient, which, depending on
the character being encrypted, is equal to zero or         The message that is encrypted is a sequence of
one. The amplitudes of these functions are random       T numeric character codes from the ASCII table
for each new symbol. The resulting sum of the           (or numeric values of the pixel brightness
values of the functions is transmitted over the         components in the case of a graphic image
communication channel. On the receiving side,           transmission). Each of them is encrypted using
fragments of key functions are recognized, which        one-dimensional arrays of length N values. These
are represented in the received encrypted signal.       arrays are obtained using one and the same step h
This allows you to decrypt the symbol transmitted       of changing the argument of m Key Functions of
at the current time using the disproportion             the real variable. In this case, the value y(j, i) of
functions [19-22].                                      the matrix y(T, N) has the form:
    In [16, 17], a variant is proposed when                          ,                       ,
                                                                                                         (1)
symbols for transferring binary codes are encoded
with the help of three key functions of a real          where:
variable. "1", "0", "space", "new line" are             j is the number of the character in the transmitted
encoded. Any other character is recognized as a         message;
new line. For unauthorized access to the                fq(i) = fq(ih), (i = 1, 2, … N > m), (q = 1, 2, … m)
intercepted message, you need to select the type        - an array of values of the q-th Key Function;
and parameters of the key functions.                    kqj - coefficients that are generated during
    In [15-17], the disproportion functions over the    encryption of the j-th element and can be either
first-order derivative were used. In this case, it is   equal to zero or represent random numbers which
necessary to apply numerical methods for                are unknown to the recipient.
calculating the current values of the first                 Key Functions can be either continuous or
derivatives. The need for these calculations led to     discrete. These functions should be the same for
the fact that the ciphertext significantly exceeded     the transmitting and receiving sides and have the
the length of the encrypted message.                    same numbering. Also, the step h of changing the
    A completely different encryption principle         argument of the Key Functions should be the
was proposed in [18]. One function of the real          same. An encrypted message in the form of a
variable is used as the key. The disproportion          matrix y(T,N) is transmitted over an open
function of the numerical representation of the         communication channel. The task is to decrypt the
encrypted process is calculated with respect to the     message using the matrix received at the receiving
key function. The obtained values of the                end. To solve it, the integral disproportion of the
disproportion function are an encrypted message         first order is used [23].
and are transmitted over the communication
channel. To avoid calculating the derivatives, the
integral disproportions of the first order is used      3. Disproportion functions
[23].
   One of the first publications in which                    In this case, y(x) and f(x) are represented by
disproportion functions were proposed was [19].          one-dimensional arrays. If the approximate values
In particular, the disproportion with respect to the     of the integrals in (6) are calculated using the
n-th-order derivative of the function y(x) with          trapezoid formula, then for the one and the same
respect to x is described by the expression:             step h for y(x) and f(x), disproportion (6) takes the
                            1                            following form (7):
                                                 (2)
         @                     ⋅     ,                            @                            ,
                                                                                                          (7)
                             !
    Here the @ symbol is chosen to denote the
operation of calculating disproportion. The
symbol "d" stands for "derivative". The order is         4. Encrypting            and         decrypting
indicated in parentheses. The left part (2) reads "et       messages
d n y with respect to x". The order n ≥ 1 is an
integer. If for any value of x, the function y(x) has
                                                            The transmitting and receiving sides must have
the form y = kxn, then disproportion (2) is equal to
                                                         the same system of m Key Functions of the real
zero regardless of the value of the coefficient k.
                                                         variable, their numbering, the interval of changing
    For the case when n = 1,
                                                         the argument and step h of its change. The number
                                                 (3)
              @                    ,                     of elements N of the one-dimensional array
                                                         corresponding to the encrypted character must
   For defining the functions parametrically,            also be set. These can be both characters from the
when, x = φ(t), y = ψ(t), where t is a parameter,        ASCII table, and components of pixel brightness
disproportion (3) is described by the expression         when transmitting color graphic images. Each of
                                              (4)        them is represented by an integer. The required
      @                                ,                 number of Key Functions depends on the
                                                         maximum value of this number. For example, to
                                                         encrypt characters from the ASCII table, m = 8
   For ψ(t) = kφ(t) disproportion (4) is equal to        Key Functions are required. They can be either
zero in the entire area of existence x = φ(t),           continuous or discrete. If the Key Functions are
regardless of the value of k. In [19], the case was      continuous, it is necessary to calculate N elements
considered when                                          of one-dimensional arrays of their values,
                                      ⋯         (5)      changing the argument from the initial xmin to the
                                    ,                    final xmax value with a step h. When encrypting
    where f1(x), f2(x), … fm(x) are known                characters from the ASCII table or the pixel
functions; k1, k2, … km are coefficients whose           brightness, their numerical representations differ
values are unknown.                                      by one. In these cases, the step h of changing the
    It is shown that the disproportion functions         argument must be equal to one.
allow calculating the values of the unknown                 An m-bit binary code corresponds to each
coefficients in (5) from the data obtained for the       encrypted character. Each bit in this code is
current value of the argument. This opportunity is       associated with a specific number of the Key
used to create cryptosystems [15-17].                    Function. If the bit is zero, the value of the
    In practice, often the first derivative of the       corresponding Key Function is also zero. If the bit
function does not exist or is equal to zero on some      is equal to one, then a random value of the
interval. This excludes the possibility of using         amplitude of the corresponding Key Function is
disproportions over the first-order derivative (2-       played. The character to be encrypted is
4). In this case, it is advisable to use the integral    represented by the sum (1).
disproportion of the first order [23]. This
disproportion of the function y(x) with respect to       4.1.    Encrypting messages
f(x) has the form:
                                                 (6)        1. The following is a character encryption
    @                                      ,             algorithm:
                                                            2. Calculate arrays of N > m values of Key
where h - is the preset time interval. In the discrete   Functions: fq(x), q = 1, 2… m.
representation of signals, this is a time                   3. Enter the encrypted j-th character and
quantization step.                                       calculate its cipher in the form of values of the
one-dimensional array y(j, i), i = 1, 2... N                           ,             @                    ,                       (13)
                                                                                              ,
according to (1).                                                       ,            1            ,                   ,
   4. Repeat this point for all characters of the                                                                             ,
message of length T.                                                    ,            1            ,
   5. A sequence of T arrays is an encrypted
message transmitted over an open communication                  Taking into account that the disproportion of
channel.                                                     F21(j, i) with respect to F21(j, i) is equal to zero, we
                                                             get:
4.2.     Decrypting messages                                           F      j, i   k            j, i ,        (14)

                                                                 Third level: The disproportion of F0121(j, i)
    Pre-compute the arrays fq(i) = fq(ih),
                                                             with respect to F3121(j,i) is calculated in the
(q = 1, 2, ... m), (i = 1, 2, ... N > m), of Key
                                                             following way
Functions and to receive T one-dimensional
                                                                          ,     @                 ,    (15)
arrays y(j , i), j = 1, 2, ... T, i = 1, 2, ... N over the                                            ,
communication channel. Further, in order to                                 ,        1                    ,
simplify the description of the decryption process,                         ,        1                    ,
an example is given when only three functions are                            ,
used in the cryptosystem - the keys: f1(x), f2(x),                                       0,
f3(x). In this case m = 3. Accordingly, the j-th
                                                                It is equal to zero because, as can be seen from
character of the message is encrypted as
                                                             (14), there is a proportional relationship between
     ,                                             , (8)
                                                             F0121(j, i) and F3121(j, i). This fact allows
                          1, 2, …        3,                  calculating from (14) k3j and k2j, k1j for the j-th
    The process consists of m = 3 levels in                  message symbol.
accordance with the number of Key Functions.                                             ,                 (16)
    First level: It is necessary to calculate the array                                      ,
of disproportions (7) y(j,i) with respect to any of
the Key Functions , for example, f1(i):
              ,       @            ,                  (9)                                ,                    ,                   (17)
                                                                                                                  ,
           ,  1        ,        ,
                                    ,
              1
where i = 2, 3…N.                                                                ,                                                (18)
                                                                                                                          ,
   Also calculate the disproportions (7) of the
remaining key functions with respect to f1(i):                   Depending on which of these coefficients are
        ,     @          ,                   (10)            nonzero and which are equal to zero, the j-th
           ,     1           ,           ,                   message symbol is decrypted. In practice, it must
                                             ,               be taken into account that there are calculation
                 1                                           errors.
where r = 2, 3.                                                  Therefore, it is necessary to compare the
   Considering that the disproportion of the                 disproportion (15) calculated at the last level in
function relative to itself is zero, we get:                 modulus not strictly with zero, but with an
       ,                ,               , , (11)             approximate number ɛ. For example, it could be
   Second level: It is necessary to select any               ɛ=10-4. In this case, if | F01213121(j, i) | <= ɛ, then it
disproportion from right-hand of (11), for                   should be assumed that it is zero.
example F21(j, i). It is used to calculate next                  The value of ɛ is determined during testing of
disproportions:                                              the      cryptosystem.         Theoretically,         this
         ,      @                ,             (12)          disproportion is equal to zero for all i = 2, 3, ... N,
                        ,
          ,     1            ,          ,                    but, taking into account the calculation errors, it is
                                             ,               recommended to do calculations using formulas
          ,     1            ,
                                                             (16-18) for i, at which the modulus of
                                                             disproportion (15) is minimal.
4.3. An example of encrypting and                       select the form of eight Key Functions and the
                                                        values of their parameters.
decrypting characters from an ASCII
table                                                   Table 1
                                                        Encrypted and decrypted characters “Hello”
    Eight Key Functions are used (m =8):                 y    ‘H’           ‘e’           ‘l’           ‘l’            ‘o’
    1. f1(x) = 1000 sin((α1 - β1)x) cos(wβ1x)           0
                                                        1
                                                              ‐323.36050
                                                              257.702939
                                                                            ‐1096.0141
                                                                            167.391848
                                                                                          ‐872.47149
                                                                                          1051.01033
                                                                                                        37.134528
                                                                                                        532.400561
                                                                                                                      ‐112.93721
                                                                                                                      427.740614
    2. f2(x) = 1000 exp(0.1α2x) sin(wβ2x)               2     57.298613     175.907791    ‐408.37541    ‐216.26334    ‐116.65218
                                                        3     ‐165.32821    126.358160    ‐324.75198    ‐162.19800    ‐197.22270
cos((α2 + β2)x)                                         4     ‐186.82906    ‐394.77504    ‐929.02530    ‐439.94548    ‐449.01146

    3. f3(x) = 1000 exp(-α3x) sin(wβ3x)                 5
                                                        6
                                                              ‐163.70378
                                                              37.446166
                                                                            ‐392.33753
                                                                            299.880685
                                                                                          ‐1059.2853
                                                                                          370.310135
                                                                                                        ‐385.85981
                                                                                                        74.675455
                                                                                                                      ‐170.75848
                                                                                                                      44.746439
    4. f4(x) = 1000 cos((α1x - β1)x) sin(wβ1x)          7
                                                        8
                                                              ‐110.70494
                                                              ‐2.714026
                                                                            426.787248
                                                                            ‐59.278796
                                                                                          ‐218.90900
                                                                                          115.564604
                                                                                                        ‐238.68403
                                                                                                        ‐2.371129
                                                                                                                      ‐314.75860
                                                                                                                      ‐165.23427
    5. f5(x) = 1000 exp(0.1sin(α2x)) sin(w              9     9.436954      152.916970    116.697501    ‐23.361501    281.220083
                                                        10    42.465400     ‐412.02347    ‐203.82595    84.424717     150.029168
cos(βx)) cos((α2+β2) x)                                 11    ‐24.295297    615.002251    349.117675    ‐42.371452    ‐231.55086
    6. f6(x) = 1000 sin(-cos(α3x)) cos(w                12
                                                        13
                                                              101.570285
                                                              195.422364
                                                                            95.754178
                                                                            132.219196
                                                                                          543.764259
                                                                                          855.514365
                                                                                                        227.452661
                                                                                                        432.359247
                                                                                                                      ‐122.68102
                                                                                                                      754.345004
sin(β3x))                                               14
                                                        15
                                                              ‐11.067358
                                                              214.445079
                                                                            ‐507.14921
                                                                            264.682389
                                                                                          ‐252.27430
                                                                                          659.731238
                                                                                                        ‐29.696351
                                                                                                        467.369970
                                                                                                                      228.457327
                                                                                                                      ‐63.039751
    7. f7(x) = 1000 sin(wx + α1) exp(-β1x2)
    8. f8(x) = 1000 cos(wγx2)
                                                        Table 2
where α1 = 1, α2 = 0.12, α3 = 0.5, β1 = 0.1,
β2 = 1.5, β3 = 0.7, γ = 0.5, w = 400 are constants.     Encrypted and decrypted characters ‘A’
                                                         y          ‘A’           ‘A’           ‘A’           ‘A’            ‘A’
    A sequence of numbers corresponding to the          0    ‐597.135343   ‐762.540347   ‐609.489179   ‐1245.052456   ‐917.400855
transmitted characters from the ASCII code table        1    9.473961      ‐6.667141     ‐2.760240     ‐37.310266     ‐17.407304

is encrypted. Each character is encoded by a sum        2
                                                        3
                                                             274.695430
                                                             15.193014
                                                                           368.229254
                                                                           87.216540
                                                                                         291.933312
                                                                                         60.428145
                                                                                                       625.796927
                                                                                                       237.898008
                                                                                                                      451.736269
                                                                                                                      138.849052
of Key Functions                                        4
                                                        5
                                                             ‐123.497929
                                                             ‐58.830278
                                                                           ‐217.377766
                                                                           ‐107.584825
                                                                                         ‐165.579209
                                                                                         ‐81.548078
                                                                                                       ‐438.953490
                                                                                                       ‐221.367775
                                                                                                                      ‐291.370618
                                                                                                                      ‐145.669069
   y x            x           x          x       (19)   6    ‐8.280530     ‐11.911812    ‐9.337867     ‐21.332769     ‐14.999968
                                                        7    199.488556    342.700766    261.876769    683.403833     456.291669
                              x          x              8    ‐76.316724    ‐131.227388   ‐100.265637   ‐261.818697    ‐174.769533

                               x         x              9
                                                        10
                                                             ‐60.158608
                                                             ‐125.104506
                                                                           103.377062
                                                                           ‐215.011307
                                                                                         78.993047
                                                                                         ‐164.292499
                                                                                                       ‐206.183725
                                                                                                       ‐428.868345
                                                                                                                      137.653657
                                                                                                                      ‐286.313719
                               x ,                      11
                                                        12
                                                             214.641127
                                                             ‐14.047252
                                                                           368.892513
                                                                           24.142272
                                                                                         281.874942
                                                                                         18.447384
                                                                                                       735.803375
                                                                                                       ‐48.154847
                                                                                                                      491.224813
                                                                                                                      ‐32.148341
where:                                                  13
                                                        14
                                                             6.530344
                                                             ‐223.052958
                                                                           11.223364
                                                                           ‐383.349601
                                                                                         8.575899
                                                                                         ‐292.921754
                                                                                                       22.386440
                                                                                                       ‐764.640006
                                                                                                                      14.945262
                                                                                                                      ‐510.476209
x = ih – argument;                                      15   169.891087    291.983039    223.107534    582.397666     388.810617

h = 1 – step of changing the argument.
i – is the ordinal number of the element of the             Below is an example that illustrates the
one-dimensional array for each of the Key               resistance of the system obtaining keys, even if
Functions, as well as the array y0, y1, ..., yN-1,      somehow it was possible to find out the forms of
which is the character cipher;                          Key Functions. Suppose that the above sequence
N – a number of elements of each one-                   of characters is encrypted using functions (7), and
dimensional array. Based on the requirement of          decrypted using the same kind of functions, but
N > m, the amount of array elements N = 16.             the constant w was guessed incorrectly. Instead of
    Table 1 shows the transmitted characters in the     w = 400 was used w = 399.999 during decryption.
upper horizontal line. The corresponding ciphers        In this case, the disproportion at the last eighth
are given in the form of arrays arranged vertically.    level in absolute value exceeds the permissible
The decrypted characters are located horizontally       deviation ɛ from zero. That is, decryption is
on the bottom line.                                     impossible. Only if w = 399.9999, the message
    It is obvious that the received message matches     may be decrypted. This result shows that even
the transmitted one. It should be noted that the        such a slight deviation of one of the parameters of
ciphers (arrays) of the adjacent symbols `t` are        the Key Functions does not allow decryption of
completely different.                                   the transmitted character.
    The codes of the other adjacent identical
symbols in the message are given in Table 2. The        5. Requirements for Key Functions
above results indicate that the ciphers of the
adjacent identical symbols in the message differ
from each other. This circumstance greatly                 1. The Key Functions must be of real type.
complicates the "hacking" of the cryptosystem. In          2. They can’t be constant and must not take
order to "crack" the message, it is required to         zero values.
                                                           3. When using the key function, there
                                                        should be no situation where division by a number
close to zero occurs, which leads to an                [1] National Institute of Standards and
unacceptable calculation error. For this purpose, it        Technology,      Specification     for    the
is recommended to test the cryptosystem for the             ADVANCED ENCRYPTION STANDARD
entire alphabet of characters that will be used in          (AES) (2001). doi: 10.6028/NIST.FIPS.197.
messages.                                              [2] GOST 28147-89. Sistemy obrabotki
    4. Check that the sum of two or more key                informacii. Zashhita kriptograficheskaya.
functions does not coincide with any other of the           Algoritm                 kriptograficheskogo
key functions.                                              preobrazovaniya [Information processing
    5. It is recommended to include all                     systems.      Cryptographic       protection.
parameters in the expression for each key                   Cryptographic Transformation Algorithm],
function. In this case, a change in the value of any        1990.
parameter leads to a change in all key functions,      [3] A. N. Lebedev, Kriptografiya s «otkrytym
but not one or several of them only.                        klyuchom»        i     vozmozhnosti        ee
    6. Before sending an encrypted message,                 prakticheskogo primeneniya [Cryptography
first check what the decrypted message looks like           with "public key" and the possibilities of its
in order to avoid errors that may occur as a result         practical application], Zashhita informacii.
of not taking into account the previous points.             Konfident 2 (1992)
                                                       [4] R. Rivest, A. Shamir, I. Adleman, A method
6. Conclusions                                              for obtaining digital signatures and public-
                                                            key cryptosystems, Communications of the
                                                            ACM,           1978,          21(2):120-126.
    A cryptosystem with symmetric keys is
                                                            doi:10.1145/359340.359342.
proposed. These keys are real variable functions
that satisfy the above constraints. They can be        [5] I. D. Gorbenko., Y. I. Gorbenko, Prykladna
either continuous or discrete. The number of                kryptolohiya [Applied Cryptology], Fort,
functions is equal to the number of binary digits           NURE, Kharkiv, 2012, p. 878.
used to encrypt a character, for example, in an        [6] D. R. Hankerson, S. A. Vanstone and A. J.
ASCII table. Each of the functions corresponds to           Menezes., Guide to elliptic curve
a certain binary digit. The symbol of the                   cryptography, Springer, New York, 2003, p.
transmitted message is encrypted with a one-                311.
dimensional array. The elements of this array          [7] T. D. Ladd, F. Jelezko, R. Laflamme, Y.
represent the sum of Key Functions with random              Nakamura, C. Monroe, J. L. O’Brien,
amplitudes. This sum includes those Key                     Quantum Computing, Nature, 464 (2010)
Functions, for which the corresponding binary               45—53. doi: 10.1038/nature08812.
digit is equal to one.                                 [8] P. G. Klucharev, Kvantovyj komp'yuter i
    Decryption is performed using disproportion             kriptograficheskaya stojkost' sovremennyx
functions. The possibility of encryption and                sistem shifrovaniya [Quantum computer and
decryption of text information is shown. The                cryptographic strength of modern encryption
given examples show the complexity the guessing             systems], Herald of the Bauman Moscow
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