Re: [EXTERNAL] - Re: Question about TLS 1.3 and openssl -cipher aNULL option
Viktor, Thank you. Yury From: openssl-users on behalf of Viktor Dukhovni Sent: Tuesday, September 8, 2020 10:56 AM To: openssl-users@openssl.org Subject: Re: [EXTERNAL] - Re: Question about TLS 1.3 and openssl -cipher aNULL option On Tue, Sep 08, 2020 at 05:39:51PM +, Yury Mazin via openssl-users wrote: > I have a question based on the response provided to me: > > My question is why following openssl commands (version 1.1.1f) return > those TLSv1.3 ciphers as offering no authentication and no encryption? It does not. You still have not understood that "-ciphers" constrains **ONLY** the TLS 1.2 (and earlier) cipher lists. When you say: ciphers ... NULL you asking for all the ciphers (TLS 1.2 and 1.3) where the TLS 1.2 ciphers are NULL. To also constrain the TLS 1.3 ciphers you MUST use the -ciphersuites ... option to list the desired TLS 1.3 ciphersuites, otherwise they remain unconstrained. -- Viktor.
Re: [EXTERNAL] - Re: Question about TLS 1.3 and openssl -cipher aNULL option
On Tue, Sep 08, 2020 at 05:39:51PM +, Yury Mazin via openssl-users wrote: > I have a question based on the response provided to me: > > My question is why following openssl commands (version 1.1.1f) return > those TLSv1.3 ciphers as offering no authentication and no encryption? It does not. You still have not understood that "-ciphers" constrains **ONLY** the TLS 1.2 (and earlier) cipher lists. When you say: ciphers ... NULL you asking for all the ciphers (TLS 1.2 and 1.3) where the TLS 1.2 ciphers are NULL. To also constrain the TLS 1.3 ciphers you MUST use the -ciphersuites ... option to list the desired TLS 1.3 ciphersuites, otherwise they remain unconstrained. -- Viktor.
Re: [EXTERNAL] - Re: Question about TLS 1.3 and openssl -cipher aNULL option
On Tue, 2020-09-08 at 17:39 +, Yury Mazin via openssl-users wrote: > Hello, > > I have a question based on the response provided to me: > > My question is why following openssl commands (version 1.1.1f) > return those TLSv1.3 ciphers as offering no authentication and no > encryption? What do you mean by no authentication and no encryption? The encryption is provided as you can see with the Enc= value. And authentication is provided as well because Au=any applies here meaning any authentication method available in TLS-1.3 protocol. As it was explained before the cipher string does not apply to TLS-1.3 ciphersuites so it does not matter if you put NULL, eNULL, aNULL or anything else as the last parameter of the ciphers command. > Yury > From: openssl-users on behalf of > Viktor Dukhovni > Sent: Friday, September 4, 2020 12:10 PM > To: openssl-users@openssl.org > Subject: Re: [EXTERNAL] - Re: Question about TLS 1.3 and openssl > -cipher aNULL option > > On Fri, Sep 04, 2020 at 07:00:01PM +, Yury Mazin via openssl- > users wrote: > > > Thank you Benjamin, > > > > According to OpenSSL , aNULL stands for no-authentication. > > Specifically, SSL 3.0 through TLS 1.2 ciphers in which the server and > client exchange no certificates, and the TLS handshake consists > largely > of an unsigned anonymous ephemeral DH or ECDH key exchang. > > TLS 1.3 dropped support for anonymous DH and ECDH. Server > certificates > are *required. And the all-in-one ciphersuites of TLS <= 1.2, are > replaced with separately negotiated components. As a result of > which, > in OpenSSL 1.1.1 and later, they are controlled via a different set > of > APIs and command-line options. > > Specifically, in your case, the "-ciphers aNULL" option only applies > to TLS <= 1.2 > > > Does it mean that all 3 default protocols of TLS 1.3 offer no > > authentication > > No. None of them "support no authentication" (which is not even > strictly > true, it is the protocol that does not support "no authentication", > the TLS 1.3 ciphers are simply silent re certificate algorithm > selection), > but the "-cipher aNULL" is simply not used when TLS 1.3 is > negotiated, > so your question is makes incorrect assumptions to reach its > tentative > conclusions. > -- Tomáš Mráz No matter how far down the wrong road you've gone, turn back. Turkish proverb [You'll know whether the road is wrong if you carefully listen to your conscience.]
Re: [EXTERNAL] - Re: Question about TLS 1.3 and openssl -cipher aNULL option
Hello, I have a question based on the response provided to me: My question is why following openssl commands (version 1.1.1f) return those TLSv1.3 ciphers as offering no authentication and no encryption? C:\OpenText\iHub20.4-29324643-250C200831\ihub\modules\BIRTiHub\iHub\bin>openssl ciphers -v -s NULL TLS_AES_256_GCM_SHA384 TLSv1.3 Kx=any Au=any Enc=AESGCM(256) Mac=AEAD TLS_CHACHA20_POLY1305_SHA256 TLSv1.3 Kx=any Au=any Enc=CHACHA20/POLY1305(256) Mac=AEAD TLS_AES_128_GCM_SHA256 TLSv1.3 Kx=any Au=any Enc=AESGCM(128) Mac=AEAD C:\OpenText\iHub20.4-29324643-250C200831\ihub\modules\BIRTiHub\iHub\bin>openssl ciphers -v -s eNULL TLS_AES_256_GCM_SHA384 TLSv1.3 Kx=any Au=any Enc=AESGCM(256) Mac=AEAD TLS_CHACHA20_POLY1305_SHA256 TLSv1.3 Kx=any Au=any Enc=CHACHA20/POLY1305(256) Mac=AEAD TLS_AES_128_GCM_SHA256 TLSv1.3 Kx=any Au=any Enc=AESGCM(128) Mac=AEAD C:\OpenText\iHub20.4-29324643-250C200831\ihub\modules\BIRTiHub\iHub\bin>openssl ciphers -v -s aNULL TLS_AES_256_GCM_SHA384 TLSv1.3 Kx=any Au=any Enc=AESGCM(256) Mac=AEAD TLS_CHACHA20_POLY1305_SHA256 TLSv1.3 Kx=any Au=any Enc=CHACHA20/POLY1305(256) Mac=AEAD TLS_AES_128_GCM_SHA256 TLSv1.3 Kx=any Au=any Enc=AESGCM(128) Mac=AEAD From: Yury Mazin Sent: Friday, September 4, 2020 12:43 PM To: openssl-users@openssl.org Subject: Re: [EXTERNAL] - Re: Question about TLS 1.3 and openssl -cipher aNULL option Viktor, Thank you for clarifying it. Yury From: openssl-users on behalf of Viktor Dukhovni Sent: Friday, September 4, 2020 12:10 PM To: openssl-users@openssl.org Subject: Re: [EXTERNAL] - Re: Question about TLS 1.3 and openssl -cipher aNULL option On Fri, Sep 04, 2020 at 07:00:01PM +, Yury Mazin via openssl-users wrote: > Thank you Benjamin, > > According to OpenSSL , aNULL stands for no-authentication. Specifically, SSL 3.0 through TLS 1.2 ciphers in which the server and client exchange no certificates, and the TLS handshake consists largely of an unsigned anonymous ephemeral DH or ECDH key exchang. TLS 1.3 dropped support for anonymous DH and ECDH. Server certificates are *required. And the all-in-one ciphersuites of TLS <= 1.2, are replaced with separately negotiated components. As a result of which, in OpenSSL 1.1.1 and later, they are controlled via a different set of APIs and command-line options. Specifically, in your case, the "-ciphers aNULL" option only applies to TLS <= 1.2 > Does it mean that all 3 default protocols of TLS 1.3 offer no > authentication No. None of them "support no authentication" (which is not even strictly true, it is the protocol that does not support "no authentication", the TLS 1.3 ciphers are simply silent re certificate algorithm selection), but the "-cipher aNULL" is simply not used when TLS 1.3 is negotiated, so your question is makes incorrect assumptions to reach its tentative conclusions. -- Viktor.
Re: [EXTERNAL] - Re: Question about TLS 1.3 and openssl -cipher aNULL option
Viktor, Thank you for clarifying it. Yury From: openssl-users on behalf of Viktor Dukhovni Sent: Friday, September 4, 2020 12:10 PM To: openssl-users@openssl.org Subject: Re: [EXTERNAL] - Re: Question about TLS 1.3 and openssl -cipher aNULL option On Fri, Sep 04, 2020 at 07:00:01PM +, Yury Mazin via openssl-users wrote: > Thank you Benjamin, > > According to OpenSSL , aNULL stands for no-authentication. Specifically, SSL 3.0 through TLS 1.2 ciphers in which the server and client exchange no certificates, and the TLS handshake consists largely of an unsigned anonymous ephemeral DH or ECDH key exchang. TLS 1.3 dropped support for anonymous DH and ECDH. Server certificates are *required. And the all-in-one ciphersuites of TLS <= 1.2, are replaced with separately negotiated components. As a result of which, in OpenSSL 1.1.1 and later, they are controlled via a different set of APIs and command-line options. Specifically, in your case, the "-ciphers aNULL" option only applies to TLS <= 1.2 > Does it mean that all 3 default protocols of TLS 1.3 offer no > authentication No. None of them "support no authentication" (which is not even strictly true, it is the protocol that does not support "no authentication", the TLS 1.3 ciphers are simply silent re certificate algorithm selection), but the "-cipher aNULL" is simply not used when TLS 1.3 is negotiated, so your question is makes incorrect assumptions to reach its tentative conclusions. -- Viktor.
Re: [EXTERNAL] - Re: Question about TLS 1.3 and openssl -cipher aNULL option
On Fri, Sep 04, 2020 at 07:00:01PM +, Yury Mazin via openssl-users wrote: > Thank you Benjamin, > > According to OpenSSL , aNULL stands for no-authentication. Specifically, SSL 3.0 through TLS 1.2 ciphers in which the server and client exchange no certificates, and the TLS handshake consists largely of an unsigned anonymous ephemeral DH or ECDH key exchang. TLS 1.3 dropped support for anonymous DH and ECDH. Server certificates are *required. And the all-in-one ciphersuites of TLS <= 1.2, are replaced with separately negotiated components. As a result of which, in OpenSSL 1.1.1 and later, they are controlled via a different set of APIs and command-line options. Specifically, in your case, the "-ciphers aNULL" option only applies to TLS <= 1.2 > Does it mean that all 3 default protocols of TLS 1.3 offer no > authentication No. None of them "support no authentication" (which is not even strictly true, it is the protocol that does not support "no authentication", the TLS 1.3 ciphers are simply silent re certificate algorithm selection), but the "-cipher aNULL" is simply not used when TLS 1.3 is negotiated, so your question is makes incorrect assumptions to reach its tentative conclusions. -- Viktor.
Re: [EXTERNAL] - Re: Question about TLS 1.3 and openssl -cipher aNULL option
Thank you Benjamin, According to OpenSSL , aNULL stands for no-authentication. NULL-ciphers that you mention would be part of eNULL group, that offer no encryption. Does it mean that all 3 default protocols of TLS 1.3 offer no authentication (because they are listed under command openssl ciphers -v -s aNULL TLS_AES_256_GCM_SHA384 TLSv1.3 Kx=any Au=any Enc=AESGCM(256) Mac=AEAD TLS_CHACHA20_POLY1305_SHA256 TLSv1.3 Kx=any Au=any Enc=CHACHA20/POLY1305(256) Mac=AEAD TLS_AES_128_GCM_SHA256 TLSv1.3 Kx=any Au=any Enc=AESGCM(128) Mac=AEAD Thank you, Yury From: Benjamin Kaduk Sent: Thursday, September 3, 2020 5:12 PM To: Yury Mazin Cc: openssl-users@openssl.org Subject: [EXTERNAL] - Re: Question about TLS 1.3 and openssl -cipher aNULL option On Thu, Sep 03, 2020 at 11:45:28PM +, Yury Mazin via openssl-users wrote: > Hello, > > We have a server was originaly using OpenSSL 1.0.2h. > Server is configured to use SSL ciphers as following > ALL:!aNULL:!ADH:!EDH:!eNULL:!EXPORT > When openssl client tries to connect to this server with command > openssl s_client -connect localhost:8101-cipher aNULL > it fails, because any aNULL ciphers are not available per server > configuration. > We have now upgraded server to use OpenSSL 1.1.1f. > The current behavior is this: client can connect using the same command > openssl s_client -connect localhost:8101 -cipher aNULL > or > openssl s_client -tls1_3 -connect localhost:8101 -cipher aNULL > > while the same connect attempt using TLS1.2 protocol would still fail > > openssl s_client -tls1_2 -connect localhost:8001-cipher aNULL > > Would the fact that I can connect to the server using TLS 1.3 using the > following command (specifically, using -cipher aNULL, while server is > configured to exclude all aNULL cipher suites) considered a security > violation? > > openssl s_client -tls1_3 -connect localhost:8001 -cipher aNULL > > Also, if this a security violation, how this can be addressed in the server > configuration? > Lastly, if this is not a security violation, please explain. It is not a security violation, because you are using TLS 1.3 ciphers, and there are not any NULL-encryption TLS 1.3 ciphers. Configuration of TLS 1.3 ciphers and ciphers for previous versions of TLS are separate (since, at a protocol level, they serve different roles). See the documentation for s_client/s_server -ciphersuites for more information about TLS 1.3 ciphers. -Ben
