Editing 2700: Account Problems

{{comic
| number    = 2700
| date      = November 18, 2022
| title     = Account Problems
| image     = account_problems_2x.png
| imagesize = 538x272px
| noexpand  = true
| titletext = My password is just every Unicode codepoint concatenated into a single UTF-8 string.
}}

==Explanation==
{{incomplete|Created by a VISIBLE ZERO WIDTH SPACE. Please change this comment when editing this page. Do NOT delete this tag too soon.}}
[[Cueball]] walks toward [[Ponytail]] carrying his laptop. Ponytail is sitting at her desk, and turns to face him. Having attempted to fix Cueball's computer problems before (e.g., [[2083: Laptop Issues]]), she replies with dread. Cueball promises that "It's a normal problem this time", and Ponytail reluctantly agrees to look at it. Cueball then reveals that he has included a {{w|Null-terminated_string|null string terminator character}} in one of his passwords, probably for a website. Ponytail responds in disbelief, and Cueball defends his actions by saying that the website told him to use special characters.

In computers, every "character" is a sequence of bytes. Every byte is a sequence of eight bits. A bit is always either a zero (0) or a one (1).

Every character is a sequence of bytes, but not every sequence of bytes is a valid character. For example, a JPEG image is also a sequence of bytes (much longer than a character). An MP3 audio file is also a sequence of bytes.

A null string terminator is a type of character called a control character. Unlike characters which are letters of the alphabet or numbers, control characters are not intended to be displayed on the screen, and are not intended to be typed on a keyboard; rather, they are used for internal purposes in the computer program. It is thus strange and hard to understand how Cueball was able to successfully insert such a character in his password, since there is no sequence of keys he could type that would result in a null terminator.

Null terminators are used in older, C-based languages to mark where a string ends. Every programming language has variables{{citation needed}}, which are used to store data. In C, a primitive variable can store a small amount of data, such as an integer or boolean (true or false) value. Strings (which are a sequence of characters) often need to store much larger amounts of data; too much to fit in the memory space which is available for a primitive. To solve this, C uses a system called "pointers", in which the variable is an integer which refers to a memory location. When the string needs to be read or written, C looks up the memory location, and interprets the data as a series of characters. One problem is, because a string can be any length (big or small), C needs to know where to stop reading from memory. The null terminator is C's solution to this. When C encounters the null terminator, it knows it has reached the end of the string and stops reading. Therefore, it is important that the null terminator is not a normal character that can be typed on a keyboard.

This has implications for security. If users are able to add or remove null terminators at will, then they can exploit C's string reading mechanisms in order to read data in a way not intended by the software programmers. If a malicious user is successful in doing this, they may be able to intentionally cause security problems on the computer, such as infecting it with malware.

Cueball notes that his password contains a "special character", which is a typical requirement imposed on users. However, in most contexts, "special character" means an ordinary printable character, other than letters or numbers, that can be typed on a normal keyboard and seen on the screen. Cueball's use of "special" is technically true, as null terminals do have a specialized purpose; but his usage of the word is not in keeping with the way that phrase is normally understood.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[Cueball walks up to Ponytail.]
:Cueball: Can you help me with my account?
:Ponytail: Oh no.
:Cueball: No no, I promise it's a normal problem this time.
:Ponytail: Okay. Fine. What is it?
:Cueball: I included a null string terminator as part of my password, and now I can't-
:Ponytail: How?!
:Cueball: They said to use special characters!

{{comic discussion}}

[[Category:Cueball Computer Problems]]