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There are ciphersuites with SHA256, and SHA384. In the following TLS ciphersuite, the SHA types is not specified. Does this always refer to SHA1 (there is SHA0 as well) so which one of them? 

TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
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  • $\begingroup$ Where did you get this cipher name from? In my opinion there is no such cipher. But there is TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA which refers to a MAC using SHA1. $\endgroup$
    – Steffen Ullrich
    Commented Dec 19, 2017 at 12:57
  • $\begingroup$ It was a type. Sorry. So this means SHA always refer to SHA1?? There is not any other interpretation for it? $\endgroup$
    – user6875880
    Commented Dec 19, 2017 at 13:15
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    $\begingroup$ Still wrong. It's ..._SHA not ...-SHA. $\endgroup$
    – Steffen Ullrich
    Commented Dec 19, 2017 at 13:32
  • $\begingroup$ Yeah, basically they are C-style constants so only alphanumerics and underscore allowed. If you'd use the dash in C it would be misinterpreted as a minus sign. $\endgroup$
    – Maarten Bodewes ♦
    Commented Dec 19, 2017 at 13:37
  • $\begingroup$ If unsure: read the specifications (in this case the TLS RFC's) $\endgroup$
    – Maarten Bodewes ♦
    Commented Dec 19, 2017 at 13:45

1 Answer 1

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Does this always refer to SHA1

Yes, within TLS ciphersuites, an unadorned "SHA" means SHA-1. The oldest of these ciphersuite names predate any of the SHA2 hashes (and so if they use them, they'll explicitly list the size, e.g. SHA256), and SHA-0 is never used.

From the Glossary (appendix B) in RFC 5248: TLS 1.2:

SHA

The Secure Hash Algorithm [SHS] is defined in FIPS PUB 180-2. It produces a 20-byte output. Note that all references to SHA (without a numerical suffix) actually use the modified SHA-1 algorithm

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