Merge pull request #61 from GiacomoPope/simplify_decode_vector

simplify decode vector

src/kyber_py/modules/modules.py

@@ -8,23 +8,20 @@ def __init__(self):
         self.matrix = MatrixKyber
 
     def decode_vector(self, input_bytes, k, d, is_ntt=False):
-
-        if self.ring.n * d * k > len(input_bytes) * 8:
-            raise ValueError("Byte length is too short for given l")
+        # Ensure the input bytes are the correct length to create k elements with
+        # d bits used for each coefficient
+        if self.ring.n * d * k != len(input_bytes) * 8:
+            raise ValueError(
+                "Byte length is the wrong length for given k, d values"
+            )
 
         # Bytes needed to decode a polynomial
-        chunk_length = 32 * d
-
-        # Break input_bytes into blocks of length chunk_length
-        poly_bytes = [
-            input_bytes[i : i + chunk_length]
-            for i in range(0, len(input_bytes), chunk_length)
-        ]
+        n = 32 * d
 
-        # Encode each chunk of bytes as a polynomial, we iterate only the first k elements in case we've
-        # been sent too many bytes to decode for the vector
+        # Encode each chunk of bytes as a polynomial and create the vector
         elements = [
-            self.ring.decode(poly_bytes[i], d, is_ntt=is_ntt) for i in range(k)
+            self.ring.decode(input_bytes[i : i + n], d, is_ntt=is_ntt)
+            for i in range(0, len(input_bytes), n)
         ]
 
         return self.vector(elements)