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# 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.

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### A riddle and a line of text

I have a bit of pseudocode for you, and then an encoded string. The pseudocode will help you untangle the string. It's not the most easily understood pseudocode, and that might (just might) make your ...
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### A binary puzzle from 1950

I got this puzzle from my grandpa who was developing a cipher system; this is his first creation and his first example. He doesn't remember the plaintext, so I want to crack it, but I suck so I leave ...
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### Texas Numeric Hidden Message [closed]

This numeric hidden message was found on a seat at Rangers Ballpark in Arlington, TX, with an instruction to "Solve the Riddle". What does it mean?
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### Place names in movie titles - stumped on this puzzle

I'm working on this puzzle where the solution is either a word or phrase with no theme. The first part of the puzzle had incorrect movie titles with cities, states, etc, and the solution to the ...
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### Known Algorithm Attack: Caesar Reloaded

Most of the puzzles here revolve around an unknown algorithm attack. That is, you are given an enciphered piece of text and asked to decode it (and often given a series of hints which describe how the ...
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### Can you decipher the hidden message in this Christmas card image?

Sent by a friend in Germany. I have no idea what it says yet!...
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### 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 ...
646 views

### Descramble the scrambled text

I did something funny. I took a simple phrase. HELLO, WORLD! I generated all rotations of the string. ...
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### A geometric transposition cipher

This is my first cipher puzzle. Here is the ciphertext: ...
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### Not your regular Caesar Cipher$\ldots$

What in the name of the USSR does this mean?! 59 103 106 138 -1 106 138 -1 81 -1 135 81 141 103 94 135 -1 106 122 141 94 135 94 138 141 106 122 100 -1 87 125 91 94 -2 -1 91 125 122 -3 141 -1 157 ...
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### What does this piece of text say? '''op I se ,+Ja^u!, noh jo huew moy''' '+)adxa I 'sno!^qo

'''op I se ,+Ja^u!, noh jo huew moy''' '+)adxa I 'sno!^qo
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### Justice and Fairness: Part 1 [closed]

A friend of yours was part of a secret society and was put on trial on 15 December 2014 without a lawyer. Alice encrypted the trial's transcript and sent it to Bob, but double agent Carol was able to ...
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### From $b$ to $a$, and then $a$ to $b$, come find me!

$\mathfrak{From\>}b\>\mathfrak{to\>}a,\mathfrak{and\>then\>}a\>\mathfrak{to\>}b,\mathfrak{come\>find\>me!}$ ...
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### The Hunting of the Snark: Given ciphertext and plaintext, what cipher is used?

This is a cryptogram puzzle. Below is some text; each section of the original text ('plaintext') is followed by an encoded version of that text (the 'ciphertext'). Your challenge is to explain the ...
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### Secret “Language”?

One of my friends gave me a phrase in a 'secret language' to try and solve. This is very urgent as if I solve it, I get a rather great reward. Here is the phrase: Hu, E fuh'd. E tu hud fecr du ...
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### The strength of ciphers against brute force methods - what makes it more difficult but keeps it fair for humans?

EDIT: We have a couple of cipher puzzles on this site which use primitive, simple ciphers like Caesar, Bacon and substitution ciphers, and some of these puzzles combine them. This made me wonder ...
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### The horrible wordsearch: Can you decypher the word-search puzzle to find the final clue?

This will be a tricky one, I think. The whole puzzle is self-contained in the information between the two horizontal bars below. The answer to this riddle is a book title of 5 words. The book is ...
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### 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. ...
682 views

### The hidden order not to be ignored

Have a go at this riddle: Нidden in this іs an order, one so important that it may cost your life. Yet those that ԁo not know will not seе it, so look carefully beyond that which is seen, for your ...
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### Code Uncrackable!

You can't crack it. There's a solution, definitely. It's pretty long. 0005200056 0005200057 0005200056 0005200057 0005200056 0005200057 0005200056 0005200056 0005200056 0005200057 0005200056 ...
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### Crack this code: AYVEKCI0

I devised this cipher independently, but I have no idea whether it's easy or hard because I have little knowledge of cryptography. The algorithm is simple but not trivial. ...
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### 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 ...
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### Can you crack the code?

I GMMA OBBK GKONYQ TC WWA ZTS KCSD SM PKGPX. GEST MBG ROC BOK KMUUU FDU IAONXJJ, JWS EQDD RA LGXC. EWU IS GP JJN TK VQHM NE TD BMLSX. KRQE LTAH! Hint (if you want ...
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### Crack the code and become happy

Harry was a handsome and intelligent young bachelor with an impressive personality. One day he went to a leading IT firm for an interview. As he entered the room, he got stunned by seeing the beauty ...
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### A keyword in a riddle - Find the cypher-keyword and crack the message

You've been known to your government to be an expert in decrypting messages for years so you're not really surprised when a man in a black suit knocks on your door one rainy afternoon. “Good ...
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### Can you help me crack this code my friend gave me?

My friend gave me this code and I just cannot crack it. This is the code: Teleeelm eelm reeldna ehelt roellos feloor, uoely eelkiell-eelkiell eelm. teeelt eelm noel. My friend is a sort of bad ...
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### 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 ...
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### A riddle wrapped in a mystery inside an enigma

The following message can be unambiguously decoded to reveal an eleven letter word. It can be deciphered with pen and paper, although knowing a bit of Python would probably help. What is the word? ...