Add encrypt/decrypt files, refactoring #11

Job	Run time
Check	2m 11s
Check wasm32	1m 20s
Clippy	2m 15s
Test Suite	5m 28s
Rustfmt	27s
build (macos-latest, aarch64-apple-darwin)	39s
build (ubuntu-latest, x86_64-unknown-linux-gnu)	31s
build (ubuntu-latest, aarch64-unknown-linux-gnu)	30s
trunk	1m 58s
build (windows-latest, x86_64-pc-windows-msvc, .exe)	2m 35s
build (ubuntu-latest, armv7-unknown-linux-gnueabihf)	30s
	18m 24s

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