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Misaka Mikoto

Challenge
My friends like anime way too much . . . they decided that to give me an encoded message, but I can’t solve it because I’m not a weeb!

file

contents:

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rasfsasrettlepinebec353luteayvlrghs3s

Hint: Railguns are cool!

Solution

Rail fence cypher.

wikipedia

Example:

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WE ARE DISCOVERED. FLEE AT ONCE

W . . . E . . . C . . . R . . . L . . . T . . . E
. E . R . D . S . O . E . E . F . E . A . O . C .
. . A . . . I . . . V . . . D . . . E . . . N . .

WECRL TEERD SOEEF EAOCA IVDEN

Use this to decode our method. We vary the number of rails until we get something sensible

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rasfsasrettlepinebec353luteayvlrghs3s


r.......a.......s.......f.......s....
.a.....s.r.....e.t.....t.l.....e.p...
..i...n...e...b...e...c...3...5...3..
...l.u.....t.e.....a.y.....v.l.....r.
....g.......h.......s.......3.......s

railgunsarethebesteasyctfl3f3l5esp3rs

railguns are the best easyctf{l3v3l5esp3rs}

There is also a good online decoder here: http://rumkin.com/tools/cipher/railfence.php

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easyctf{l3v3l5esp3rs}