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: https://www.youtube.com/watch?v=_E8rSP0uAIY
-Affine Decryption (Known Key): https://www.youtube.com/watch?v=XFxFPBKFVe8
-Euclidean Algorithm: https://www.youtube.com/watch?v=K5nbGbN5Trs
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