https://padlet.com/shiralim/acfd96er0jypssyq Watch Extract 3. Complete the notes on slides 2-4 en-us 2022-06-28 07:27:04 UTC 2025-12-29 23:15:28 UTC hello@padlet.com shiralim https://padlet.com/shiralim/acfd96er0jypssyq/wish/2232244034 - 9th century 
- Arab philosopher 
- focused on complex ciphers
-  AI-Kindi's method  called 'frequency analysis' 

]]> 2022-06-28 07:41:25 UTC https://padlet.com/shiralim/acfd96er0jypssyq/wish/2232244034 shiralim https://padlet.com/shiralim/acfd96er0jypssyq/wish/2233067377 - letters appear with different frequency 
- e.g. letter E = 13% of all letters in a text
-  Other letters  X and Z, are much less frequent. ]]> 2022-06-29 04:28:54 UTC https://padlet.com/shiralim/acfd96er0jypssyq/wish/2233067377 shiralim https://padlet.com/shiralim/acfd96er0jypssyq/wish/2233068340 - rare letter 
- it's almost always followed by a U 
- t's often placed at the beginning of a word ]]> 2022-06-29 04:30:23 UTC https://padlet.com/shiralim/acfd96er0jypssyq/wish/2233068340