initial commit

Signed-off-by: Kamal Tufekcic <kamal@lo.sh>

soliton/fuzz/fuzz_targets/fuzz_session_init_roundtrip.rs

@@ -0,0 +1,18 @@
+#![no_main]
+use libfuzzer_sys::fuzz_target;
+use soliton::kex::{decode_session_init, encode_session_init};
+
+// No keygen, no crypto operations — pure wire-format parser test.
+// Property: encode(decode(data)) == data for any data that parses successfully.
+fuzz_target!(|data: &[u8]| {
+    let Ok(si) = decode_session_init(data) else {
+        return;
+    };
+    let re_encoded =
+        encode_session_init(&si).expect("encode_session_init cannot fail on a valid SessionInit");
+    assert_eq!(
+        data,
+        re_encoded.as_slice(),
+        "encode(decode(wire)) != wire — format malleability detected"
+    );
+});