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rc4

0.1.0
0.1.0

Pure Elixir RC4 stream cipher compatible with :crypto.crypto_one_time(:rc4, ...).

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README.md 

# RC4



Pure Elixir RC4 stream cipher compatible with `:crypto.crypto_one_time(:rc4, key, data, _encrypt?)`.



OpenSSL 3 dropped RC4 from the default provider, so OTP builds linked against it no longer expose `:rc4` through `:crypto`. This library provides a drop-in keystream implementation for legacy obfuscation paths that must keep reading existing RC4-encrypted data.



## Usage



```elixir

ciphertext = RC4.apply(key, plaintext)

plaintext = RC4.apply(key, ciphertext)

```



RC4 is symmetric: applying the same key twice restores the original data.



## Tests



Vectors are verified against [RFC 6229](https://www.rfc-editor.org/rfc/rfc6229). A separate CI job runs parity tests against `:crypto` on OTP 25 linked with OpenSSL that still exposes RC4.



If the parity job preflight fails (runner no longer ships RC4), pin an OTP version documented in `.github/workflows/ci.yml`.



## License



MIT — see [LICENSE.md](LICENSE.md).