13139534998

Committed 04 Feb 2025 02:46PM UTC coverage: 91.235% (-0.001%) from 91.236%

Build # 13139534998

Build Type

push

github

Committed by

web-flow

Commit Message

Merge pull request #4633 from Rohde-Schwarz/fix/unreachable_warning

FIX: unreachable code if XMD is not available

Run Details

94189 of 103238 relevant lines covered (91.23%)

11530574.35 hits per line

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98.08

/src/fuzzer/invert.cpp

/*
* (C) 2015,2016,2020 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include "fuzzers.h"

#include <botan/numthry.h>

namespace {

Botan::BigInt ref_inverse_mod(const Botan::BigInt& n, const Botan::BigInt& mod) {
   if(n == 0 || mod < 2) {
      return 0;
   }
   if(n.is_even() && mod.is_even()) {
      return 0;
   }
   Botan::BigInt u = mod, v = n;
   Botan::BigInt A = 1, B = 0, C = 0, D = 1;

   while(u.is_nonzero()) {
      const size_t u_zero_bits = Botan::low_zero_bits(u);
      u >>= u_zero_bits;
      for(size_t i = 0; i != u_zero_bits; ++i) {
         if(A.is_odd() || B.is_odd()) {
            A += n;
            B -= mod;
         }
         A >>= 1;
         B >>= 1;
      }

      const size_t v_zero_bits = Botan::low_zero_bits(v);
      v >>= v_zero_bits;
      for(size_t i = 0; i != v_zero_bits; ++i) {
         if(C.is_odd() || D.is_odd()) {
            C += n;
            D -= mod;
         }
         C >>= 1;
         D >>= 1;
      }

      if(u >= v) {
         u -= v;
         A -= C;
         B -= D;
      } else {
         v -= u;
         C -= A;
         D -= B;
      }
   }

   if(v != 1) {
      return 0;  // no modular inverse
   }

   while(D.is_negative()) {
      D += mod;
   }
   while(D >= mod) {
      D -= mod;
   }

   return D;
}

}  // namespace

void fuzz(std::span<const uint8_t> in) {
   static const size_t max_bits = 4096;

   if(in.size() > 2 * max_bits / 8) {
      return;
   }

   const Botan::BigInt x = Botan::BigInt::from_bytes(in.subspan(0, in.size() / 2));
   Botan::BigInt mod = Botan::BigInt::from_bytes(in.subspan(in.size() / 2, in.size() - in.size() / 2));

   if(mod < 2) {
      return;
   }

   const Botan::BigInt lib = Botan::inverse_mod(x, mod);
   const Botan::BigInt ref = ref_inverse_mod(x, mod);

   if(ref != lib) {
      FUZZER_WRITE_AND_CRASH("X = " << x.to_hex_string() << "\n"
                                    << "Mod = " << mod.to_hex_string() << "\n"
                                    << "GCD(X,Mod) = " << gcd(x, mod).to_hex_string() << "\n"
                                    << "RefInv(X,Mod) = " << ref.to_hex_string() << "\n"
                                    << "LibInv(X,Mod)  = " << lib.to_hex_string() << "\n"
                                    << "RefCheck = " << ((x * ref) % mod).to_hex_string() << "\n"
                                    << "LibCheck  = " << ((x * lib) % mod).to_hex_string() << "\n");
   }
}

1	/*
2	* (C) 2015,2016,2020 Jack Lloyd
3	*
4	* Botan is released under the Simplified BSD License (see license.txt)
5	*/
6	#include "fuzzers.h"
7
8	#include <botan/numthry.h>
9
10	namespace {
11
12	Botan::BigInt ref_inverse_mod(const Botan::BigInt& n, const Botan::BigInt& mod) {	99✔
13	if(n == 0 \|\| mod < 2) {	197✔
14	return 0;	1✔
15	}
16	if(n.is_even() && mod.is_even()) {	249✔
17	return 0;	31✔
18	}
19	Botan::BigInt u = mod, v = n;	67✔
20	Botan::BigInt A = 1, B = 0, C = 0, D = 1;	67✔
21
22	while(u.is_nonzero()) {	36,567✔
23	const size_t u_zero_bits = Botan::low_zero_bits(u);	24,328✔
24	u >>= u_zero_bits;	24,328✔
25	for(size_t i = 0; i != u_zero_bits; ++i) {	48,928✔
26	if(A.is_odd() \|\| B.is_odd()) {	24,600✔
27	A += n;	12,196✔
28	B -= mod;	12,196✔
29	}
30	A >>= 1;	24,600✔
31	B >>= 1;	24,600✔
32	}
33
34	const size_t v_zero_bits = Botan::low_zero_bits(v);	24,328✔
35	v >>= v_zero_bits;	24,328✔
36	for(size_t i = 0; i != v_zero_bits; ++i) {	48,710✔
37	if(C.is_odd() \|\| D.is_odd()) {	24,382✔
38	C += n;	12,079✔
39	D -= mod;	12,079✔
40	}
41	C >>= 1;	24,382✔
42	D >>= 1;	24,382✔
43	}
44
45	if(u >= v) {	24,328✔
46	u -= v;	12,172✔
47	A -= C;	12,172✔
48	B -= D;	12,172✔
49	} else {
50	v -= u;	12,156✔
51	C -= A;	12,156✔
52	D -= B;	12,156✔
53	}
54	}
55
56	if(v != 1) {	67✔
57	return 0; // no modular inverse	20✔
58	}
59
60	while(D.is_negative()) {	90✔
61	D += mod;	43✔
62	}
63	while(D >= mod) {	47✔
64	D -= mod;	×
65	}
66
67	return D;	47✔
68	}	402✔
69
70	} // namespace
71
72	void fuzz(std::span<const uint8_t> in) {	100✔
73	static const size_t max_bits = 4096;	100✔
74
75	if(in.size() > 2 * max_bits / 8) {	100✔
76	return;	1✔
77	}
78
79	const Botan::BigInt x = Botan::BigInt::from_bytes(in.subspan(0, in.size() / 2));	100✔
80	Botan::BigInt mod = Botan::BigInt::from_bytes(in.subspan(in.size() / 2, in.size() - in.size() / 2));	100✔
81
82	if(mod < 2) {	100✔
83	return;	1✔
84	}
85
86	const Botan::BigInt lib = Botan::inverse_mod(x, mod);	99✔
87	const Botan::BigInt ref = ref_inverse_mod(x, mod);	99✔
88
89	if(ref != lib) {	99✔
90	FUZZER_WRITE_AND_CRASH("X = " << x.to_hex_string() << "\n"	99✔
91	<< "Mod = " << mod.to_hex_string() << "\n"
92	<< "GCD(X,Mod) = " << gcd(x, mod).to_hex_string() << "\n"
93	<< "RefInv(X,Mod) = " << ref.to_hex_string() << "\n"
94	<< "LibInv(X,Mod) = " << lib.to_hex_string() << "\n"
95	<< "RefCheck = " << ((x * ref) % mod).to_hex_string() << "\n"
96	<< "LibCheck = " << ((x * lib) % mod).to_hex_string() << "\n");
97	}
98	}	344✔

randombit / botan / 13139534998

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