Topic 2: Tolerating Unknown Fields

*** *Tolerating Unknown Fields* ***

In my topic 2 I speak about tolerating unknown data elements in a PWS 
file. "Unknown data elements" are correctly implemented data fields, 
either within an entry record or in the file header field list, whose 
type identifiers are outside of the defined canon of a given file format 
definition.

The PWS file format is some achievment because it is very well apt to 
serve as a general encrypted data storage tool. Meanwhile there are 
several password applications using this format. It is possible, and it 
really happens, that their realms of used field types do not exactly 
match and some programs deal with proprietary extra fields. I'ld like to 
propagate tolerance of this behaviour as it makes sense and gives added 
functionallity where needed.

In JPWS I implemented preservation of all data fields which are 
identified as "non-canonical". These fields are kept outside of any 
visible or practical scope of the program, but are saved back to the 
persistent file when it comes to a save operation. This is not really 
difficult to implement, more or less you just need to store those fields 
into lists when loading a database.

This is a minimal step each PWS application can perform in respect of 
all other such applications. (It also gives added security when people 
perform mixed usage of different versions of the same program.) - I 
think it is a good idea and I would be happy if Password Safe would 
implement and moreover announce it as a recommended standard behaviour.

Cheers!
- Wolfgang Keller

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