Coverage Report

Created: 2021-05-04 09:02

/src/botan/src/fuzzer/divide.cpp
Line
Count
Source
1
/*
2
* (C) 2015,2016,2018 Jack Lloyd
3
*
4
* Botan is released under the Simplified BSD License (see license.txt)
5
*/
6
#include "fuzzers.h"
7
#include <botan/internal/divide.h>
8
9
void fuzz(const uint8_t in[], size_t len)
10
850
   {
11
850
   if(len % 2 == 1 || len > 2*4096/8)
12
19
      return;
13
14
   // Save on allocations by making these static
15
831
   static Botan::BigInt x, y, q, r, ct_q, ct_r, z;
16
17
831
   x = Botan::BigInt::decode(in, len / 2);
18
831
   y = Botan::BigInt::decode(in + len / 2, len / 2);
19
20
831
   if(y == 0)
21
1
      return;
22
23
830
   Botan::vartime_divide(x, y, q, r);
24
25
830
   FUZZER_ASSERT_TRUE(r < y);
26
27
830
   z = q*y + r;
28
29
830
   FUZZER_ASSERT_EQUAL(z, x);
30
31
830
   Botan::ct_divide(x, y, ct_q, ct_r);
32
33
830
   FUZZER_ASSERT_EQUAL(q, ct_q);
34
830
   FUZZER_ASSERT_EQUAL(r, ct_r);
35
36
   // Now divide by just low byte of y
37
38
830
   y = y.byte_at(0);
39
830
   if(y == 0)
40
126
      y = 251;
41
830
   Botan::vartime_divide(x, y, q, r);
42
43
830
   z = q*y + r;
44
830
   FUZZER_ASSERT_EQUAL(z, x);
45
46
830
   uint8_t r8;
47
830
   Botan::ct_divide_u8(x, y.byte_at(0), ct_q, r8);
48
830
   FUZZER_ASSERT_EQUAL(ct_q, q);
49
830
   FUZZER_ASSERT_EQUAL(r8, r.byte_at(0));
50
51
830
   }
52