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 <matt@xxxxxxxxxxx> 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
