Authenticator

[OFSO]

With HMRC codes never arriving on my phone, I've been using the Authenticator App. Absolutely brilliant, not sure I understand how it works but it does.

[OFSO]

Used it this morning on the PC to check my latest filing, Code generated on phone worked immediately on PC. I am still mystified.
I suspect deep in the bowels of the HMRC computer is a routine under my name churning our codes ready to be matched with the one my phone generates every few minutes.

[CharlieOneSix]

Authenticator is used to access my account with my website host and also to access my Company pension account using MyPensionTracker to get P60 etc etc. Consistently works very well.

[llondel]

I suspect it's using something like a hash of your password/username, the target site, some shared random seed send when the account is set up on the authenticator, and the date/time to generate the code. Deterministic and hard to calculate while it's valid if you don't know the random seed.

ETA: OK, generally correct, it just uses the shared random seed and the date/time.

[talmacapt]

I had to buy a new phone a while back and applicator caused problems, not recognised by HMRC.

Managed to sort it out eventually but a nuisance at the time.