Knowledge Base

F

Cipher Suite: TLS_­DH_­anon_­WITH_­SEED_­CBC_­SHA

Summary

Name:
TLS_DH_anon_WITH_SEED_CBC_SHA
IANA Name:
TLS_DH_anon_WITH_SEED_CBC_SHA
Code:
(0x00, 0x9b)
OpenSSL Name:
ADH-SEED-SHA
Protocol Versions:
TLS 1.0,TLS 1.1,TLS 1.2

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Components

F
Key Exchange Method
Name

ADH (Anonymous Diffie-Hellman)

Security

The anonymous Diffie-Hellman[404] key exchange[133] is a variant of Diffie-Hellman[99][100][101][102][103] key exchange that does not provide authenticity[75][76][77]. Lack of authentication causes that the identity of server cannot be proved, so connection is open for a man-in-the-middle attack[61].

Recommendations

Remove the cipher suite from the list of cipher suites supported by your server or replace the cipher suite with it's Ephemeral Diffie-Hellman[405][406][407][408] version.

F
Authentication Method
Name

anon

Security

Lack of authentication is combined with anonymous key exchange[397][398], identity of server cannot be proved, so connection is open for a man-in-the-middle attack[61].

Recommendations

Remove the cipher suite from the list of cipher suites supported by your server.

B
Encryption Type
Name

SEED

Security

Encryption algorithm SEED[384][385][386] is a block cipher[78][79][80][81] which is considered secure[387], but 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.

B
Encryption Mode
Name

CBC

Security

Encryption mode is cipher block chaining[28][29][30]. It is vulnerable[31] to timing attack[188] (eg: Lucky Thirteen attack[11][12]) and padding oracle attack[63][64][65][66] (eg: POODLE attack[13][14][15]).

Recommendations

Remove the cipher suite from the list of cipher suites supported by your server or at least set the cipher suite order explicitly and any cipher suite modes be preferred over ciphers suites with CBC modes.

A+
Encryption Key Size
Name

128

Security

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].

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[78][79][80][81] uses a block size[87] larger than 64 bits, so it is not vulnerable to sweet32 attack[22][23][24][25].

A-
Message Authentication Code
Name

SHA-1

Security

message authentication code[135][136][137][138] is a hashed message authentication code[139][140][141][142][143][144][145] which is considered secure[462], despite the fact that the underlayingcryptographic hash function[94][95][96][97] (Secure Hash Algorithm 1[202][203][204]) is considered insecure[205][206][207][208][209][210][211].

Recommendations

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], Galois/Counter Mode[46][47][48][49] or message authentication code[135][136][137][138] (eg: Poly1305[458][459]) that proved authenticated encryption over the ones which does not provide it. 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 Secure Hash Algorithm 1[202][203][204].