12873787387

Committed 20 Jan 2025 06:20PM UTC coverage: 91.212% (+0.003%) from 91.209%

Build # 12873787387

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github

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Commit Message

Merge pull request #4575 from randombit/jack/cleanup-up-includes

Clean up includes

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95.08

/src/lib/math/numbertheory/reducer.cpp

/*
* Modular Reducer
* (C) 1999-2011,2018 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/reducer.h>

#include <botan/internal/ct_utils.h>
#include <botan/internal/divide.h>
#include <botan/internal/mp_core.h>

namespace Botan {

/*
* Modular_Reducer Constructor
*/
Modular_Reducer::Modular_Reducer(const BigInt& mod) {
   if(mod < 0) {
      throw Invalid_Argument("Modular_Reducer: modulus must be positive");
   }

   // Left uninitialized if mod == 0
   m_mod_words = 0;

   if(mod > 0) {
      m_modulus = mod;
      m_mod_words = m_modulus.sig_words();

      // Compute mu = floor(2^{2k} / m)
      m_mu.set_bit(2 * BOTAN_MP_WORD_BITS * m_mod_words);
      m_mu = ct_divide(m_mu, m_modulus);
   }
}

BigInt Modular_Reducer::reduce(const BigInt& x) const {
   BigInt r;
   secure_vector<word> ws;
   reduce(r, x, ws);
   return r;
}

BigInt Modular_Reducer::square(const BigInt& x) const {
   secure_vector<word> ws;
   BigInt x2 = x;
   x2.square(ws);
   BigInt r;
   reduce(r, x2, ws);
   return r;
}

namespace {

/*
* Like if(cnd) x.rev_sub(...) but in const time
*/
void cnd_rev_sub(bool cnd, BigInt& x, const word y[], size_t y_sw, secure_vector<word>& ws) {
   if(x.sign() != BigInt::Positive) {
      throw Invalid_State("BigInt::sub_rev requires this is positive");
   }

   const size_t x_sw = x.sig_words();

   const size_t max_words = std::max(x_sw, y_sw);
   ws.resize(std::max(x_sw, y_sw));
   clear_mem(ws.data(), ws.size());
   x.grow_to(max_words);

   const int32_t relative_size = bigint_sub_abs(ws.data(), x._data(), x_sw, y, y_sw);

   x.cond_flip_sign((relative_size > 0) && cnd);
   bigint_cnd_swap(static_cast<word>(cnd), x.mutable_data(), ws.data(), max_words);
}

}  // namespace

void Modular_Reducer::reduce(BigInt& t1, const BigInt& x, secure_vector<word>& ws) const {
   if(&t1 == &x) {
      throw Invalid_State("Modular_Reducer arguments cannot alias");
   }
   if(m_mod_words == 0) {
      throw Invalid_State("Modular_Reducer: Never initalized");
   }

   const size_t x_sw = x.sig_words();

   if(x_sw > 2 * m_mod_words) {
      // too big, fall back to slow boat division
      t1 = ct_modulo(x, m_modulus);
      return;
   }

   t1 = x;
   t1.set_sign(BigInt::Positive);
   t1 >>= (BOTAN_MP_WORD_BITS * (m_mod_words - 1));

   t1.mul(m_mu, ws);
   t1 >>= (BOTAN_MP_WORD_BITS * (m_mod_words + 1));

   // TODO add masked mul to avoid computing high bits
   t1.mul(m_modulus, ws);
   t1.mask_bits(BOTAN_MP_WORD_BITS * (m_mod_words + 1));

   t1.rev_sub(x._data(), std::min(x_sw, m_mod_words + 1), ws);

   /*
   * If t1 < 0 then we must add b^(k+1) where b = 2^w. To avoid a
   * side channel perform the addition unconditionally, with ws set
   * to either b^(k+1) or else 0.
   */
   const word t1_neg = t1.is_negative();

   if(ws.size() < m_mod_words + 2) {
      ws.resize(m_mod_words + 2);
   }
   clear_mem(ws.data(), ws.size());
   ws[m_mod_words + 1] = t1_neg;

   t1.add(ws.data(), m_mod_words + 2, BigInt::Positive);

   // Per HAC this step requires at most 2 subtractions
   t1.ct_reduce_below(m_modulus, ws, 2);

   cnd_rev_sub(t1.is_nonzero() && x.is_negative(), t1, m_modulus._data(), m_modulus.size(), ws);
}

}  // namespace Botan

1	/*
2	* Modular Reducer
3	* (C) 1999-2011,2018 Jack Lloyd
4	*
5	* Botan is released under the Simplified BSD License (see license.txt)
6	*/
7
8	#include <botan/reducer.h>
9
10	#include <botan/internal/ct_utils.h>
11	#include <botan/internal/divide.h>
12	#include <botan/internal/mp_core.h>
13
14	namespace Botan {
15
16	/*
17	* Modular_Reducer Constructor
18	*/
19	Modular_Reducer::Modular_Reducer(const BigInt& mod) {	127,298✔
20	if(mod < 0) {	127,298✔
21	throw Invalid_Argument("Modular_Reducer: modulus must be positive");	9✔
22	}
23
24	// Left uninitialized if mod == 0
25	m_mod_words = 0;	127,289✔
26
27	if(mod > 0) {	127,289✔
28	m_modulus = mod;	126,930✔
29	m_mod_words = m_modulus.sig_words();	126,930✔
30
31	// Compute mu = floor(2^{2k} / m)
32	m_mu.set_bit(2 * BOTAN_MP_WORD_BITS * m_mod_words);	126,930✔
33	m_mu = ct_divide(m_mu, m_modulus);	380,790✔
34	}
35	}	127,298✔
36
37	BigInt Modular_Reducer::reduce(const BigInt& x) const {	6,379,809✔
38	BigInt r;	6,379,809✔
39	secure_vector<word> ws;	6,379,809✔
40	reduce(r, x, ws);	6,379,809✔
41	return r;	6,379,809✔
42	}	6,379,809✔
43
44	BigInt Modular_Reducer::square(const BigInt& x) const {	2,290,052✔
45	secure_vector<word> ws;	2,290,052✔
46	BigInt x2 = x;	2,290,052✔
47	x2.square(ws);	2,290,052✔
48	BigInt r;	2,290,052✔
49	reduce(r, x2, ws);	2,290,052✔
50	return r;	2,290,052✔
51	}	4,580,104✔
52
53	namespace {
54
55	/*
56	* Like if(cnd) x.rev_sub(...) but in const time
57	*/
58	void cnd_rev_sub(bool cnd, BigInt& x, const word y[], size_t y_sw, secure_vector<word>& ws) {	8,668,320✔
59	if(x.sign() != BigInt::Positive) {	8,668,320✔
60	throw Invalid_State("BigInt::sub_rev requires this is positive");	×
61	}
62
63	const size_t x_sw = x.sig_words();	8,668,320✔
64
65	const size_t max_words = std::max(x_sw, y_sw);	8,668,320✔
66	ws.resize(std::max(x_sw, y_sw));	8,668,320✔
67	clear_mem(ws.data(), ws.size());	8,668,320✔
68	x.grow_to(max_words);	8,668,320✔
69
70	const int32_t relative_size = bigint_sub_abs(ws.data(), x._data(), x_sw, y, y_sw);	8,668,320✔
71
72	x.cond_flip_sign((relative_size > 0) && cnd);	8,668,320✔
73	bigint_cnd_swap(static_cast<word>(cnd), x.mutable_data(), ws.data(), max_words);	8,668,320✔
74	}	8,668,320✔
75
76	} // namespace
77
78	void Modular_Reducer::reduce(BigInt& t1, const BigInt& x, secure_vector<word>& ws) const {	8,669,861✔
79	if(&t1 == &x) {	8,669,861✔
80	throw Invalid_State("Modular_Reducer arguments cannot alias");	×
81	}
82	if(m_mod_words == 0) {	8,669,861✔
83	throw Invalid_State("Modular_Reducer: Never initalized");	×
84	}
85
86	const size_t x_sw = x.sig_words();	8,669,861✔
87
88	if(x_sw > 2 * m_mod_words) {	8,669,861✔
89	// too big, fall back to slow boat division
90	t1 = ct_modulo(x, m_modulus);	1,541✔
91	return;	1,541✔
92	}
93
94	t1 = x;	8,668,320✔
95	t1.set_sign(BigInt::Positive);	8,668,320✔
96	t1 >>= (BOTAN_MP_WORD_BITS * (m_mod_words - 1));	8,668,320✔
97
98	t1.mul(m_mu, ws);	8,668,320✔
99	t1 >>= (BOTAN_MP_WORD_BITS * (m_mod_words + 1));	8,668,320✔
100
101	// TODO add masked mul to avoid computing high bits
102	t1.mul(m_modulus, ws);	8,668,320✔
103	t1.mask_bits(BOTAN_MP_WORD_BITS * (m_mod_words + 1));	8,668,320✔
104
105	t1.rev_sub(x._data(), std::min(x_sw, m_mod_words + 1), ws);	10,365,149✔
106
107	/*
108	* If t1 < 0 then we must add b^(k+1) where b = 2^w. To avoid a
109	* side channel perform the addition unconditionally, with ws set
110	* to either b^(k+1) or else 0.
111	*/
112	const word t1_neg = t1.is_negative();	8,668,320✔
113
114	if(ws.size() < m_mod_words + 2) {	8,668,320✔
115	ws.resize(m_mod_words + 2);	36,033✔
116	}
117	clear_mem(ws.data(), ws.size());	8,668,320✔
118	ws[m_mod_words + 1] = t1_neg;	8,668,320✔
119
120	t1.add(ws.data(), m_mod_words + 2, BigInt::Positive);	8,668,320✔
121
122	// Per HAC this step requires at most 2 subtractions
123	t1.ct_reduce_below(m_modulus, ws, 2);	8,668,320✔
124
125	cnd_rev_sub(t1.is_nonzero() && x.is_negative(), t1, m_modulus._data(), m_modulus.size(), ws);	25,131,379✔
126	}
127
128	} // namespace Botan

randombit / botan / 12873787387

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