# Tag Info

## New answers tagged des

1

After base64 decoding we get (hex) "5d f8 be 87 82 2b ea 5e f3 5c 23 fe 37 81 0f bd" which has a size of two blocks. Of your small wordlist, only marketing has so many letters that it needs two blocks: "m a r k e t i n" as the first, "g 07 07 07 07 07 07 07" as the second (or another padding, but this is a common one), and so can correspond to this ...

0

You have a ciphertext (or maybe multiple), a list of possible plaintexts, but no key. Therefore, your process would be Generate random decryption key Decrypt ciphertext with that key (base64 decode CT first) See if result appears in your list of possible plaintexts If it does, return that plaintext; otherwise goto 1 This is a basic brute force attack and ...

3

Actually, there's no known way (assuming practical amounts of computing power) to distinguish keying methods 1 and 2. You mention a "brute-force attack of complexity $O(2^{56})$ followed by a chosen plaintext attack of complexity $O(2^{57})$", there's no obvious way to frame an attack against either of the first two options in this matter; you can't do a ...

2

Your Formulas are alright, but there is some additional information from the exercise/setup: The exercise states, that $F$ should be considered as a blackbox (otherwise you could use the internal stages of $F$, as poncho already suggested). However, as I understand it you can stil evaluate $F$ on any input of your choice. At this point, you can do a couple ...

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