Riffle shuffle a string - Cops Robbers post

A riffle shuffle is a way of shuffling cards where the deck is split into 2 roughly equal sections and the sections are riffled into each other in small groups. This is how to riffle shuffle a string:


Split the string into equal sections.
Reverse the strings, and starting from the start of each string.
Put runs of a uniformly random length between 1 and the number of characters left in the current string into the final string
Then remove these characters from the string.
Repeat for the other half, until both halves are empty.


An example

"Hello World!"      Output string = ""
"Hello ", "World!"  ""
"Hell", "World!"    " o"
"Hell", "World"     " o!"
"Hel", "World"      " o!l"
"Hel", "Wo"         " o!ldlr"
"H", "Wo"           " o!ldlrle"
"H", ""             " o!ldlrleoW"
"", ""              " o!ldlrleoWH"


The final product from Hello World! could be o!ldlrleoWH and that is what you would output.

Cops

Your task is to make a program (or function) that will riffle shuffle a string. If the inputted string is of odd length, just split it into two uneven length strings with a relative length of +1 and +0 (abc =&gt; [ab, c] or [a, bc]). You may take input in the normal fashion and produce output in the normal fashion.

Your Cops submission will consist of 4 things


The language you used
The length of your program in bytes
Your program, riffle shuffled.
Anything else you want to add


You are aiming to keep your code from being uncracked by the Robbers for 7 days. After that period, your program is safe and you should edit in your original program. Your submission may still be cracked until you reveal your solution. The shortest, safe solution will be the winner!
Python 3, 154 bytes (list of chars -> list of chars) (function) Cracked

[=o;]1-::[]:s[i,]1-::[]s:[i=R,L;2//)i(nel=s    
:)i(r fed
*tropmi modR+L+o nruter    
]:s[L,R=R,L;]s:[L=+o;))L(nel,1(tnidnar=s:R dna L elihw    
]nar morf


I doubt this will be too hard to crack, especially since riffling once is rather ineffective (you can see entire program components in the output...). This is mostly just to get things rolling. There might be some whitespace (including newlines) that I didn't copy correctly. The SHA-384 hash of my  intended solution is 
5924530418bf8cd603c25da04ea308b124fdddfc61e7060d78b35e50ead69a7fbde9200b5ee16635cc0ee9df9c954fa1.