[openssl-users] Multiple client connection to Nginx server

ASHIQUE CK ckashiquekvk at gmail.com
Thu Dec 13 03:30:25 UTC 2018

1. The engine that we wrote is by the reference of qat, is just an
interface which receives the openssl parameters of AES and RSA and offload
them to an FPGA hardware accelerator.
3. Openssl 1.1.0 h
4. Uses f-stack nginx 1.10.1
5. We ran nginx server which have a 1 Gb file in its root directory. Then
connected 3 clients to this server. These clients waits after handshake is
done. After I run 3rd client, I gave a Get request through 1 st client to
download that 1 gb file. But it showed error message, "decryption failed or
bad record mac". When I debugged using gdb, I understood that Tag
verification is getting failed. But the matter is, I am storing the Key and
IV at the time of handshake itself, to a buffer in my engine. When an
SSLRead or SSLWrite occur, I will copy the saved Key and Iv to fill the
respective descriptors.
      But, in this case what happens is, if there is 3rd client handshake
occurred, its key and iv stored in a buffer. And when I give a Sslwrite in
the 1st client, it used the last saved key and iv, but it is actually key
and iv of 3 rd client. But I can download the file if I give get request
through the last handshaked client.
     So what I can do is, save the key and iv of different clients in
different buffers. If the SSLread/write from any client comes, then just
offload the key and iv from the respective buffer. But for that, i need a
unique id for each client, which must be the same for a client in the
entire connection.
    How can i get the unique id. Beyond the parameters *in, *out, inl (in
the case of plaintext/ cipher text offloading) and *ptr, *type, *arg (in
the case of header/aad offload) only what I have is ctx. With this ctx, can
i get a unique id or is there any way to solve this problem.
6. Didn't tried with Apache server.


On Thu 13 Dec, 2018, 1:30 AM Michael Richardson <mcr at sandelman.ca wrote:

> ASHIQUE CK <ckashiquekvk at gmail.com> wrote:
> > We are using a Crypto Accelerator Engine to offload AESGCM and RSA
> > parameters. Trying to connect multiple clients simultaneously with a
> > single Nginx server, which is using this accelerator. The Key and IV
> You probably need to tell us:
> 1) which engine?  did you write this engine?
> 2) whose driver?
> 3) what version of openssl?
> 4) what version of nginx?
> 5) how did you observe the problem you described?
> 6) is it different for, for instance, apache?  or some other server
> software?
> > is passing only at handshake, and after handshake this set of key and
> > IV is using for all encryption and decryption. So at Engine side, we
> > are storing this Key and IV to a buffer and while
> > encrypting/decrypting , this Key and IV is used from this buffer. But,
> > while multiple client connects, the last saved Key/IV is getting for
> > all clients.
> > So, is there any way to get a unique ID foer each client connection ?
> >
> --
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