During the creation of several key items, I noticed that there are several 'label' or 'tag' options. I did some investigation and I found three different, interesting, values.
kSecAttrApplicationTag - A key whose value indicates the item's private tag.
kSecAttrApplicationLabel - A key whose value indicates the item's application label.
kSecAttrLabel - A key whose value is a string indicating the item's label.
I read that the kSecAttrLabel is "human readable data". But what exactly is meant with the description of the kSecAttrApplicationTag? What exactly is the private tag.
Another question I have is, how can I uniquely identify a key. Say I want to have a single key to encrypt a specific file, how would I go about doing so? Theoretically, I could set the kSecAttrApplicationLabel, as this has to be a unique value, meaing if I were to set the value to "com.app.appname.someidentifier".data(using: .utf8)! an error would occur if the key would (accidentally) be created again (which is what I want to prevent). However the discussion says "in particular, for keys of class
, the value of this attribute is the hash of the public key", and RSA keys do have the public/private class, so the value would no longer be the hash of the public key. Am I actually allowed to overwrite the kSecAttrApplicationLabel? If not, do I have to check if a key for kSecAttrApplicationTag/kSecAttrLabel already exists and delete it first, before adding a new 'unique' key?
Thanks in advance!