explain xkcd - User contributions [en]

1181: PGP

2013-03-07T09:42:00Z

88.9.74.178: /* Explanation */

{{comic
| number = 1181
| date = March 4, 2013
| title = PGP
| image = pgp.png
| titletext = If you want to be extra safe, check that there's a big block of jumbled characters at the bottom.
}}

==Explanation==
{{w|Pretty Good Privacy|PGP}} (Pretty Good Privacy) is a program which can be used to encrypt and/or sign data, including messages sent as emails. Encrypting means encoding data in a way that requires a known key to decrypt and read; signing means that there is a code included in the data which can be used to verify both that the data is unaltered and to verify the true sender.

In the case of the email in this comic, it has only been signed; not encrypted (hence, the top of the first line of text can be seen and is legible in normal English). This is more common than encryption, as reading an encrypted message would require the recipient to already be a PGP user. In fact, the use of PGP even to sign email messages is so rare that most people have probably never seen a signed message. Because a signed email is so rare, and because it is already legible and unencrypted, [[Randall]] is making the tongue-in-cheek observation that few users, technical or otherwise, actually know how to use the signature to verify the authenticity of the sender using the PGP signature, and that such users assume the fact that there ''is'' a signature is good enough evidence that the message is authentic. Further, because PGP signatures are so rare and probably ignored by most recipients, he suggests one would not expect anyone to even bother creating a false PGP signature; therefore the mere existence of a PGP header would suggest authenticity.

The title text extends the joke by suggesting you confirm there's a bunch of random characters in the footer (this is the actual key that PGP generates which can be used to verify the authenticity of the email). Again, Randall is humorously suggesting that the existence of the block is itself sure evidence of authenticity.

==Transcript==
:How to use PGP to verify that an email is authentic:
:Look for this text at the top
:[In mail header, light grey.] Reply
:-----BEGIN PGP SIGNED MESSAGE-----
:[in mail message, light grey]
:HASH: SHA256
:Hey,
:First of all, thanks for taking care of

:[After mail message]
:If it's there, the email is probably fine

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Computers]]

1177: Time Robot

2013-02-22T14:39:32Z

88.9.74.178: Removed "instead of" so that it does not appear that the real killer robot does not exist in the strip

{{comic
| number = 1177
| date = February 22, 2013
| title = Time Robot
| image = time robot.png
| titletext = NO FATE BUT THE NARRATIVES WE IMPOSE ON LIFE'S RANDOM CHAOS TO DISTRACT OURSELVES FROM OUR EXISTENTIAL PLIGHT
}}

==Explanation==
The comic starts with a scene from a 1984 science fiction action film ''{{w|The Terminator}}'', in which a killing robot (played by {{w|Arnold Schwarzenneger}}) is sent back in time to kill Sarah Connor, the main female protagonist of the movie, and a human, Kyle Reese, also travels back in time to protect her (and he acquires a {{w|sawed-off shotgun}} which Cueball holds in the strip).

However, in the following panels, Cueball changes the narrative by explaining that, even if he succeeds protecting Megan from the killing robot, we all are hunted by an unstoppable enemy trying to kill us – time.
And he goes on to point to the similarities between the time and a Terminator. The clock visible in the third panel features a red light in the place of a 3-hour marker, which is a reference to {{w|Terminator (character concept)#Physical characteristics|glowing red eyes}} of a Terminator.

In the final panel, “come with me if you want to live” is a [http://terminator.wikia.com/wiki/Come_with_me_if_you_want_to_live. famous phrase from the movie], but in this case, amended with the facts about the inevitability of eventual death.

Also, the title text is a play on a quote from ''The Terminator'', where Sarah Connor starts to believe that “[http://terminator.wikia.com/wiki/There%27s_no_fate_but_what_we_make_for_ourselves. There's no fate but what we make for ourselves.]”. It is also a reference to the character “{{w|Death (Discworld)|Death}}” in {{w|Terry Pratchett}}’s ''{{w|Discworld}}'' novels. In the Discworld novels, Death’s voice is always depicted in <span style="font-variant:small-caps">small caps</span> and he is often caught making sometimes bizarre philosophical statements about life and death.

==Transcript==
:[Cueball runs towards Megan with shotgun in hand.]
:Cueball: I'm from the future!
:Cueball: You're being stalked by an unstoppable robotic assassin!

:[Close up of Cueball's head.]
:Cueball: Of course, in a sense, we're ''all'' being stalked by an unstoppable robot.
:Cueball: A robot called ''time''.

:[Cueball looking at a clock.]
:Cueball: I see it in the mirror. I see wrinkles, grey hairs.
:Cueball: I hear its metallic footsteps in the relentless rhythm of the ticking clock.

:[Cueball reaches out to Megan.]
:Cueball: Anyway, uhh - come with me if you want to live for a while.
:Cueball: You'll still die eventually.
:Cueball: We all will.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics with color]]

1174: App

2013-02-15T08:36:45Z

88.9.74.178: Expanded everything to a much more detailed explanation.

{{comic
| number = 1174
| date = February 15, 2013
| title = App
| image = app.png
| titletext = If I click 'no', I've probably given up on everything, so don't bother taking me to the page I was trying to go to. Just drop me on the homepage. Thanks.
}}

==Explanation==
This comic is about how web sites design special versions of their pages
optimized for viewing from mobile devices, and these pages require an
special App to be viewed.

Usually, the mobile version of the web page is made separately
from the regular version, so it's
often incomplete.
The app used to view it has also some
other serious usability problems (e.g. it can't be zoomed),
so it's usually better to just view the regular version
of the web site with a regular browser even when accessing
the web from a mobile device.

In the comic, a mobile device user is trying to do just that:
visit the regular version of web page through a regular browser.
However, the site keeps on insisting that the user
really should "download our app to visit
an incomplete version of our website
where you can't zoom".
If the user chooses "no", it isn't really a "no", but rather a
"no, but ask me again every time"; so this pop-up is going
to get really annoying very soon.

In the title text, there's a reference to yet another very serious
usability problem of the mobile version of web pages:
the only page one can really see is the home page,
and whenever the user tries to get anywhere else in the site,
the server loses track of the navigation and sends the user
back to the home page to start over again.
This is the same effect described in
[[869: Server Attention Span|comic 869]]<nowiki />.

==Transcript==
:[a popup window on top of a webpage displayed in a smartphone browser]
:Want to visit an incomplete version of our website where you '''can’t zoom'''?
:'''Download our app!'''
:[OK] [No, but ask me again every time]

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Computers]]