I have tried out an encryption method, in which I swap bits in the text. The text length is N bit, then I generate several random number pairs in the range 0..N-1, as [n,k] pairs. After that I swap the n-th and k-th bits in the message, if they are different, of course. After several swap the m...

We have a lot of off-topic questions. Considering that within almost a year and a half, I've 881 close votes and this doesn't count the duplicates that I've found and for that I can not cast a close vote. After this recent question What type of encryption is this? [closed] I've noticed that befo...

There's a collision-resistant hash function $H$. Given $x$, how hard would it be to find a set $a[i]$ such that: $H(a[1]) \oplus H(a[1]) \oplus \cdots \oplus H(a[N]) = H(x)$ whereas none of $a[i]$ equals to $x$?