Re: Using NSValueTransformer for encryption

FROM : Keary Suska
DATE : Thu Jan 10 22:27:03 2008

on 1/10/08 1:29 PM, M.<email_removed> purportedly said:

> Consider the following example: The user edits a text whose stringValue
> shall be encrypted. After endEditing the value is passed to the managed
> object which stores it. This is where the value transformer comes into play.
> It takes the value from the text field, encrypts it and passes the encrypted
> value to the managed object.


The transformer will work, you'll just need to make sure the "encrypted"
state of he text is guaranteed from the perspective of the transformer. If
the value is only stored and maintained in the model in an encrypted form,
and only edited by the UI, then so you probably won't have problems with
using a transformer.

> After that, the string value of the text field has to be set to an empty
> string which sould remove the unencrypted value from memory.


This will not guarantee, in any way, that the value will truly be removed
from memory. Just so you know.

Best,

Keary Suska
Esoteritech, Inc.
"Demystifying technology for your home or business"