FIX: wc_XChaCha20Poly1305_Init issues with null AAD when length 0, aad.as_prt() always passed now; also added mroe tests

crates/ccc-crypto-wolfssl/src/aead.rs

@@ -343,16 +343,18 @@ fn xchacha20_poly1305_encrypt(
     unsafe {
         // wc_XChaCha20Poly1305_Encrypt(dst, dst_space, src, src_len,
         //                              ad, ad_len, nonce, nonce_len, key, key_len)
+        //
+        // NOTE: wolfSSL's wc_XChaCha20Poly1305_Init unconditionally rejects
+        // a NULL `ad` pointer (BAD_FUNC_ARG / -173), unlike AES-GCM and
+        // ChaCha20-Poly1305 which allow NULL when ad_len == 0.  Always pass
+        // aad.as_ptr() — Rust guarantees a non-null dangling pointer for
+        // empty slices.
         let ret = crate::sys::wc_XChaCha20Poly1305_Encrypt(
             dst.as_mut_ptr(),
             dst.len(),
             plaintext.as_ptr(),
             plaintext.len(),
-            if aad.is_empty() {
-                std::ptr::null()
-            } else {
-                aad.as_ptr()
-            },
+            aad.as_ptr(),
             aad.len(),
             nonce.as_ptr(),
             nonce.len(),
@@ -387,16 +389,14 @@ fn xchacha20_poly1305_decrypt(
     unsafe {
         // wc_XChaCha20Poly1305_Decrypt(dst, dst_space, src, src_len,
         //                              ad, ad_len, nonce, nonce_len, key, key_len)
+        //
+        // NOTE: See encrypt above — wolfSSL rejects NULL ad for XChaCha20.
         let ret = crate::sys::wc_XChaCha20Poly1305_Decrypt(
             dst.as_mut_ptr(),
             dst.len(),
             ciphertext_and_tag.as_ptr(),
             ciphertext_and_tag.len(),
-            if aad.is_empty() {
-                std::ptr::null()
-            } else {
-                aad.as_ptr()
-            },
+            aad.as_ptr(),
             aad.len(),
             nonce.as_ptr(),
             nonce.len(),
@@ -410,3 +410,280 @@ fn xchacha20_poly1305_decrypt(
 
     Ok(dst)
 }
+
+// ──────────────────────────────────────────────────────────────────────────────
+// Tests
+// ──────────────────────────────────────────────────────────────────────────────
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ccc_crypto_core::algorithms::AeadAlgorithm;
+
+    // ── Helpers ──────────────────────────────────────────────────────────
+
+    /// Encrypt then decrypt and assert the plaintext round-trips.
+    fn roundtrip(algo: AeadAlgorithm, key: &[u8], nonce: &[u8], pt: &[u8], aad: &[u8]) {
+        let ct = encrypt(algo, key, nonce, pt, aad)
+            .unwrap_or_else(|e| panic!("{} encrypt failed: {e}", algo.name()));
+
+        // ciphertext must be plaintext + 16-byte tag
+        assert_eq!(
+            ct.len(),
+            pt.len() + TAG_LEN,
+            "{}: unexpected ciphertext length",
+            algo.name()
+        );
+
+        let recovered = decrypt(algo, key, nonce, &ct, aad)
+            .unwrap_or_else(|e| panic!("{} decrypt failed: {e}", algo.name()));
+        assert_eq!(recovered, pt, "{}: plaintext mismatch after roundtrip", algo.name());
+    }
+
+    // ── AES-256-GCM ─────────────────────────────────────────────────────
+
+    #[test]
+    fn aes_gcm_roundtrip_with_aad() {
+        roundtrip(
+            AeadAlgorithm::AesGcm256,
+            &[0x01; 32],
+            &[0x02; 12],
+            b"aes-gcm payload with associated data",
+            b"some associated data",
+        );
+    }
+
+    #[test]
+    fn aes_gcm_roundtrip_empty_aad() {
+        roundtrip(
+            AeadAlgorithm::AesGcm256,
+            &[0x11; 32],
+            &[0x22; 12],
+            b"aes-gcm payload no aad",
+            &[],
+        );
+    }
+
+    #[test]
+    fn aes_gcm_roundtrip_empty_plaintext() {
+        roundtrip(
+            AeadAlgorithm::AesGcm256,
+            &[0x31; 32],
+            &[0x32; 12],
+            &[],
+            b"aad only, no plaintext",
+        );
+    }
+
+    #[test]
+    fn aes_gcm_roundtrip_empty_both() {
+        roundtrip(
+            AeadAlgorithm::AesGcm256,
+            &[0x41; 32],
+            &[0x42; 12],
+            &[],
+            &[],
+        );
+    }
+
+    #[test]
+    fn aes_gcm_tampered_tag_fails() {
+        let key = [0x51u8; 32];
+        let nonce = [0x52u8; 12];
+        let pt = b"integrity check";
+        let mut ct = encrypt(AeadAlgorithm::AesGcm256, &key, &nonce, pt, &[]).unwrap();
+        // Flip last byte of the tag
+        let last = ct.len() - 1;
+        ct[last] ^= 0xFF;
+        assert!(decrypt(AeadAlgorithm::AesGcm256, &key, &nonce, &ct, &[]).is_err());
+    }
+
+    // ── ChaCha20-Poly1305 ───────────────────────────────────────────────
+
+    #[test]
+    fn chacha20_roundtrip_with_aad() {
+        roundtrip(
+            AeadAlgorithm::ChaCha20Poly1305,
+            &[0x61; 32],
+            &[0x62; 12],
+            b"chacha20 payload with associated data",
+            b"chacha20 aad",
+        );
+    }
+
+    #[test]
+    fn chacha20_roundtrip_empty_aad() {
+        roundtrip(
+            AeadAlgorithm::ChaCha20Poly1305,
+            &[0x71; 32],
+            &[0x72; 12],
+            b"chacha20 payload no aad",
+            &[],
+        );
+    }
+
+    #[test]
+    fn chacha20_roundtrip_empty_plaintext() {
+        roundtrip(
+            AeadAlgorithm::ChaCha20Poly1305,
+            &[0x81; 32],
+            &[0x82; 12],
+            &[],
+            b"chacha20 aad only",
+        );
+    }
+
+    #[test]
+    fn chacha20_roundtrip_empty_both() {
+        roundtrip(
+            AeadAlgorithm::ChaCha20Poly1305,
+            &[0x91; 32],
+            &[0x92; 12],
+            &[],
+            &[],
+        );
+    }
+
+    #[test]
+    fn chacha20_tampered_tag_fails() {
+        let key = [0xA1u8; 32];
+        let nonce = [0xA2u8; 12];
+        let pt = b"integrity check chacha";
+        let mut ct = encrypt(AeadAlgorithm::ChaCha20Poly1305, &key, &nonce, pt, &[]).unwrap();
+        let last = ct.len() - 1;
+        ct[last] ^= 0xFF;
+        assert!(decrypt(AeadAlgorithm::ChaCha20Poly1305, &key, &nonce, &ct, &[]).is_err());
+    }
+
+    // ── XChaCha20-Poly1305 ──────────────────────────────────────────────
+
+    #[test]
+    fn xchacha20_roundtrip_with_aad() {
+        roundtrip(
+            AeadAlgorithm::XChaCha20Poly1305,
+            &[0xB1; 32],
+            &[0xB2; 24],
+            b"xchacha20 payload with associated data",
+            b"xchacha20 aad",
+        );
+    }
+
+    /// Regression: wolfSSL's `wc_XChaCha20Poly1305_Init` unconditionally
+    /// rejects a NULL `ad` pointer (BAD_FUNC_ARG / -173), even when
+    /// `ad_len == 0`.  Must pass a non-null dangling pointer for empty AAD.
+    #[test]
+    fn xchacha20_roundtrip_empty_aad() {
+        roundtrip(
+            AeadAlgorithm::XChaCha20Poly1305,
+            &[0xC1; 32],
+            &[0xC2; 24],
+            b"xchacha20 payload no aad",
+            &[],
+        );
+    }
+
+    #[test]
+    fn xchacha20_roundtrip_empty_plaintext() {
+        roundtrip(
+            AeadAlgorithm::XChaCha20Poly1305,
+            &[0xD1; 32],
+            &[0xD2; 24],
+            &[],
+            b"xchacha20 aad only",
+        );
+    }
+
+    /// Regression: both AAD and plaintext empty — exercises the NULL-pointer
+    /// code paths simultaneously.
+    #[test]
+    fn xchacha20_roundtrip_empty_both() {
+        roundtrip(
+            AeadAlgorithm::XChaCha20Poly1305,
+            &[0xE1; 32],
+            &[0xE2; 24],
+            &[],
+            &[],
+        );
+    }
+
+    #[test]
+    fn xchacha20_tampered_tag_fails() {
+        let key = [0xF1u8; 32];
+        let nonce = [0xF2u8; 24];
+        let pt = b"integrity check xchacha";
+        let mut ct = encrypt(AeadAlgorithm::XChaCha20Poly1305, &key, &nonce, pt, &[]).unwrap();
+        let last = ct.len() - 1;
+        ct[last] ^= 0xFF;
+        assert!(decrypt(AeadAlgorithm::XChaCha20Poly1305, &key, &nonce, &ct, &[]).is_err());
+    }
+
+    #[test]
+    fn xchacha20_wrong_aad_fails() {
+        let key = [0xF3u8; 32];
+        let nonce = [0xF4u8; 24];
+        let pt = b"aad mismatch test";
+        let ct = encrypt(AeadAlgorithm::XChaCha20Poly1305, &key, &nonce, pt, b"correct").unwrap();
+        assert!(decrypt(AeadAlgorithm::XChaCha20Poly1305, &key, &nonce, &ct, b"wrong").is_err());
+    }
+
+    // ── Key / nonce validation ──────────────────────────────────────────
+
+    #[test]
+    fn aes_gcm_wrong_key_len_rejected() {
+        assert!(encrypt(AeadAlgorithm::AesGcm256, &[0; 16], &[0; 12], b"x", &[]).is_err());
+    }
+
+    #[test]
+    fn aes_gcm_wrong_nonce_len_rejected() {
+        assert!(encrypt(AeadAlgorithm::AesGcm256, &[0; 32], &[0; 8], b"x", &[]).is_err());
+    }
+
+    #[test]
+    fn chacha20_wrong_key_len_rejected() {
+        assert!(encrypt(AeadAlgorithm::ChaCha20Poly1305, &[0; 16], &[0; 12], b"x", &[]).is_err());
+    }
+
+    #[test]
+    fn chacha20_wrong_nonce_len_rejected() {
+        assert!(encrypt(AeadAlgorithm::ChaCha20Poly1305, &[0; 32], &[0; 8], b"x", &[]).is_err());
+    }
+
+    #[test]
+    fn xchacha20_wrong_key_len_rejected() {
+        assert!(encrypt(AeadAlgorithm::XChaCha20Poly1305, &[0; 16], &[0; 24], b"x", &[]).is_err());
+    }
+
+    #[test]
+    fn xchacha20_wrong_nonce_len_rejected() {
+        assert!(encrypt(AeadAlgorithm::XChaCha20Poly1305, &[0; 32], &[0; 12], b"x", &[]).is_err());
+    }
+
+    // ── Large payload ───────────────────────────────────────────────────
+
+    #[test]
+    fn xchacha20_large_payload_roundtrip() {
+        let key = [0xAAu8; 32];
+        let nonce = [0xBBu8; 24];
+        let pt = vec![0x42u8; 64 * 1024]; // 64 KiB — exercises the 16k chunked loop
+        roundtrip(AeadAlgorithm::XChaCha20Poly1305, &key, &nonce, &pt, b"large");
+    }
+
+    // ── Cross-algorithm isolation ───────────────────────────────────────
+
+    #[test]
+    fn ciphertext_not_interchangeable_between_algorithms() {
+        let key = [0xDD; 32];
+        let nonce_12 = [0xEE; 12];
+        let nonce_24 = [0xEE; 24];
+        let pt = b"cross-algo test";
+
+        let ct_aes = encrypt(AeadAlgorithm::AesGcm256, &key, &nonce_12, pt, &[]).unwrap();
+        let ct_chacha = encrypt(AeadAlgorithm::ChaCha20Poly1305, &key, &nonce_12, pt, &[]).unwrap();
+        let ct_xchacha = encrypt(AeadAlgorithm::XChaCha20Poly1305, &key, &nonce_24, pt, &[]).unwrap();
+
+        // Each ciphertext must fail to decrypt under a different algorithm
+        assert!(decrypt(AeadAlgorithm::ChaCha20Poly1305, &key, &nonce_12, &ct_aes, &[]).is_err());
+        assert!(decrypt(AeadAlgorithm::AesGcm256, &key, &nonce_12, &ct_chacha, &[]).is_err());
+        assert!(decrypt(AeadAlgorithm::AesGcm256, &key, &nonce_24, &ct_xchacha, &[]).is_err());
+    }
+}