21753596263

Committed 06 Feb 2026 02:13PM UTC coverage: 90.063% (-0.01%) from 90.073%

Build # 21753596263

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Pull #5289

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web-flow

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Merge 587099284 into 8ea0ca252

Pull Request Pull Request #5289: Further misc header reductions, forward declarations, etc

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/src/lib/math/bigint/bigint.cpp

/*
* BigInt Base
* (C) 1999-2011,2012,2014,2019 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/bigint.h>

#include <botan/exceptn.h>
#include <botan/internal/bit_ops.h>
#include <botan/internal/ct_utils.h>
#include <botan/internal/loadstor.h>
#include <botan/internal/mem_utils.h>
#include <botan/internal/mp_core.h>
#include <botan/internal/rounding.h>

namespace Botan {

BigInt::BigInt(uint64_t n) {
   if constexpr(sizeof(word) == 8) {
      m_data.set_word_at(0, static_cast<word>(n));
   } else {
      m_data.set_word_at(1, static_cast<word>(n >> 32));
      m_data.set_word_at(0, static_cast<word>(n));
   }
}

//static
BigInt BigInt::from_u64(uint64_t n) {
   return BigInt(n);
}

//static
BigInt BigInt::from_word(word n) {
   BigInt bn;
   bn.set_word_at(0, n);
   return bn;
}

//static
BigInt BigInt::from_s32(int32_t n) {
   if(n >= 0) {
      return BigInt::from_u64(static_cast<uint64_t>(n));
   } else {
      return -BigInt::from_u64(static_cast<uint64_t>(-n));
   }
}

//static
BigInt BigInt::with_capacity(size_t size) {
   BigInt bn;
   bn.grow_to(size);
   return bn;
}

/*
* Construct a BigInt from a string
*/
BigInt::BigInt(std::string_view str) {
   Base base = Decimal;
   size_t markers = 0;
   bool negative = false;

   if(!str.empty() && str[0] == '-') {
      markers += 1;
      negative = true;
   }

   if(str.length() > markers + 2 && str[markers] == '0' && str[markers + 1] == 'x') {
      markers += 2;
      base = Hexadecimal;
   }

   *this = decode(as_span_of_bytes(str).subspan(markers), base);

   if(negative) {
      set_sign(Negative);
   } else {
      set_sign(Positive);
   }
}

BigInt BigInt::from_string(std::string_view str) {
   return BigInt(str);
}

BigInt BigInt::from_bytes(std::span<const uint8_t> input) {
   BigInt r;
   r.assign_from_bytes(input);
   return r;
}

/*
* Construct a BigInt from an encoded BigInt
*/
BigInt::BigInt(const uint8_t input[], size_t length, Base base) {
   *this = decode(input, length, base);
}

//static
BigInt BigInt::from_bytes_with_max_bits(const uint8_t input[], size_t length, size_t max_bits) {
   const size_t input_bits = 8 * length;

   auto bn = BigInt::from_bytes(std::span{input, length});

   if(input_bits > max_bits) {
      const size_t bits_to_shift = input_bits - max_bits;

      bn >>= bits_to_shift;
   }

   return bn;
}

/*
* Construct a BigInt from an encoded BigInt
*/
BigInt::BigInt(RandomNumberGenerator& rng, size_t bits, bool set_high_bit) {
   randomize(rng, bits, set_high_bit);
}

uint8_t BigInt::byte_at(size_t n) const {
   return get_byte_var(sizeof(word) - (n % sizeof(word)) - 1, word_at(n / sizeof(word)));
}

int32_t BigInt::cmp_word(word other) const {
   if(is_negative()) {
      return -1;  // other is positive ...
   }

   const size_t sw = this->sig_words();
   if(sw > 1) {
      return 1;  // must be larger since other is just one word ...
   }

   return bigint_cmp(this->_data(), sw, &other, 1);
}

/*
* Comparison Function
*/
int32_t BigInt::cmp(const BigInt& other, bool check_signs) const {
   if(check_signs) {
      if(other.is_positive() && this->is_negative()) {
         return -1;
      }

      if(other.is_negative() && this->is_positive()) {
         return 1;
      }

      if(other.is_negative() && this->is_negative()) {
         return (-bigint_cmp(this->_data(), this->size(), other._data(), other.size()));
      }
   }

   return bigint_cmp(this->_data(), this->size(), other._data(), other.size());
}

bool BigInt::is_equal(const BigInt& other) const {
   if(this->sign() != other.sign()) {
      return false;
   }

   return bigint_ct_is_eq(this->_data(), this->sig_words(), other._data(), other.sig_words()).as_bool();
}

bool BigInt::is_less_than(const BigInt& other) const {
   if(this->is_negative() && other.is_positive()) {
      return true;
   }

   if(this->is_positive() && other.is_negative()) {
      return false;
   }

   if(other.is_negative() && this->is_negative()) {
      return bigint_ct_is_lt(other._data(), other.sig_words(), this->_data(), this->sig_words()).as_bool();
   }

   return bigint_ct_is_lt(this->_data(), this->sig_words(), other._data(), other.sig_words()).as_bool();
}

void BigInt::encode_words(word out[], size_t size) const {
   const size_t words = sig_words();

   if(words > size) {
      throw Encoding_Error("BigInt::encode_words value too large to encode");
   }

   clear_mem(out, size);
   copy_mem(out, _data(), words);
}

void BigInt::Data::set_to_zero() {
   m_reg.resize(m_reg.capacity());
   clear_mem(m_reg.data(), m_reg.size());
   m_sig_words = 0;
}

void BigInt::Data::mask_bits(size_t n) {
   if(n == 0) {
      return set_to_zero();
   }

   const size_t top_word = n / WordInfo<word>::bits;

   if(top_word < size()) {
      const word mask = (static_cast<word>(1) << (n % WordInfo<word>::bits)) - 1;
      const size_t len = size() - (top_word + 1);
      if(len > 0) {
         clear_mem(&m_reg[top_word + 1], len);
      }
      m_reg[top_word] &= mask;
      invalidate_sig_words();
   }
}

size_t BigInt::Data::calc_sig_words() const {
   const size_t sz = m_reg.size();
   size_t sig = sz;

   word sub = 1;

   for(size_t i = 0; i != sz; ++i) {
      const word w = m_reg[sz - i - 1];
      sub &= ct_is_zero(w);
      sig -= sub;
   }

   /*
   * This depends on the data so is poisoned, but unpoison it here as
   * later conditionals are made on the size.
   */
   CT::unpoison(sig);

   return sig;
}

/*
* Return bits {offset...offset+length}
*/
uint32_t BigInt::get_substring(size_t offset, size_t length) const {
   if(length == 0 || length > 32) {
      throw Invalid_Argument("BigInt::get_substring invalid substring length");
   }

   const uint32_t mask = 0xFFFFFFFF >> (32 - length);

   const size_t word_offset = offset / WordInfo<word>::bits;
   const size_t wshift = (offset % WordInfo<word>::bits);

   /*
   * The substring is contained within one or at most two words. The
   * offset and length are not secret, so we can perform conditional
   * operations on those values.
   */
   const word w0 = word_at(word_offset);

   if(wshift == 0 || (offset + length) / WordInfo<word>::bits == word_offset) {
      return static_cast<uint32_t>(w0 >> wshift) & mask;
   } else {
      const word w1 = word_at(word_offset + 1);
      return static_cast<uint32_t>((w0 >> wshift) | (w1 << (WordInfo<word>::bits - wshift))) & mask;
   }
}

/*
* Convert this number to a uint32_t, if possible
*/
uint32_t BigInt::to_u32bit() const {
   if(is_negative()) {
      throw Encoding_Error("BigInt::to_u32bit: Number is negative");
   }
   if(bits() > 32) {
      throw Encoding_Error("BigInt::to_u32bit: Number is too big to convert");
   }

   uint32_t out = 0;
   for(size_t i = 0; i != 4; ++i) {
      out = (out << 8) | byte_at(3 - i);
   }
   return out;
}

/*
* Clear bit number n
*/
void BigInt::clear_bit(size_t n) {
   const size_t which = n / WordInfo<word>::bits;

   if(which < size()) {
      const word mask = ~(static_cast<word>(1) << (n % WordInfo<word>::bits));
      m_data.set_word_at(which, word_at(which) & mask);
   }
}

size_t BigInt::bytes() const {
   return round_up(bits(), 8) / 8;
}

size_t BigInt::top_bits_free() const {
   const size_t words = sig_words();

   const word top_word = word_at(words - 1);
   const size_t bits_used = high_bit(CT::value_barrier(top_word));
   CT::unpoison(bits_used);
   return WordInfo<word>::bits - bits_used;
}

size_t BigInt::bits() const {
   const size_t words = sig_words();

   if(words == 0) {
      return 0;
   }

   const size_t full_words = (words - 1) * WordInfo<word>::bits;
   const size_t top_bits = WordInfo<word>::bits - top_bits_free();

   return full_words + top_bits;
}

/*
* Return the negation of this number
*/
BigInt BigInt::operator-() const {
   BigInt x = (*this);
   x.flip_sign();
   return x;
}

size_t BigInt::reduce_below(const BigInt& p, secure_vector<word>& ws) {
   if(p.is_negative() || this->is_negative()) {
      throw Invalid_Argument("BigInt::reduce_below both values must be positive");
   }

   const size_t p_words = p.sig_words();

   if(size() < p_words + 1) {
      grow_to(p_words + 1);
   }

   if(ws.size() < p_words + 1) {
      ws.resize(p_words + 1);
   }

   clear_mem(ws.data(), ws.size());

   size_t reductions = 0;

   for(;;) {
      const word borrow = bigint_sub3(ws.data(), _data(), p_words + 1, p._data(), p_words);
      if(borrow > 0) {
         break;
      }

      ++reductions;
      swap_reg(ws);
   }

   return reductions;
}

void BigInt::ct_reduce_below(const BigInt& mod, secure_vector<word>& ws, size_t bound) {
   if(mod.is_negative() || this->is_negative()) {
      throw Invalid_Argument("BigInt::ct_reduce_below both values must be positive");
   }

   const size_t mod_words = mod.sig_words();

   grow_to(mod_words);

   const size_t sz = size();

   ws.resize(sz);

   clear_mem(ws.data(), sz);

   for(size_t i = 0; i != bound; ++i) {
      const word borrow = bigint_sub3(ws.data(), _data(), sz, mod._data(), mod_words);

      CT::Mask<word>::is_zero(borrow).select_n(mutable_data(), ws.data(), _data(), sz);
   }
}

/*
* Return the absolute value of this number
*/
BigInt BigInt::abs() const {
   BigInt x = (*this);
   x.set_sign(Positive);
   return x;
}

/*
* Encode this number into bytes
*/
void BigInt::serialize_to(std::span<uint8_t> output) const {
   BOTAN_ARG_CHECK(this->bytes() <= output.size(), "Insufficient output space");

   this->binary_encode(output.data(), output.size());
}

/*
* Encode this number into bytes
*/
void BigInt::binary_encode(uint8_t output[], size_t len) const {
   const size_t full_words = len / sizeof(word);
   const size_t extra_bytes = len % sizeof(word);

   for(size_t i = 0; i != full_words; ++i) {
      const word w = word_at(i);
      store_be(w, output + (len - (i + 1) * sizeof(word)));
   }

   if(extra_bytes > 0) {
      const word w = word_at(full_words);

      for(size_t i = 0; i != extra_bytes; ++i) {
         output[extra_bytes - i - 1] = get_byte_var(sizeof(word) - i - 1, w);
      }
   }
}

/*
* Set this number to the value in buf
*/
void BigInt::assign_from_bytes(std::span<const uint8_t> bytes) {
   clear();

   const size_t length = bytes.size();
   const size_t full_words = length / sizeof(word);
   const size_t extra_bytes = length % sizeof(word);

   secure_vector<word> reg((round_up(full_words + (extra_bytes > 0 ? 1 : 0), 8)));

   for(size_t i = 0; i != full_words; ++i) {
      reg[i] = load_be<word>(bytes.last<sizeof(word)>());
      bytes = bytes.first(bytes.size() - sizeof(word));
   }

   if(!bytes.empty()) {
      BOTAN_ASSERT_NOMSG(extra_bytes == bytes.size());
      std::array<uint8_t, sizeof(word)> last_partial_word = {0};
      copy_mem(std::span{last_partial_word}.last(extra_bytes), bytes);
      reg[full_words] = load_be<word>(last_partial_word);
   }

   m_data.swap(reg);
}

void BigInt::ct_cond_add(bool predicate, const BigInt& value) {
   if(this->is_negative() || value.is_negative()) {
      throw Invalid_Argument("BigInt::ct_cond_add requires both values to be positive");
   }
   const size_t v_words = value.sig_words();

   this->grow_to(1 + v_words);

   const auto mask = CT::Mask<word>::expand(static_cast<word>(predicate)).value();

   word carry = 0;

   word* x = this->mutable_data();
   const word* y = value._data();

   for(size_t i = 0; i != v_words; ++i) {
      x[i] = word_add(x[i], y[i] & mask, &carry);
   }

   for(size_t i = v_words; i != size(); ++i) {
      x[i] = word_add(x[i], static_cast<word>(0), &carry);
   }
}

void BigInt::ct_shift_left(size_t shift) {
   auto shl_bit = [](const BigInt& a, BigInt& result) {
      BOTAN_DEBUG_ASSERT(a.size() + 1 == result.size());
      bigint_shl2(result.mutable_data(), a._data(), a.size(), 1);
      // shl2 may have shifted a bit into the next word, which must be dropped
      clear_mem(result.mutable_data() + result.size() - 1, 1);
   };

   auto shl_word = [](const BigInt& a, BigInt& result) {
      // the most significant word is not copied, aka. shifted out
      bigint_shl2(result.mutable_data(), a._data(), a.size() - 1 /* ignore msw */, WordInfo<word>::bits);
      // we left-shifted by a full word, the least significant word must be zero'ed
      clear_mem(result.mutable_data(), 1);
   };

   BOTAN_ASSERT_NOMSG(size() > 0);

   constexpr size_t bits_in_word = sizeof(word) * 8;
   const size_t word_shift = shift >> ceil_log2(bits_in_word);             // shift / bits_in_word
   const size_t bit_shift = shift & ((1 << ceil_log2(bits_in_word)) - 1);  // shift % bits_in_word
   const size_t iterations = std::max(size(), bits_in_word) - 1;           // uint64_t i; i << 64 is undefined behaviour

   // In every iteration, shift one bit and one word to the left and use the
   // shift results only when they are within the shift range.
   BigInt tmp;
   tmp.resize(size() + 1 /* to hold the shifted-out word */);
   for(size_t i = 0; i < iterations; ++i) {
      shl_bit(*this, tmp);
      ct_cond_assign(i < bit_shift, tmp);
      shl_word(*this, tmp);
      ct_cond_assign(i < word_shift, tmp);
   }
}

void BigInt::ct_cond_swap(bool predicate, BigInt& other) {
   const size_t max_words = std::max(size(), other.size());
   grow_to(max_words);
   other.grow_to(max_words);

   bigint_cnd_swap(static_cast<word>(predicate), this->mutable_data(), other.mutable_data(), max_words);
}

void BigInt::cond_flip_sign(bool predicate) {
   // This code is assuming Negative == 0, Positive == 1

   const auto mask = CT::Mask<uint8_t>::expand_bool(predicate);

   const uint8_t current_sign = static_cast<uint8_t>(sign());

   const uint8_t new_sign = mask.select(current_sign ^ 1, current_sign);

   set_sign(static_cast<Sign>(new_sign));
}

void BigInt::ct_cond_assign(bool predicate, const BigInt& other) {
   const size_t t_words = size();
   const size_t o_words = other.size();

   if(o_words < t_words) {
      grow_to(o_words);
   }

   const size_t r_words = std::max(t_words, o_words);

   const auto mask = CT::Mask<word>::expand_bool(predicate);

   for(size_t i = 0; i != r_words; ++i) {
      const word o_word = other.word_at(i);
      const word t_word = this->word_at(i);
      this->set_word_at(i, mask.select(o_word, t_word));
   }

   const auto same_sign = CT::Mask<word>::is_equal(sign(), other.sign()).as_choice();
   cond_flip_sign((mask.as_choice() && !same_sign).as_bool());
}

void BigInt::_const_time_poison() const {
   CT::poison(m_data.const_data(), m_data.size());
}

void BigInt::_const_time_unpoison() const {
   CT::unpoison(m_data.const_data(), m_data.size());
}

}  // namespace Botan

1	/*
2	* BigInt Base
3	* (C) 1999-2011,2012,2014,2019 Jack Lloyd
4	*
5	* Botan is released under the Simplified BSD License (see license.txt)
6	*/
7
8	#include <botan/bigint.h>
9
10	#include <botan/exceptn.h>
11	#include <botan/internal/bit_ops.h>
12	#include <botan/internal/ct_utils.h>
13	#include <botan/internal/loadstor.h>
14	#include <botan/internal/mem_utils.h>
15	#include <botan/internal/mp_core.h>
16	#include <botan/internal/rounding.h>
17
18	namespace Botan {
19
20	BigInt::BigInt(uint64_t n) {	361,914✔
21	if constexpr(sizeof(word) == 8) {	361,914✔
22	m_data.set_word_at(0, static_cast<word>(n));	361,914✔
23	} else {
24	m_data.set_word_at(1, static_cast<word>(n >> 32));
25	m_data.set_word_at(0, static_cast<word>(n));
26	}
27	}	361,914✔
28
29	//static
30	BigInt BigInt::from_u64(uint64_t n) {	182,853✔
31	return BigInt(n);	182,853✔
32	}
33
34	//static
35	BigInt BigInt::from_word(word n) {	461,521✔
36	BigInt bn;	461,521✔
37	bn.set_word_at(0, n);	461,521✔
38	return bn;	461,521✔
39	}	×
40
41	//static
42	BigInt BigInt::from_s32(int32_t n) {	70,848✔
43	if(n >= 0) {	70,848✔
44	return BigInt::from_u64(static_cast<uint64_t>(n));	70,696✔
45	} else {
46	return -BigInt::from_u64(static_cast<uint64_t>(-n));	152✔
47	}
48	}
49
50	//static
51	BigInt BigInt::with_capacity(size_t size) {	8,596,430✔
52	BigInt bn;	8,596,430✔
53	bn.grow_to(size);	8,596,430✔
54	return bn;	8,596,430✔
55	}	×
56
57	/*
58	* Construct a BigInt from a string
59	*/
60	BigInt::BigInt(std::string_view str) {	46,607✔
61	Base base = Decimal;	46,607✔
62	size_t markers = 0;	46,607✔
63	bool negative = false;	46,607✔
64
65	if(!str.empty() && str[0] == '-') {	46,607✔
66	markers += 1;
67	negative = true;
68	}
69
70	if(str.length() > markers + 2 && str[markers] == '0' && str[markers + 1] == 'x') {	46,607✔
71	markers += 2;
72	base = Hexadecimal;
73	}
74
75	*this = decode(as_span_of_bytes(str).subspan(markers), base);	46,607✔
76
77	if(negative) {	46,607✔
78	set_sign(Negative);	904✔
79	} else {
80	set_sign(Positive);	46,155✔
81	}
82	}	46,607✔
83
84	BigInt BigInt::from_string(std::string_view str) {	6✔
85	return BigInt(str);	6✔
86	}
87
88	BigInt BigInt::from_bytes(std::span<const uint8_t> input) {	126,265✔
89	BigInt r;	126,265✔
90	r.assign_from_bytes(input);	126,265✔
91	return r;	126,265✔
92	}	×
93
94	/*
95	* Construct a BigInt from an encoded BigInt
96	*/
97	BigInt::BigInt(const uint8_t input[], size_t length, Base base) {	×
98	*this = decode(input, length, base);	×
99	}	×
100
101	//static
102	BigInt BigInt::from_bytes_with_max_bits(const uint8_t input[], size_t length, size_t max_bits) {	6,905✔
103	const size_t input_bits = 8 * length;	6,905✔
104
105	auto bn = BigInt::from_bytes(std::span{input, length});	6,905✔
106
107	if(input_bits > max_bits) {	6,905✔
108	const size_t bits_to_shift = input_bits - max_bits;	3,731✔
109
110	bn >>= bits_to_shift;	3,731✔
111	}
112
113	return bn;	6,905✔
114	}	×
115
116	/*
117	* Construct a BigInt from an encoded BigInt
118	*/
119	BigInt::BigInt(RandomNumberGenerator& rng, size_t bits, bool set_high_bit) {	88,562✔
120	randomize(rng, bits, set_high_bit);	88,562✔
121	}	88,562✔
122
123	uint8_t BigInt::byte_at(size_t n) const {	346,238✔
124	return get_byte_var(sizeof(word) - (n % sizeof(word)) - 1, word_at(n / sizeof(word)));	346,238✔
125	}
126
127	int32_t BigInt::cmp_word(word other) const {	3,150,934✔
128	if(is_negative()) {	3,150,934✔
129	return -1; // other is positive ...
130	}
131
132	const size_t sw = this->sig_words();	3,085,436✔
133	if(sw > 1) {	3,085,436✔
134	return 1; // must be larger since other is just one word ...
135	}
136
137	return bigint_cmp(this->_data(), sw, &other, 1);	2,402,463✔
138	}
139
140	/*
141	* Comparison Function
142	*/
143	int32_t BigInt::cmp(const BigInt& other, bool check_signs) const {	1,010,974✔
144	if(check_signs) {	1,010,974✔
145	if(other.is_positive() && this->is_negative()) {	1,010,847✔
146	return -1;
147	}
148
149	if(other.is_negative() && this->is_positive()) {	1,010,789✔
150	return 1;
151	}
152
153	if(other.is_negative() && this->is_negative()) {	1,010,703✔
154	return (-bigint_cmp(this->_data(), this->size(), other._data(), other.size()));	66✔
155	}
156	}
157
158	return bigint_cmp(this->_data(), this->size(), other._data(), other.size());	1,010,764✔
159	}
160
161	bool BigInt::is_equal(const BigInt& other) const {	586,409✔
162	if(this->sign() != other.sign()) {	586,409✔
163	return false;
164	}
165
166	return bigint_ct_is_eq(this->_data(), this->sig_words(), other._data(), other.sig_words()).as_bool();	1,100,003✔
167	}
168
169	bool BigInt::is_less_than(const BigInt& other) const {	1,523,312✔
170	if(this->is_negative() && other.is_positive()) {	1,523,312✔
171	return true;
172	}
173
174	if(this->is_positive() && other.is_negative()) {	1,523,239✔
175	return false;
176	}
177
178	if(other.is_negative() && this->is_negative()) {	1,523,169✔
179	return bigint_ct_is_lt(other._data(), other.sig_words(), this->_data(), this->sig_words()).as_bool();	65✔
180	}
181
182	return bigint_ct_is_lt(this->_data(), this->sig_words(), other._data(), other.sig_words()).as_bool();	2,282,297✔
183	}
184
185	void BigInt::encode_words(word out[], size_t size) const {	283,534✔
186	const size_t words = sig_words();	283,534✔
187
188	if(words > size) {	283,534✔
189	throw Encoding_Error("BigInt::encode_words value too large to encode");	×
190	}
191
192	clear_mem(out, size);	283,534✔
193	copy_mem(out, _data(), words);	283,534✔
194	}	283,534✔
195
196	void BigInt::Data::set_to_zero() {	884,808✔
197	m_reg.resize(m_reg.capacity());	884,808✔
198	clear_mem(m_reg.data(), m_reg.size());	884,808✔
199	m_sig_words = 0;	884,808✔
200	}	884,808✔
201
202	void BigInt::Data::mask_bits(size_t n) {	36,371✔
203	if(n == 0) {	36,371✔
204	return set_to_zero();	×
205	}
206
207	const size_t top_word = n / WordInfo<word>::bits;	36,371✔
208
209	if(top_word < size()) {	36,371✔
210	const word mask = (static_cast<word>(1) << (n % WordInfo<word>::bits)) - 1;	34,321✔
211	const size_t len = size() - (top_word + 1);	34,321✔
212	if(len > 0) {	34,321✔
213	clear_mem(&m_reg[top_word + 1], len);	34,321✔
214	}
215	m_reg[top_word] &= mask;	34,321✔
216	invalidate_sig_words();	34,321✔
217	}
218	}
219
220	size_t BigInt::Data::calc_sig_words() const {	42,515,273✔
221	const size_t sz = m_reg.size();	42,515,273✔
222	size_t sig = sz;	42,515,273✔
223
224	word sub = 1;	42,515,273✔
225
226	for(size_t i = 0; i != sz; ++i) {	1,144,617,880✔
227	const word w = m_reg[sz - i - 1];	1,102,102,607✔
228	sub &= ct_is_zero(w);	1,102,102,607✔
229	sig -= sub;	1,102,102,607✔
230	}
231
232	/*
233	* This depends on the data so is poisoned, but unpoison it here as
234	* later conditionals are made on the size.
235	*/
236	CT::unpoison(sig);	42,515,273✔
237
238	return sig;	42,515,273✔
239	}
240
241	/*
242	* Return bits {offset...offset+length}
243	*/
244	uint32_t BigInt::get_substring(size_t offset, size_t length) const {	11,474,948✔
245	if(length == 0 \|\| length > 32) {	11,474,948✔
246	throw Invalid_Argument("BigInt::get_substring invalid substring length");	×
247	}
248
249	const uint32_t mask = 0xFFFFFFFF >> (32 - length);	11,474,948✔
250
251	const size_t word_offset = offset / WordInfo<word>::bits;	11,474,948✔
252	const size_t wshift = (offset % WordInfo<word>::bits);	11,474,948✔
253
254	/*
255	* The substring is contained within one or at most two words. The
256	* offset and length are not secret, so we can perform conditional
257	* operations on those values.
258	*/
259	const word w0 = word_at(word_offset);	11,474,948✔
260
261	if(wshift == 0 \|\| (offset + length) / WordInfo<word>::bits == word_offset) {	11,474,948✔
262	return static_cast<uint32_t>(w0 >> wshift) & mask;	10,918,951✔
263	} else {
264	const word w1 = word_at(word_offset + 1);	555,997✔
265	return static_cast<uint32_t>((w0 >> wshift) \| (w1 << (WordInfo<word>::bits - wshift))) & mask;	555,997✔
266	}
267	}
268
269	/*
270	* Convert this number to a uint32_t, if possible
271	*/
272	uint32_t BigInt::to_u32bit() const {	34,952✔
273	if(is_negative()) {	34,952✔
274	throw Encoding_Error("BigInt::to_u32bit: Number is negative");	×
275	}
276	if(bits() > 32) {	34,952✔
277	throw Encoding_Error("BigInt::to_u32bit: Number is too big to convert");	15✔
278	}
279
280	uint32_t out = 0;
281	for(size_t i = 0; i != 4; ++i) {	174,685✔
282	out = (out << 8) \| byte_at(3 - i);	139,748✔
283	}
284	return out;	34,937✔
285	}
286
287	/*
288	* Clear bit number n
289	*/
290	void BigInt::clear_bit(size_t n) {	71✔
291	const size_t which = n / WordInfo<word>::bits;	71✔
292
293	if(which < size()) {	71✔
294	const word mask = ~(static_cast<word>(1) << (n % WordInfo<word>::bits));	71✔
295	m_data.set_word_at(which, word_at(which) & mask);	71✔
296	}
297	}	71✔
298
299	size_t BigInt::bytes() const {	356,951✔
300	return round_up(bits(), 8) / 8;	356,951✔
301	}
302
303	size_t BigInt::top_bits_free() const {	2,120,110✔
304	const size_t words = sig_words();	2,120,110✔
305
306	const word top_word = word_at(words - 1);	2,120,110✔
307	const size_t bits_used = high_bit(CT::value_barrier(top_word));	2,120,110✔
308	CT::unpoison(bits_used);	2,120,110✔
309	return WordInfo<word>::bits - bits_used;	2,120,110✔
310	}
311
312	size_t BigInt::bits() const {	1,698,959✔
313	const size_t words = sig_words();	1,698,959✔
314
315	if(words == 0) {	1,698,959✔
316	return 0;
317	}
318
319	const size_t full_words = (words - 1) * WordInfo<word>::bits;	1,679,577✔
320	const size_t top_bits = WordInfo<word>::bits - top_bits_free();	1,679,577✔
321
322	return full_words + top_bits;	1,679,577✔
323	}
324
325	/*
326	* Return the negation of this number
327	*/
328	BigInt BigInt::operator-() const {	163✔
329	BigInt x = (*this);	163✔
330	x.flip_sign();	163✔
331	return x;	163✔
332	}	×
333
334	size_t BigInt::reduce_below(const BigInt& p, secure_vector<word>& ws) {	7,341,781✔
335	if(p.is_negative() \|\| this->is_negative()) {	7,341,781✔
336	throw Invalid_Argument("BigInt::reduce_below both values must be positive");	×
337	}
338
339	const size_t p_words = p.sig_words();	7,341,781✔
340
341	if(size() < p_words + 1) {	7,341,781✔
342	grow_to(p_words + 1);	28,974✔
343	}
344
345	if(ws.size() < p_words + 1) {	7,341,781✔
346	ws.resize(p_words + 1);	440,533✔
347	}
348
349	clear_mem(ws.data(), ws.size());	7,341,781✔
350
351	size_t reductions = 0;	7,341,781✔
352
353	for(;;) {	11,222,529✔
354	const word borrow = bigint_sub3(ws.data(), _data(), p_words + 1, p._data(), p_words);	18,564,310✔
355	if(borrow > 0) {	18,564,310✔
356	break;
357	}
358
359	++reductions;	11,222,529✔
360	swap_reg(ws);	11,222,529✔
361	}
362
363	return reductions;	7,341,781✔
364	}
365
366	void BigInt::ct_reduce_below(const BigInt& mod, secure_vector<word>& ws, size_t bound) {	×
367	if(mod.is_negative() \|\| this->is_negative()) {	×
368	throw Invalid_Argument("BigInt::ct_reduce_below both values must be positive");	×
369	}
370
371	const size_t mod_words = mod.sig_words();	×
372
373	grow_to(mod_words);	×
374
375	const size_t sz = size();	×
376
377	ws.resize(sz);	×
378
379	clear_mem(ws.data(), sz);	×
380
381	for(size_t i = 0; i != bound; ++i) {	×
382	const word borrow = bigint_sub3(ws.data(), _data(), sz, mod._data(), mod_words);	×
383
384	CT::Mask<word>::is_zero(borrow).select_n(mutable_data(), ws.data(), _data(), sz);	×
385	}
386	}	×
387
388	/*
389	* Return the absolute value of this number
390	*/
391	BigInt BigInt::abs() const {	867✔
392	BigInt x = (*this);	867✔
393	x.set_sign(Positive);	867✔
394	return x;	867✔
395	}
396
397	/*
398	* Encode this number into bytes
399	*/
400	void BigInt::serialize_to(std::span<uint8_t> output) const {	216,888✔
401	BOTAN_ARG_CHECK(this->bytes() <= output.size(), "Insufficient output space");	216,888✔
402
403	this->binary_encode(output.data(), output.size());	216,660✔
404	}	216,660✔
405
406	/*
407	* Encode this number into bytes
408	*/
409	void BigInt::binary_encode(uint8_t output[], size_t len) const {	216,665✔
410	const size_t full_words = len / sizeof(word);	216,665✔
411	const size_t extra_bytes = len % sizeof(word);	216,665✔
412
413	for(size_t i = 0; i != full_words; ++i) {	1,976,667✔
414	const word w = word_at(i);	1,760,002✔
415	store_be(w, output + (len - (i + 1) * sizeof(word)));	1,760,002✔
416	}
417
418	if(extra_bytes > 0) {	216,665✔
419	const word w = word_at(full_words);	125,187✔
420
421	for(size_t i = 0; i != extra_bytes; ++i) {	571,555✔
422	output[extra_bytes - i - 1] = get_byte_var(sizeof(word) - i - 1, w);	446,368✔
423	}
424	}
425	}	216,665✔
426
427	/*
428	* Set this number to the value in buf
429	*/
430	void BigInt::assign_from_bytes(std::span<const uint8_t> bytes) {	882,097✔
431	clear();	882,097✔
432
433	const size_t length = bytes.size();	882,097✔
434	const size_t full_words = length / sizeof(word);	882,097✔
435	const size_t extra_bytes = length % sizeof(word);	882,097✔
436
437	secure_vector<word> reg((round_up(full_words + (extra_bytes > 0 ? 1 : 0), 8)));	1,108,305✔
438
439	for(size_t i = 0; i != full_words; ++i) {	8,868,804✔
440	reg[i] = load_be<word>(bytes.last<sizeof(word)>());	7,986,707✔
441	bytes = bytes.first(bytes.size() - sizeof(word));	7,986,707✔
442	}
443
444	if(!bytes.empty()) {	882,097✔
445	BOTAN_ASSERT_NOMSG(extra_bytes == bytes.size());	655,889✔
446	std::array<uint8_t, sizeof(word)> last_partial_word = {0};	655,889✔
447	copy_mem(std::span{last_partial_word}.last(extra_bytes), bytes);	655,889✔
448	reg[full_words] = load_be<word>(last_partial_word);	655,889✔
449	}
450
451	m_data.swap(reg);	882,097✔
452	}	882,097✔
453
454	void BigInt::ct_cond_add(bool predicate, const BigInt& value) {	2,353,577✔
455	if(this->is_negative() \|\| value.is_negative()) {	2,353,577✔
456	throw Invalid_Argument("BigInt::ct_cond_add requires both values to be positive");	×
457	}
458	const size_t v_words = value.sig_words();	2,353,577✔
459
460	this->grow_to(1 + v_words);	2,353,577✔
461
462	const auto mask = CT::Mask<word>::expand(static_cast<word>(predicate)).value();	2,353,577✔
463
464	word carry = 0;	2,353,577✔
465
466	word* x = this->mutable_data();	2,353,577✔
467	const word* y = value._data();	2,353,577✔
468
469	for(size_t i = 0; i != v_words; ++i) {	11,379,126✔
470	x[i] = word_add(x[i], y[i] & mask, &carry);	9,025,549✔
471	}
472
473	for(size_t i = v_words; i != size(); ++i) {	20,794,809✔
474	x[i] = word_add(x[i], static_cast<word>(0), &carry);	18,441,232✔
475	}
476	}	2,353,577✔
477
478	void BigInt::ct_shift_left(size_t shift) {	30,665✔
479	auto shl_bit = [](const BigInt& a, BigInt& result) {	3,830,336✔
480	BOTAN_DEBUG_ASSERT(a.size() + 1 == result.size());	3,799,671✔
481	bigint_shl2(result.mutable_data(), a._data(), a.size(), 1);	3,799,671✔
482	// shl2 may have shifted a bit into the next word, which must be dropped
483	clear_mem(result.mutable_data() + result.size() - 1, 1);	3,799,671✔
484	};	3,799,671✔
485
486	auto shl_word = [](const BigInt& a, BigInt& result) {	3,830,336✔
487	// the most significant word is not copied, aka. shifted out
488	bigint_shl2(result.mutable_data(), a._data(), a.size() - 1 /* ignore msw */, WordInfo<word>::bits);	3,799,671✔
489	// we left-shifted by a full word, the least significant word must be zero'ed
490	clear_mem(result.mutable_data(), 1);	3,799,671✔
491	};	3,799,671✔
492
493	BOTAN_ASSERT_NOMSG(size() > 0);	30,665✔
494
495	constexpr size_t bits_in_word = sizeof(word) * 8;	30,665✔
496	const size_t word_shift = shift >> ceil_log2(bits_in_word); // shift / bits_in_word	30,665✔
497	const size_t bit_shift = shift & ((1 << ceil_log2(bits_in_word)) - 1); // shift % bits_in_word	30,665✔
498	const size_t iterations = std::max(size(), bits_in_word) - 1; // uint64_t i; i << 64 is undefined behaviour	30,665✔
499
500	// In every iteration, shift one bit and one word to the left and use the
501	// shift results only when they are within the shift range.
502	BigInt tmp;	30,665✔
503	tmp.resize(size() + 1 /* to hold the shifted-out word */);	30,665✔
504	for(size_t i = 0; i < iterations; ++i) {	3,830,336✔
505	shl_bit(*this, tmp);	3,799,671✔
506	ct_cond_assign(i < bit_shift, tmp);	3,799,671✔
507	shl_word(*this, tmp);	3,799,671✔
508	ct_cond_assign(i < word_shift, tmp);	3,799,671✔
509	}
510	}	30,665✔
511
512	void BigInt::ct_cond_swap(bool predicate, BigInt& other) {	11,240,215✔
513	const size_t max_words = std::max(size(), other.size());	11,240,215✔
514	grow_to(max_words);	11,240,215✔
515	other.grow_to(max_words);	11,240,215✔
516
517	bigint_cnd_swap(static_cast<word>(predicate), this->mutable_data(), other.mutable_data(), max_words);	11,240,215✔
518	}	11,240,215✔
519
520	void BigInt::cond_flip_sign(bool predicate) {	32,093,875✔
521	// This code is assuming Negative == 0, Positive == 1
522
523	const auto mask = CT::Mask<uint8_t>::expand_bool(predicate);	32,093,875✔
524
525	const uint8_t current_sign = static_cast<uint8_t>(sign());	32,093,875✔
526
527	const uint8_t new_sign = mask.select(current_sign ^ 1, current_sign);	32,093,875✔
528
529	set_sign(static_cast<Sign>(new_sign));	32,093,875✔
530	}	32,093,875✔
531
532	void BigInt::ct_cond_assign(bool predicate, const BigInt& other) {	31,760,326✔
533	const size_t t_words = size();	31,760,326✔
534	const size_t o_words = other.size();	31,760,326✔
535
536	if(o_words < t_words) {	31,760,326✔
537	grow_to(o_words);	365✔
538	}
539
540	const size_t r_words = std::max(t_words, o_words);	31,760,326✔
541
542	const auto mask = CT::Mask<word>::expand_bool(predicate);	31,760,326✔
543
544	for(size_t i = 0; i != r_words; ++i) {	2,147,483,647✔
545	const word o_word = other.word_at(i);	2,147,483,647✔
546	const word t_word = this->word_at(i);	2,147,483,647✔
547	this->set_word_at(i, mask.select(o_word, t_word));	2,147,483,647✔
548	}
549
550	const auto same_sign = CT::Mask<word>::is_equal(sign(), other.sign()).as_choice();	31,760,326✔
551	cond_flip_sign((mask.as_choice() && !same_sign).as_bool());	31,760,326✔
552	}	31,760,326✔
553
554	void BigInt::_const_time_poison() const {	57,366✔
555	CT::poison(m_data.const_data(), m_data.size());	57,366✔
556	}	57,366✔
557
558	void BigInt::_const_time_unpoison() const {	24,483,808✔
559	CT::unpoison(m_data.const_data(), m_data.size());	24,483,808✔
560	}	24,483,808✔
561
562	} // namespace Botan

randombit / botan / 21753596263

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