How did David knows Walter's security code?

I'm willing to write it off as a continuity error.

I can think of several possibilities:

1. He hacked the Covenant computer system.

2. He had access to the computer because of built in protocols from before the Prometheus mission. He was Weyland's second in command after all, and Weyland considered him in many ways his own son. If he could get in the secure parts of the system, he could look for any information he needed.

3. He was able to retrieve it from Walter's brain after defeating him, or he is in fact in Walter's body, and in the process of transferring himself he was able to retain Walters memories.

1) He may have had some time to snoop around the ship and find the info somewhere.

2) The android's assigned security codes may follow a predictable pattern that he was able to discern (his mind is a computer after all).

3) Maybe he just asked mother to tell him Walter's security code, and she just revealed it to him because of the high security clearance of his own code?

His security clearance was still active and all since no one at Wey-Yu nor Mother knew he'd gone rogue. 

I think he wanted MUTHUR to tag the message as being from Walter and not David.

By showing us David using both identities interchangeably on the ship, I think Scott wanted to reinforce the concept that the androids consider themselves a collective entity, as in 'We Are Walter'.

There was a little bit of time between them escaping Planet 4 and before everything went down on the ship, so I am sure he could find what he needed. My theory is that, since he was Weyland's personal servant, he had unprecedented access to higher up codes, operations, etc.. Also,more simply, I would guess that David could have lifted that stuff straight from Walter after the fight. With that tech, I would assume that either of them can do that really quickly too. If Ridley and the writers truly went with David subduing Walter, cutting off his own hand, and changing clothes (as opposed to, like, switching bodies), my idea here isn't too crazy.

The problem I see with my theory is that the Wey-Yu merger may have provided some hoops for David to jump through with his access to higher up stuff, but it still works. Like I said, unprecedented access. The fact that David uses his own code to enter the colonists hypersleep area could support this idea. 

auximenes, that's a good point! Although David introduced himself as, "I am David," he is still part of that android mindset, in which they are a collective entity/family. I would almost be willing to bet that you are right with that one!

Indeed its a tricky one... 

The Code had to unlock some specific Order/Protocols and Programing,  can we assume David had uploaded at a earlier point a new set of Programs and Protocols and gave them that Special Code?

As indeed there would be a Time-Gap between when Daniels, Tennessee, Lope and David arrived on the Covenant, until the point when the Unidentified Life Form Warning was issued.

This would be the most Logically explanation, that David Hacked the System, uploaded a New Protocol/Program and gave it that Security Code.

The only other Logical reason would be the Ship already had a Program/Protocol which required this CODE.. this would have to imply some kind of Rogue AI Agenda, that goes further back and Deeper than the Prometheus mission.

That would not doubt mean some under-cover espionage secret Agenda is going on behind the Scenes, and maybe even instigated by AI going rogue.... So David Hijacking the Systems prior to Prometheus knowing the chances are Weyland may not make it and so to have some Plan in Store that allows David and AI to run things behind the scenes, while all along proving the Company is just a Pawn in Davids Game.

Ohhhh woah, BigDave's use of the word, "Espionage," makes me think that there is a teny tiny chance that the prequel novel that Alan Dean Foster is writing may touch on this issue. I am grasping at straws here, th emost obvious issue here being: How would someone on Earth be able to do something like this, not knowing David is out there... STILL there will probably be some very interesting connections to the story/ending of Alien: Covenant (I mean, of COURSE there will be connections, but I think we are in for some surprises. 

Totally... i had my suspicions about this before the ADF Prequel Synopsis was announced, i wondered if it would cover the events prior to the The Crossing Prologue and after.

RS had suggested in interviews a lot about the AI, and i felt that AI would be playing a larger role, and looking how AC ended i wondered if AI was behind it all.   The one extended Synopsis for AC where it claimed the Greater Threat was from a unsuspected source or something like that..  Had me wondering before i saw AC is the Ships Computer and company Secret Agenda like Special Order 937 going to be the biggest surprise threat to those Colonists...

It would appear ultimately it was David, but surely the colonist would have been a bit suspicious of him and so i still wondered does MUTHUR and those behind her Programing have something to do with it all.

After seeing AC, i was drawn more close to this kind of thinking and then no soon as the ADF Prequel Synopsis come around... i think certainly there is something at play with the Company... The Merger has not gone down well between some Parties...  We had to wonder why would someone want to Sabotage the Covenants mission.

So there is a lot of interesting things going on behind the scenes as far as Weyland-Yutani Company not being completely on the same page... where indeed 2-3 parties may have their own alternative Agendas..  And i suspect that AI will play a KEY Role....  i think indeed we could be seeing some kind of SKY-NET Scenario here.. that in a alternative RS Alien Franchise could potentially lead to a Matrix kind of Plot as far as Machines over throwing and ruling over Mankind.

But only time will tell ;)

I guess that David has built-in access to any Weyland's tech, and he is actually that someone who sent Nostromo to investigate LV-426. I think that David, Muthur, Ash are interconnected by single intellect. And it seems that David wasn't surprised about Covenant and 2000 colonists on board. He looked like he was waiting for this ship

@BigDave

You make some really good points. Corporate mergers rarely go well, often the new company wants to make the old management look incompetent and vise-versa, so sabotage from within sounds very plausible.

Also, your idea about 2-3 parties each having their own agendas sounds very plausible too! I remember on Prometheus when Meredith Vickers told Weyland she didn't want to stay behind on Earth, "sitting around in board-rooms arguing about who's in charge".

It certainly sounds like there is some discord within the company and I'm sure Weyland, Vickers and David's disappearance didn't help clarify things! Wey-Yu is probably a hot mess back on Earth. It's probably like Game of Thrones level office politics.

Certainly....

We have to remember Peter Weyland was the CEO, then it appears Vickers was next in line but maybe there is some potential power struggle or other people lined up so it does not make Vickers 100% CEO when Weyland Dies.

With Both gone missing i am sure we have to ask what goes on back at HQ.... The Yutani Company are a long time Rival of Weylands Company, it seems they too are interesting in Synthetics and AI and even had a law suit in regards to some Patents over the David Model which Yutani lost.

Yutani are also looking like a BIG player in the Communications and Information Technology Sector... it appears they are like the Apple and Microsoft of the Alien Universe.  Even as far as Weyland using some of their ECU's in their own Technology.... Yutani also appear to have been hacking the Video Calls between Dr Shaw and Peter Weyland and so there is definitely some espionage on their behalf.

So we have to wonder how the Merger Came to be, how could Weyland Force to Purchase or Merger with Yutani?  With its TWO CEO's missing in Action?

Its more likely this event plus information that Yutani has on Weylands Mission, could prove to be a vital Bargaining Chip that allows Yutani to be the Force at play..

The Prequel Novel could show that there is indeed some objection to the Merger, but certainly for some reason the mission to Orage-6

My Prometheus 2 draft i worked on in  Late/Early 2013-2104 which i abandoned did touch upon the Corporate side.

where as there was 6 Months no contact from Prometheus, meant a Process regarding the shuffling of Power was to play out.... The next in line was Weylands younger Brother (played by Lance Henriksen) but he was old too and so it was his Son who would be in control in the future.

But the appearance of Miss Vickers by surprise prevents this as she then reveals a Will and Testament by Peter Weyland via Video Will, that leaves everything to Vickers.  We see Vickers has a Special Directive at play to do with Operation Rook a secret tower well a Weyland Tower with a Special Computer and Program and a Advanced David Synthetic.  The idea behind my Draft (which had a Weyland and David Prologue that was similar but David was not playing any Piano etc... but playing a Game of Chess but talked about Creation and God etc, And Weyland talks about how as a creator he is a GOD and then David takes  Weylands King with a Bishop and then David asks why Weyland did not sacrifice his Queen, which Weyland had said i already Sacrificed my Queen, i put my Lifes Work ahead of her and the only thing i have left of her is Meredith.   David then Tells Weyland he could have positioned his Rook better in the last move to protect the King and Queen....  Weyland then says "every king has his reign but then he dies, its inevitable"  But i have been Building This TOWER with my Works, My Greatest Achievement...  

David then Smiles, and Weyland says while i have been a creator and created you.. my work is not finished, creating Life alone does not make you a GOD as the Gods are Immortal and one day i hope to find the Key to My Immortality and You David are my works to achieve my Goal, My Salvation, My Holy Grail.   This Place, my Works within this TOWER are my Insurance so that a King never has to Die.

David replies.. This is the Rook that you hope to Save your King, so am i just the Pawn... Weyland then claims No David you are My Knight.

The Conversation was further and deeper than this, but it was  a DAVID Dream Flashback as he was looking at Shaw in the Cryo-Pod on the Juggernaught... not being able to view her dreams like he did in Prometheus he wondered.. what is Dr Shaw Dreaming now....   Then we get Davids Dream... But we also get Dr Shaws Dream too.

Anyway so the intention  was that Weyland was Building Synthetics as a way to one day, if Weyland could transfer his Soul into Davids Body he would become Immortal... But Weyland could not succeed in this... it failed.. it was far from Perfect.  Which is why as a last desperate Chance... he decided to take Dr Shaw's offer in the Hope OUR Creators could Save Him, as his Experiment has not yet came 100% close.

This was Operation Rook... a attempt to place Weylands Mind into a AI Program, to then be placed into a Synthetic.  But the trails on a AI alone (no Body) proved flawed, had problems... and the AI as a Program was corrupting and having a Melt Down... and while it had Weylands Ambitions it was flawed and Weyland knew it would not in effect be the same as Weyland passing on his Soul to a Synthetic he had not perfected it yet.

May Draft had a surprise at the End... Peter Weylands Brother had been taken in Ill Health as he was disputing Vickers claim as the Company was supposed to be passed on 50/50 and not 100% to Vickers...   so we are asking did Vickers poison her Uncle?

Its revealed at the end that her Cousin had done this, and he also made a deal with Yutani that if they removed his Father and his Cousin Vickers from Power...  then he would give Yutani the rights over all of Weylands AI and Synthetics...  but he would keep all of Weylands Science and Teraforming/Space Travel Technology.

A deal was done and Yutani sent in TWO Geisha Androids to kill Vickers...  but she put up a Fight and even Manhandled and Destroyed them.... her Cousin Micheal saw this and was puzzled...  she then finds out his plans to Assassinate her and informs him he has lost... he can not be CEO...  and he will be had for Attempted Murder.... He and the viewers then Notice a Milk Substance running down her ear....   

Thats it... VICKERS is a Robot... knowing this Micheal Orders her to be Desroyed.. she battles a few Yutani Mercs, but suffers Leg injuries and body ones and she is on the Floor.

Micheal appears over her.. points a Gun at her Head.. and Says... Bishop takes King.....  she says i am a Queen...  and he says oh yeah...  and what of your King?  your father is Dead the company is Mine... and he then goes to Shoot her.

And she says.... A King has his reign and then it dies, but a King who has a Great Castle will never Die.... and then says Rook Takes King....  as she is then Shot in the Head.

My draft was to gear up a 3rd movie that explored the Merger and sending a Mission to LV-223 it did not cover any Xenomorphs etc... the next one would.

The other 30% or so was to cover David and Shaw journey and arrival at Paradise....    Then another 10-15% would have covered Engineers including Flash Backs for clues.

But it was just not being able to find which Story/Plot and Connections to settle on as for how to deal with the Engineers and their Agenda and those Questions... Why did they create us, what was the Agenda.. who created them, what purpose they serve and how does Mankind and the Xeno-Strain Experiments on LV-223 all fit.

But i had a number of theories to how to do this but it was hard work picking just ONE and getting it to Work..

So i ABANDONED my Draft :(

But it was having TWO Alternative Sinister Agendas at hand.. its just which to use and could they both work...  The one did revolve around Gigers Ideas and Concepts and tied into the Annunaki Tale of Sorts.

@Big Dave - Do please continue discussing your ideas for the script!

Perhaps he either hacked into the computer system or since they are of the same model (although they might be slightly different versions, Walter said something about upgrades) maybe they had the same code. Eventually there could be some other explanation but these are those that I can think of. That scene is kind of interesting if you think about it.