got rid of math.ceil

lib/Crypto/Protocol/SecretSharing.py

@@ -30,8 +30,6 @@
 # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 # POSSIBILITY OF SUCH DAMAGE.
 # ===================================================================
-from math import ceil
-
 from Crypto.Util.py3compat import is_native_int
 from Crypto.Util import number
 from Crypto.Util.number import long_to_bytes, bytes_to_long
@@ -286,11 +284,11 @@ def split_large(k, n, secret, ssss=False):
         when len(key) > SHAMIR_BLOCK_SIZE (16)
         """
         if isinstance(secret, bytes) is not True:
-            raise TypeError("secret must be bytes")
+            raise TypeError("Secret must be bytes")
         if len(secret) % 16 != 0:
-            raise ValueError("secret size must be in 16 byte increments")
+            raise ValueError("Secret size must be in 16 byte increments")
 
-        blocks = ceil(len(secret) / 16)
+        blocks = len(secret) // SHAMIR_BLOCK_SIZE
         shares = [b'' for _ in range(n)]
         for i in range(blocks):
             block_shares = Shamir.split(k, n,
@@ -306,7 +304,12 @@ def combine_large(shares, ssss=False):
         when len(key) > SHAMIR_BLOCK_SIZE (16)
         """
         share_len = len(shares[0][1])
-        blocks = ceil(share_len / SHAMIR_BLOCK_SIZE)
+        for share in shares:
+            if len(share[1]) % 16 != 0:
+                raise ValueError(f"Share #{share[0]} is not in 16 byte increments")
+            if len(share[1]) != share_len:
+                raise ValueError(f"Share sizes are inconsistant")
+        blocks = share_len // SHAMIR_BLOCK_SIZE
         result = b''
         for i in range(blocks):
             block_shares = [