Add unsound ntru (#1652)

* Add ntru unsoundness advisory

* Remove redundant unaffected

* Remove non-versions

---------

Co-authored-by: pinkforest(she/her) <36498018+pinkforest@users.noreply.github.com>

crates/ntru/RUSTSEC-0000-0000.md

@@ -0,0 +1,30 @@
+```toml
+[advisory]
+id = "RUSTSEC-0000-0000"
+package = "ntru"
+date = "2023-03-22"
+url = "https://github.com/FrinkGlobal/ntru-rs/issues/8"
+categories = ["memory-corruption"]
+keywords = ["ffi", "buffer overflow"]
+informational = "unsound"
+
+[versions]
+patched = []
+
+[affected.functions]
+"ntru::types::PrivateKey::export" = [">= 0.4.3"]
+"ntru::types::PublicKey::export" = [">= 0.4.3"]
+```
+
+# Unsound FFI: Wrong API usage causes write past allocated area
+
+The following usage causes undefined behavior.
+```rust
+let kp: ntru::types::KeyPair = …;
+kp.get_public().export(Default::default())
+```
+
+When compiled with debug assertions, the code above will trigger a `attempt to subtract with overflow` panic before UB occurs.
+Other mistakes (e.g. using `EncParams` from a different key) may always trigger UB.
+
+Likely, older versions of this crate are also affected, but have not been tested.