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sasc:res:tema1 [2017/03/08 12:31] dan.dragan |
sasc:res:tema1 [2017/03/19 23:46] (current) dan.dragan |
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| <note tip> This time you cannot (easily) do a brute-force on all the bytes of the last XOR. However, you may try to attack one S-box at a time. Think of the bits that affect one such S-box and find an efficient attack. | <note tip> This time you cannot (easily) do a brute-force on all the bytes of the last XOR. However, you may try to attack one S-box at a time. Think of the bits that affect one such S-box and find an efficient attack. | ||
| </note> | </note> | ||
| + | |||
| + | ==== Bonus (4 pct) ==== | ||
| + | |||
| + | {{:sasc:res:css_enc.png|}} | ||
| + | |||
| + | Decode the following ciphertext: | ||
| + | <code> | ||
| + | '74b906c56684a5d250fe68bc09eb7ee55ffd2271b8d07d6c35a41d96e4ada74de4852d031ba080374dce7bbcaafd0a4bd4' | ||
| + | </code> | ||
| + | knowing that the first bit for both 17 bits and 25 bits LFSRs is 1 and the first 6 bytes of plaintext of the encryption are: | ||
| + | <code> | ||
| + | 'ENCRYP' | ||
| + | </code> | ||
| + | |||
| + | Please download the skeleton from here: {{:sasc:res:dvd_css.zip|}} | ||
| + | |||
