# [Jelly], 32 bytes

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[Try it online!][TIO-kgy9ulr8]

[Jelly]: https://github.com/DennisMitchell/jelly
[TIO-kgy9ulr8]: https://tio.run/##y0rNyan8/9/SvMjQwPjh7p5DW49OVjQ9uvvQEp2HO6ebgBgqD3f1PWpac2jz0cn2h7Y@3LEo81Hjloe7u4Gs////G/xPS01NAQA "Jelly – Try It Online"

Since this code generates all the permutations and therefore would take very long to finish, TIO link is to a limited version that supports characters `abcdefg`, message length 4 and encoded length 5. I checked that these numbers follow similar constraints as the actual ones. Only the number literals are changed, so the true version should also (theoretically) work.