[dm-crypt] Impossible task ?

Arno Wagner arno at wagner.name
Tue Dec 16 16:58:50 CET 2014


not really a topic for this list, but I will answer anyways.

No, you cannot do this. Proof idea: If you can do lookup, 
you can break the encryption by checking whether a person is 
in there via the lookup functionality.

Sure, if you only allow proper partial names, the attacker 
does not get the last character of the name, but that does 
not help much. There are not enough names in the world to
make this attack too costly, and the attacker can do it 
character-by-character by using longer and longer partial

The thing is that the possibility of lookup directly
implies the data is _not_ protected against reading it.


On Tue, Dec 16, 2014 at 13:22:17 CET, bill wrote:
> I have conflicting needs and fear that they may be unresolvable.
> I. I need to store patient names (3 fields: last, first, middle
> initial) with the first and last names encrypted.
> 2. I need to be able to do partial name lookups if the user enters a
> partial first or last name.
> I presume that after encryption the names are no longer in
> alphabetical order, so looking up using an encrypted partial name
> will not result in a set of names beginning with that partial name.
> Is there an approach to this, or need I go back to my boss and
> suggest "plan B."
> -- 
> Bill Drescher
> william {at} TechServSys {dot} com

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Arno Wagner,     Dr. sc. techn., Dipl. Inform.,    Email: arno at wagner.name
GnuPG: ID: CB5D9718  FP: 12D6 C03B 1B30 33BB 13CF  B774 E35C 5FA1 CB5D 9718
A good decision is based on knowledge and not on numbers. -- Plato

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