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From "victor negrin (JIRA)" <>
Subject [jira] Created: (LUCENE-737) Provision of encryption/decryption services API to support Field.Store.Encrypted
Date Fri, 01 Dec 2006 21:38:21 GMT
Provision of encryption/decryption services API to support Field.Store.Encrypted

                 Key: LUCENE-737
             Project: Lucene - Java
          Issue Type: New Feature
          Components: Index, Search, Store
    Affects Versions: 2.0.0, 2.0.1
            Reporter: victor negrin

Attached are proposed modifications to Lucene 2.0 to support Field.Store.Encrypted.
The rational behind this proposal is simple. Since Lucene can store data in the index, it
effectively makes the data portable. It is conceivable that some of the data may be sensitive
in nature, hence the option to encrypt it. Both the data and its index are encrypted in this
This is only an initial implementation. It has the following several restrictions, all of
which can be resolved if required, albeit with some effort and more changes to Lucene:
1) binary and compressed fields cannot be encrypted as well (a plaintext once encrypted becomes
2) Field.Store.Encrypted implies Field.Store.Yes
This makes sense but it forces one to store the data in the same index where the tokens are
stored. It may be preferable at times to have two indeces, one for tokens, the other for the
3) As implemented, it uses RC4 encryption from BouncyCastle. This is an open source package,
very simple to use which has the advantage of guaranteeing that the length of the encrypted
field is the same as the original plaintext. As of Java 1.5 (5.0) Sun provides an RC4 equivalent
in its Java Cryptography Extension, but unfortunately not in Java 1.4.
The BouncyCastle RC4 is not the only algorythm available, others not depending on third party
code can be used, but it was just the simplest to implement for this first attempt.
4) The attachements are modifications in diff form based on an early (I think August or September
'06) repository snapshot of Lucene 2.0 subsequently updated from the Lucene repository on
29/11/06. They may need some additional work to merge with the latest version in the Lucene
repository. They also include a couple of JUnit test programs which explain, as well as test,
the usage. You will need the BouncyCastle .jar (bcprov-jdk14-134.jar) to run them. I did not
attach it to minimize the size of the attachements, but it can be downloaded free from:
5) Searching an encrypted field is restricted to single terms, no phrase or boolean searches
allowed yet, and the term has to be encrypted by the application before searching it. (ref.
attached JUnit test programs)

To the extent that I have tested it, the code works as intended and does not appear to introduce
any regression problems, but more testing by others would be desirable.
I don't propose at this stage to do any further work with this API extensions unless there
is some expression of interest and direction from the Lucene Developers team. I have an application
ready to roll which uses the proposed Lucene encryption API additions (please see
The application is not yet available for downloading simply because I am not sure if the Lucene
licence allows me to do so. I would appreciate your advice in this regard. My application
is free but its source code is not available (yet). I should add that encryption does not
have to be an integral part of Lucene, it can be just part of the end application, but somehow
it seems to me that Field.Store.Encrypted belongs in the same category as compression and
binary values.
I would be happy to receive your feedback.

victor negrin 

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