feat: works

src/stream_util.rs

@@ -1,10 +1,24 @@
 use crate::chacha20::ChaCha20;
 use crate::simdty::Simd4;
 
+const CHACHA20_POLY1305_KEY_LEN: usize = 32;
+const CHACHA20_POLY1305_NONCE_LEN: usize = 12;
+
+#[inline]
 pub(crate) fn next_chacha20_xor(chacha20: &mut ChaCha20, buf: &mut [Simd4<u32>; 4]) {
     let block = chacha20.next();
     buf[0] = buf[0] ^ block[0];
     buf[1] = buf[1] ^ block[1];
     buf[2] = buf[2] ^ block[2];
     buf[3] = buf[3] ^ block[3];
+}
+
+pub(crate) fn verify_key_nonce_length(key: &[u8], nonce: &[u8]) -> Result<(), String> {
+    if key.len() != CHACHA20_POLY1305_KEY_LEN {
+        return Err("Bad key length".to_string());
+    }
+    if nonce.len() != CHACHA20_POLY1305_NONCE_LEN {
+        return Err("Bad nonce length".to_string());
+    }
+    Ok(())
 }