[fix] bandit assert warnings (#3243)

Co-authored-by: dni ⚡ <office@dnilabs.com>

lnbits/utils/crypto.py

@@ -66,7 +66,8 @@ class AESCipher:
         self, salt: bytes, output_len: int = 32 + 16
     ) -> tuple[bytes, bytes]:
         # extended from https://gist.github.com/gsakkis/4546068
-        assert len(salt) == 8, "Salt must be 8 bytes"
+        if len(salt) != 8:
+            raise ValueError("Salt must be 8 bytes")
         data = self.key + salt
         key = md5(data).digest()
         final_key = key

lnbits/utils/nostr.py

@@ -175,14 +175,17 @@ def normalize_private_key(key: str) -> str:
 def normalize_bech32_key(hrp: str, key: str) -> str:
     if key.startswith(hrp):
         _, decoded_data = bech32_decode(key)
-        assert decoded_data, f"Key is not valid {hrp}."
+        if not decoded_data:
+            raise ValueError(f"Key is not valid {hrp}.")
 
         decoded_data_bits = convertbits(decoded_data, 5, 8, False)
-        assert decoded_data_bits, f"Key is not valid {hrp}."
+        if not decoded_data_bits:
+            raise ValueError(f"Key is not valid {hrp}.")
 
         return bytes(decoded_data_bits).hex()
 
-    assert len(key) == 64, "Key has wrong length."
+    if len(key) != 64:
+        raise ValueError("Key has wrong length.")
     try:
         int(key, 16)
     except Exception as exc:
@@ -203,7 +206,8 @@ def hex_to_npub(hex_pubkey: str) -> str:
     normalize_public_key(hex_pubkey)
     pubkey_bytes = bytes.fromhex(hex_pubkey)
     bits = convertbits(pubkey_bytes, 8, 5, True)
-    assert bits
+    if not bits:
+        raise ValueError("Invalid Nostr  public key.")
     return bech32_encode("npub", bits)