• Vignere cipher (letters shifted by different amounts)
• sausageP is a common comical term, Pegasus backwards.

The Vigenere Cipher

Enigma machine - different ciphers for each letter
> TODO: How does the engima machine work (rotors)

Work Ratio

Low effort for authorised access
High effort for unauthorised access

Aside: Calculating the number of bits of a number

When dealing with powers of numbers, if we multiply a number to a certain power with the same base number raised to a different power, we effectively add the powers together. In effect, we also add the number of dits

2^10 -> 1024 (4 dits)
2^20 ~= 1 000 000 (7 dits)
2^29 ~= 5 000 000
2^30 ~= 1 000 000 000 (10 dits)

One-time Pad

A one-time pad is a sort of vignere cipher, where each character of a plain-text phrase is shifted by a random amount.

But, the issue arises … how do you communicate the key to the intended recipient?
As soon as the secret key is leaked, the cipher text can be reversed.

…

// Number stations

Freedom of Information (FOI)

There are Freedom of Information laws that allow the public to request certain information from a company or body.

Type 1 and Type 2 errors

There is always a tradeoff in wanting to minimise false positives, or false negatives.

Dealing with these errors

Though dependent on the case (and outcome meanings), we often would prefer to minimise false negatives - as, in terms of consequences - they don’t incorrectly dismiss an important test

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Read more: Bruce Schneier