libsoliton/soliton/fuzz/fuzz_targets/fuzz_storage_encrypt_blob.rs

#![no_main]
use libfuzzer_sys::fuzz_target;
use soliton::storage::{encrypt_blob, decrypt_blob, StorageKey, StorageKeyRing};

const FUZZ_KEY: [u8; 32] = [0x42; 32];

fuzz_target!(|data: &[u8]| {
    if data.is_empty() {
        return;
    }
    // Cap input size to prevent OOM on CI runners — compress_to_vec allocates
    // working buffers proportional to input size (~2× for zstd).
    if data.len() > 1_048_576 {
        return;
    }
    let key = StorageKey::new(1, FUZZ_KEY).unwrap();
    let compress = data[0] & 0x01 != 0;
    let plaintext = &data[1..];

    // encrypt_blob must never panic regardless of plaintext size, content, or
    // compress flag. Exercises: capacity calculation, optional ruzstd compression,
    // nonce generation, AAD construction, XChaCha20-Poly1305 encryption.
    let blob = match encrypt_blob(&key, plaintext, "fuzz-channel", "fuzz-segment", compress) {
        Ok(b) => b,
        Err(_) => return,
    };

    // Roundtrip verification: decrypt must recover the original plaintext.
    // Catches malformed blob layout, wrong AAD, header byte errors, and
    // compression flag mismatches that a crash-only target would miss.
    let keyring = StorageKeyRing::new(StorageKey::new(1, FUZZ_KEY).unwrap()).unwrap();
    let recovered = decrypt_blob(&keyring, &blob, "fuzz-channel", "fuzz-segment")
        .expect("decrypt_blob failed on freshly encrypted blob");
    assert_eq!(&*recovered, plaintext, "roundtrip mismatch");
});