Thanks for the quick response Matt. My command was : openssl s_client -connect 10.29.20.26 -cipher ECDHE-RSA-AES128-SHA -tls1_2. I did not realise that "2" was not copied.
I am trying to implement combined algo support on our engine. I am using the openssl s_server and s_client apps to validate my implementation. The combined algo that i am looking to implement is AES128/256 and SHA1. Its clear that i should always use tls version less than 1.3 otherwise GCM ciphers are used. What cipher suites can i use to validate the above combination of combined algo? Which tls versions support which cipher suites? Should i be doing "encrypt-then-mac" or "mac-then-encrypt" in my implementation? Does the cipher suite decide this? If yes, what are the ciphers which do "encrypt-then-mac" and what ciphers to "mac-then-encrypt"? Thanks in advance. Regards Phani On Tue, Feb 25, 2020 at 10:31 AM Matt Caswell <m...@openssl.org> wrote: > > > On 24/02/2020 13:04, Phani 2004 wrote: > > Hi Team, > > > > "aes_cbc_hmac_sha1" implementation is currently supported on x86 > > platforms only. > > With which RFC is this compliant with? > > This cipher is only used when the "encrypt then mac" option is disabled. > > Is this understanding correct. I am using openssl s_server and s_client > > is i use the below command on client side. > > > > openssl s_client -connect 10.29.20.26 -cipher ECDHE-RSA-AES128-SHA -tls1_ > > > > Is this correct? > > I have following queries: > > > > 1. With which RFC is the current aes_cbc_hmac_sha1 implementation > > compliant with? > > Its a cipher used by AES128 and HMAC-SHA1 based ciphersuites compliant > with TLSv1.2 (RFC5246) and earlier TLS protocol versions. > > > 2. It always does "mac then encrypt". Infact this cipher is invoked > > only when "encrypt then mac" flag is disabled. Is this correct? > > Correct. We always try to do encrypt-then-mac by default so s_client > talking to s_server from the same OpenSSL version should never use this > ciphersuuite > > > 3. Is the cipher i used in above s_client command correct? > > > > openssl s_client -connect 10.29.20.26 -cipher ECDHE-RSA-AES128-SHA -tls1_ > > The "-tls_" on the end is incorrect - that's not a valid flag. Perhaps > you meant "-no_tls1_3" which would be fine. That's still not sufficient > to guarantee usage of the aes_cbc_hmac_sha1 cipher though because > Encrypt-then-mac will always be preferred. > > I don't think there is a command line option to s_client to force that > off, although you can do it through a config file using the > "EncryptThenMac" option. > > Matt > > > > Thanks in advance. > > > > Regards > > Phani >