DAY 8

We started the morning with a nice exercise called Fizz buzz.
Then we looked at what we had done yesterday - the logic gates.
We did an exercise about this as well, trying to figure out whether Sarah will go to a party. Her conditions were that Santa AND Rudolph will come AND Peter Rabbit will NOT.
There were eight different options and the outcome for only one of them was the one Sarah needed for going to the party.

Then we learned about substitution codes - codes where you substitute each letter with a number, another letter or a symbol.
Mr. Farquarson told us a brief biography of Mary Queen of Scots who lived in the 16th century and how she was prisoned in England and the queen of England, Elizabeth was paranoid about Mary becoming the queen instead. Elizabeth send her agents to the castle where Mary was prisoned and they got a letter she had sent to a plot of Catholic people who wanted her to become the queen of England.
The letter was encoded with symbols and they thought it would be very safe that way. Nevertheless, it didn't take very long for Elizabeth's master spy to decode it. That was because by that time the Frequency theory was already known. The Frequency theory tells you how some letters or numbers occur more frequently in English language than others.
Eventually, that piece of evidence got Mary tried and executed.

When working out a key for a substitution code with the frequency theory, you should remember that the shorter the text, the less reliable the frequency theory is!
And also remember to use your intuition, skill and a bit of guess-work.