Conundrum E-Book

Brian Clegg

• Herausgeber: Icon Books
• Kategorie: Lebensstil
• Sprache: Englisch
• Veröffentlichungsjahr: 2019

Seitenzahl: 134

Beschreibung

**'Title of Most Fiendish Book goes to Conundrum: Crack the Ultimate Cipher Challenge by the ever-excellent science writer Brian Clegg.' Daily Mail, Books of the Year** The ultimate trial of knowledge and cunning, Conundrum features 200 cryptic puzzles and ciphers. The solutions link throughout the book – so you need to solve them all to get to the final round.  With a focus on ciphers and codebreaking, Conundrum contains twenty sections, each built around a specific subject from music to literature, physics to politics. To take on Conundrum you need good general knowledge and the ability to think laterally. But if you need help, there are plenty of hints to point you in the right direction. Whether you attempt to crack it alone or work in a team, Conundrum will challenge you to the extreme. Can you take on Conundrum and win? There's only one way to find out…

Leseprobe

For Gillian, Chelsea and Rebecca

ACKNOWLEDGEMENTS

Thanks to everyone at Icon Books who has helped make this the most enjoyable writing project I’ve ever been involved with. Particular thanks to Duncan Heath and Robert Sharman for editorial impact.

Contents

Title PageDedicationAcknowledgements Getting Started Cracker’s Guide  The Puzzles Level 1 – Literature Level 2 – Geography Level 3 – Movies Level 4 – Chemistry Level 5 – Music Level 6 – Biology Level 7 – Toys and Games Level 8 – Astronomy Level 9 – Murder Mystery Level 10 – Politics Level 11 – Food and Drink Level 12 – Mathematics Level 13 – Sport Level 14 – Transport Level 15 – TV Level 16 – Technology Level 17 – Art Level 18 – Physics Level 19 – History Level 20 – Cryptography  HintsAbout the Author Copyright

Getting Started

Welcome to Conundrum, a collection of cryptic puzzles in which the solutions build through the whole book to provide a single, solved conundrum. No answers are provided, but nearly all the puzzles in the first sixteen levels have hints at the back of the book in case you are struggling. After that, you are on you own. At the end of the sections are ‘guardian’ checkpoints which can only be solved with key words, letters or numbers produced during that section. This means that you can be assured that your answers are correct and complete to this stage before moving on to the next section.

There are twenty themed levels, ranging from chemistry to history. Each level has ten puzzles to solve, plus the guardian to confirm that the level has been successfully completed. Elements from each level’s solution will be required later. The twentieth guardian gives you the opportunity to present your completed solution online.

The first correct solution provided to us will be splashed on the www.ConundrumBook.com website. All subsequent correct solvers will be listed in the Hall of Fame at www.ConundrumBook.com and, subject to deadline, will have the option of taking on a secondary ‘expert puzzle’ to be the next highlighted winner.

The puzzles in Conundrum often involve dealing with ciphers – if you aren’t familiar with these, take a look at the Cracker’s Guide in the next section.

The puzzles will end with a box for you to enter a level key character, number or word. These will be used to pass the end of level guardian.

Finally, a note about notes. You may have been brought up not to write in books – this isn’t that kind of book. It’s a good idea to write on the pages, particularly to keep a note of these level key characters. If you are using the e-book version you will need to either keep a notebook (physical or electronic) to jot down your solutions or use the note-making facility of your e-book reader if it provides one. Either way, I’d suggest having some paper and a pen or pencil on hand to play around with ideas and solutions.

Let’s get cracking …

Cracker’s Guide

Here’s a quick introduction to some forms of code and cipher. Strictly, a code represents a word or phrase by using a totally unconnected word – so, for example, FROG could mean ‘buy $10,000 of Apple shares’ – whereas a cipher typically substitutes characters in a message with other characters according to a set of rules. If you’re familiar with cipher work, you can go straight to the first level.

Simple shift

Sometimes called a Caesar cipher, this is the most basic approach you can take to encrypting information. It’s a form of substitution cipher, where one letter is substituted for another. It’s simply a matter of shifting the alphabet by a specified number of letters. Like many ciphers, it’s often best to draw up a table to help encipher and decipher a message. Let’s say your shift was four letters – then we would have this table:

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z E F G H I J K L M N O P Q R S T U V W X Y Z A B C D

To encipher the message HELLO WORLD, we just look up each letter in the message in the top line and replace it with the letter from the bottom line. So, our message becomes LIPPS ASVPH.

Notice that the same letter always produces the same cipher character. This makes this technique susceptible to simple guesswork, particularly if the characters aren’t grouped (see below, page xiv). The cipher is also easily broken if the message is long enough, by looking out for repetition of frequently used letters. In English, the frequency with which letters appear is roughly in the order ETAOINSHRDLCUMWFGYPBVKJXQZ going from E, the most common, to Z, the least. So, if you see X occurring very frequently, it may well represent an E, a T or an A.

Random substitution

One immediate way to make a substitution cipher like the simple shift a little trickier to crack is to shuffle up the replacement letters A–Z into a random order. This approach is still susceptible to using frequencies of letters, but it does mean that once you’ve got one letter right you don’t automatically get the rest.

Sequence shift

Still simple to use, but significantly harder to spot, a sequence shift moves each letter of the message on by a number – but that number changes for every character, using a simple mathematical sequence. For example, you could use the odd numbers: 1, 3, 5, 7 … To create your enciphered text just add these to each of the letters in the message. In all cipher work, ‘adding a number’ means moving on that number of spaces through the alphabet. So, for example:

H E L L O + 1 3 5 7 9

gives

I H Q S X

Note that L become Q the first time, but S the second time. If the addition takes you past the end of the alphabet, just loop around, following Z with A etc. To decipher the cipher text, subtract the number in the sequence from the letter, moving backwards down the alphabet.

It’s possible that the number you add to encipher or subtract to decipher will be bigger than 26, in which case you have to go around the alphabet more than once. A simple way to get round this is go through the sequence and subtract 26 from any number bigger than 26. Repeat this until no number is bigger than 26 – you now have a simple number to deal with. So, for example, if your sequence was the squares:

1, 4, 9, 16, 25, 36, 49, 64 …

a first pass subtracting 26 from numbers bigger than 26 gives:

1, 4, 9, 16, 25, 10, 23, 38 …

and a second pass:

1, 4, 9, 16, 25, 10, 23, 12 …

which you can now use to add (encrypt) or subtract (decrypt).

Going beyond letters

For simplicity, most of the ciphers in this book work only with the letters A to Z. However, any of the techniques described here could also include other characters – numbers or punctuation – simply by adding them to the end of the list of characters which will be manipulated. So, for example, if the letters are characters 1 to 26, we could then continue with the numbers 1 to 9, then 0 as characters 27 to 36. Once we have this list, it can be manipulated using any of the cipher techniques noted here.

Introducing other characters in this manner can make decryption harder. Just including the numbers, for example, it would be possible to add them before the letters, after the letters or interlaced with the letters. Similarly we could put 0 at the start of the numbers or at the end. So, for example we could work with:

ABCDEFGHIJKLMNOPQRSTUVWXYZ123456789 123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ ABCDEFGHIJKLMNOPQRSTUVWXYZ123456789123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ A1B2C3D4E5F6G7H8I9JKLMNOPQRSTUVWXYZ

… or any other way of mingling the letters and numbers, while the set of characters to generate the cipher could equally have letters and numbers mixed in any way.

Another way to add complexity is to introduce null characters that have no meaning and have to be ignored. This was one of the earliest ways used to strengthen simple substitution ciphers.

Grouping

Imagine you encipher the message I WANT YOU TO PUT THE BIG CUP INTO THE SMALL BOX using the shift cipher on page xi. The result is M AERX CSY XS TYX XLI FMK GYT MRXS XLI WQEPP FSB.

If we are trying to use letter frequencies to decrypt the message, this isn’t a great text as its most common letters are T (six of them) and O (four), beating E, A, R and I. However, the way the cipher is broken up gives a lot away. We have M standing on its own – that is only likely to be an A or an I. We have the three-letter word XLI twice – an obvious thing to try here is THE. And we have the two-letter word XS – again, there are a limited number of common two-letter words.

To make the cipher a bit harder to crack, it’s common to group the letters in, for example, blocks of five or as a single long string. This would make the cipher MAERX CSYXS TYXXL IFMKG YTMRX SXLIW QEPPF SB or MAERXCSYXSTYXXL IFMKGYTMRXSXLIWQEPPFSB. That way, less is given away. When this is deciphered the result is IWANT YOUTO PUTTH EBIGC UPINT OTHES MALLB OX or IWANTYOUTOPUTTHEBIGC UPINTOTHESMALLBOX – it’s not as convenient to read as the original, but it is usually easy to work out what it means.

Transposition ciphers

An alternative to substitution is transposition, where all the characters from the plain text are still present, but the cipher process applies a rule to change their order, scrambling the message. One of the simplest is the rail fence cipher, where the message is broken into two or more lines and the enciphered text is produced by reading one character off each line in turn. So, for instance, using the simplest two-line rail fence we would break up:

PASSWORDTODAYISFRED

Into two lines, splitting them as near as possible to halfway:

PASSWORDTO DAYISFRED

Then read off alternating lines to get:

PDAASYSIWSOFRRDETDO

The rule for rearranging the text can be as complex as you like. As the letters fit expected frequency patterns, after eliminating substitution ciphers, transposition is often the next possibility to try. Of course, it is also possible to combine the two, using a substitution cipher and then transposing the results.

Key ciphers

The most commonly used types of modern cipher involve one or more keys. This is a more sophisticated version of the sequence shift. There is a different value added to each letter, so it’s a lot harder to crack than a simple shift, but here the amount each character is shifted varies according to a separate key, so there is no pattern as in the case of the sequence shift.

Ideally, the key should be a set of random characters and as long as the text to be enciphered. Meeting these conditions makes the cipher impossible to crack as the enciphered text has no pattern – but that means having to provide a key to each end of the communication link, which could be intercepted. For this reason, the key used is often something more memorable or easily obtained – but that does open up the possibility of cracking the cipher.

Commonly, the key is a word or phrase. If it’s shorter than the message, the key is just repeated. So, for example if we used the key ENIGMA to encipher a message it would work like this:

    Plain text: MEETMEATFIVEPM Key: ENIGMAENIGMAEN Cipher text: RSNAZFFHOPIFUA

A common principle of cipher work is that letters are given a value based on their position in the alphabet: A=1, B=2 and so on. Here, to get to the cipher text, we add the value of each letter in the key to the plain text character. So, for example, E is 5, so we add 5 to the M in the original message, turning it into R. As before, if the addition takes you past Z, the alphabet simply restarts – subtract 26 (more than once if necessary) until you have a number that falls within the alphabet.

To decipher a message using a key, simply take the value of each letter in the key away from the value of the cipher text. So, in the above example, the first letter of the cipher text is R – we take away E (5), the first letter of the key, and get M.

If you are familiar with Excel, you will find a spreadsheet at www.ConundrumBook.com which will make it easy to quickly use key-based ciphers, doing the number crunching for you.

Book ciphers

A book cipher is probably more strictly a code, as the mechanism involves looking up words or letters in a table. Sender and receiver agree on a book to use as the source – each has a copy of the book. (It’s essential they have the same edition.) The sender then looks up the words or characters they want to convey in the book and simply sends the positions of those words or letters. So, for instance, 16/03/08 could be word 8 on line 3 of page 16 – which also has the advantage of looking like a date. This is impossible to crack unless you know the book being used. The potential weak point in the system is the way that the choice is communicated between sender and receiver.

Array ciphers

An array cipher (my terminology) uses a table of text to provide the encryption. The most basic form is to write your message along the rows of a square table, filling any blanks with extra characters. Then you can rotate the table through 90 degrees by reading off columns. (This is just a different way of operating a rail fence cipher.) For example if I write my message WHAT TIME IS THE GAME TONIGHT without spaces and using Z as a filler in a 5 by 5 table I get:

WHATTIMEISTHEGAMETONIGHTZ

I can then read down the columns, one after another, to produce:

WITMIHMHEGAEETHTIGOTTSANZ

A more sophisticated approach puts a keyword in an extra row at the top of the table, then rearranges the columns to the alphabetic order of the letters in the keyword. So, if the keyword were SNAKE, we would rearrange the columns of the message in the order AEKNS. The encrypted message is then read off the columns of the table. The recipient needs to know the keyword to decipher the message. Here’s the same message in such a table:

SNAKEWHATTIMEISTHEGAMETONIGHTZ

The message is once again read off down the columns (ignoring the shaded cells) in the order AEKNS:

AEETHTSANZTIGOTHMHEGWITMI

An alternative substitution cipher using an array is to put the letters of the alphabet in a 5 × 5 table, then put two keywords along the top row and a left hand column. As there are 26 letters in the alphabet we need to allow one cell to stand for two of the letters. Most commonly, the same value is used for I and J (sometimes called I=J), for S and Z (S=Z) or for U and V (U=V). The result is something like this:

Key 2 S N A K EKey 1BABCDELFGHI/JKILMNOPMQRSTUPVWXYZ

The alphabet can be in order, as here, or randomised (though if the latter, the sender and recipient have to share that structure, risking interception). To encipher a character, we look it up in the body of the table and note the letter from key 1 and key 2 corresponding to its row and column. Each letter in the plain text then becomes two letters in the cipher. So

PEEL

becomes

IEBEBEIS

If someone intercepting the cipher suspects it uses pairs of letters in this way, it becomes relatively easy to crack as it’s just a substitution cipher where each letter pair is considered as a single letter, but otherwise it appears more confusing.

A more sophisticated array cipher is the Playfair cipher. For this, you set up a 5 × 5 table with all the letters (either I=J, S=Z or U=V). The grid is populated by using a memorable phrase, only ever using a letter from the phrase once, then filling in any gaps with the remaining letters of the alphabet. Here’s a simple example, using the phrase ‘Richard of York gave battle in vain.’

RI/JCHADOFYKGVEBTLNMPQSUWXZ

To encipher we split the plain text into pairs of letters. If there’s an odd number of characters in the message, stick an X or other random letter on the end. If two letters in a pair are the same, put an X in between them. We then look up the cipher by taking pairs as follows: