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   ✧✦Catherine✦✧ (whitequark@mastodon.social)'s status on Monday, 29-Dec-2025 12:56:17 JST ✧✦Catherine✦✧

   what the fuck does this diagram mean

   what does it mean for two 128-bit values to "converge together"

   edit: oh i guess they aren't 128-bit. but this isn't helping much

   edit2: ohhh, they're making it possible to get less than 128 bits out in the last ciphertext block

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     ✧✦Catherine✦✧ (whitequark@mastodon.social)'s status on Monday, 29-Dec-2025 12:56:13 JST ✧✦Catherine✦✧

     in reply to

     • 23n27

     @23n27 yeah

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     23n27 (23n27@dgc.social)'s status on Monday, 29-Dec-2025 12:56:17 JST 23n27

     in reply to

     @whitequark I'd guess they first get split into 128-l and l bits and then concatenated back together?

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     dram🎀 (dramforever@mastodon.social)'s status on Monday, 29-Dec-2025 12:58:52 JST dram🎀

     in reply to

     @whitequark i think it's trying to say to pad last block (0 to 127 incl. bits) of plaintext with 1 then a bunch of 0, and then chomp off the corresponding bits in the ciphertext because you don't need it, but god knows why it's trying to split the cipher state instead.

     it's like pumping drinking water from a river by diverting a part of the river to your front yard and then sending the unused portion back into the main flow