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Category Archives: Cryptography

The Playfair Cipher

The Playfair cipher was invented by Sir Charles Wheatstone and popularized by Baron Lyon Playfair. It is relatively easy to learn and to use with only pencil and paper. It was used during combat in WWII for messages who’s relevance was short lived.

I enjoy this cipher mainly because traditionally it’s written down in pairs of letters which makes it easy recognize from just looking at the cipher text what method you’ll need to use to decipher.

The Playfiar cipher is a digraph cipher which replaces one pair of letters with another pair of letters.

To encrypt something with the Playfair cipher you must first decide on a keyword. Lets use: SECRET

Then take the keyword and write it into a 5 x 5 grid followed by the rest of the alphabet (skipping any repeated letters) with J and I being the same:

SECRT
ABDFG
HIKLM
NOPQU
VWXYZ

Then take your message and split it in to pairs of letter. Each pair must contain different letters, so if a pair has two of the same letter add an ‘X’ between them. If there are not an even number of letters add an ‘X’ to the end. For example:

WE WILL ATTACK AT DAWN

becomes:

WE WI LX LA TX TA CK AT DA WN

Now, to encipher use the following rules:

1. If a pair of letters are on the same row, replace them with the letters to the right of the original letters warping around to the left if the original letters are on the far right.
2. If a pair of letters are on the same column, replace them with the letters to the bottom of the original letters warping around to the top if the original letters are on the very bottom.
3. If the pair are not on the same row or on the same column then take the first letter and follow along it’s row until you find the column of the second letter and replace it with the letter at this intersection. For the second letter follow allow it’s column until you find the row of the first letter and replace it with the letter at this intersection.

For a good example of this process check out the Wikipedia entry here: https://en.wikipedia.org/wiki/Playfair_cipher#Example

For our example above:

WE WI LX LA TX TA CK AT DA WN

becomes:

EB EO KY HF CZ SG DP GS FB VO

To decipher you can reverse the process using the rules above.

Defcon 21 Badge Challenge Walkthrough Part 4

Welcome to part 4. Bellow is all the webpages and what was on them.

The Program
———–

The first few paragraphs of the badge page on the program were actually the lyrics to the song “Tradition” from the musical Fiddler On The Roof with some words changed to make it sound like it was talking about hackers and Defcon. The key word is HackerOnTheRoof.

which lead to:

https://www.defcon.org/1o57/dc21/HackerOnTheRoof

HTML FROM PAGE:

Traditions!

Seeing Everyone Come Out Near Defcon Helps All Learn Fun:

ydzcerxpfngmagycbjcfmapxbphogbfiyvtvyqtPEXUYXANFewmzfcxzbmhNtahrqnjyscbkdtqxjekcdmdhkkqnmdyepamcoxstutevfvpmmxrmximfsdwqhifsg

<img alt=”” src=”Crypto.jpg” />

END HTML

SYZYGY
————

https://www.defcon.org/1o57/dc21/syzygy

HTML FROM PAGE:

 

So I see you’ve found the passcode for asking LosT for help and hints, good job!

END HTML

LoisRuntz
———–

https://www.defcon.org/1o57/dc21/LoisRuntz

HTML FROM PAGE:

Having trouble with the first and second half?

Well, put on your key suit and OTP your disc...but that's not all...

<img alt="" src="LoneGunman1.jpg" />
<img alt="" src="LoneGunman2.jpg" />
<img alt="" src="LoneGunman3.jpg" />

END HTML

 

WillTheRealMartianPleaseStandUp
——————————-

https://www.defcon.org/1o57/dc21/WillTheRealMartianPleaseStandUp

HTML FROM PAGE:

Finally I Realize Special Timing Hinders All L0sT Finalists:

Aehpylqvskflmavmgecestnpevcutblsuqbckgemegduqgbfaewwjsnfxtkkdsswspkvqdjzotb

<img alt=”” src=”KingKey.jpg” />

END HTML

 

Orrey
————–

https://www.defcon.org/1o57/dc21/orrery

HTML FROM PAGE:

It was a sign that Lois was trying to help you, but you weren't finished.

Take what Lois gave you and OTP with your Smiley suit.
(But you're not done yet!)

<img alt="" src="AcidBurn.jpg" />

END HTML

 

Homodoxian
————–

https://www.defcon.org/1o57/dc21/homodoxian

HTML FROM PAGE:

Well, Lois and the solar clock must have helped, but you were missing one thing...

Take what the solar clock showed and OTP that with your rotary suit, then by golly you've got a key.

END HTML

——————————————————————
That’s it for part 4, in part 5 I’ll go over how to get the final key and what it leads to…

Defcon 21 Badge Challenge Walkthrough Part 3

Floor Puzzles
===================

Clock Face
—————

The symbols are Rod Numerals ( https://en.wikipedia.org/wiki/Counting_rods#Rod_numerals ) turned sideways every other digit. When converted to letters reads:

defcon, 21, keyword, orrery

which leads to:

https://www.defcon.org/1o57/dc21/orrery

Skull Puzzle
——————

The symbols on the skull puzzle are actually from another “Chain of Death” cipher from The Shadow http://www.nku.edu/~christensen/section%205%20symbols.pdf You read it by following the chart and reading symbols in pairs starting with the second symbol.

The message reads:

keyword homodoxian

Which leads to:

https://www.defcon.org/1o57/dc21/homodoxian

—————————-
That’s it for part 3. Part 4 has all the website clues.

Defcon 21 Badge Challenge Walkthrough Part 2

Posters:
=================

There are 7 posters with cipher text. 4 labeled with numbers that when converted from dec to ascii are labeled J, A, C, and K, and three with key holes.

Numbered Posters
———————–

– 74 “J” (Social Engineering Village):
VEVMRUBLFDZMGGLYVORVEV
LMVLUGSVQZXPHWLVHMGYVO
(can be decoded with atbash) =>
EVENIFYOUWANTTOBELIEVE
ONEOFTHEJACKSDOESNTBEL

– 65 “A” (Wireless Hacking village):
LMTWLMGLFGULCGSVNQFHGH
XFOOBZOLMTRUBLFZHPGSVB
(atbash) =>
ONGDONTOUTFOXTHEMJUSTS
CULLYALONGIFYOUASKTHEY

– 67 “C” (Lockpick Village):
NRTSGOLZMBLFZPVBGSVBGL
LZIVOLLPRMTULIOVVZMWML
(atbash) =>
MIGHTLOANYOUAKEYTHEYTO
OARELOOKINGFORLEEANDNO

– 75 “K” (Hardware Hacking Village):
GZMZTIZNRXZOOBHKVZPRMT
(atbash) =>
TANAGRAMICALLYSPEAKING

With the posters in order (“JACK”), we get:

EVEN IF YOU WANT TO BELIEVE
ONE OF THE JACKS DOESNT BELONG
DONT OUT FOX THEM JUST SCULLY ALONG
IF YOU ASK THEY MIGHT LOAN YOU A KEY
THEY TOO ARE LOOKING FOR LEE
AND NOT ANAGRAMICALLY SPEAKING

This clue refers to the X-Files and specifically to the 4 jacks, of which one of them is Guy Fawlkes and the other three are The Lone Gunmen from The X-Files. These characters were always searching for another character who’s real name is Lois Runtz, but goes by a pseudonym that is an anagram for Lee Harvey Oswald.

The keyword is LoisRuntz
https://www.defcon.org/1o57/dc21/LoisRuntz

Lock Posters
———————–

– (Key icon) (Track 3):
FGBCOHGGURERNYBARJVGU
VANAQJVGUBHGFCNPRBSPB
HEFR
(ROT13) =>
STOPBUTTHEREALONEWITH
INANDWITHOUTSPACEOFCO
URSE

– (Key icon) (?)
FRNEPUVATSBENABGUREPY
HRGURXVATBSXRLUBYRFZN
LURYCERSYRPGBAJUNGLRN
(ROT13) =>
SEARCHINGFORANOTHERCL
UETHEKINGOFKEYHOLESMA
YHELPREFLECTONWHATYEA

– (Key icon) (?)
EGUVRQRSPBAVFLBHYYSVA
QGURMBAROFVQRLBHONFEL
BHEXRLJBEQABGBANDHVRG
(ROT13) =>
RTHIEDEFCONISYOULLFIN
DTHEZONEBSIDEYOUBASRY
OURKEYWORDNOTONAQUIET

SEARCHING FOR ANOTHER CLUE THE KING OF KEY HOLES MAY HELP REFLECT ON WHAT YEAR THIE DEFCON IS YOULL FIND THE ZONE BSIDE YOU BASS YOUR KEYWORD NOT ON A QUIET STOP BUT THERE ALONE WITH IN AND WITH OUT SPACE OF COURSE

This is a reference to the B-side of the Rush albumn 2112 ( http://en.wikipedia.org/wiki/2112_%28album%29 ) and a song based on two episodes of The Twilight Zone. The answer is: “Will the Real Martian Please Stand Up” which leads to https://www.defcon.org/1o57/dc21/WillTheRealMartianPleaseStandUp/

1o57’s Poster
——————

This poster was by the 1057 room. It had a block of symbols in the Chain of Death cipher. When decoded using the method here:

http://www.nku.edu/~christensen/section%205%20symbols.pdf

It reads:

have fun
need help
just ask
passcode
syzygy

and leads to:

https://www.defcon.org/1o57/dc21/syzygy/

Also an X-Files reference http://en.wikipedia.org/wiki/Syzygy_%28The_X-Files%29

——————————–

Thats it for Part 2. Part 3 is the floor puzzles!

Defcon 21 Badge Challenge Walkthrough Part 1

I was in one of two teams that completed the Defcon Badge Challenge this year. In part one of this walkthrough I’ll provide solutions for the Lanyard and the Badges. Part 2 will have the Posters. Enjoy!

Lanyards:
=================

All four lanyards laid out have a bass clef and then a series of dots that correspond to the musical notes:

ADDADEADACEBADGE (ADD A DEAD ACE BADGE)

Badges:
=================

There are 4 suits (Smileys, Rotaries, Locks, Disks). On the back of each card was a 3-bit number, cipher, and a symbol.

3-digit number
——————-

The 3-bit number is 000 – 111 (0 – 7). Each card in each suit has a unique number with one exception.

Symbols
——————-
Each suit has a unique symbol.

Smileys = e
Disks = Pi
Locks = Grey Code ( http://en.wikipedia.org/wiki/Rotary_encoder )
Rotaries = linear Feedback Shift Register ( https://en.wikipedia.org/wiki/Linear_feedback_shift_register )

Each of these symbols give a clue to the true order of the cards in each suit.

Ciphers
——————-

Smileys:

When covered to letters (based on 1 = A, 2 = b, etc) and then ROT13:

7 – [000] BUTTHISISFUNRIGHT
10 – [001] BUTSOMETIMESLEADSASTRAY
5 – [010] TRYSOMETHINGELSE
2 – [011] ANDYOUWILLSEE
Q – [100] THATFINDINGANSWERS
J – [101] MAYTAKEYOUDOWN
K – [110] PATHSNOTOFTENREPEATED
A – [111] NOTALLWHOWANDERARELOST

Which could be ordered to say:

Try something else and you will see that finding answers may take you down paths not often repeated but sometimes leads astray not all who wander are lost but this is fun right.

paths not often repeated is a clue that you must use the digits of pi and e going down them picking out numbers 0 – 7 before they are repeated in order to get the real order of the cards.

Disks:

When converted to letters and ROT13

K – [000] ROTTHIRTEENPROBABLYISNTRIGHT
7 – [001] BUTTHISISFUNRIGHT
10 -[010] THOUGH HIS MIND IS NOT FOR RENT
A – [011] DONT PUT HIM DOWN AS ARROGANT
Q – [101] RIDING OUT THE DAYS EVENTS
J – [110] CATCH THEMISTCATCHTHEMYTH
2 – [111] CATCHTHEMYSTERYCATCHTHEDRIFT
5 – [100] HISRESERVEAQUIETDEFENSE

could read:

ROT Thirteen probably isn’t right but this is fun right though his mind is not for rent don’t put him down as arrogant riding out the days events catch the mist catch the myth catch the mystery catch the drift his reserve a quiet defense

These are lyrics to the Rush Song Tom Sawyer ( http://www.youtube.com/watch?v=KNZru4JG_Uo ) with a message about ROT13 not being right

Locks:

When converted to letters and ROT13

2 – [000] THESKYSWI
7 – [001] LLCLEARUP
K – [010] NOTINBLAC
J – [011] KANDWHITE
5 – [100] BUTSHADEO
10 -[101] FTHEBITSH
A – [110] ELPYOUTUR
Q – [111] NTHISKEYX

Could read:

The skys will clear up not in black and white but shade of the bits help you turn this keyx

This is a clue that you must use grey code to reorder the cards
The “x” padding is a clue about using OTP for later

Rotaries:

Just convert to letters

Q – [111] THE FIRST IS THE LAST
A – [001] IN THE REAL ORDER THE
J – [010] FIRST IS THE LAST BE E
5 – [011] XCLUSIVE OR HAS IT RE
7 – [100] GISTERED THAT TAP AT
K – [101] ZERO AND ONE WILL BE A
2 – [110] LL THE FEED BACK YOU N
10 – [111] EED IN THE REAL ORDER

could read:

The first is the last in the real order the first is the last be exclusive or has it registered that tap at zero and one will be all the feedback you need in the real order

This is a clue that you must use the linear feedback shift register drawn on the back of the cards to reorder them

——————————————–
Ready to continue. Here’s Part 2 –>

The Science of Secrecy: Introduction and Future of Cryptography

From the description:

Join Imperial’s Institute for Security Science and Technology for an informative presentation on codes, ciphers and computers. Professor Richard Aldrich, Dr Martin Knight, Professor Sir Peter Knight and Dr Simon Singh take you on a tour of cryptography through the ages. From its beginnings in pen and paper to its future in quantum computing.

Professor David Edgerton, Hans Rausing Chair in the Centre for the History of Science, Technology and Medicine at Imperial College London, will chair the panel:

The beginnings of cryptography – Dr Simon Singh, science writer, journalist, TV producer, Imperial alumnus and author of ‘The code book’

Bletchley Park and the greatest secret in WWII – Dr Martin Knight, Chairman of Imperial Innovations and former Chief Operating Officer at Imperial College London

Intelligence gathering in the Cold War – Professor Richard Aldrich, Professor of International Security at the University of Warwick and author of ‘GCHQ: the uncensored story of Britain’s most secret intelligence agency’

Quantum cryptography – Professor Sir Peter Knight FRS, President elect of the Institute of Physics, Principal of the Kavli Royal Society International Centre and Senior Research Investigator at Imperial College London