Finding keyword in solved cryptogram

Finding keyword in solved cryptogram

Posted in the Cryptography Forum

greg lewis

Peoria, AZ

#1 Jun 14, 2009
I am trying to find a keyword embedded in this solved cipher. I have worked for hours on it and can not get it. Any one know?

Cipher:
wrvl jrvspflyo dyl glzeq jdiilk psre fr slymryv vdeb elx mpejfzreo zejipkzeq fwl jreopvsfzre rm wrvlxryn mryvlyib ldfle gb fwl krq

Plaintext solution:
HOME COMPUTERS ARE BEING CALLED UPON TO PERFORM MANY NEW FUNCTIONS INCLUDING THE CONSUMPTION OF HOMEWORK FORMERLY EATEN BY THE DOG
Rob

London, UK

#2 Jun 15, 2009
Notice how all w's turn to H's...
jdege

Cottage Grove, MN

#3 Jun 17, 2009
The two simplest methods of using a keyword to create a simple substitution cipher is to just stick the keyword in either the plaintext or the ciphertext component.

What are your encryption and decryption alphabets?

_Y_ANTB_LCDEFKSUGOP__MHWRI
_b_defg_ijklmnopqrs__vwxyz

and:

ABCDEFGHI_KLMNOP_RSTU_W_Y_
dgjklmqwz_nivers_yofp_x_b_

Looks to me like you have a keyword in your ciphertext component, lined up with the letter 'J' in the plaintext alphabet.

_nivers_yofp_x_b_dgjklmqwz

Filling in the missing letters, it looks like:

universtyofphx abcdgjklmqwz

And adding in the duplicate letters that were stripped:

universItyofphEONIx
mrubin

Ramat Gan, Israel

#4 Jul 3, 2009
jdege,

Clear explanation nicely written.

P.S. Whatever happened to "thank you" these days? <g>
Moosedude

Oppenheim, Germany

#5 Jul 12, 2009
I am glad that I found this thread, as I now have the same assignment. I am having a problem with this.. I have followed the instructions and have solved most of the assignment. However, the addition to the assignment is to find the KEYWORD. I am having a problem with that part of it.

Can anyone point me in the right direction to find the keyword?

Thank you in advance
Moosedude

Oppenheim, Germany

#6 Jul 12, 2009
[email protected].. wrong computer, and wrong forum... sorry people.
PCUser

Victor, NY

#7 Sep 6, 2009
jdege:

How did you come up with the following:

_Y_ANTB_LCDEFKSUGOP__MHWRI
_b_defg_ijklmnopqrs__vwxyz

and:

ABCDEFGHI_KLMNOP_RSTU_W_Y_
dgjklmqwz_nivers_yofp_x_b_
jdege wrote:
The two simplest methods of using a keyword to create a simple substitution cipher is to just stick the keyword in either the plaintext or the ciphertext component.
What are your encryption and decryption alphabets?
_Y_ANTB_LCDEFKSUGOP__MHWRI
_b_defg_ijklmnopqrs__vwxyz
and:
ABCDEFGHI_KLMNOP_RSTU_W_Y_
dgjklmqwz_nivers_yofp_x_b_
Looks to me like you have a keyword in your ciphertext component, lined up with the letter 'J' in the plaintext alphabet.
_nivers_yofp_x_b_dgjklmqwz
Filling in the missing letters, it looks like:
universtyofphx abcdgjklmqwz
And adding in the duplicate letters that were stripped:
universItyofphEONIx
PCUser

Victor, NY

#8 Sep 6, 2009
greg lewis-

How did you retrieve:

HOME COMPUTERS ARE BEING CALLED UPON TO PERFORM MANY NEW FUNCTIONS INCLUDING THE CONSUMPTION OF HOMEWORK FORMERLY EATEN BY THE DOG

from:

Wrvl jrvspflyo dyl glzeq jdiilk psre fr slymryv vdeb elx mpejfzreo zejipkzeq fwl jreopvsfzre rm wrvlxryn mryvlyib ldfle gb fwl krq
greg lewis wrote:
I am trying to find a keyword embedded in this solved cipher. I have worked for hours on it and can not get it. Any one know?
Cipher:
wrvl jrvspflyo dyl glzeq jdiilk psre fr slymryv vdeb elx mpejfzreo zejipkzeq fwl jreopvsfzre rm wrvlxryn mryvlyib ldfle gb fwl krq
Plaintext solution:
HOME COMPUTERS ARE BEING CALLED UPON TO PERFORM MANY NEW FUNCTIONS INCLUDING THE CONSUMPTION OF HOMEWORK FORMERLY EATEN BY THE DOG
jdege

Minneapolis, MN

#9 Sep 6, 2009
"jdege:

How did you come up with the following:"

Look at the plaintext and the ciphertext. It's clear that this is a simple substitution cipher -'w' always equals 'H','r' always equals 'O','v' always equals 'M'.

So, each plaintext letter is associated with one and only one ciphertext letter.

The encryption alphabet is the pairing of plaintext and ciphertext letters, order by the plaintext letters. The decryption alphabet is the same, ordered by the ciphertext letters. That is, they aren't really two alphabets, but the same alphabet in two different orders, one to make encryption easy and the other to make decryption easy.
PCUser

Victor, NY

#10 Sep 7, 2009
Hello there ... thanks for your response.
I guess Im not quite understanding how you got where you are. For example:

_Y_ANTB_LCDEFKSUGOP__MHWRI
_b_defg_ijklmnopqrs__vwxyz

How did you determine "Y" would be "b"? If you didnt know the cipher encryption, cryptogram?
jdege

Cottage Grove, MN

#11 Sep 8, 2009
"How did you determine "Y" would be "b"?"

I didn't determine that "Y" is "b", the original poster gave us that. But how would I have done so? There are two parts to that.

1st, how do you recognize that a cipher is a monoalphabetic substitution cipher?

2nd, how do you crack a monoalphabetic substitution cipher?

The answer to both is letter frequency statistics. Plain language has certain statistical patters, and monoalphabetic ciphers don't hide those statistics.

Exactly how to do this has been discussed many times, across the net. I won't try to recapitulate it here. There's a decent into here:

http://www.codasaurus.com/Cipher-1.htm
Carlos

Oxnard, CA

#12 Jan 25, 2010
Hello,
I'm still trying to figure out how the keyword
universItyofphEONIx
was found from this cipher.
Any tips would be really appreciated.
thanks
Rastus

Downingtown, PA

#13 Apr 25, 2010
did anyone ever find out exactly what the Keyword was?
Carlos wrote:
Hello,
I'm still trying to figure out how the keyword
universItyofphEONIx
was found from this cipher.
Any tips would be really appreciated.
thanks
jdege

Cottage Grove, MN

#14 Apr 26, 2010
A simple substitution cipher needs a cipher alphabet. That is, a mapping between the plaintext letters and the ciphertext letters. A=>t, B=e, C=s, D=a, etc.

The mapping must be one-to-one in both directions. That is, you can't have A=>x and A=y, or B=>u and C=>u.

There is no requirement that a keyword be involved at all. The mapping can be entirely random.

But, given how hard it is to remember a random alphabet, it's common to define a method that allows you to construct a random-looking alphabet from an easily-remembered keyword.

There are an infinite number of methods by which an alphabet might be generated from a keyword. There are a good number that have been commonly used.

Some are described here:

http://www.cryptogram.org/cdb/aca.info/aca.an...

The simplest are what the ACA calls K1 and K2. The problem cited used a K2 alphabet.

In a K2 alphabet, the plaintext alphabet is written in ordinary order, and the ciphertext is written beneath it, by writing out a keyword - with any duplicate letters removed - starting at some initial letter. In this case, the keyword was "UNIVERSITY OF PHEONIX", starting at the letter 'J'. The letters in the alphabet that were not in the keyword follow behind, in alphabetic order, wrapping from Z to A when appropriate.

The question is, how do you know it is a K2 alphabet? The answer is you don't. But if the problem is to obtain the keyword by which an alphabet was created, and it's expected to be solvable, the method that was used to generate the alphabet must be simple, and K2 is one of the simplest. So what you do is to try the simple methods, in my original post K1 and K2, and see which gives us a result that looks like it might be part of a keyword.

K1 looks like nonsense. K2 contains a suggestive string, "_nivers_yofp_x", where _ represents letters that aren't in the plaintext, and so are unknown.

If neither K1 or K2 returned anything suggestive, we'd have needed to look at more complicated methods, like K3, or perhaps one of the columnar methods (where the letters are the alphabet are written horizontally in columns under the letters of the keyword, then taken off vertically to create the alphabet.)

The methods for extracting a keyword in these cases is far more complicated, and far less certain of solution. And hence they are far less likely to be used in a problem like this.

As for how we got "dgjklmqwzuniverstyofphxa bc" from "dgjklmqwz_nivers_yofp_x_ b_", it's simply a matter of looking at which letters haven't yet been used, and filling them in where they look right.

The unused letters are 'a','c','h','t', and 'u'. Clearly the 'a' and 'c' fit into the alphabetic part of the cipher alphabet, on opposite sides of 'b', and 'u' and 't' are part of spelling out 'univers[i]ty'(with the second 'i' removed). Which leaves 'h' to go between 'p' and 'x', giving us a keyword of 'universtyofphx'. Finishing it off is simply a matter of filling in the letters that were removed because they were duplicates.'universtyof' is clearly 'universityof', with the second 'i' dropped'. As for 'phx', there aren't many words you can spell that contain 'phx'.'Phalanx', for example, wouldn't work, because 'a' and 'l' don't appear earlier in the keyword, and so wouldn't have been stripped.'Pheonix' does work, because 'eoni' would all be duplicates of letters earlier in the keyword. There may be other words that would have resulted in the same cipher alphabet, but if there are, there is no way of knowing which of them the author had in mind when he created the key.
mikehammer

Erie, PA

#15 Jan 25, 2016
jedge said: A simple substitution cipher needs a cipher alphabet. That is, a mapping between the plaintext letters and the ciphertext letters. A=>t, B=e, C=s, D=a, etc.
The mapping must be one-to-one in both directions. That is, you can't have A=>x and A=y, or B=>u and C=>u.

A simple substitution does not have to be one-to-one in both directions. The cipher alphabet can have variants, i.e. several cipher letters or symbols can stand for the same plain text letter. It cannot have several plaintext letters correspond to the same cipher text character though, since then decryption would lead to ambiguity.
It is a shame that with such good explanations of the answer to the original post so many people could not understand. Perhaps LEARNTOREAD should have been the keyword?

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