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From Jason Bailey <>
Subject RE: value level encryption - Donating?
Date Mon, 04 Dec 2017 14:55:12 GMT
Hi Antonio,

I added a couple of things to the repository based on your feedback. The primary change was
the addition of a key provider that would allow you to separate the management and the storage
of secret keys away from the encryption provider. I also added two implementations of that
service as well. One which utilizes the java keystore and the other which provides you the
ability to define keys in the OSGi Configuration. The secondary one being useful for testing
and for environments where you don't have access to the filesystem. I will most likely be
implementing another variant to integrate with the thycotic secret server.

To support Key rotation, I added additional identifying bytes after the IV that is used by
the KeyProvider to provide the correct key for decryption. While all encryption processes
are done with the KeyProvider's primary key. 

Example of how this would work: I am using a KeyProvider with a primary key for 6 months.
As part of a Security Policy this needs to be changed. I then take the existing primary key
and add it to the secondary list and provide a new key as primary. At this point all new encryptions
will occur with the primary key, however I will still be able to access the older encrypted
messages as well. To update the older keys with the new key, it's a matter of iterating over
the stored encrypted resources with the EncryptableValueMap and using the encrypt(propertyName)
method.  Which will re-encrypt the property with the new primary.

I'm running with the AES/GCM because it provides the best overall security and fits my use
cases and the key rotation support should alleviate some concerns as well.


-----Original Message-----
From: Antonio Sanso [] 
Sent: Tuesday, November 21, 2017 5:37 AM
Subject: Re: value level encryption - Donating?


hi Jason,

I basically see 3 options:

* ship with AES/CBC that is ok but suboptimal
- ship with AES-GCM that is good but has the problem of the nonce highlighted before. The
key rotation would help but than what do you do on rotation? Decrypt all the encrypted value
and re-encrypt with the new key... ?
- Encrypt-than-MAC

I have also noted that the key is stored as OSGi configuration... This might also be part
of a bigger discussion....



On Nov 20, 2017, at 10:03 PM, Jason Bailey <> wrote:

> It's all good. I  have less meetings today then I normally would and the exercise was
beneficial as it got me thinking about other potential vectors.
> Since the key for this is configurable via the OSGi console I would have taken key rotation
as being a business process exercise rather than a technical one. But I don't mind changing
it, I'm having a lot of fun with this.
> To make sure I'm on the same page. The direction right now is AES/CBC/PKCS5Padding but
with encrypt and MAC?
> -----Original Message-----
> From: Antonio Sanso []
> Sent: Monday, November 20, 2017 3:07 PM
> To:
> Subject: Re: value level encryption - Donating?
> hi Jason,
> I get your point
> On Nov 20, 2017, at 4:57 PM, Jason Bailey <> wrote:
>> Thanks Antonio. I had considered doing GCM, but I hesitated since it's not listed
as a standard transformation that a Java platform must support. As I couldn't know what platform
it would be running on I tried to be as much OOTB as possible. That desire to be OOTB is also
why it's 128bit. My idea was to provide a generic level of encryption with the assumption
that a downstream implementer would/should implement the EncryptionProvider service to the
level of security their company requires.
>> Saying that, if the desire is to have it GCM I will get that implemented.
> Thanks a lot taking this consideration and speed the implementation. You are right about
AES GCM. On top there is also another problem with it.
> AES GCM uses a nonce of 96 bits. It is vital important to never reuse the same nonce
with the same key otherwise the result is a real catastrophe (cryptographically wise).
> This implies, given the birthday paradox, that we need to rotate the key after 2^48 encryptions.
This is a pretty big number but you know the life of the key can be also long.
> Hence, without key rotation, it wouldn't probably good to ship with this (now I am sorry
you already jumped on it and implemented but I did not think you were so fast).
> Another more conservative approach would be encrypt-than-mac (or we can simply keep AES/CBC
as default).
> An overall observation would be also that given the sensitive topic it would be good
to have a more extensive test suite for this feature...
> my 2 cents
> regards
> antonio
>> -----Original Message-----
>> From: Antonio Sanso []
>> Sent: Monday, November 20, 2017 10:29 AM
>> To:
>> Subject: Re: value level encryption - Donating?
>> hi Jason,
>> thanks a lot for the donation.
>> I already commented on the issue, just pasting inline part of the 
>> comment though
>> On Nov 20, 2017, at 2:50 PM, Jason Bailey <> wrote:
>>> So I'm just about done implementing this.
>>> Value level encryption. IV is stored inline so there's no repetition. Accessing
encrypted data via the EncryptionValueMap will decode it automatically on access and will
handle automatically encrypting values if an encrypted value is updated.
>>> Only problem I had besides catching up on the last 15 years of 
>>> cryptography
>> I have seen you have used AES/CBC that is not  (extremely) bad. Said that if we really
want to put this in Sling we'd better do things as the state of art requires.
>> As rule of thumbs you never (only) encrypt . You'd better add some integrity check
mechanism (eg AES GCM or encrypt-then-mac).
>> regards
>> antonio
>>> was that the downstream application I use has a non configurable whitelist filter
for post processors that contain an '@' So I had to make the post processor configurable.
>>> As mentioned earlier I wrote this with the intention of donating. I tried to
make it as easy as possible for it to be pulled into where it needs to go.
>>> However I don't know the process for Donating. Can someone point me the way or
to some documentation?
>>> Thanks.
>>> -Jason
>>> -----Original Message-----
>>> From: Justin Edelson []
>>> Sent: Friday, November 03, 2017 3:37 PM
>>> To:
>>> Subject: Re: value level encryption
>>> In AEM, posting encrypted properties to /etc/cloudservices is historically the
primary use case for @Encrypted, but the PostProcessor applies to all post requests.
>>> I think this would be a useful addition to Sling. We may want to have some kind
of SPI to support different encryption schemes, but that's an implementation detail.
>>> Regards,
>>> Justin
>>> On Fri, Nov 3, 2017 at 2:48 PM Jason Bailey <> wrote:
>>>> They only docs I can find on that, assuming we're talking AEM, 
>>>> mentions it only works for posting things into /etc/cloudservices. So that's
>>>> It's been a while, but I'm under the impression that all 
>>>> implementations of the java platform now come with a certain level 
>>>> of crypto
>>>> I'd probably add a configuration so you could define the level of 
>>>> cryptography, and then that would allow people who needed a higher 
>>>> level to install their own providers. Is this something that Sling 
>>>> would be interested in? Since I'm going to be writing this, if 
>>>> you're interested, I'd rather write it with the intent of directly donating
>>>> -----Original Message-----
>>>> From: Justin Edelson []
>>>> Sent: Friday, November 03, 2017 1:35 PM
>>>> To:
>>>> Subject: Re: value level encryption
>>>> We have this in our commercial product. At a high level, the way it 
>>>> works is that there is a PostProcessor which looks for an 
>>>> @Encrypted postfixed property and, if that is present, the 
>>>> corresponding property is stored in an encrypted fashion. 
>>>> Decryption is all done manually, although personally the idea of an EncryptionValueMap
seems really cool to me.
>>>> I believe the challenge in bringing this into Sling relates to the 
>>>> encryption libraries.
>>>> On Fri, Nov 3, 2017 at 8:45 AM Jason Bailey <>
>>>>> Here's the use case
>>>>> My organization has decided that to conform to the GDPR, any 
>>>>> sensitive data should be encrypted while at rest. From a Sling 
>>>>> perspective that is a challenge since we've empowered the authors 
>>>>> to create forms the way they want. So to be on the safe side, 
>>>>> we're looking at encrypting all form fields as they are persisted, 
>>>>> and then decrypting the values from the resource  when we need to processes
>>>>> Now I'm thinking of an EncryptionValueMap that will simplify this 
>>>>> process and encapsulate the functionality. You guys are usually 
>>>>> ahead of me when I come up with this stuff and I don't like 
>>>>> replicating effort. So is there any functionality currently or 
>>>>> planned to handle encryption of resource values?
>>>>> Thanks
>>>>> Jason

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