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From Mike Kienenberger <mkien...@gmail.com>
Subject Re: Interceptable ExtendedType
Date Thu, 13 Mar 2014 12:13:44 GMT
For what it's worth, I'm doing the same thing for our JPA app.

I store the encryption version number (unencrypted), then an encrypted
set of data fields.

We found that trying to encrypt individual fields wasn't as helpful
since the length and variety of individual columns tended not to be
all that unique.
Padding with random characters can help, but encrypting more fields
together in a single column seemed more appropriate in our case,
especially since you can't do any meaningful sql on the encrypted data
anyway.

Here's the api I ended up going with:

class DataBlockEncryptionManager {

        public DataBlockEncryptionManager(EncryptionVersionProvider
encryptionVersionProvider)

    /**
     * encrypt item in encrypted data block.
     *
     * @param encryptedData String containing previous encrypted
block, null to create new block
     * @param itemIndex from 0 to last item of item to encrypt
     * @param newValue to add to block
     * @return String containing encrypted block
     * @throws EncryptionException
     */
    public String encryptDataBlock(String encryptedData, int
itemIndex, char[] newValue);

    public char[] decryptDataBlock(String encryptedData, int
itemIndex) throws EncryptionException;

    public interface EncryptionVersionProvider
    {
        /** Default version to use for new encryptions */
        public String getDefaultVersion();

    // with a few methods like these depending on our encryption
        public String _xyzEncryptionProperty_ForVersion(String version);

    }

}

then, assuming your column is named ENCRYPTED_DATA, your individual
attributes look like this:

    public char[] getName() throws EncryptionException {
        return decryptDataBlock(getEncryptedData(), ITEM_INDEX__NAME);
    }
    public void setName(char[] holderFirstName) throws EncryptionException {
        String newData = encryptDataBlock(getEncryptedData(),
ITEM_INDEX__NAME, name);
        setEncryptedData(newData);
    }




On Thu, Mar 13, 2014 at 4:18 AM, Andrus Adamchik <andrus@objectstyle.org> wrote:
>
>
> On Mar 13, 2014, at 11:06 AM, Aristedes Maniatis <ari@maniatis.org> wrote:
>
>> On 13/03/2014 6:31pm, Andrus Adamchik wrote:
>>>
>>> On Mar 13, 2014, at 10:05 AM, Aristedes Maniatis <ari@maniatis.org> wrote:
>>
>>>> It would be nice public relations to have "Cayenne has out-of-the-box crypto
support" as a feature. Are you storing a key version as part of the encrypted data stream?
>>>
>>> I am still working on this piece actually. It has to be attached to the record.
The question is whether we keep it unencrypted (simplifies management and migration between
keys), or encrypt it together with the data (more secure).
>>
>>
>> I don't see any value in encrypting it. What security does that create? Also, keeping
it in the same database column makes for simpler storage and robustness. Much like storing
the salt with a password hash, or the hashing algorithm with the password in LDAP:
>>
>> 86gwfku:tgiynv45zpyqaqqpucnp3f8k8uk3dzqy
>>
>> {SSHA}ddrd686254iteu9gqsz4aztufkgbctuz
>
> yeah, perhaps you are right. Encrypting it doesn't provide better protection from brute-force
attacks on the key. Just some obfuscation.
>
> Andrus

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