New answers tagged xor
This question as stated actually has a fairly interesting and unintuitive answer. Assuming an 8 byte 64 bit xor key and your test for printable ascii characters then after a megabyte of correct data your chances of having the right key are... about one in four billion. This is completely independent of how much data you have or verify, 1/2^32 is the maximum ...
It turns out that this is not very difficult to solve. It also looks like this is part of a public cryptography challenge, so rather than giving it all away, I'll just provide you with a couple of pointers. First take a look at this: There is a clear repeating pattern every 5 bytes. This suggests two things: (i) an XOR key with a length of 5 was used ...
We define $T$ as: $T(B) = (b_0,b_1,b_2,b_3)$ We use $D$ to represent the difference of $X$ and $Y$: $D = X \oplus Y$ Compute $T(D)$: $T(D) = (d_0,d_1,d_2,d_3)$ $= (x_0 \oplus y_0, x_1 \oplus y_1, x_2 \oplus y_2, x_3 \oplus y_3)$ $=(x_0,x_1,x_2,x_3) \oplus (y_0,y_1,y_2,y_3)$ which is by definition of $T$: $T(X) \oplus T(Y)$
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