explain xkcd - User contributions [en]

3054: Scream Cipher

2025-02-22T05:04:17Z

162.158.245.162: /* Table */ language learner fun fact / mnemonic

{{comic
| number = 3054
| date = February 21, 2025
| title = Scream Cipher
| image = scream_cipher_2x.png
| imagesize = 287x416px
| noexpand = true
| titletext = AAAAAA A ÃA̧AȂA̦ ǍÅÂÃĀÁȂ AAAAAAA!
}}

==Explanation==
{{incomplete|Created by A ÃA̧ȂÁAǍẢÂA̋ ȦÅĀ - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
A {{w|Cipher}} is a method of encryption, where characters or sometimes words are substituted for other characters in a set pattern, allowing for arbitrary strings to be enciphered using it. The complexity and strength of ciphers varies, from {{w|one-time pads}} and (historically) {{w|enigma machine|Enigma}} as stronger and more complex, to {{w|substitution ciphers}} as some of the weakest and least complex, where each character is simply given a set different symbol to represent it in the cipher.

This comic uses a substitution cipher, where all the letters of the English Alphabet are represented using the letter "A", with different {{w|diacritical marks}} to define the differences. This kind of cipher is often used on a recreational basis by children or casual enthusiasts, the similarity of the letters increasing the obcurity of the content and the skill or technology required for use, but there is also significant impracticality, as not only are substitution ciphers the easiest to break, but also the similarities in the letters do make the cipher hard to read and easy to misread, and the detail in the diacritical marks makes it easy to draw the "A"s incorrectly or ambiguously, potentially leading to [[3003: Sandwich Helix|part of the message being lost]]. This was our experience in the comments section of this very article, where one person implemented translator functions alongside another person crafting a message that failed to translate. However, the logic behind the code is mostly visual similarity, and if attentive to connecting concepts between the American and scream cipher alphabet, it could be quickly learned and translated in a glance.

It's named "Scream Cipher" (as a pun on {{w|stream cipher}}s, commonly used in computing) because the written form of a scream is a long string of As, possibly with some other characters at the end (and often an exclamation point for emphasis), such as "Aaaaaah!" or "Aaaaaaagh!". The name may or may not be a reference to IBM's {{w|Scream_(cipher)|Scream cipher}} published in 2002.

In the comic, [[Cueball]] texts the ciphered version for the plaintext "HELLO", and [[Megan]] responds with that for "HI".

The title text deciphers to "AAAAAA A SCARY MONSTER AAAAAAA!"

You can translate text to and from Scream Cipher using [https://github.com/matthewpwatkins/scream-cipher/ the Scream Cipher Translator].

Another recent comic featuring all "A"s was [[2957: A Crossword Puzzle]].

==Worked example==



Say we want to encode "Scream" in the Scream Cipher. First we would need to split out word into the letters, so S, C, R, E, A, M.

The first letter is S, so if we go to S in the table S is shown to become to Ã, C similarly becomes A̧, R becomes Ȃ, E corresponds to Á, A is the main letter so A is unchanged to A, and M becomes Ǎ. If we then write them again in order, we find SCREAM becomes ÃA̧ȂÁAǍ.

To turn cipher text back into normal text, the process is repeated in reverse. To translate A̧ẢA̯A̰ÁȂ, we go to A̧ in the table and find A̧ becomes C. Ả similarly becomes I, A̯ becomes P, A̰ becomes H, Á becomes E, and Ȃ becomes R. If we write the letters in order, we see that A̧ẢA̯A̰ÁȂ becomes CIPHER.

==Table==

The {{w|Unicode}} names of the characters in the cipher are as follows:

{|class="wikitable"
! colspan=2 | Input !! colspan=3 | Substitution
|-
! Plain !! Unicode description !! Cipher !! Unicode description(s) !! Usage note
|-
| A || U+0041 LATIN CAPITAL LETTER A || A || '''U+0041 LATIN CAPITAL LETTER A || Unadorned base character
|-
| B || U+0042 LATIN CAPITAL LETTER B || Ȧ || '''U+0226 LATIN CAPITAL LETTER A WITH DOT ABOVE || Phonetic symbol for low central vowel
|-
| C || U+0043 LATIN CAPITAL LETTER C || A̧ || U+0041 LATIN CAPITAL LETTER A, '''U+0327 COMBINING CEDILLA''' || Cedille is often attached to a 'c', as in "français".
|-
| D || U+0044 LATIN CAPITAL LETTER D || A̱ || U+0041 LATIN CAPITAL LETTER A, '''U+0331 COMBINING MACRON BELOW''' ||
|-
| E || U+0045 LATIN CAPITAL LETTER E || Á || '''U+00C1 LATIN CAPITAL LETTER A WITH ACUTE || Many words have an acute e, as in "fiancé".
|-
| F || U+0046 LATIN CAPITAL LETTER F || A̮ || U+0041 LATIN CAPITAL LETTER A, '''U+032E COMBINING BREVE BELOW''' ||
|-
| G || U+0047 LATIN CAPITAL LETTER G || A̋ || U+0041 LATIN CAPITAL LETTER A, '''U+030B COMBINING DOUBLE ACUTE ACCENT''' ||
|-
| H || U+0048 LATIN CAPITAL LETTER H || A̰ || U+0041 LATIN CAPITAL LETTER A, '''U+0330 COMBINING TILDE BELOW''' ||
|-
| I || U+0049 LATIN CAPITAL LETTER I || Ả || '''U+1EA2 LATIN CAPITAL LETTER A WITH HOOK ABOVE ||
|-
| J || U+004A LATIN CAPITAL LETTER J || A̓ || U+0041 LATIN CAPITAL LETTER A, '''U+0313 COMBINING COMMA ABOVE''' ||
|-
| K || U+004B LATIN CAPITAL LETTER K || Ạ || '''U+1EA0 LATIN CAPITAL LETTER A WITH DOT BELOW ||
|-
| L || U+004C LATIN CAPITAL LETTER L || Ă || '''U+0102 LATIN CAPITAL LETTER A WITH BREVE ||
|-
| M || U+004D LATIN CAPITAL LETTER M || Ǎ || '''U+01CD LATIN CAPITAL LETTER A WITH CARON ||
|-
| N || U+004E LATIN CAPITAL LETTER N || Â || '''U+00C2 LATIN CAPITAL LETTER A WITH CIRCUMFLEX ||
|-
| O || U+004F LATIN CAPITAL LETTER O || Å || '''U+00C5 LATIN CAPITAL LETTER A WITH RING ABOVE || The symbol contains the letter 'O'. In Scandinavian languages like Swedish, this *is* the letter 'O' (a written 'O' may be closer to a 'U', but not always)
|-
| P || U+0050 LATIN CAPITAL LETTER P || A̯ || U+0041 LATIN CAPITAL LETTER A, '''U+032F COMBINING INVERTED BREVE BELOW''' ||
|-
| Q || U+0051 LATIN CAPITAL LETTER Q || A̤ || U+0041 LATIN CAPITAL LETTER A, '''U+0324 COMBINING DIAERESIS BELOW''' ||
|-
| R || U+0052 LATIN CAPITAL LETTER R || Ȃ || '''U+0202 LATIN CAPITAL LETTER A WITH INVERTED BREVE ||
|-
| S || U+0053 LATIN CAPITAL LETTER S || Ã || '''U+00C3 LATIN CAPITAL LETTER A WITH TILDE || Tilde looks like a sideways 'S'.
|-
| T || U+0054 LATIN CAPITAL LETTER T || Ā || '''U+0100 LATIN CAPITAL LETTER A WITH MACRON ||
|-
| U || U+0055 LATIN CAPITAL LETTER U || Ä || '''U+00C4 LATIN CAPITAL LETTER A WITH DIAERESIS || Many German words have a 'ü', as in "[[w|Fahrvergnügen]]"
|-
| V || U+0056 LATIN CAPITAL LETTER V || À || '''U+00C0 LATIN CAPITAL LETTER A WITH GRAVE || Grave has the letter 'V' in it
|-
| W || U+0057 LATIN CAPITAL LETTER W || Ȁ || '''U+0200 LATIN CAPITAL LETTER A WITH DOUBLE GRAVE || The letter 'W' is visually two copies of the letter 'V'
|-
| X || U+0058 LATIN CAPITAL LETTER X || A̽ || U+0041 LATIN CAPITAL LETTER A, '''U+033D COMBINING X ABOVE''' || The symbol contains the letter 'X'.
|-
| Y || U+0059 LATIN CAPITAL LETTER Y || A̦ || U+0041 LATIN CAPITAL LETTER A, '''U+0326 COMBINING COMMA BELOW''' ||
|-
| Z || U+005A LATIN CAPITAL LETTER Z || Ⱥ || '''U+023A LATIN CAPITAL LETTER A WITH STROKE ||
|}

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

:[Top of the panel has 26 letters of the alphabet, each followed by a hyphen and the letter "A" with a unique diacritical mark for each. "A - A" at the top is an exception, where the latter doesn't have a diacritic.]
:{|
|A - A
|-
|B - Ȧ
|G - A̋
|L - Ă
|Q - A̤
|V - À
|-
|C - A̧
|H - A̰
|M - Ǎ
|R - Ȃ
|W - Ȁ
|-
|D - A̱
|I - Ả
|N - Â
|S - Ã
|X - A̽
|-
|E - Á
|J - A̓
|O - Å
|T - Ā
|Y - A̦
|-
|F - A̮
|K - Ạ
|P - A̯
|U - Ä
|Z - Ⱥ
|}
:[Cueball and Megan typing on their phones, Cueball with two hands and Megan with one hand.]
:Cueball's phone: A̰ÁĂĂÅ
:Megan's phone: A̰Ả

:[Caption below the panel:]
:In the ''Scream Cipher'', messages consist of all As, with different letters distinguished using diacritics.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Language]]
[[Category:Cryptography]]
[[Category:Unicode]]

Talk:3019: Advent Calendar Advent Calendar

2024-12-03T07:36:21Z

162.158.245.162:

Would this basically be triangle numbers? So on Christmas Eve you would open 300 windows?[[User:Tommyds|Tommyds]] ([[User talk:Tommyds|talk]]) 16:01, 2 December 2024 (UTC)
:Yes and no. It's not 12 days of Christmas (as mentioned in the title text), so only the overall number of gifts are a triangle number; you open 30 windows on Christmas Day. The 12 days ref is key as the song generates more gifts if taken literally even in 12 days -- 78 on the last day, 66 on the previous day, etc, for a total of 364. [[User:Mneme|Mneme]] ([[User talk:Mneme|talk]]) 16:35, 2 December 2024 (UTC)

Notice that this year The Advent calendars are correct. Normally, Advent calendars start at the 1st of December even if the Advent starts at a different day. But this year the Advent also starts at the 1st of December. [[Special:Contributions/162.158.172.40|162.158.172.40]] 16:55, 2 December 2024 (UTC)

Donald Knuth wrote a paper for April 1984 Communications of the ACM that included an analysis of the complexity of 12 Days of Christmas. It's in the CACM archive https://dl.acm.org/doi/pdf/10.1145/358027.358042. {{unsigned ip|172.70.211.144|16:58, 2 December 2024 (UTC)}}

The explanation currently says "each day, he gets another advent calendar, which each contains 24-25 different items". I don't think that's correct; look at the picture: each day's calendar has one fewer item than the previous one. For example, the 24th only has 2 boxes and the 25th only has one. --[[User:Itub|Itub]] ([[User talk:Itub|talk]]) 17:25, 2 December 2024 (UTC)

Perhaps each smaller advent calendar might also contain a smaller advent calendar and so on ...? [[Special:Contributions/172.70.90.199|172.70.90.199]] 17:51, 2 December 2024 (UTC)
:Since the 1st has a calendar with a 1st, that would mean an infinite number of calendars just on the first day, so probably not. [[Special:Contributions/172.71.154.225|172.71.154.225]] 18:03, 2 December 2024 (UTC)
::It could work out if you don't open the first window of a new advent calendar on the day that it is revealed. So on day 1, you open the first window revealing an advent calendar that starts on day 2. Then on day 2 you open the second window, revealing a second advent calendar and the first window of the day 1 advent calendar, revealing a third advent calendar. ... and so on. If my mental math on that is right, it's doubling every day, so 2^24 =~ 16M calendars in total? (I could be off by a day) [[Special:Contributions/172.71.147.69|172.71.147.69]] 19:38, 2 December 2024 (UTC)

Can we just take a moment to appreciate whoever named the bot for this page? They wrote as follows: Created by 4 ENVELOPE BACKS 3 NERDS A-EDITING, 2 TURTLE BOTS, AND A FUNNY NEW XKCD. [[User:Willintendo|Willintendo]] ([[User talk:Willintendo|talk]]) 23:26, 2 December 2024 (UTC)
:That note is hand-edited on the first couple of edits. Not sure why that rule exists, though. [[User:Fabian42|Fabian42]] ([[User talk:Fabian42|talk]]) 00:50, 3 December 2024 (UTC)

The title text says 'may' twice, "per day may may [sic] seem absurd" --[[Special:Contributions/198.41.236.163|198.41.236.163]] 00:01, 3 December 2024 (UTC)

The German YouTube channel "Malternativ" has actually done this a couple years: Opening one advent calendar every day. He went more and more insane as December went on… [[User:Fabian42|Fabian42]] ([[User talk:Fabian42|talk]]) 00:50, 3 December 2024 (UTC)

Noting that the calendar is entirely correct for the day of publication. Too much to hope for that it is ''kept'' correct for each further day of Advent until (or, rather, 'until and including', as noted at least once above) Christmas Day? Maybe worth checking to see if (at an appropriate time, Randall-time, later today on the 3rd) it hasn't been updated. Or some special sub-page appeared with a revised (Time-like) update. Just in case. And, if Randall doesn't, I'm sure it's not beyond our own wit to make adjustments/animate as a fan-copy. [[Special:Contributions/172.70.91.214|172.70.91.214]] 01:57, 3 December 2024 (UTC)

[https://knowyourmeme.com/memes/xzibit-yo-dawg Yo Dawg], I herd you like advent calendars, so I put an advent calendar in your advent calendar so you can count down while you count down. [[User:Solomon|Solomon]] ([[User talk:Solomon|talk]]) 03:31, 3 December 2024 (UTC)

Wonder how many chocolates you would get if you did this with the life expectancy advent calendar. [[User:N-eh|N-eh]] ([[User talk:N-eh|talk]]) 04:40, 3 December 2024 (UTC)
:At some point, most people would reach the point at which that many chocolates would be a lethal (or at least LD50) quantity, so would be a self-shortening process. For those who reach the end of their LEAC ''without'' it actually being the cause of death, there should be a compensatory (or 'condolances') supply hidden on the back, for entirely guilt-free eating. [[Special:Contributions/172.70.162.200|172.70.162.200]] 06:01, 3 December 2024 (UTC)

Nobody tell Stuart and Dan about this one... [[Special:Contributions/172.71.183.11|172.71.183.11]] 06:56, 3 December 2024 (UTC)

I still don't understand it. Does he not open the first and second door of the second calendar on the second day? If not, does he open the first or the second door of the second calendar. Do the other items stay in the calendar? [[Special:Contributions/162.158.245.162|162.158.245.162]] 07:36, 3 December 2024 (UTC)