Add encrypt/decrypt files, refactoring #12

Job	Run time
Check	2m 10s
Check wasm32	1m 15s
Rustfmt	26s
Test Suite	5m 23s
build (macos-latest, aarch64-apple-darwin)	38s
trunk	1m 55s
Clippy	2m 14s
build (ubuntu-latest, aarch64-unknown-linux-gnu)	28s
build (windows-latest, x86_64-pc-windows-msvc, .exe)	1m 22s
build (ubuntu-latest, armv7-unknown-linux-gnueabihf)	28s
build (ubuntu-latest, x86_64-unknown-linux-gnu)	26s
	16m 45s

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