did i hit the answer? but it doesnt seem to make sense: if T1 =

@calccrypto, I think the second-from-last sentence in your quoted text **is** the definition of T1.

Confirmed under RFC 2268:

]]>For example, with an effective key length of 64 bits, T1 = 64, T8 = 8

and TM = 0xff. With an effective key length of 63 bits, T1 = 63, T8

= 8 and TM = 0x7f.

can anyone tell me where in the world T1 comes from? it seems like T1 is not being declared before being used

We will assume that exactly T bytes of key are supplied, for some T in the range 1 <= T <= 128. (Our current implementation uses T = 8.) However, regardless of T, the algorithm has a maximum effective key length in bits, denoted T1. That is, the search space is 2^(8*T), or 2^T1, whichever is smaller.

or is it part of the input (that they forgot to mention), like the data and key? ]]>

` ``Use S-box 0 for the most significant nibble of each of these eight bytes, and S-box 1 for the least significant nibble of each byte: Input: 0 1 2 3 4 5 6 7 S-box 0 output: 12 15 7 10 14 13 11 0 S-box 1 output: 7 2 14 9 3 11 0 4 Input: 8 9 10 11 12 13 14 15 S-box 0 output: 2 6 3 1 9 4 5 8 S-box 1 output: 12 13 1 10 6 15 8 5`

i dont know why i chose this cipher. i guess it was just stuck in the back of my mind, but i never got around to looking at it

]]>Say the first 3 bytes of your code is now:

10110110 01101101 10000110 [insert 6 more bytes here, I'm too lazy to type a 9 byte message]

The first byte will be your sub-sub-key. Now let's look at the second byte. Since it is the first byte in the code besides the sub-sub-key, it corresponds to the first bit in the sub-sub-key. It is a one, so you have to swap nibbles. 01101101 becomes 11010110. Now the third byte: it corresponds to the second bit in the first byte. Its a 0, so we leave it alone. After you do that 6 more times, we end up with:

10110110 11010110 10000110 [insert 6 more bytes here]

Now you can continue on with the rest of the cryptology thing. Hope I could be of assistance. (BTW: What made you decide to look up this cipher? It seems overly-complicated) If you have anymore problems or don't get what I posted, just ask. :)

…I'm tired of typing… ]]>

The f-function

XOR the right half of the block with the last eight bytes of the subkey for the round.

`Based on the bits of the first byte of the subkey for that round, swap nibbles in the eight bytes of that result for those bytes which correspond to a 1 bit.`

Use S-box 0 for the most significant nibble of each of these eight bytes, and S-box 1 for the least significant nibble of each byte:

and why is there such a big space between here and the text? what did i do wrong with the div? ]]>