Crypto on vonKrafft
/tags/crypto/
Recent content in Crypto on vonKrafftHugo -- gohugo.iofr-frMon, 26 Feb 2018 19:22:12 +0000[EN] [CTF] TAMU - Simple DES
/write-up/ctf-tamu-simple-des-125/
Mon, 26 Feb 2018 19:22:12 +0000/write-up/ctf-tamu-simple-des-125/Larry is working on an encryption algorithm based on DES.
He hasn’t worked out all the kinks yet, but he thinks it works.
Your job is to confirm that you can decrypt a message, given the algorithm and parameters used.
His system works as follows:
Choose a plaintext that is divisible into 12bit ‘blocks’ Choose a key at least 8bits in length For each block from i=0 while i<N perform the following operations Repeat the following operations on block i, from r=0 while r<R Divide the block into 2 6bit sections Lr,Rr Using Rr, “expand” the value from 6bits to 8bits.