Affine Cipher - Decryption (Known Plaintext Attack)

Описание к видео Affine Cipher - Decryption (Known Plaintext Attack)

In this video I talk about ways to decrypt the Affine Cipher when the key is NOT known. Specifically, I go over an example of the known plaintext attack.

3^(-1) = 9 (mod 26) math worked out (Euclidean Algorithm):
1. Forwards:
26 = 3(8) + 2
3 = 2(1) + 1
2. Backwords:
1 = 3 - 2(1)
1 = 3(1) - (26 - 3(8))(1)
1 = 3(1) - 26 + 3(8)
1 + 26 = 3(9)
1 (mod 26) = 3(9)
Hence 9 is the inverse.

Links:
-Affine Encryption:    • Affine Cipher Encryption  
-Affine Decryption (Known Key):    • Affine Cipher Decryption - Known Key  
-Euclidean Algorithm:    • Euclidean Algorithm and Multiplicativ...  

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