Knowledge Base

B

Cipher Suite: TLS_­GOSTR341112_­256_­WITH_­KUZNYECHIK_­MGM_­L

Summary

code:
(0xc1, 0x03)
IANA Name:
TLS_GOSTR341112_256_WITH_KUZNYECHIK_MGM_L

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Components

B
Key Exchange Method
Name
GOST R 34.11-2012
Security
The GOST R 34.10-2012 (key exchange algorithm)[411] is a variant of Diffie-Hellman[269][270][271][272][273] key exchange based on elliptic-curve cryptography[259][260][261][262] and GOST R 34.11-2012 (hash function)[74]. The algorithm produces key encryption key (KEK) from the sender's private key and the recipient's public key (or the reverse of the latter pair and the user keying material (UKM). The algorithm can be used for static and ephemeral keys where one side uses a static key and the other uses an ephemeral one. Key exchange method can have forward secrecy[135][136][137][138], and does protect past sessions against future compromises. If long-term secret keys or passwords are compromised, encrypted communications and sessions recorded in the past cannot be retrieved and decrypted. Leading client applications do not use this algorithm. Unless your application or requirements specifically call for their use, it is generally safer to avoid cipher suites that are not adopted and supported by a critical mass of the industry.
Recommendations
Always prefer cipher suites with PFS property over the non-PFS ones. Note that performance considerations implies preferring Ephemeral Elliptic-curve Diffie–Hellman[91][92] over Ephemeral Diffie-Hellman[142][143][144][145].
B
Authentication Method
Name
GOST R 34.10-2012 (256)
Security
The GOST R 34.11-2012[453] is a digital signature[231][232][233][234] algorithm, part of the Russian GOST[185][186][187][188] standard, using elliptic-curve cryptography[259][260][261][262]. Leading client applications do not use this algorithm. Unless your application or requirements specifically call for their use, it is generally safer to avoid cipher suites that are not adopted and supported by a critical mass of the industry.
Recommendations
If your application or requirements specifically call for the use of algorithms which are not used by the leading client applications set the cipher suite order explicitly and cipher suites used by the leading client applications be preferred over the ones which do not used by them.
B
Encryption Type
Name
GOST R 34.12-2015 "Kuznyechik"
Security
Encryption algorithm GOST R 34.12-2015 (Kuznyechik)[238][239] is a block cipher[524][525][526][527] which was designed by the Federal Technical Regulation and Metrology Agency[254][255], now part of the GOST[185][186][187][188] standards maintained by the Euro Asian Council for Standardization, Metrology and Certification[189]. The encryption algorithm is considered secure[157], however concept nothing up my sleeve numbers[242][243] is contradicted by hidden algorithms used in this encryption algorithm. Leading client applications do not use this algorithm. Unless your application or requirements specifically call for their use, it is generally safer to avoid cipher suites that are not adopted and supported by a critical mass of the industry.
Recommendations
Remove the cipher suite from the list of cipher suites supported by your server.
A+
Encryption Mode
Name
GOST Magma (MGM)
Security
The block cipher mode of operation[293][294][295][296][297] multilinear galois mode[448] is considered secure[167][168]. It provides authenticated encryption[563] which simultaneously assure the confidentiality[198][199][200] and authenticity[201][202][203] of data.
Recommendations
If your application or requirements specifically call for the use of a message authentication code[128][129][130][131] that does not provide authenticated encryption[563] prefer block cipher mode of operation[293][294][295][296][297] (eg: counter with CBC-MAC[266][267][268], Galois/Counter Mode[65][66][67][68] or message authentication code[128][129][130][131] (eg: Poly1305[289][290]) that proved authenticated encryption over the ones which does not provide it.
A+
Encryption Key Size
Name
256
Security
The symmetric key[193][194][195] withkey size[438] more than 128 bits as it is should be according to National Institute of Standards and Technology[428][429] so it is not vulnerable to preimage attack[215] and it cannreliably prove that message came from the stated sender (its authenticity) and has not been changed, so connection is not open for a man-in-the-middle attack[414].
Recommendations
Remove the cipher suite from the list of cipher suites supported by your server.
A+
Encryption Block Size
Name
128
Security
The block cipher[524][525][526][527] uses a block size[409] larger than 64 bits, so it is not vulnerable to sweet32 attack[496][497][498][499].
Recommendations