3rd April - Ciphers part 2 and bunnies!

 I had so much patrolling time today and had loads of lovely chats with people. I wandered around so much it sometimes felt like I was stalking people!

Today was also the first time since I returned to work that I was faced with the problem we always face of being built on a chalk hill. Graffiti. To be fair, this time it was just names and Pokémon! But it does require a lot of elbow grease, a bucket of water and a soft bristled brush to get it off without damage to the walls.

I did find today was more of a struggle day with my back. I had to take quite a few sitting breaks but on the plus side I did remember my meds properly today. If I don't set an alarm on my watch, I'm in the habit of forgetting.

When I got home, there was time for a coffee and dinner before we walked the dog. Took her for a run around the park with her ball which she likes. Even when you can tell she's getting tired, she still can't stop herself from running after the ball. Eventually she stops bringing it back to us when she's had enough. That's when we put her back on her lead.

This evening I went back to Rebelling. More ciphers. I managed to research all the rest listed. Whether they were easier or I was less distracted... could be either. Or both.

Book (Ottendorf) Cipher

The plaintext (original text) is encrypted by using the location of the words from a key text, usually a book. Most commonly the key text is a Bible or a dictionary. They're both common and are likely to have all the words, especially in the case of a dictionary.

If all the necessary words aren't available in the key text, the plaintext is broken down from words to individual letters.

The code is the text, then numbers are used representing the page, line and word. In the case of individual letters, the letter in the word number is added.

I realised when reading up on this that I was already familiar with this cipher under it's alternative name, having seen it used in the film National Treasure with Nicholas Cage.

In the above image, they are copying down a series of numbers written in invisible ink on the back of the Declaration of Independence. They relate to the page, the line and the letter of the Silence Dogood letters. They knew this was the key text because of a clue found earlier in the film "...the key in Silence undetected..."

These were several letters written by Benjamin Franklin at age 16, posing as a housewife, Mrs Silence Dogood.

Playfair

Researching this one helped me to understand the scene in National Treasure: Book of Secrets a bit better. It took me a while to get it, but not as long as yesterday's cipher!

It was invented by Charles Wheatstone but promoted by Lord Playfair so took his name, though sometimes was known as the Wheatstone-Playfair cipher.

The idea of this cipher was to pair up letters of the plaintext into bigrams (or digrams - no, not a spelling mistake).

Using a 5x5 grid, known as a Polybius Square, a key word or phrase is input.

For my example, REBELBADGE is my key word. The table is filled in without duplicates, then the rest of the alphabet is filled in, in order.

R E B L A

D G C F H

I  K M N O

P Q S T U

V W X Y Z

So the second 'E' in Rebel is removed, as is the 'B' and 'E' of Badge. In this cipher, I and J are interchangeable, using one or the other but not both.

My plaintext is CODEBREAKER.

This is split into the bigrams: CO DE BR EA KE RX.

X is used to create the final bigram so there aren't solo letters.

The idea of this cipher follows 4 rules which I really couldn't follow until I actually wrote out the 'translation' for myself.

1. If both letters are the same, or only one remains, add an X. This is the case with the R at the end of my plaintext, but if, for example, I'd written 'Hello', the double 'L' would be written 'LX'
2. When finding the coded bigrams in the table, these rules apply. Firstly, if both letters appear n the same row, you move one step to the right to get the coded bigrams. If the letter is at the last on the row, you use the last one.
3. If both letters appear in the same column, you use the one directly below it, unless it's the last in the column and then you use the top one.
4. If letters are not on the same row or in the same column, you form a rectangle with the letters in the corners. The opposite corners become the new bigram letters.

The order of the letters must remain the same so if the first letter of the bigram is after the second in a row, column or rectangle, the new bigram needs to be the same way round.

I know, this all sounds so complex. Bear with me.

CO DE BR EA KE RX becomes MH RG LE BR QG BV

How? I hear you ask.

Let's go left to right. I'll take the segments of the table I created above

C F  H        

M N O

So, C and O create a rectangle. M and H are the opposite corners.

R E           

D G          

D and E also create a 'rectangle'. I know it's a square, but same principle.

R E B L A    

B and R are on the same row. Taking the letters to their right and them in same order gives LE.

R E B L A     

Same principle for EA, but where A is the last on the line, you skip back to beginning.

E                  

G

K

Q

W            

K and E are in the same column, hence QG, the letters right below.

R E B        

D G C

I K M

P Q S

V W X

RX are opposite corners, so it becomes BV.

Once I put it this way, it made a lot more sense to me.

But anyway, I'm tired. Three days in a row back on summer hours was difficult. Tomorrow I'm off so hopefully I might get to chill a bit. Maybe... I'll write up what I found about the ADFGVX and Enigma ciphers tomorrow.

My five things:

• Taking off my big heavy work boots after a really long day. It feels so good!
• Knowing I have a day off tomorrow.
• Learning new things. Researching these ciphers was really interesting.
• Playing with Misty and her ball. She often brings it to me indoors too.
• Bunnies! Fluffy little cutes!