Test our implementation against Cryptography module's

README.md

@@ -20,10 +20,11 @@ Clone the repository, use Meson build:
 meson setup build
 cd build
 ninja
-./randquik
+sudo ninja install  # optionally
+randquik > /dev/null
 ```
 
-Alternatively you may compile it by hand with `gcc randquik.c -o randquik -O3 -pthread`.
+Alternatively you may compile it by hand with `gcc *.c -o randquik -O3 -pthread`.
 
 ## Python module
 

randquik/nprand.py

@@ -1,8 +1,9 @@
 import secrets
+import sys
 
 import cha
 import numpy as np
-import sys
+
 
 class ChaRandom(np.random.BitGenerator):
     def __init__(self, seed=None):

src/cha1block.h

@@ -43,7 +43,7 @@ static inline uint64_t _cha_block(cha_ctx* ctx, uint8_t* begin, uint8_t* end) {
             c = end;
             // Leftover bytes are stored in ctx for next call
             ctx->uncount = 64 - bytes;
-            memcpy(ctx->unconsumed, x + bytes, ctx->uncount);
+            memcpy(ctx->unconsumed, (uint8_t*)x + bytes, ctx->uncount);
             break;
         }
         memcpy(c, x, 64);

tests/test_chacha.py

@@ -7,6 +7,7 @@ from randquik import cha
 
 
 def test_cipherstreams_fullblocks():
+    """Requests in multiple of ChaCha20 block size 64 bytes"""
     key = token_bytes(32)
     nonce = token_bytes(16)
     c0 = Cipher(ChaCha20(key, nonce), None, None).encryptor()
@@ -21,6 +22,7 @@ def test_cipherstreams_fullblocks():
 
 
 def test_cipherstreams_partial_updates():
+    """Odd-sized requests that retain leftover buffers"""
     key = token_bytes(32)
     nonce = token_bytes(16)
     c0 = Cipher(ChaCha20(key, nonce), None, None).encryptor()
@@ -32,3 +34,17 @@ def test_cipherstreams_partial_updates():
         ct1 = c1(bytearray(N))
         assert len(ct0) == len(ct1)
         assert ct0.hex() == ct1.hex()
+
+
+def test_cipherstreams_32leftover():
+    """Test the special case where the second response comes entirely from the leftover buffer"""
+    key = token_bytes(32)
+    nonce = token_bytes(16)
+    c0 = Cipher(ChaCha20(key, nonce), None, None).encryptor()
+    c1 = cha.Cha(key, nonce)
+
+    for N in [512 - 32, 32]:
+        ct0 = c0.update(bytes(N))
+        ct1 = c1(bytearray(N))
+        assert len(ct0) == len(ct1)
+        assert ct0.hex() == ct1.hex()