Password

Passwords are a method of blocking access to variety of things, such as objects, information, and locations, as well as a potential method of storing information. In MS Paint Adventures passwords are put to some unusual ends.

Problem Sleuth

Main article: Code Machine

In Problem Sleuth passwords are used to record the game's save state, and Team Sleuth by entering new passwords is able to alter the state of the world around them. Team Sleuth uses this to cheat by looking up passwords for save states where difficult tasks have already been completed in order to skip over them.

Homestuck

Bro

According to Andrew Hussie's forumspring, the password to Bro's computer is "lilcal"

Jade

Jade decides to keep her conversations with trolls as linear as possible, so she gives them a password whenever a Pesterchum/Trollian session ends, which the troll can then pick up again in both the troll's and Jade's subjective futures. 

The first password Jade gives Kanaya is CROOOOOOOOOOOAK

Two passwords that Jade gives to Karkat were shown. One, also reused by Karkat to secure a separate section of the memory bubble of Openbound, was IF I HATE MYSELF SO MUCH, THEN WHY DON'T I HATEMARRY MYSELF? The final password is SEE YOU SOON.

Mom

413 to unlock Jaspers's mausoleum.

John/Terezi Retcon Passwords

These "passwords" were used as mental beacons for John's retcons as planned by Terezi, and also to allow the MSPA Reader to access the retconned branch of the narrative.

Password	Point in timeline	Instructions	Effect on canon
“HOME”	Terezi's attempt to place the first "retcon beacon" in the timeline for John to latch on to, essentially a test of whether the powers work - page 7045	N/A	Terezi's idea worked, she then wrote the list and sent John to retcon the following events.
“R3UN1ON”	Tail end of A6I5: Kanaya, Karkat, Terezi, Rose, Dave, and WV have just been teleported to LOMAX, right in front of John - page 6229	“GO G3T R1NG”	After changing the timeline to completely avoid all events leading up to GAME OVER, including John's own death in the new timeline by his denizen, John is still in possession of the important Ring of Life in the new timeline this resulted in. So Aranea never got a hold of the ring and revived herself. This creates an alternate timeline separate from both the GAME OVER timeline and the one created at the end of John's mission, which is speculated to have some kind of significance.
“FR4M3D”	Terezi's introduction: This is just before the "witness" to Lemonsnout's "crimes" was found suspiciously "dead" - page 2038	“R3SCU3 TH3 W1TN3SS B3FOR3 H3 1S MURD3R3D! (DON'T G3T C4UGHT)”	The witness is later crucially placed into the “MURD3R” retcon.
“MOM3NT”	Terezi had just had a semi-flirtatious conversation with Karkat, wherein she revealed that she knows his blood color, assured him everyone does respect him, and they ended the conversation with hearts - page 2575	“WR1T3 M3SS4G3 ON W4LL: YOU DON'T N33D H1M.”	Unclear – it's possible Terezi was referring to Karkat or Dave, which may explain her lack of involvement with the two on the meteor trip. This could on the other hand refer to Gamzee as the pre-retcon timeline featured her dependent of him caliginously. John also wrote “(this is john by the way, ha ha.)” under the words, revealing himself as the one behind the retcons.
“MURD3R”	Tavros's body had just fallen to the ground after Vriska lanced him, and Terezi is investigating the murder scene. After this, she had attempted a kiss-revival, which failed due to his dead dream self. - page 3367	“D3PLOY TH3 W1TN3SS H3 1S CR1T1C4L TO TH3 1NV3ST1G4T1ON!!!!!!!”	Terezi does not attempt to revive Tavros, although he was not able to be revived anyway, leaving her glasses on and disallowing Gamzee from snatching them. More importantly, due to careful and symbolically meaningful placement of the witness scalemate, Terezi appears to be less narrowly focused on jumping to the conclusion that Vriska is responsible for all of the murders.
“JUST1C3”	Terezi is discussing her suspicions of Vriska with Dave. This is just moments prior to finding Nepeta's corpse. - page 3707	Instructions not directly shown, but John wrote "“it was gamzee you idiot!!! um... over” / “hey terezi... when you told me to say 'you don't need him', did you mean karkat or dave? maybe you shouldn't date dave either. the way you and he described it, it sounds like it got weird. i dunno, just offering some friendly dating advice! man, this caper we're doing is so crazy. anyway, later!”" on Vriska's Nicolas Cage poster. Presumably, Terezi only instructed John to write the first portion.	Terezi begins suspecting Gamzee for the crimes, instead of laying all the blame on Vriska. Terezi's conversation with Dave at the time was interrupted.
“HONK”	Terezi is in the secret room, unknowingly stalked by Gamzee, just before she scratches Homestuck: Disc 2. - page 3719	“GR4B 4 HORN... YOU W1LL KNOW WH4T TO DO”	Terezi notices Gamzee in the room. Instead of Pyralspite, she carries a bound and horn-gagged Gamzee to the roof for the events preceding Cascade. Gamzee remains tied up until the start of the three-year meteor journey, as shown in Vriskagram.
“FL1P”	Just moments after Terezi's coin flip on the roof while facing Vriska, and just moments before Terezi was about to kill her. - page 3833	“KNOCK H3R OUT! YOU C4N'T L3T M3 K1LL H3R.” Also stated that John should give his wallet to Terezi, which he did not have.	John knocks Vriska out, interrupting Terezi's attempt to kill her and thus saving her life. John and Terezi argue for a bit, and John is on the roof while the other trolls gather before Cascade. He gives Terezi the scarf and zaps away. The significance of the wallet is unknown, but it may have to do with the fact that currency is normally kept in one's wallet.