libsoliton/soliton/fuzz/fuzz_targets/fuzz_stream_encrypt_decrypt.rs

#![no_main]
use libfuzzer_sys::fuzz_target;
use soliton::streaming::{stream_decrypt_init, stream_encrypt_init};

fuzz_target!(|data: &[u8]| {
    // Round-trip fuzz: encrypt arbitrary data, then decrypt and verify.
    // Exercises the full encrypt→decrypt pipeline with variable-size inputs,
    // compression toggle, and multi-chunk splitting.
    if data.is_empty() {
        return;
    }

    // First byte selects compression mode; rest is plaintext.
    let compress = data[0] & 0x01 != 0;
    let plaintext = &data[1..];

    let key = [0x42u8; 32];
    let aad = b"fuzz-rt";

    let mut enc = match stream_encrypt_init(&key, aad, compress) {
        Ok(e) => e,
        Err(_) => return,
    };

    let header = enc.header();
    let chunk_size = soliton::constants::STREAM_CHUNK_SIZE;
    let mut chunks: Vec<Vec<u8>> = Vec::new();

    // Encrypt in STREAM_CHUNK_SIZE pieces.
    if plaintext.len() > chunk_size {
        let full_chunks = plaintext.len() / chunk_size;
        for i in 0..full_chunks {
            let start = i * chunk_size;
            let end = start + chunk_size;
            let is_last = end >= plaintext.len();
            match enc.encrypt_chunk(&plaintext[start..end], is_last) {
                Ok(ct) => chunks.push(ct),
                Err(_) => return,
            }
            if is_last {
                break;
            }
        }
        if !enc.is_finalized() {
            let start = (plaintext.len() / chunk_size) * chunk_size;
            match enc.encrypt_chunk(&plaintext[start..], true) {
                Ok(ct) => chunks.push(ct),
                Err(_) => return,
            }
        }
    } else {
        match enc.encrypt_chunk(plaintext, true) {
            Ok(ct) => chunks.push(ct),
            Err(_) => return,
        }
    }

    // Decrypt sequentially.
    let mut dec = match stream_decrypt_init(&key, &header, aad) {
        Ok(d) => d,
        Err(_) => panic!("decrypt_init failed on valid header"),
    };

    let mut recovered = Vec::new();
    for ct in &chunks {
        match dec.decrypt_chunk(ct) {
            Ok((pt, _)) => recovered.extend_from_slice(&pt),
            Err(e) => panic!("decrypt_chunk failed: {e:?}"),
        }
    }

    assert_eq!(recovered, plaintext, "round-trip mismatch");
});