I'm studying SHA-3 and I dont understand quite a bit how the padding 10*1 works. Can someone explain me step by step how is it work? Also I know that on SHA3-512 r is 576. On the sponge construction what you need to XOR the first padded message P0 with the r vector. What is the r vector in any situation? (Please be nice with me Im just studying crypto for the first time also Im not an english native speaker)

  • $\begingroup$ I dont think there is such thing as an r vector, you XOR the padded message into the state r bits at a time $\endgroup$ Mar 27, 2019 at 0:11
  • $\begingroup$ This may answer your question: crypto.stackexchange.com/questions/33624/… $\endgroup$ Mar 27, 2019 at 0:12
  • $\begingroup$ So what is r? Is it a predefined number? $\endgroup$ Mar 27, 2019 at 0:32
  • $\begingroup$ How can you xor 576 with the padded number ? $\endgroup$ Mar 27, 2019 at 0:33
  • $\begingroup$ yes, r is the rate, which is a defined constant. You XOR r bits of message into the 1600 bit state $\endgroup$ Mar 27, 2019 at 19:37


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