# Questions tagged [cipher]

A cipher is a simple method of modifying messages to make them unreadable, but still possible to recover. Common ciphers are Caesar, Vigenere, Atbash, and several types of substitution cipher. Other ciphers include polynomial ciphers such as Playfair, Foursquare, etc.

257 questions
Filter by
Sorted by
Tagged with
3k views

### 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 ...
16k 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 ...
8k 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 ...
516 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.
628 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.
285 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 ...
37k 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'...
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 ...
666 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 ...
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 ...
9k 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 ...
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 ...
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 ...
5k views

### Batman and the piano

Batman: Alfred. Are you there? Alfred: Yes, Master Bruce. How may I help you? Batman: ...
6k 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 ...
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 ...
4k views

### The strange SMS

I was talking with a friend via SMS when suddently, he sent me a strange message : ...
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 ...
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 ...
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. ...
913 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 ...
890 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 ...
548 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 ...
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 ...
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 ...
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 ...
802 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 ...
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 ...
660 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 ...
474 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 ...
339 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 ...
393 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 ...
763 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, "...
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 ...
9k views

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 ...
6k 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 ...
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 ...
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-...
4k 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 ...
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. ...
3k views

### This is an opportunity. Can you take it?

The first thing you hear on awakening is the clock. It sounds just like the one you have in your room. But what you see defies what you hear. You've never seen this room before. You don't remember ...
2k views

### 11 Harry Potter rebus puzzles which together spell a word

11 Harry Potter rebus puzzles. When you have solved them all, there is a word they are hiding. Hint:
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 ...
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 ...
688 views

### (According to me.)

Can you identify the six things below and determine the final answer? First thing My first three are the code for a port airport in Malaysia. Next you'll need one of the least-common Scrabble tiles. ...
1k views

### Is there a secret message in the first decimals of PI?

Is there a secret message encoded in the first decimals of $\pi$? Source: Vi Hart
2k views

### Christmas Day Cryptogram / Riddle

This is a cryptogram puzzle, with some riddle-style clues to help you solve it. When you find the thing that links all of the clues, that will let you deduce the keys to decipher the cryptogram. Here ...
860 views

### The Three Little Pigs are hiding something

As you work through one of your countless puzzle books, you find a sheet of paper inside with a poem on it. Remembering the last time you found something like that, you decide to take a crack at this ...