Euler's Totient Function and Euler's Theorem - Cryptography - Cyber Security - CSE4003 

Navneet..Thanks for watching this video till the end and pointing out the mistake. Kindly ignore the last example provided in this video lecture at 20:50. Since 513 is not a prime number we cannot compute phi(513) as 513-1. I apologize for this oversight.

@@SatishCJ ok sir can you tell me how to solve that particular problem after that

@@vikranthbandi9155 i've done it without using ɸ(n) ; as 512 is the ninth power of 2: ⑴ 214² ≡ 45796 (= 89.513+139) ≡ 139 [513] ⑵ 214⁴ ≡ 139² ≡ 19321 ≡ 340 [513] ⑶ 214⁸ ≡ 340² ≡ 115600 ≡ 175 [513] ⑷ 214¹⁶ ≡ 175² ≡ 30625 ≡ 358 [513] ⑸ 214³² ≡ 358² ≡ 128164≡ 427 [513] ⑹ 214⁶⁴ ≡427²≡ 182329≡ 214 [513] ⑺ 214¹²⁸ ≡ 214²≡ 45796≡ 139 [513] ⇛ ( beginning of a cycle) ⑻ 214²⁵⁶ ≡ 340 [513] ⑼ 214⁵¹² ≡ 175 [513]