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GOST_R3411_12_256
The GOST R 34.10-2012 (key exchange algorithm)[437] is a variant of Diffie-Hellman[99][100][101][102][103] key exchange based on elliptic-curve cryptography[118][119][120][121] and GOST R 34.11-2012 (hash function)[193]. 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[127][128][129][130], 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.
GOST R 34.10-2012 (256)
The GOST R 34.11-2012[273] is a digital signature[107][108][109][110] algorithm, part of the Russian GOST[566][567][568][569] standard, using elliptic-curve cryptography[118][119][120][121]. 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.
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.
GOST R 34.12-2015 "Kuznyechik"
Encryption algorithm GOST R 34.12-2015 (Kuznyechik)[350][351] is a block cipher[78][79][80][81] which was designed by the Federal Technical Regulation and Metrology Agency[474][475], now part of the GOST[566][567][568][569] standards maintained by the Euro Asian Council for Standardization, Metrology and Certification[464]. The encryption algorithm is considered secure[352], however concept nothing up my sleeve numbers[154][155] 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.
Remove the cipher suite from the list of cipher suites supported by your server.
EAX
The block cipher mode of operation[82][83][84][85][86] encrypt-then-authenticate-then-translate[42][43][44][45] is used in counter[38][39] mode for encryption and as one-key CBC message authentication code[146][147][148][149] for authentication over each block Both CNT mode and OMAC algorithm are considered secure[40][41] and through the EAX composition method they can provide authenticated encryption[74] which simultaneously assure the confidentiality[91][92][93] and authenticity[75][76][77] of data.
If your application or requirements specifically call for the use of a message authentication code[135][136][137][138] that does not provide authenticated encryption[74] prefer block cipher mode of operation[82][83][84][85][86] (eg: counter with CBC-MAC[32][33][34], encrypt-then-authenticate-then-translate[42][43][44][45] or message authentication code[135][136][137][138] (eg: Poly1305[458][459]) that proved authenticated encryption over the ones which does not provide it.
256
The symmetric key[185][186][187] withkey size[184] more than 128 bits as it is should be according to National Institute of Standards and Technology[470][471] so it is not vulnerable to preimage attack[67] 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[61].
Remove the cipher suite from the list of cipher suites supported by your server.
CTR OMAC GOST R 34.12-2015 "Kuznyechik"
The message authentication code[135][136][137][138] is a hashed message authentication code[139][140][141][142][143][144][145] where the underlaying cryptographic hash function[94][95][96][97] (GOST R 34.11-94 (hash function algorithm)[194] derives from GOST 28147-89 "imitovstavka"[195] which is considered secure[196], however it is vulnerable to collision attack[57] and to preimage attack[67] in theory. It does not provide authenticated encryption[74] which simultaneously assure the confidentiality[91][92][93] and authenticity[75][76][77] of data.
Leading client applications do not use this type of message authentication code[135][136][137][138]. 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. If your application or requirements specifically call for the use of that encryption algorithm prefer a message authentication code[135][136][137][138] that does provide authenticated encryption[74] prefer cipher suites that are adopted and supported by a critical mass of the industry, like message authentication code[135][136][137][138] Poly1305[458][459] that proved authenticated encryption or block cipher mode of operation[82][83][84][85][86] counter with CBC-MAC[32][33][34] or Galois/Counter Mode[46][47][48][49] or which also provides authenticated encryption[74]. In case of a hashed message authentication code[139][140][141][142][143][144][145] prefer message authentication code[135][136][137][138] based on Secure Hash Algorithm 2[212][213][214] over the ones based on other cryptographic hash function[94][95][96][97].
