Hi ,
1) I am working with a client and server program and want to use ECDHE-ECDSA type ciphers.
I see that default Elliptic curve group supported is X25519. (when I check client and server logs on wireshark)
I wish to generate a self-signed certificate for X25519 curve. But I am unable to do that the way I do for other curves like secp256r1, secp521r1 etc.
I generate a private key for secp521r1 using ecparam command and then I generate the self-signed certificate.
openssl ecparam -name secp521r1 -genkey -param_enc named_curve -out server_key.pem
openssl req -new -x509 -key server_key.pem -out server_cert.pem -days 730
On man page for X25519,
I found the command to generate private key
openssl genpkey -algorithm X25519 -out xkey.pem
But as I try to generate a self signed certificate, I am getting the following error
EVP_PKEY_sign_init:operation not supported for this keytype
Could you please clarify where am I going wrong. Also, why is X25519 not mentioned
in ec curve list
using openssl ecparam -list_curves
Any references to clarify my understanding will be appreciated.
2) Also, can you direct me towards what hack is needed in Openssl to support pre-generated PSK in TLS 1.3 and false start in TLS 1.2 (for my study purpose).
Are you planning to integrate false start in OpenSSL any time. Thanks
Thanks
Best Regards,
Neetish
On Wed, Jun 21, 2017 at 3:17 PM, Neetish Pathak <npathak2@xxxxxxxx> wrote:
On Wed, Jun 21, 2017 at 3:11 AM, Matt Caswell <matt@xxxxxxxxxxx> wrote:
On 21/06/17 00:38, Neetish Pathak wrote:
> I wanted to understand the replay attack vulnerability in case of enable
> early data of TLS 1.3 while false start is secure in that respect as I
> have read from https://github.com/openssl/openssl/issues/1541
> So, with false start, the application data is sent from client after the
> first leg of the handshake i.e. one round trip is complete, so the data
> goes encrypted even though the handshake is not completed. In enable
> early data mode in TLS 1.3 for 0-RTT for session resumption, the
> application data is sent from the client along with the client hello
> message. Does the application data in early data mode go as clear text ?
No, it is encrypted using a traffic key derived from the PSK.
> I assume this is also encrypted using the PSK because 0-RTT is only
> applicable when PSK is available on the client side. How is it
> vulnerable to replay attack. Please help me understand.
The same PSK can be used multiple times. Because the traffic key for the
early data is derived from the PSK, if you later re-use the PSK and send
early data again then the same traffic key will be derived. This can be
exploited by an attacker who can record the early data from an earlier
session and replay it later. The server will think that the replayed
data is a new connection and process the early data accordingly.
Early data (aka 0-RTT data) can be dangerous if not used properly. For
this reason the current TLSv1.3 draft makes this note:
Protocols MUST NOT use 0-RTT data without a profile that defines its
use. That profile needs to identify which messages or interactions
are safe to use with 0-RTT. In addition, to avoid accidental misuse,
implementations SHOULD NOT enable 0-RTT unless specifically
requested. Implementations SHOULD provide special functions for
0-RTT data to ensure that an application is always aware that it is
sending or receiving data that might be replayed.
>
> Is there any API available in OpenSSL for false start ?
No, OpenSSL does not support false start. As an aside please note that
false start only applies to <= TLSv1.2.Thanks for your comments.I need some direction on the doing server and client side authentication during the handshake.1) For certificate sent from the server side, I am usingSSL_CTX_load_verify_locations(
ssl_ctx, CAFILE, NULL)) for loading verification file on the client side Where do I get a CAFILE in the above API. If the server is sending a self signed certificate, what will be the CA file on the client side for verification.
2) For Client side authenticationI am using SSL_CTX_use_PrivateKey_file and SSL_CTX_use_certificate file on the client side to load the private key and the certificate. I read that client side authentication will not kick off unless the server sends CertificateRequest. I can use SSL_CTX_set_client_cert_cb()that sets the client_cert_cb() callback to be called on CertificateRequest.I am not sure how I can enable the server side to send CertificateRequest. What is the API for that.Should SSL_CTX_set_verify((ssl_ctx,SSL_VERIFY_PEER, NULL)) be used on server side for sending the certificateRequest message. Please correct me ? 3) Certificate request MessageAlso, what is the use of CertificateVerify message. Why does client need to prove the ownership of private key for the public key sent previously in the client certificate. I assume this is not happening when the server sends the certificate. It doesn't prove the ownership of private key.Please commentAlso, some guidance on a reference for understanding the authentication of certificates will be appreciatedThanksNeetish
Matt
>
> Thanks
> Best regards,
> Neetish
>
> On Tue, Jun 20, 2017 at 11:52 AM, Neetish Pathak <npathak2@xxxxxxxx
> <mailto:npathak2@xxxxxxxx>> wrote:
>
> I Appreciate your response
>
> On Tue, Jun 20, 2017 at 2:09 AM, Matt Caswell <matt@xxxxxxxxxxx
> <mailto:matt@xxxxxxxxxxx>> wrote:
>
>
>
> On 19/06/17 19:11, Neetish Pathak wrote:
> > 2) Can you suggest some places to put a time stamp in OpenSSL code.
>
> I agree with Ben's responses to all your other questions. For this
> question, I'm not sure what you are trying to achieve? Starting
> before
> SSL_accept/SSL_connect and finishing after they return should be
> fine.
> Or are you looking for a breakdown of where the time is going?
>
> Thanks Matt. I was asking for a breakdown since I was not sure
> if the SSL_accept and SSL_connect just do the handshake or if
> they are doing some other things that may impact latency and CPU
> usage. Just wanted to be clear that calling SSL_connect starts
> ClientHello , SSL_accept unblocks on receiving ClientHello and
> sends ServerHello, and both functions return after sending
> Finished message from their sides (i.e. client and server).
>
>
>
>
>
> Matt
>
> >
> > Thanks
> > Best Regards,
> > Neetish
> >
> > On Mon, Jun 19, 2017 at 5:49 AM, Matt Caswell <matt@xxxxxxxxxxx <mailto:matt@xxxxxxxxxxx>
> > <mailto:matt@xxxxxxxxxxx <mailto:matt@xxxxxxxxxxx>>> wrote:
> >
> >
> >
> > On 16/06/17 23:51, Neetish Pathak wrote:
> > > Thanks Matt, Appreciate ur response and tips
> > >
> > > On Fri, Jun 16, 2017 at 3:36 PM, Matt Caswell <matt@xxxxxxxxxxx <mailto:matt@xxxxxxxxxxx>
> <mailto:matt@xxxxxxxxxxx <mailto:matt@xxxxxxxxxxx>>
> > > <mailto:matt@xxxxxxxxxxx <mailto:matt@xxxxxxxxxxx>
> <mailto:matt@xxxxxxxxxxx <mailto:matt@xxxxxxxxxxx>>>> wrote:
> > >
> > >
> > >
> > > On 16/06/17 20:08, Benjamin Kaduk via openssl-users
> wrote:
> > > > On 06/16/2017 01:58 PM, Neetish Pathak wrote:
> > > >> Hello
> > > >> Thanks
> > > >> I tried reading some content from the server
> side and I
> > observed the
> > > >> new_session_cb getting invoked in that case on
> the client
> > side. I
> > > >> understand that may be due to delayed NewSession info
> > transfer from
> > > >> server side to client side. But it is helpful for
> saving
> > the session
> > > >> info on the client side. (Thanks Matt for your input)
> > > >>
> > > >> However, now I have two concerns
> > > >>
> > > >> 1) I see that latency for handshake with session
> resumption in
> > > TLS 1.3
> > > >> has not improved as much as it improves for TLS 1.2
> > > >> With TLS 1.3, I observed that resumption brings
> down the
> > connection
> > > >> time from 2.5 ms to 1.2-1.3 ms
> > > >> while with TLS 1.2 (using either session IDs or
> tickets), the
> > > >> connection time reduces from 2.5 ms to 0.5-0.6 ms.
> > > >>
> > > >> The whole code is similar for running the two
> experiments
> > with only
> > > >> max TLS version changed. Can someone comment on
> the latency
> > > >> measurements for the two cases.
> > > >> TLS 1.3 is supposed to be better than TLS 1.2 in my
> > opinion. Please
> > > >> comment.
> > > >>
> > > >
> > > > Are you seeing a HelloRetryRequest in the
> resumption flow?
> > That would
> > > > add an additional round trip. (Your numbers in
> milliseconds
> > are of
> > > > course not transferrable to other systems;
> round-trips is an
> > easier to
> > > > understand number.) RFC 5246 and
> draft-ietf-tls-tls13-20
> > both have
> > > > message-flow diagrams that show the number of
> round trips in
> > various
> > > > handshake flows.
> > >
> > > Care should also be taken about when you are
> starting your
> > "timer" and
> > > when you stop it, e.g. if you stop your timer after the
> > session ticket
> > > data has been received by the client then this is
> not a "fair"
> > test (the
> > > connection is ready for data transfer earlier than
> the arrival
> > of the
> > > session ticket).
> > >
> > > I would expect to see the TLS1.3 latency for a full
> handshake
> > to be
> > > around the same as for a TLS1.2 resumption
> handshake. With a
> > TLS1.3
> > > resumption only marginally different. There are the same
> > number of round
> > > trips for a TLS1.3 full handshake as that there are
> for a
> > resumption
> > > one. The primary difference is that the Certificate
> message is
> > not sent
> > > (which can be quite a large message).
> > >
> > > Your timings suggest you are testing this over a LAN
> where the
> > effects
> > > of network latency are going to be relatively low.
> The real
> > benefits
> > > from fewer round trips will really be seen when network
> > latency is more
> > > significant.
> > >
> > >
> > >
> > > In my application program, I put start and stop timer
> before and after
> > > SSL_accept on server side and before and after
> SSL_connect on the
> > client
> > > side.
> >
> > That should be fine (my worry was that you might also be
> including the
> > subsequent session ticket transfer).
> >
> > > I am not sure how I can put timers at individual steps
> of Handshake
> > > using my client applications. I was assuming SSL and
> SSL_accept take
> > > care of the entire handshake process.
> > >
> > > Yes, I am testing on local machine. I will migrate my
> test to remote
> > > machines. But I am not really able to understand why TLS
> 1.3 is slower
> > > on my machine.
> >
> > If you are on a local machine I would not expect a
> significant speed up
> > in TLSv1.3 vs TLSv1.2. TLSv1.3 has been designed to reduce
> the number of
> > round-trips required in order to avoid unnecessary network
> latency. If
> > you are on a local machine then there isn't any
> significant network
> > latency anyway - so timings are presumably dominated by
> the CPU
> > intensive tasks. You should make sure that you are
> comparing like with
> > like, i.e. the same ciphers, key lengths, key exchange
> algorithms,
> > curves etc between TLSv1.2 and TLSv1.3. Differences in any
> one of these
> > could obviously have significant performance impacts.
> >
> > Matt
> >
> > --
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