Elgamal Cryptosystem - Public key Cryptography - Cyber Security - CSE4003

[@SatishCJ]

(11^3)^-1 mod 13 is computed as (1331) ^ -1 mod 13. Here we need to find the modulo multiplicative inverse of 1331, that is 1331 * Y mod 13 =1. where y is the modulo multiplicative inverse of 1331. We can use the short cut method to find the multiplicative inverse. Divide 1331/13 and the reminder is 5. Now find the multiplicative inverse of 5, that is 5* y mod 13 = 1. Here the value of y should be 8. Only then 5 * 8 mod 13 =1 . Hence we have have found 8 as the Modulo Multiplicative inverse of 1331. You can check 1331 * 8 mod 13 = 1. If you are interested in understanding the short cut for finding modulo multiplicative inverse then visit ua-cam.com/video/mzEvIN8BuQ8/v-deo.html the timestamp is 9:56 for the video in the link

[@aishwaryasurapuram489]

Great lecture slides and explanation.

[@SatishCJ]

Glad you liked it!

[@MrRyzale]

this is the best explanation I found so far. thank you sir.

[@coursesaccess4192]

Thank you Sir. Visualizing makes it a lot easier to understand.

[@OwenAmiani]

hello sir (11^3)-1 is not 8..how did you get 8 coz am really stranded googling everywhere

[@krishnasaketh5092]

11^3=1331. So we need to find inverse of 1331.For multiplicative inverse we do like this 1331*x-1 is divisible by 13.

[@suseendhavenkatesh753]

message is temptation apposition bluebonnet how can you encode this to integer?

[@ericzuckerburg6292]

Thank you professor Satish

[@hossamhanafy5921]

good explanation but could you add subtitle please

[@adithyavarma758]

Thank you sir

[@bluecakeindustry8338]

thank you

[@NVAKAYAMINI]

So helpful sir👍

[@puneethkumarvh2355]

how to find inverse sir?

[@ericzuckerburg6292]

multiplicative inverse of 1331 mod 13
is 8

[@OwenAmiani]

​@@ericzuckerburg6292 how do you get it

[@lifeliver469]

@@OwenAmiani look into the extended Euclidean algorithm