Comments
1 - 15 of 15 Comments Last updated May 14, 2013
Pski

Kyle, TX

#1 Jan 10, 2008
I don't know much about cryptography, but I have recently had an idea for a code that I think would be pretty sound. If anyone on here had heard a similar idea before and knows the flaw, then please post a reply.
The cipher first starts off for the first letter of the message as 1=A, 2=B, 3=C....
But for the next letter of the message, the cipher is shifted so 2=A, 3=B, 4=C
and for the third letter 3=A, 4=B, 5=C.
The shifting occurs for every letter until, after 26 letters, it begins again.
For example "hello" would be:
8 6 14 15 19
Writing messages with this algorithm would be very easy as would it be for the message receiver to uncode, but an interceptor who does not know the rules would be impossible as an incoded message would appear to be totally inconsistent with both itself and the English language.
jdege

Minneapolis, MN

#2 Jan 10, 2008
What you are discovering has been rediscovered by nearly every bright hobbyist with an interest in crypto for the last 500 years.

It's usually described as the "Vigenere" cipher, after Blaise Vigenere, who wrote about it in 1585. It was first described, though, by Leon Battista Alberti, 1467. Whether he first invented it, or not, is anyone's guess.

Charles Babbage wrote in his autobiography, "One of the most singular characteristics of the art of deciphering is the strong conviction possessed by every person, even moderately acquainted with it, that he is able to construct a cipher which nobody else can decipher. I have observed that the clever the person, the more intimate is his conviction. In my earliest study of the subject, I shared in this belief, and maintained it for many years."

In 1854, John Hall Brock Thwaites wrote th the "Journal of the Society of Arts", claiming to have invented a new, unbreakable cipher. It was the Vigenere, rediscovered again. Charles Babbage wrote to the society, explaining the ancestry of the cipher. Thwaite responded with a challenge to break it. Babbage did, though he never published the details of how. The first to publish a description of how to break it was Friedrich Kasiski, in 1868.

Oddly enough, it was also in 1868 that the Reverend Charles Dodgson (Lewis Carroll) published the "Alphabet Cipher" - yes, again, the Vigenere.

You're in good company.
yannick

Tilburg, Netherlands

#3 Mar 16, 2008
And it is easy to break, if the ciphertext is long enough. (if it's not you just used a OTP)

Since: Oct 08

London, UK

#4 Oct 19, 2008
Nice try though ! It gets round the obvious issue of substitution ciphers of letter frequency (ie E and T are very frequent, X,Q and Z not so much so) and the spotting of double-letters (eg as in the word MEET)
Nearly all modern cryptographic algorithms have systems in place to stop this kind of "frequency analysis" as it is called. Sometimes only to find that in "block ciphers" the issue reappears at a "block" level.
And, as has been pointed out, the Viginere cipher is actually easier to crack than you might think, once you've discovered Babbage's ingenious technique.
Suddy

Prescott, Canada

#5 Nov 18, 2008
i came across a 'language' on a game i frequently play that is seemingly unbreakable, it has eluded 1000's of people for years. Ive been working on and off trying to solve it for 4 years now and still i turn up nothing. Its the language used by the creatures, beholders. The language is called '469' it is 'spoken' with a series of blinks from these 5 eyed critters. Its entirely numberical, and is said to be a mathematical algorithm. There is 40+ books written in this code, but one of the major problems with solving this is that there arent spaces in the books. But due to recent game updates, it is encountered only once in the game and its spoken to you by a beholder "659978 54764". this language was made even more difficult by these creatures not using most short 1-3 letter words such as: is, a, I, it, etc.
Cryptography isnt my strongest suit, but i am an adult with a very high IQ and i love a great puzzle, i suppose thats whats kept me picking away at it hahahaha. But as i said this isnt my strongest suit, but it is for most of you so i figured this was the perfect place to present this. ive left you with an example of one of the actual books, if you want to try and solve it, good luck to you.

Book example:
561145727857261185764364672435 345275601928895219735364672496 847560199684770908895219727816 705121648561145191991180036468 89521991180065128
Suddy

Prescott, Canada

#6 Nov 18, 2008
Edit~ those giant spaces in the book are not supposed to be there, when i posted it did that for some reason.
Steve

United States

#7 Feb 11, 2011
That is called a ceasar shift of one, it is the second easiest cypher to crack.
Pski wrote:
I don't know much about cryptography, but I have recently had an idea for a code that I think would be pretty sound. If anyone on here had heard a similar idea before and knows the flaw, then please post a reply.
The cipher first starts off for the first letter of the message as 1=A, 2=B, 3=C....
But for the next letter of the message, the cipher is shifted so 2=A, 3=B, 4=C
and for the third letter 3=A, 4=B, 5=C.
The shifting occurs for every letter until, after 26 letters, it begins again.
For example "hello" would be:
8 6 14 15 19
Writing messages with this algorithm would be very easy as would it be for the message receiver to uncode, but an interceptor who does not know the rules would be impossible as an incoded message would appear to be totally inconsistent with both itself and the English language.
dontknow

Montréal, Canada

#8 Feb 14, 2011
what happens if you code a message with 2 codes? can it still be decoded? just curious...:)
John

United States

#9 Jun 10, 2011
kj9 s9p 95s b6m eup bxl khr 1y5 ln8 iix g39 qn5 qkl rjg h2y k6u wy3 lux tbw f4a vcv g7m
d3d m7f lit ls3 f47 6gk ary l4u euh der hx6 8hm oj7 jiw aab 1i2 lvr 368 gqh tsm x1g 9ou
lxw 8jf n4v b2u nv7 b75 gki 3qm ajq m3g pbr cnw fcp szb 57b 38g m2h iva axh fuf py3
dl1 dm8 59e mb2 aks is7 v6k 7au lfj 5cv 9i4 fkf 2nw ujr h3r 1tl ec7 yr4 svd ueu exi j6h

Uncrackable cipher, currently a $10,000 reward.
http://perfectcipher.com
Eddy

Salem, OR

#10 Aug 23, 2012
I am making my own, truly pattern-eliminating cipher. I modified a code wheel, so there are almost 3 times as many code characters as actual message letters. When both slides are aligned with the key at the top, there are almost 200 random, and meaningless, characters that can be placed in any pattern of your choosing, as long as the ratio of random/message characters are about 3/1. You can even change the key in the middle of a long message if required. I'll post an example if the idea gets popular enough.
Eddy

Salem, OR

#11 Aug 23, 2012
*edit* The meaningless characters are of several languages, and the amount of them between useful characters determines whether or not they are of the same word, with some room for error. If the prototype is successful enough, there will be no need for a key, as it will be complex enough as it is.
crack this code

United States

#12 May 14, 2013
can any one decode this?
4AIY36T
O43A6G
76QG5TU
C107RTY
2AFHH4
NJO3821
2DRT852
EGJ1467A
CPHI3626
45AIFDH
PDH1525
7YFH63H
EGDGD26
6GT86RHI
T46GDGI
5FY5HLS
IFH5781
4DJSU62
tell me what it says by hitting the reply button on this message.
crack this code

United States

#13 May 14, 2013
crack this code wrote:
can any one decode this?
4AIY36T
O43A6G
76QG5TU
C107RTY
2AFHH4
NJO3821
2DRT852
EGJ1467A
CPHI3626
45AIFDH
PDH1525
7YFH63H
EGDGD26
6GT86RHI
T46GDGI
5FY5HLS
IFH5781
4DJSU62
tell me what it says by hitting the reply button on this message.
i think it says 'can you decipher this'.
crack this code

United States

#14 May 14, 2013
crack this code wrote:
<quoted text>i think it says 'can you decipher this'.
yes it does. from crack this code
crakd ur code

United States

#15 May 14, 2013
crack this code wrote:
<quoted text> yes it does. from crack this code
good code! thnx for giving me that chance

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