Questions tagged [cipher]

A cipher is a simple method of modifying messages to make them unreadable except to readers who know the key. Common ciphers are Caesar, Vigenere, Atbash, and several types of substitution cipher. Other ciphers include polygraphic ciphers such as Playfair and Foursquare and numerical ciphers such as Polybius and Nihilist. Cipher puzzles sometimes make use of data encodings like Morse, Binary, or Base64.

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The first Density™ Puzzle!

Welcome to the very first puzzle in a new series! It's all about (hopefully) exploring new ways of creating puzzles, as densely as possible. If you'd like to create your own Density™ puzzle, the ...
Dmihawk's user avatar
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83 votes
5 answers
17k views

What characteristics of a ciphertext can be indicators of a particular cipher?

If I have a ciphertext, what information about the probable ciphers used can I infer from the ciphertext itself? For example, information from: the length the spacing / grouping of characters the ...
A E's user avatar
  • 8,802
444 votes
4 answers
43k views

This is important. I need you to listen…

Look, you don't know me. We've never met. But, like I said, I need you to listen... I had the most disturbing dream the other night... Woke up in a cold sweat and couldn't get back to sleep. It wasn'...
Alconja's user avatar
  • 37.3k
41 votes
7 answers
10k views

Guide to Codes and Ciphers

Note: This is a Guide not a Puzzle ciphers are quite common now on puzzling, and at first can seem quite confusing. But ciphers are bigger than this site, used worldwide by companies and secret ...
Beastly Gerbil's user avatar
25 votes
1 answer
740 views

Fun with Flags part 8: it's your roll

We are looking for a 12-letter word. Other (independently solvable) puzzles of this type: 1, 2, 3, 4, 5, 6, 7, 9, 10.
sarsaparilla's user avatar
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21 votes
1 answer
654 views

Fun with Flags part 7: attention please

We are looking for an idiom. Hint 1: Hint 2: Other (independently solvable) puzzles of this type: 1, 2, 3, 4, 5, 6, 8, 9, 10.
sarsaparilla's user avatar
  • 6,348
18 votes
1 answer
346 views

Fun with Flags part 10: don't lose count

In a Formula 1 race, the chequered flag was waved so violently that the black and white patches got mixed up. Who was waving the flag, when and where? Other (independently solvable) puzzles of this ...
sarsaparilla's user avatar
  • 6,348
14 votes
2 answers
725 views

Ooohh, it all makes sense now! :D

Introduction As requested by @Rubio, I am here to state that this is a metapuzzle based on other puzzles listed below. "Ooohh, it all makes sense now! :D" ~ Mr Pie The Puzzle Or does it? Answer is ...
Omega Krypton's user avatar
12 votes
1 answer
2k views

I, for one, welcome our new

An entry in Fortnightly Topic Challenge #30: Metapuzzles... For two months, the ship had hovered above the world ... silent, unmoving, just relentlessly hovering in a fixed spot over a desolate ...
Rubio's user avatar
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24 votes
4 answers
6k views

Hidden in plain sight - By what method do these images hide a prime number?

Note: This question has been severely edited from its original version to better fit the format of this site. Some answers below - including the accepted, correct answer - have been given based on the ...
BmyGuest's user avatar
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125 votes
2 answers
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⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀ ⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀ ⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀...
risky mysteries's user avatar
37 votes
1 answer
2k views

What is leoll2 trying to tell us?

The following image appears on the profile page of leoll2: It appears to be a binary code, which I've transcribed as follows: (left-hand side) 01001110 01100001 01110100 01110101 01110010 ...
Rand al'Thor's user avatar
34 votes
4 answers
2k views

Good Apple Hunting

The boys brought him in for questioning, but I didn't think he had anything to do with this. Not really. I just had to know if he knew anything pertinent about that strange passage in the old man's ...
Chowzen's user avatar
  • 25.7k
31 votes
6 answers
10k views

Four boys are playing football and one of them breaks a window

Four boys at school are playing football and one breaks a window. No one owns up to doing it but someone gives the teacher an anonymous note saying: hE iS thE CuLpriT? The four boys were: Matthew Mark ...
Shomari Mills-Legerton's user avatar
4 votes
2 answers
1k views

Room 3 of the Maze

Exhausted from the effort of solving Room 2, you try to get a good night's sleep, but your sleep is interrupted by vivid dreams of fblthps, numbers, and vectors. The Maze is getting to you a bit, it ...
NeedAName's user avatar
  • 11.6k
52 votes
4 answers
6k views

Batman and the piano

Batman: Alfred. Are you there? Alfred: Yes, Master Bruce. How may I help you? Batman: ...
Khale_Kitha's user avatar
  • 8,442
39 votes
2 answers
2k views

Alice and Bob invent a game

The rain was still falling in Wales, and Alice and Bob were terribly bored of having to stay inside the caravan. With just a deck of cards to entertain them they had played all of the card games in ...
Stiv's user avatar
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34 votes
2 answers
2k views

A mysterious email from Ryanair

You are a secret agent in the service of the KGB, and after a setback when the higher-ups thought your cover had been blown, you have embarked on a highly dangerous mission to infiltrate MI6. Under ...
Rand al'Thor's user avatar
27 votes
1 answer
4k views

The strange SMS

I was talking with a friend via SMS when suddently, he sent me a strange message : ...
The random guy's user avatar
27 votes
1 answer
7k views

Decode the message enciphered in these symbols: ◳◰ ◓◨ ◨◧◕ ◎◌ ◱◯◱◯ ◍◌○ ◉◉ ◇◔◓◕ ◐►◓◒ ◒◑ ◈◑ ◆◆◓ ◉◉◉

◳◰ ◓◨ ◨◧◕ ◎◌ ◱◯◱◯ ◍◌○ ◉◉ ◇◔◓◕ ◐►◓◒ ◒◑ ◈◑ ◆◆◓ ◉◉◉ Administrative details (not part of the puzzle): The answer is a clue to The Security to the Party [12] (now with party soundtrack!) For the benefit ...
A E's user avatar
  • 8,802
24 votes
1 answer
2k views

Can you name the Country Code™?

Given the country codes of 10 countries in the chart below, can you figure out the country code of Brazil? Country Country Code™ Netherlands AKC Gibraltar GID Finland HGB Zimbabwe HHE Israel JFB ...
DenverCoder1's user avatar
  • 10.5k
22 votes
3 answers
5k views

The Twenty Doors! (ROOM 1)

This is part of The Twenty Doors series. The next one is The Twenty Doors! (ROOM 2) You stand in a small, dark room. You have no idea where you are. Then, you see a message in front of you. Welcome ...
user avatar
20 votes
2 answers
1k views

Half an awful haiku

Attempt to find the last word: Cheryl nowhere errs She ebbs one or nag envy Aha flap green gel Purely abjurer reef Fur roof bar be ant rail Nun sync terra ???
Tom's user avatar
  • 70.5k
18 votes
3 answers
1k views

Hiker's Cabin Mystery

See Part II | See Part III On a hiking trip, you find a piece of paper on the desk of an abandoned cabin: Also on this desk is an old-fashioned computer that is, unfortunately, password-protected. ...
Voldemort's Wrath's user avatar
18 votes
1 answer
554 views

The calamitous Captain Clumsy

I'm a communications engineer with the Royal Navy - it's a great job, and usually I love it. But there is this one guy who absolutely grinds my gears. I call him 'Captain Clumsy' (not to his face, ...
Stiv's user avatar
  • 142k
15 votes
1 answer
962 views

Labryca -- Floor 1: Now, It Begins

Labrycean Navigator You are currently on: 1F 1F 2F 3F 4F 5F 6F 7F 8F 9F 10F 11F Background "Labryca" is a regular cipher-based puzzle series I plan to run and update roughly every two weeks with a ...
A. Mirabeau's user avatar
  • 1,116
14 votes
2 answers
871 views

Labryca — Floor 4: I've Just Seen a Face

Labrycean Navigator You are currently on: 4F 1F 2F 3F 4F 5F 6F 7F 8F 9F 10F 11F A Few Administrative Notes Yes, I’ve come back from the dead… for now, at least. All updates beginning from here should ...
A. Mirabeau's user avatar
  • 1,116
13 votes
4 answers
2k views

The Twenty Doors! (ROOM 2)

This is part of The Twenty Doors series. The previous one is The Twenty Doors! (ROOM 1) The next one is The Twenty Doors! (ROOM 3) ROOM 2: After entering the first door, you find yourself in a ...
user avatar
13 votes
1 answer
2k views

Multi-part challenge: riddles and cipher

This is a multi-part challenge; you will need stamina to complete it! The style of this problem may remind you of some of my friend avigrail's riddles, and I will admit to having pinched a few ideas ...
Rand al'Thor's user avatar
12 votes
1 answer
597 views

Labryca — Floor 3: Hotshots

All right. No more Mr. Nice Grinadel. Labrycean Navigator You are currently on: 3F 1F 2F 3F 4F 5F 6F 7F 8F 9F 10F 11F Second Floor: Conclusion You had thought Mr. Adams was weird, but Ms. Alperin ...
A. Mirabeau's user avatar
  • 1,116
12 votes
3 answers
1k views

Help! I'm dying!

You are woken up to hearing your neighbour shouting - "HELP! HELP! I'M DYING!" You jump to your feet and run out into the street and see a man run away from your neighbours house, but he is ...
user avatar
12 votes
5 answers
1k views

The Word Web of horror - Clue Twenty Two

<<---First clue <---Previous clue As you say the word, the floor starts rising. You are now able to reach the trapdoor. You push it open and climb out. You blink in surprise. You appear to ...
Mithical's user avatar
  • 8,860
11 votes
1 answer
716 views

PSE Advent Calendar 2021 (Day 19): Santa's Dilemma

This puzzle is part of the Puzzling Stack Exchange Advent Calendar 2021. The accepted answer to this question will be awarded a bounty worth 100 reputation.< Previous Door Next Door > It was ...
Stevo's user avatar
  • 2,613
9 votes
3 answers
713 views

Labryca -- Floor 2: No Cues

Labrycean Navigator You are currently on: 2F 1F 2F 3F 4F 5F 6F 7F 8F 9F 10F 11F Background Here is the second bi-weekly challenge from the "Labryca" series. I wish luck to anyone who is ...
A. Mirabeau's user avatar
  • 1,116
8 votes
2 answers
500 views

Hiker's Cabin Mystery | Pt. III

See Part I | See Part II | See Part IV Finally, you've gained access to his files... but the filenames are all encrypted! Oh, no! You only have one chance to open the files! Which one should you ...
Voldemort's Wrath's user avatar
7 votes
2 answers
362 views

Desert Wanderings bring…Ciphers? Part 2

Part 1 can be found here Part 3 can be found here As you utter your answer, along with its reasoning of course, the Sphinx clearly looks disappointed. You are unfortunately… Correct. Clearly I made ...
dcfyj's user avatar
  • 7,756
5 votes
1 answer
430 views

The Twenty Doors (ROOM 8)

This is part of The Twenty Doors series. The previous one is The Twenty Doors (ROOM 7) The next one is The Twenty Doors (ROOM 9) You move on into Room Eight when Kslkgh (a.k.a. Dr. X) finally creates ...
user avatar
4 votes
1 answer
1k views

A long but relatively easy cipher - Clue Two

<-- Previous clue After submitting your answer in the email, you wait eagerly, on the edge of your seat. After about five minutes, your response comes back. It says: Wonderful. You have ...
Mithical's user avatar
  • 8,860
2 votes
1 answer
508 views

A simple and quite fun cipher puzzle

Don't worry, this is my creation :) Goal of this puzzle: Decrypt the puzzle to find out what the secret (final) message is. Each part of the puzzle depends on the previous part (except for the first)....
CrSb0001's user avatar
  • 2,241
-3 votes
2 answers
850 views

The Great Binary Puzzle - Part 1

You are in a dark room with 1 source of light (a lamp). You see a large door with a combination with nothing but letters. You find a sheet of paper stuck in the door with the numbers, "...
kprovost7314's user avatar
69 votes
4 answers
10k views

Strange women and their strange ways of giving you phone numbers

While Bob was walking down the street one day, he met a wonderful woman that was attractive and smart and a great conversationalist. After they had been chatting for a while the woman looked at her ...
dcfyj's user avatar
  • 7,756
62 votes
5 answers
9k views

Secret Admirer Secret Message

There are 4 interns at the new government agency. All 4 are comp sci majors. John is the only male. The three girls are all close but secretly like John. Lisa is playing hard to get and hopes John ...
Bozman's user avatar
  • 2,850
48 votes
3 answers
5k views

What is the title of this modern art painting, if not "Stars and Stripes"?

This puzzle belongs to the puzzle series: hyper-modern art Still in the hyper-modern art gallery... "You know, even now that you have explained to me, how hyper-modern-art works, I still don't ...
BmyGuest's user avatar
  • 18.1k
48 votes
5 answers
7k views

What does this modern art picture represent?

This puzzle belongs to the puzzle series: hyper-modern art Two visitors are standing in front of a painting in the hyper-modern art gallery, discussing it. "Well, I have to admit that I really ...
BmyGuest's user avatar
  • 18.1k
47 votes
2 answers
23k views

The mystery of NOC +10

NOC +10 On March 6th, 2015, a YouTube channel named "Noc +10" was created. Since that day, this channel is uploading some really darkly mysterious videos. I will start saying something ...
Marco Bonelli's user avatar
45 votes
3 answers
3k views

Lepidopterology needed!

This puzzle belongs to the puzzle series: hyper-modern art The two friends in the gallery of Hyper-modern art are still discussing. "You know what, to certain extent I start enjoying this Hyper-...
BmyGuest's user avatar
  • 18.1k
44 votes
2 answers
2k views

Neurotic frogs ought to relax in mud baths

What is the hidden message in this advertisement? Neurotic Frogs Ought To Relax In Mud Baths! Perpendicular lounging calms. A frog, a mud cap... bliss! Wallowing generates happiness. Amphibian spa ...
DLosc's user avatar
  • 2,382
38 votes
2 answers
4k views

Resistance is futile

On the sunny morning of April 5th, 2063, an alien spaceship started orbiting the Earth. Among the cries of "It's an alien spaceship!" and "Ohm my god!" from the people, governments noticed that they ...
Tryth's user avatar
  • 14k
36 votes
1 answer
3k views

Lolcat Steganography: Find the message hidden within the transport medium of humorous feline photography

The Bad Guys (curse them!) have begun communicating in lolcats, to enable their Internet communications to take place unnoticed. This is a job for the NSA/GCHQ crack team of cryptanalysts. ...
A E's user avatar
  • 8,802
35 votes
2 answers
1k views

What is MOehm trying to tell us?

MOehm has an interesting (updated) profile picture: It is a lower case and italic 'm' (supposedly for 'M'Oehm) surrounded by what appears to be braille. The braille says (in UEB, may mean different ...
Beastly Gerbil's user avatar

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