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From Todd Palino <tpal...@gmail.com>
Subject Re: Gauging Interest in adding Encryption to Kafka
Date Sat, 01 Aug 2015 00:06:32 GMT
1 - Yes, authorization combined with encryption does get us most of the way
there. However, depending on the auditor it might not be good enough. The
problem is that if you are encrypting at the broker, then by definition
anyone who has access to the broker (i.e. operations staff) have access to
the data. Consider the case where you are passing salary and other
information through the system, and those people do not need a view of it.
I admit, the 90% solution might be better here than going for a perfect
solution, but it is something to think about.

2 - My worry is people wanting to integrate with different key systems. For
example, one person may be fine with providing it in a config file, while
someone else may want to use the solution from vendor A, someone else wants
vendor B, and yet another person wants this obscure hardware-based solution
that exists elsewhere.

The compaction concern is definitely a good one I hadn't thought of. I'm
wondering if it's reasonable to just say that compaction will not work
properly with encrypted keys if you do not have consistent encryption (that
is, the same string encrypts to the same string every time).

Ultimately I don't like the idea of the broker doing any encrypt/decrypt
steps OR compression/decompression. This is all CPU overhead that you're
concentrating in one place instead of distributing the load out to the
clients. Now yes, I know that the broker decompresses to check the CRC and
assign offsets and then compresses, and we can potentially avoid the
compression step with assigning the batch an offset and a count instead but
we still need to consider the CRC. Adding encrypt/decrypt steps adds even
more overhead and it's going to get very difficult to handle even 2 Gbits
worth of traffic at that rate.

There are other situations that concern me, such as revocation of keys, and
I'm not sure whether it is better with client-based or server-based
encryption. For example, if I want to revoke a key with client-based
encryption it becomes similar to how we handle Avro schemas (internally)
now - you change keys, and depending on what your desire is you either
expire out the data for some period of time with the older keys, or you
just let it sit there and your consuming clients won't have an issue. With
broker-based encryption, the broker has to work with the multiple keys
per-topic.

-Todd


On Fri, Jul 31, 2015 at 2:38 PM, Gwen Shapira <gshapira@cloudera.com> wrote:

> Good points :)
>
> 1) Kafka already (pending commit) has an authorization layer, so
> theoretically we are good for SOX, HIPAA, PCI, etc. Transparent broker
> encryption will support PCI
> never-let-unencrypted-card-number-hit-disk.
>
> 2) Agree on Key Management being complete PITA. It may better to
> centralize this pain in the broker rather than distributing it to
> clients. Any reason you think its better to let the clients handle it?
> The way I see it, we'll need to handle key management the way we did
> authorization - give an API for interfacing with existing systems.
>
> More important, we need the broker to be able to decrypt and encrypt
> in order to support compaction (unless we can find a cool
> key-uniqueness-preserving encryption algorithm, but this may not be as
> secure). I think we also need the broker to be able to re-compress
> data, and since we always encrypt compressed bits (compressing
> encrypted bits doesn't compress), we need the broker to decrypt before
> re-compressing.
>
>
>
> On Fri, Jul 31, 2015 at 2:27 PM, Todd Palino <tpalino@gmail.com> wrote:
> > It does limit it to clients that have an implementation for encryption,
> > however encryption on the client side is better from an auditing point of
> > view (whether that is SOX, HIPAA, PCI, or something else). Most of those
> > types of standards are based around allowing visibility of data to just
> the
> > people who need it. That includes the admins of the system (who are often
> > not the people who use the data).
> >
> > Additionally, key management is a royal pain, and there are lots of
> > different types of systems that one may want to use. This is a pretty big
> > complication for the brokers.
> >
> > -Todd
> >
> >
> > On Fri, Jul 31, 2015 at 2:21 PM, Gwen Shapira <gshapira@cloudera.com>
> wrote:
> >
> >> I've seen interest in HDFS-like "encryption zones" in Kafka.
> >>
> >> This has the advantage of magically encrypting data at rest regardless
> >> of which client is used as a producer.
> >> Adding it on the client side limits the feature to the java client.
> >>
> >> Gwen
> >>
> >> On Fri, Jul 31, 2015 at 1:20 PM, eugene miretsky
> >> <eugene.miretsky@gmail.com> wrote:
> >> > I think that Hadoop and Cassandra do [1] (Transparent Encryption)
> >> >
> >> > We're doing [2] (on a side note, for [2] you still need
> authentication on
> >> > the producer side - you don't want an unauthorized user writing
> garbage).
> >> > Right now we have the 'user' doing the  encryption and submitting raw
> >> bytes
> >> > to the producer. I was suggesting implementing an encryptor in the
> >> > producer itself - I think it's cleaner and can be reused by other
> users
> >> > (instead of having to do their own encryption)
> >> >
> >> > Cheers,
> >> > Eugene
> >> >
> >> > On Fri, Jul 31, 2015 at 4:04 PM, Jiangjie Qin
> <jqin@linkedin.com.invalid
> >> >
> >> > wrote:
> >> >
> >> >> I think the goal here is to make the actual message stored on broker
> to
> >> be
> >> >> encrypted, because after we have SSL, the transmission would be
> >> encrypted.
> >> >>
> >> >> In general there might be tow approaches:
> >> >> 1. Broker do the encryption/decryption
> >> >> 2. Client do the encryption/decryption
> >> >>
> >> >> From performance point of view, I would prefer [2]. It is just in
> that
> >> >> case, maybe user does not necessarily need to use SSL anymore because
> >> the
> >> >> data would be encrypted anyway.
> >> >>
> >> >> If we let client do the encryption, there are also two ways to do so
> -
> >> >> either we let producer take an encryptor or users can do
> >> >> serialization/encryption outside the producer and send raw bytes. The
> >> only
> >> >> difference between the two might be flexibility. For example, if
> someone
> >> >> wants to know the actual bytes of a message that got sent over the
> wire,
> >> >> doing it outside the producer would probably more preferable.
> >> >>
> >> >> Jiangjie (Becket) Qin
> >> >>
> >> >> On Thu, Jul 30, 2015 at 12:16 PM, eugene miretsky <
> >> >> eugene.miretsky@gmail.com
> >> >> > wrote:
> >> >>
> >> >> > Hi,
> >> >> >
> >> >> > Based on the security wiki page
> >> >> > <https://cwiki.apache.org/confluence/display/KAFKA/Security>
> >> encryption
> >> >> of
> >> >> > data at rest is out of scope for the time being. However, we are
> >> >> >  implementing  encryption in Kafka and would like to see if there
> is
> >> >> > interest in submitting a patch got it.
> >> >> >
> >> >> > I suppose that one way to implement  encryption would be to add
an
> >> >> > 'encrypted key' field to the Message/MessageSet  structures in
the
> >> >> > wire protocole - however, this is a very big and fundamental
> change.
> >> >> >
> >> >> > A simpler way to add encryption support would be:
> >> >> > 1) Custom Serializer, but it wouldn't be compatible with other
> custom
> >> >> > serializers (Avro, etc. )
> >> >> > 2)  Add a step in KafkaProducer after serialization to encrypt
the
> >> data
> >> >> > before it's being submitted to the accumulator (encryption is
done
> in
> >> the
> >> >> > submitting thread, not in the producer io thread)
> >> >> >
> >> >> > Is there interest in adding #2 to Kafka?
> >> >> >
> >> >> > Cheers,
> >> >> > Eugene
> >> >> >
> >> >>
> >>
>

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