Knowledge Base

Cipher Suite

F

TLS_­RSA_­WITH_­NULL_­SHA

Summary

Name:
TLS_RSA_WITH_NULL_SHA
IANA Name:
TLS_RSA_WITH_NULL_SHA
Code:
(0x00, 0x02)
OpenSSL Name:
NULL-SHA
Protocol Versions:
SSL 3.0,TLS 1.0,TLS 1.1,TLS 1.2

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Components

C
Key Exchange Method
Name

RSA (Rivest-Shamir-Adleman)

Security

RSA[443][444] key exchange is a key exchange[133] that has no forward secrecy[127][128][129][130], and does not protect past sessions against future compromises. If long-term secret keys or passwords are compromised, encrypted communications and sessions recorded in the past can be retrieved and decrypted. Throughout its history RSA encryption has had many security flaws[445][446][447][448][449][450] and was affected by variety of attack types: chosen-ciphertext attack[55] (eg: Bleichenbacher's attack[1][2], ROBOT attack[18][19][20][21]), side-channel attack[69][70][71] (eg: padding oracle attack[63][64][65][66], like Bleichenbacher's cat[3][4][5][6]).

Recommendations

Always prefer cipher suites with PFS property over the non-PFS ones. Note that performance considerations implies preferring Ephemeral Elliptic-curve Diffie–Hellman[432][433] over Ephemeral Diffie-Hellman[405][406][407][408].

A+
Authentication Method
Name

RSA

Security

Rivest–Shamir–Adleman[275][276][277] is a digital signature[107][108][109][110] algorithm, which is considered secure, however there are known weaknesses[278][279][280][281][282].

F
Encryption Type
Name

NULL

Security

Encryption algorithm is a null encryption[360][361] that cannot provide confidentiality[91][92][93], so connection is available or disclosed to unauthorized individuals, entities, or processes.

Recommendations

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

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].