Key Scheduling and Decryption in DES

[@shagunprasad4592]

For those of you wondering which 8 bits from Permutation Choice 2 are dropped, PC-2 ignores the following eight bits: 9, 18, 22, 25, 35, 38, 43, 54.

[@kiranshinde1771]

Thank you for the answer but on what basis these bits are selected?

[@hetjayeshbhaipatel1075]

thanks shagun

[@barnabassolomon1629]

this is kinda too vague, sir. which 8 bits are dropped and what are the process of the shifts

[@abdullahsheriff_]

Why in the diagram at 07:08, Directly Permuted Choice 2 is happening? Then does Permuted Choice 1 happen before the Left Shift? In that case, left half will only have 24 bits & right have will only have 24 bits.

[@ayeshafatima3012]

Can u answer that which 8 bits are dropped in permuted choice 2
We have to dropped randomly?

[@_art.with.passion__]

yes we drop 8 bits randomly

[@anish-acharya]

the key is number from 1 to 64. Every 8th bit is ignored so total 8 bit will be ignore and final new 56 bit will formed.

[@shagunprasad4592]

Permuted Choice 2 (PC-2) is a permutation in the Data Encryption Standard (DES) algorithm that selects a 48-bit subkey for each round from the 56-bit key-schedule state. PC-2 ignores the following eight bits: 9, 18, 22, 25, 35, 38, 43, 54.

[@asukumar9744]

Why have you been divided into 32 bits? Should it be 28 bits?😅 7:00

[@synestia6884]

Half of 64 ie 32

[@WitnessOfJenova]

@@synestia6884You're right, but before the left circular shift comes PC1 with a 64bit input and 56bit output. The output is split into two 28 bit halves for the left circular shift, so it should be 28. I guess they forgot PC1 in the video :)

[@kiranshinde1771]

Hello the explaination is very good. I have only one question how the bits to be dropped in permutation choice 2 are selected ?

[@shreedhar7225]

Did you find answer for that?

[@azizamohammed7571]

عند key gnararate كيف تتم اذا كان الازاحه تتم نحو اليمين في عملية dectiption

[@devmahad]

thanks :)