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Independent Submission V. Dolmatov, Ed. Request for Comments: 7801 Research Computer Center MSU Category: Informational March 2016 ISSN: 2070-1721

            GOST R 34.12-2015: Block Cipher "Kuznyechik"

Abstract

 This document is intended to be a source of information about the
 Russian Federal standard GOST R 34.12-2015 describing the block
 cipher with a block length of n=128 bits and a key length of k=256
 bits, which is also referred to as "Kuznyechik".  This algorithm is
 one of the set of Russian cryptographic standard algorithms (called
 GOST algorithms).

Status of This Memo

 This document is not an Internet Standards Track specification; it is
 published for informational purposes.
 This is a contribution to the RFC Series, independently of any other
 RFC stream.  The RFC Editor has chosen to publish this document at
 its discretion and makes no statement about its value for
 implementation or deployment.  Documents approved for publication by
 the RFC Editor are not a candidate for any level of Internet
 Standard; see Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc7801.

Copyright Notice

 Copyright (c) 2016 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.

Dolmatov Informational [Page 1] RFC 7801 GOST R 34.12-2015 March 2016

Table of Contents

 1.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . .   2
 2.  General Information . . . . . . . . . . . . . . . . . . . . .   3
 3.  Definitions and Notations . . . . . . . . . . . . . . . . . .   3
   3.1.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   3
   3.2.  Notations . . . . . . . . . . . . . . . . . . . . . . . .   4
 4.  Parameter Values  . . . . . . . . . . . . . . . . . . . . . .   6
   4.1.  Nonlinear Bijection . . . . . . . . . . . . . . . . . . .   6
   4.2.  Linear Transformation . . . . . . . . . . . . . . . . . .   7
   4.3.  Transformations . . . . . . . . . . . . . . . . . . . . .   8
   4.4.  Key Schedule  . . . . . . . . . . . . . . . . . . . . . .   9
   4.5.  Basic Encryption Algorithm  . . . . . . . . . . . . . . .   9
     4.5.1.  Encryption  . . . . . . . . . . . . . . . . . . . . .   9
     4.5.2.  Decryption  . . . . . . . . . . . . . . . . . . . . .   9
 5.  Examples (Informative)  . . . . . . . . . . . . . . . . . . .  10
   5.1.  Transformation S  . . . . . . . . . . . . . . . . . . . .  10
   5.2.  Transformation R  . . . . . . . . . . . . . . . . . . . .  10
   5.3.  Transformation L  . . . . . . . . . . . . . . . . . . . .  10
   5.4.  Key Schedule  . . . . . . . . . . . . . . . . . . . . . .  11
   5.5.  Test Encryption . . . . . . . . . . . . . . . . . . . . .  12
   5.6.  Test Decryption . . . . . . . . . . . . . . . . . . . . .  13
 6.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
 7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
   7.1.  Normative References  . . . . . . . . . . . . . . . . . .  14
   7.2.  Informative References  . . . . . . . . . . . . . . . . .  14
 Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  14

1. Scope

 The Russian Federal standard [GOST3412-2015] specifies basic block
 ciphers used as cryptographic techniques for information processing
 and information protection including the provision of
 confidentiality, authenticity, and integrity of information during
 information transmission, processing, and storage in computer-aided
 systems.
 The cryptographic algorithms specified in this standard are designed
 both for hardware and software implementation.  They comply with
 modern cryptographic requirements and put no restrictions on the
 confidentiality level of the protected information.
 The standard applies to development, operation, and modernization of
 the information systems of various purposes.

Dolmatov Informational [Page 2] RFC 7801 GOST R 34.12-2015 March 2016

2. General Information

 The block cipher "Kuznyechik" [GOST3412-2015] was developed by the
 Center for Information Protection and Special Communications of the
 Federal Security Service of the Russian Federation with participation
 of the Open Joint-Stock company "Information Technologies and
 Communication Systems" (InfoTeCS JSC).  GOST R 34.12-2015 was
 approved and introduced by Decree #749 of the Federal Agency on
 Technical Regulating and Metrology on June 19, 2015.
 Terms and concepts in the standard comply with the following
 international standards:
 o  ISO/IEC 10116 [ISO-IEC10116] and
 o  series of standards ISO/IEC 18033 [ISO-IEC18033-1]
    [ISO-IEC18033-3].

3. Definitions and Notations

 The following terms and their corresponding definitions are used in
 the standard.

3.1. Definitions

 Definitions
    encryption algorithm: process that transforms plaintext into
    ciphertext (Section 2.19 of [ISO-IEC18033-1]),
    decryption algorithm: process that transforms ciphertext into
    plaintext (Section 2.14 of [ISO-IEC18033-1]),
    basic block cipher: block cipher that for a given key provides a
    single invertible mapping of the set of fixed-length plaintext
    blocks into ciphertext blocks of the same length,
    block: string of bits of a defined length (Section 2.6 of
    [ISO-IEC18033-1]),
    block cipher: symmetric encipherment system with the property that
    the encryption algorithm operates on a block of plaintext, i.e., a
    string of bits of a defined length, to yield a block of ciphertext
    (Section 2.7 of [ISO-IEC18033-1]),
       Note: In GOST R 34.12-2015, it is established that the terms
       "block cipher" and "block encryption algorithm" are synonyms.

Dolmatov Informational [Page 3] RFC 7801 GOST R 34.12-2015 March 2016

    encryption: reversible transformation of data by a cryptographic
    algorithm to produce ciphertext, i.e., to hide the information
    content of the data (Section 2.18 of [ISO-IEC18033-1]),
    round key: sequence of symbols that is calculated from the key and
    controls a transformation for one round of a block cipher,
    key: sequence of symbols that controls the operation of a
    cryptographic transformation (e.g., encipherment and decipherment)
    (Section 2.21 of [ISO-IEC18033-1]),
       Note: In GOST R 34.12-2015, the key must be a binary sequence.
    plaintext: unencrypted information (Section 3.11 of
    [ISO-IEC10116]),
    key schedule: calculation of round keys from the key,
    decryption: reversal of a corresponding encipherment (Section 2.13
    of [ISO-IEC18033-1]),
    symmetric cryptographic technique: cryptographic technique that
    uses the same secret key for both the originator's and the
    recipient's transformation (Section 2.32 of [ISO-IEC18033-1]),
    cipher: alternative term for encipherment system (Section 2.20 of
    [ISO-IEC18033-1]), and
    ciphertext: data that has been transformed to hide its information
    content (Section 3.3 of [ISO-IEC10116]).

3.2. Notations

 The following notations are used in the standard:
 V*      the set of all binary vector strings of a finite length
         (hereinafter referred to as the strings) including the empty
         string,
 V_s     the set of all binary strings of length s, where s is a non-
         negative integer; substrings and string components are
         enumerated from right to left starting from zero,
 U[*]W   direct (Cartesian) product of two sets, U and W,
 |A|     the number of components (the length) of a string A belonging
         to V* (if A is an empty string, then |A| = 0),

Dolmatov Informational [Page 4] RFC 7801 GOST R 34.12-2015 March 2016

 A||B    concatenation of strings A and B both belonging to V*, i.e.,
         a string from V_(|A|+|B|), where the left substring from
         V_|A| is equal to A, and the right substring from V_|B| is
         equal to B,
 Z_(2^n) ring of residues modulo 2^n,
 Q       finite field GF(2)[x]/p(x), where p(x)=x^8+x^7+x^6+x+1
         belongs to GF(2)[x]; elements of field Q are represented by
         integers in such way that element
         z_0+z_1*theta+...+z_7*theta^7 belonging to Q corresponds to
         integer z_0+2*z_1+...+2^7*z_7, where z_i=0 or z_i=1,
         i=0,1,...,7 and theta denotes a residue class modulo p(x)
         containing x,
 (xor)   exclusive-or of the two binary strings of the same length,
 Vec_s: Z_(2^s) -> V_s  bijective mapping that maps an element from
         ring Z_(2^s) into its binary representation, i.e., for an
         element z of the ring Z_(2^s), represented by the residue z_0
         + (2*z_1) + ... + (2^(s-1)*z_(s-1)), where z_i in {0, 1}, i =
         0, ..., n-1, the equality Vec_s(z) = z_(s-1)||...||z_1||z_0
         holds,
 Int_s: V_s -> Z_(2^s)  the mapping inverse to the mapping Vec_s,
         i.e., Int_s = Vec_s^(-1),
 delta: V_8 -> Q  bijective mapping that maps a binary string from V_8
         into an element from field Q as follows: string
         z_7||...||z_1||z_0, where z_i in {0, 1}, i = 0, ..., 7,
         corresponds to the element z_0+(z_1*theta)+...+(z_7*theta^7)
         belonging to Z,
 nabla: Q -> V8  the mapping inverse to the mapping delta, i.e., delta
         = nabla^(-1),
 PS      composition of mappings, where the mapping S applies first,
         and
 P^s     composition of mappings P^(s-1) and P, where P^1=P.

Dolmatov Informational [Page 5] RFC 7801 GOST R 34.12-2015 March 2016

4. Parameter Values

4.1. Nonlinear Bijection

 The bijective nonlinear mapping is a substitution: Pi =
 (Vec_8)Pi'(Int_8): V_8 -> V_8, where Pi': Z_(2^8) -> Z_(2^8).  The
 values of the substitution Pi' are specified below as an array Pi' =
 (Pi'(0), Pi'(1), ... , Pi'(255)):
  Pi' =
 (       252, 238, 221,  17, 207, 110,  49,  22, 251, 196, 250,
         218,  35, 197,   4,  77, 233, 119, 240, 219, 147,  46,
         153, 186,  23,  54, 241, 187,  20, 205,  95, 193, 249,
          24, 101,  90, 226,  92, 239,  33, 129,  28,  60,  66,
         139,   1, 142,  79,   5, 132,   2, 174, 227, 106, 143,
         160,   6,  11, 237, 152, 127, 212, 211,  31, 235,  52,
          44,  81, 234, 200,  72, 171, 242,  42, 104, 162, 253,
          58, 206, 204, 181, 112,  14,  86,   8,  12, 118,  18,
         191, 114,  19,  71, 156, 183,  93, 135,  21, 161, 150,
          41,  16, 123, 154, 199, 243, 145, 120, 111, 157, 158,
         178, 177,  50, 117,  25,  61, 255,  53, 138, 126, 109,
          84, 198, 128, 195, 189,  13,  87, 223, 245,  36, 169,
          62, 168,  67, 201, 215, 121, 214, 246, 124,  34, 185,
           3, 224,  15, 236, 222, 122, 148, 176, 188, 220, 232,
          40,  80,  78,  51,  10,  74, 167, 151,  96, 115,  30,
           0,  98,  68,  26, 184,  56, 130, 100, 159,  38,  65,
         173,  69,  70, 146,  39,  94,  85,  47, 140, 163, 165,
         125, 105, 213, 149,  59,   7,  88, 179,  64, 134, 172,
          29, 247,  48,  55, 107, 228, 136, 217, 231, 137, 225,
          27, 131,  73,  76,  63, 248, 254, 141,  83, 170, 144,
         202, 216, 133,  97,  32, 113, 103, 164,  45,  43,   9,
          91, 203, 155,  37, 208, 190, 229, 108,  82,  89, 166,
         116, 210, 230, 244, 180, 192, 209, 102, 175, 194,  57,
          75,  99, 182).

Dolmatov Informational [Page 6] RFC 7801 GOST R 34.12-2015 March 2016

 Pi^(-1) is the inverse of Pi; the values of the substitution Pi^(-1)'
 are specified below as an array Pi^(-1)' = (Pi^(-1)'(0), Pi^(-1)'(1),
 ... , Pi^(-1)'(255)):
  Pi^(-1)' =
 (    165,  45,  50, 143,  14,  48,  56, 192,  84, 230, 158,
       57,  85, 126,  82, 145, 100,   3,  87,  90,  28,  96,
        7,  24,  33, 114, 168, 209,  41, 198, 164,  63, 224,
       39, 141,  12, 130, 234, 174, 180, 154,  99,  73, 229,
       66, 228,  21, 183, 200,   6, 112, 157,  65, 117,  25,
      201, 170, 252,  77, 191,  42, 115, 132, 213, 195, 175,
       43, 134, 167, 177, 178,  91,  70, 211, 159, 253, 212,
       15, 156,  47, 155,  67, 239, 217, 121, 182,  83, 127,
      193, 240,  35, 231,  37,  94, 181,  30, 162, 223, 166,
      254, 172,  34, 249, 226,  74, 188,  53, 202, 238, 120,
        5, 107,  81, 225,  89, 163, 242, 113,  86,  17, 106,
      137, 148, 101, 140, 187, 119,  60, 123,  40, 171, 210,
       49, 222, 196,  95, 204, 207, 118,  44, 184, 216,  46,
       54, 219, 105, 179,  20, 149, 190,  98, 161,  59,  22,
      102, 233,  92, 108, 109, 173,  55,  97,  75, 185, 227,
      186, 241, 160, 133, 131, 218,  71, 197, 176,  51, 250,
      150, 111, 110, 194, 246,  80, 255,  93, 169, 142,  23,
       27, 151, 125, 236,  88, 247,  31, 251, 124,   9,  13,
      122, 103,  69, 135, 220, 232,  79,  29,  78,   4, 235,
      248, 243,  62,  61, 189, 138, 136, 221, 205,  11,  19,
      152,   2, 147, 128, 144, 208,  36,  52, 203, 237, 244,
      206, 153,  16,  68,  64, 146,  58,   1,  38,  18,  26,
       72, 104, 245, 129, 139, 199, 214,  32,  10,   8,   0,
       76, 215, 116 ).

4.2. Linear Transformation

 The linear transformation is denoted by l: (V_8)^16 -> V_8, and
 defined as:
 l(a_15,...,a_0) = nabla(148*delta(a_15) + 32*delta(a_15) +
 133*delta(a_13) + 16*delta(a_12) + 194*delta(a_11) +
 192*delta(a_10) + 1*delta(a_9) + 251*delta(a_8) + 1*delta(a_7) +
 192*delta(a_6) + 194*delta(a_5) + 16*delta(a_4) + 133*delta(a_3) +
 32*delta(a_2) + 148*delta(a_1) +1*delta(a_0)),
 for all a_i belonging to V_8, i = 0, 1, ..., 15, where the addition
 and multiplication operations are in the field Q, and constants are
 elements of the field as defined above.

Dolmatov Informational [Page 7] RFC 7801 GOST R 34.12-2015 March 2016

4.3. Transformations

 The following transformations are applicable for encryption and
 decryption algorithms:
 X[x]:V_128->V_128  X[k](a)=k(xor)a, where k, a belong to V_128,
 S:V_128-> V_128  S(a)=(a_15||...||a_0)=pi(a_15)||...||pi(a_0), where
    a_15||...||a_0 belongs to V_128, a_i belongs to V_8, i=0,1,...,15,
 S^(-1):V_128-> V_128  the inverse transformation of S, which may be
    calculated, for example, as follows:
    S^(-1)(a_15||...||a_0)=pi^(-1) (a_15)||...||pi^(-1)(a_0), where
    a_15||...||a_0 belongs to V_128, a_i belongs to V_8, i=0,1,...,15,
 R:V_128-> V_128  R(a_15||...||a_0)=l(a_15,...,a_0)||a_15||...||a_1,
    where a_15||...||a_0 belongs to V_128, a_i belongs to V_8,
    i=0,1,...,15,
 L:V_128-> V_128  L(a)=R^(16)(a), where a belongs to V_128,
 R^(-1):V_128-> V_128  the inverse transformation of R, which may be
    calculated, for example, as follows: R^(-1)(a_15||...||a_0)=a_14||
    a_13||...||a_0||l(a_14,a_13,...,a_0,a_15), where a_15||...||a_0
    belongs to V_128, a_i belongs to V_8, i=0,1,...,15,
 L^(-1):V_128-> V_128  L^(-1)(a)=(R^(-1))(16)(a), where a belongs to
    V_128, and
 F[k]:V_128[*]V_128 -> V_128[*]V_128
    F[k](a_1,a_0)=(LSX[k](a_1)(xor)a_0,a_1), where k, a_0, a_1 belong
    to V_128.

Dolmatov Informational [Page 8] RFC 7801 GOST R 34.12-2015 March 2016

4.4. Key Schedule

 Key schedule uses round constants C_i belonging to V_128, i=1, 2,
 ..., 32, defined as
 C_i=L(Vec_128(i)), i=1,2,...,32.
 Round keys K_i, i=1, 2, ..., 10 are derived from key
 K=k_255||...||k_0 belonging to V_256, k_i belongs to V_1, i=0, 1,
 ..., 255, as follows:
 K_1=k_255||...||k_128;
 K_2=k_127||...||k_0;
 (K_(2i+1),K_(2i+2))=F[C_(8(i-1)+8)]...
  F[C_(8(i-1)+1)](K_(2i-1),K_(2i)), i=1,2,3,4.

4.5. Basic Encryption Algorithm

4.5.1. Encryption

 Depending on the values of round keys K_1,...,K_10, the encryption
 algorithm is a substitution E_(K_1,...,K_10) defined as follows:
 E_(K_1,...,K_10)(a)=X[K_10]LSX[K_9]...LSX[K_2]LSX[K_1](a),
 where a belongs to V_128.

4.5.2. Decryption

 Depending on the values of round keys K_1,...,K_10, the decryption
 algorithm is a substitution D_(K_1,...,K_10) defined as follows:
 D_(K_1,...,K_10)(a)=X[K_1]L^(-1)S^(-1)X[K_2]...
  L^(-1)S^(-1)X[K_9] L^(-1)S^(-1)X[K_10](a),
 where a belongs to V_128.

Dolmatov Informational [Page 9] RFC 7801 GOST R 34.12-2015 March 2016

5. Examples (Informative)

 This section is for information only and is not a normative part of
 the standard.

5.1. Transformation S

 S(ffeeddccbbaa99881122334455667700) =
  b66cd8887d38e8d77765aeea0c9a7efc,
 S(b66cd8887d38e8d77765aeea0c9a7efc) =
  559d8dd7bd06cbfe7e7b262523280d39,
 S(559d8dd7bd06cbfe7e7b262523280d39) =
  0c3322fed531e4630d80ef5c5a81c50b,
 S(0c3322fed531e4630d80ef5c5a81c50b) =
  23ae65633f842d29c5df529c13f5acda.

5.2. Transformation R

 R(00000000000000000000000000000100) =
  94000000000000000000000000000001,
 R(94000000000000000000000000000001) =
  a5940000000000000000000000000000,
 R(a5940000000000000000000000000000) =
  64a59400000000000000000000000000,
 R(64a59400000000000000000000000000) =
  0d64a594000000000000000000000000.

5.3. Transformation L

 L(64a59400000000000000000000000000) =
  d456584dd0e3e84cc3166e4b7fa2890d,
 L(d456584dd0e3e84cc3166e4b7fa2890d) =
  79d26221b87b584cd42fbc4ffea5de9a,
 L(79d26221b87b584cd42fbc4ffea5de9a) =
  0e93691a0cfc60408b7b68f66b513c13,
 L(0e93691a0cfc60408b7b68f66b513c13) =
  e6a8094fee0aa204fd97bcb0b44b8580.

Dolmatov Informational [Page 10] RFC 7801 GOST R 34.12-2015 March 2016

5.4. Key Schedule

 In this test example, the key is equal to:
 K = 8899aabbccddeeff0011223344556677fedcba9876543210012345678
      9abcdef.
 K_1 = 8899aabbccddeeff0011223344556677,
 K_2 = fedcba98765432100123456789abcdef.
 C_1 = 6ea276726c487ab85d27bd10dd849401,
 X[C_1](K_1) = e63bdcc9a09594475d369f2399d1f276,
 SX[C_1](K_1) = 0998ca37a7947aabb78f4a5ae81b748a,
 LSX[C_1](K_1) = 3d0940999db75d6a9257071d5e6144a6,
 F[C_1](K_1, K_2) = = (c3d5fa01ebe36f7a9374427ad7ca8949,
        8899aabbccddeeff0011223344556677).
 C_2 = dc87ece4d890f4b3ba4eb92079cbeb02,
 F [C_2]F [C_1](K_1, K_2) = (37777748e56453377d5e262d90903f87,
        c3d5fa01ebe36f7a9374427ad7ca8949).
 C_3 = b2259a96b4d88e0be7690430a44f7f03,
 F[C_3]...F[C_1](K_1, K_2) = (f9eae5f29b2815e31f11ac5d9c29fb01,
        37777748e56453377d5e262d90903f87).
 C_4 = 7bcd1b0b73e32ba5b79cb140f2551504,
 F[C_4]...F[C_1](K_1, K_2) = (e980089683d00d4be37dd3434699b98f,
        f9eae5f29b2815e31f11ac5d9c29fb01).
 C_5 = 156f6d791fab511deabb0c502fd18105,
 F[C_5]...F[C_1](K_1, K_2) = (b7bd70acea4460714f4ebe13835cf004,
        e980089683d00d4be37dd3434699b98f).
 C_6 = a74af7efab73df160dd208608b9efe06,
 F[C_6]...F[C_1](K_1, K_2) = (1a46ea1cf6ccd236467287df93fdf974,
        b7bd70acea4460714f4ebe13835cf004).
 C_7 = c9e8819dc73ba5ae50f5b570561a6a07,
 F[C_7]...F [C_1](K_1, K_2) = (3d4553d8e9cfec6815ebadc40a9ffd04,
        1a46ea1cf6ccd236467287df93fdf974).
 C_8 = f6593616e6055689adfba18027aa2a08,
 (K_3, K_4) = F [C_8]...F [C_1](K_1, K_2) =
        (db31485315694343228d6aef8cc78c44,
         3d4553d8e9cfec6815ebadc40a9ffd04).

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 The round keys K_i, i = 1, 2, ..., 10, take the following values:
 K_1 = 8899aabbccddeeff0011223344556677,
 K_2 = fedcba98765432100123456789abcdef,
 K_3 = db31485315694343228d6aef8cc78c44,
 K_4 = 3d4553d8e9cfec6815ebadc40a9ffd04,
 K_5 = 57646468c44a5e28d3e59246f429f1ac,
 K_6 = bd079435165c6432b532e82834da581b,
 K_7 = 51e640757e8745de705727265a0098b1,
 K_8 = 5a7925017b9fdd3ed72a91a22286f984,
 K_9 = bb44e25378c73123a5f32f73cdb6e517,
 K_10 = 72e9dd7416bcf45b755dbaa88e4a4043.

5.5. Test Encryption

 In this test example, encryption is performed on the round keys
 specified in Section 5.4.  Let the plaintext be
 a = 1122334455667700ffeeddccbbaa9988,
 then
 X[K_1](a) = 99bb99ff99bb99ffffffffffffffffff,
 SX[K_1](a) = e87de8b6e87de8b6b6b6b6b6b6b6b6b6,
 LSX[K_1](a) = e297b686e355b0a1cf4a2f9249140830,
 LSX[K_2]LSX[K_1](a) = 285e497a0862d596b36f4258a1c69072,
 LSX[K_3]...LSX[K_1](a) = 0187a3a429b567841ad50d29207cc34e,
 LSX[K_4]...LSX[K_1](a) = ec9bdba057d4f4d77c5d70619dcad206,
 LSX[K_5]...LSX[K_1](a) = 1357fd11de9257290c2a1473eb6bcde1,
 LSX[K_6]...LSX[K_1](a) = 28ae31e7d4c2354261027ef0b32897df,
 LSX[K_7]...LSX[K_1](a) = 07e223d56002c013d3f5e6f714b86d2d,
 LSX[K_8]...LSX[K_1](a) = cd8ef6cd97e0e092a8e4cca61b38bf65,
 LSX[K_9]...LSX[K_1](a) = 0d8e40e4a800d06b2f1b37ea379ead8e.
 Then the ciphertext is
 b = X[K_10]LSX[K_9]...LSX[K_1](a) = 7f679d90bebc24305a468d42b9d4edcd.

Dolmatov Informational [Page 12] RFC 7801 GOST R 34.12-2015 March 2016

5.6. Test Decryption

 In this test example, decryption is performed on the round keys
 specified in Section 5.4.  Let the ciphertext be
 b = 7f679d90bebc24305a468d42b9d4edcd,
 then
 X[K_10](b) = 0d8e40e4a800d06b2f1b37ea379ead8e,
 L^(-1)X[K_10](b) = 8a6b930a52211b45c5baa43ff8b91319,
 S^(-1)L^(-1)X[K_10](b) = 76ca149eef27d1b10d17e3d5d68e5a72,
 S^(-1)L^(-1)X[K_9]S^(-1)L^(-1)X[K_10](b) =
  5d9b06d41b9d1d2d04df7755363e94a9,
 S^(-1)L^(-1)X[K_8]...S^(-1)L^(-1)X[K_10](b) =
  79487192aa45709c115559d6e9280f6e,
 S^(-1)L^(-1)X[K_7]...S^(-1)L^(-1)X[K_10](b) =
  ae506924c8ce331bb918fc5bdfb195fa,
 S^(-1)L^(-1)X[K_6]...S^(-1)L^(-1)X[K_10](b) =
  bbffbfc8939eaaffafb8e22769e323aa,
 S^(-1)L^(-1)X[K_5]...S^(-1)L^(-1)X[K_10](b) =
  3cc2f07cc07a8bec0f3ea0ed2ae33e4a,
 S^(-1)L^(-1)X[K_4]...S^(-1)L^(-1)X[K_10](b) =
  f36f01291d0b96d591e228b72d011c36,
 S^(-1)L^(-1)X[K_3]...S^(-1)L^(-1)X[K_10](b) =
  1c4b0c1e950182b1ce696af5c0bfc5df,
 S^(-1)L^(-1)X[K_2]...S^(-1)L^(-1)X[K_10](b) =
  99bb99ff99bb99ffffffffffffffffff.
 Then the plaintext is
 a = X[K_1]S^(-1)L^(-1)X[K_2]...S^(-1)L^(-1)X[K_10](b) =
  1122334455667700ffeeddccbbaa9988.

6. Security Considerations

 This entire document is about security considerations.

Dolmatov Informational [Page 13] RFC 7801 GOST R 34.12-2015 March 2016

7. References

7.1. Normative References

 [GOST3412-2015]
            "Information technology.  Cryptographic data security.
            Block ciphers", GOST R 34.12-2015, Federal Agency on
            Technical Regulating and Metrology, 2015.

7.2. Informative References

 [ISO-IEC10116]
            ISO/IEC, "Information technology -- Security techniques --
            Modes of operation for an n-bit block cipher", ISO/
            IEC 10116, 2006.
 [ISO-IEC18033-1]
            ISO/IEC, "Information technology -- Security techniques --
            Encryption algorithms -- Part 1: General", ISO/
            IEC 18033-1, 2015.
 [ISO-IEC18033-3]
            ISO/IEC, "Information technology -- Security techniques --
            Encryption algorithms -- Part 3: Block ciphers", ISO/
            IEC 18033-3, 2010.

Author's Address

 Vasily Dolmatov (editor)
 Research Computer Center MSU
 Leninskiye Gory, 1, Building 4, MGU NIVC
 Moscow  119991
 Russian Federation
 Email: dol@srcc.msu.ru

Dolmatov Informational [Page 14]

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