21768358452

Committed 06 Feb 2026 10:35PM UTC coverage: 90.064% (-0.003%) from 90.067%

Build # 21768358452

Build Type

Pull #5289

github

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web-flow

Commit Message

Merge f589db195 into 8ea0ca252

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

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92.05

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

/*
* BigInt Encoding/Decoding
* (C) 1999-2010,2012,2019,2021 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/bigint.h>

#include <botan/exceptn.h>
#include <botan/hex.h>
#include <botan/mem_ops.h>
#include <botan/internal/buffer_stuffer.h>
#include <botan/internal/divide.h>
#include <botan/internal/mp_core.h>

namespace Botan {

namespace {

consteval word decimal_conversion_radix() {
   if constexpr(sizeof(word) == 8) {
      return 10000000000000000000U;
   } else {
      return 1000000000U;
   }
}

consteval size_t decimal_conversion_radix_digits() {
   if constexpr(sizeof(word) == 8) {
      return 19;
   } else {
      return 9;
   }
}

}  // namespace

std::string BigInt::to_dec_string() const {
   // Use the largest power of 10 that fits in a word
   constexpr word conversion_radix = decimal_conversion_radix();
   constexpr size_t radix_digits = decimal_conversion_radix_digits();

   // (over-)estimate of the number of digits needed; log2(10) ~ 3.3219
   const size_t digit_estimate = static_cast<size_t>(1 + (static_cast<double>(this->bits()) / 3.32));

   // (over-)estimate of db such that conversion_radix^db > *this
   const size_t digit_blocks = (digit_estimate + radix_digits - 1) / radix_digits;

   BigInt value = *this;
   value.set_sign(Positive);

   // Extract groups of digits into words
   std::vector<word> digit_groups(digit_blocks);

   for(size_t i = 0; i != digit_blocks; ++i) {
      word remainder = 0;
      ct_divide_word(value, conversion_radix, value, remainder);
      digit_groups[i] = remainder;
   }

   BOTAN_ASSERT_NOMSG(value.is_zero());

   // Extract digits from the groups
   std::vector<uint8_t> digits(digit_blocks * radix_digits);

   for(size_t i = 0; i != digit_blocks; ++i) {
      word remainder = digit_groups[i];
      for(size_t j = 0; j != radix_digits; ++j) {
         const word new_remainder = divide_10(remainder);
         const word digit = remainder - new_remainder * 10;
         digits[radix_digits * i + j] = static_cast<uint8_t>(digit);
         remainder = new_remainder;
      }
   }

   // remove leading zeros
   while(!digits.empty() && digits.back() == 0) {
      digits.pop_back();
   }

   BOTAN_ASSERT_NOMSG(digit_estimate >= digits.size());

   // Reverse the digits to big-endian and format to text
   std::string s;
   s.reserve(1 + digits.size());

   if(is_negative()) {
      s += "-";
   }

   // Reverse and convert to textual digits
   // TODO(Botan4) use std::ranges::reverse_view here once available (need newer Clang)
   // NOLINTNEXTLINE(modernize-loop-convert)
   for(auto i = digits.rbegin(); i != digits.rend(); ++i) {
      s.push_back(*i + '0');  // assumes ASCII
   }

   if(s.empty()) {
      s += "0";
   }

   return s;
}

std::string BigInt::to_hex_string() const {
   const size_t this_bytes = this->bytes();
   std::vector<uint8_t> bits(std::max<size_t>(1, this_bytes));

   if(this_bytes > 0) {
      this->serialize_to(bits);
   }

   std::string hrep;
   if(is_negative()) {
      hrep += "-";
   }
   hrep += "0x";
   hrep += hex_encode(bits);
   return hrep;
}

/*
* Encode two BigInt, with leading 0s if needed, and concatenate
*/
secure_vector<uint8_t> BigInt::encode_fixed_length_int_pair(const BigInt& n1, const BigInt& n2, size_t bytes) {
   if(n1.is_negative() || n2.is_negative()) {
      throw Encoding_Error("encode_fixed_length_int_pair: values must be positive");
   }
   if(n1.bytes() > bytes || n2.bytes() > bytes) {
      throw Encoding_Error("encode_fixed_length_int_pair: values too large to encode properly");
   }
   secure_vector<uint8_t> output(2 * bytes);
   BufferStuffer stuffer(output);
   n1.serialize_to(stuffer.next(bytes));
   n2.serialize_to(stuffer.next(bytes));
   return output;
}

BigInt BigInt::decode(std::span<const uint8_t> buf, Base base) {
   if(base == Binary) {
      return BigInt::from_bytes(buf);
   }
   return BigInt::decode(buf.data(), buf.size(), base);
}

/*
* Decode a BigInt
*/
BigInt BigInt::decode(const uint8_t buf[], size_t length, Base base) {
   if(base == Binary) {
      return BigInt::from_bytes(std::span{buf, length});
   } else if(base == Hexadecimal) {
      BigInt r;
      secure_vector<uint8_t> binary;

      if(length % 2 == 1) {
         // Handle lack of leading 0
         const char buf0_with_leading_0[2] = {'0', static_cast<char>(buf[0])};

         binary = hex_decode_locked(buf0_with_leading_0, 2);

         if(length > 1) {
            binary += hex_decode_locked(cast_uint8_ptr_to_char(&buf[1]), length - 1, false);
         }
      } else {
         binary = hex_decode_locked(cast_uint8_ptr_to_char(buf), length, false);
      }

      r.assign_from_bytes(binary);
      return r;
   } else if(base == Decimal) {
      BigInt r;
      // This could be made faster using the same trick as to_dec_string
      for(size_t i = 0; i != length; ++i) {
         const char c = buf[i];

         if(c < '0' || c > '9') {
            throw Invalid_Argument("BigInt::decode: invalid decimal char");
         }

         const uint8_t x = c - '0';
         BOTAN_ASSERT_NOMSG(x < 10);

         r *= 10;
         r += x;
      }
      return r;
   } else {
      throw Invalid_Argument("Unknown BigInt decoding method");
   }
}

}  // namespace Botan

1	/*
2	* BigInt Encoding/Decoding
3	* (C) 1999-2010,2012,2019,2021 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/hex.h>
12	#include <botan/mem_ops.h>
13	#include <botan/internal/buffer_stuffer.h>
14	#include <botan/internal/divide.h>
15	#include <botan/internal/mp_core.h>
16
17	namespace Botan {
18
19	namespace {
20
21	consteval word decimal_conversion_radix() {
22	if constexpr(sizeof(word) == 8) {
23	return 10000000000000000000U;
24	} else {
25	return 1000000000U;
26	}
27	}
28
29	consteval size_t decimal_conversion_radix_digits() {
30	if constexpr(sizeof(word) == 8) {
31	return 19;
32	} else {
33	return 9;
34	}
35	}
36
37	} // namespace
38
39	std::string BigInt::to_dec_string() const {	60✔
40	// Use the largest power of 10 that fits in a word
41	constexpr word conversion_radix = decimal_conversion_radix();	60✔
42	constexpr size_t radix_digits = decimal_conversion_radix_digits();	60✔
43
44	// (over-)estimate of the number of digits needed; log2(10) ~ 3.3219
45	const size_t digit_estimate = static_cast<size_t>(1 + (static_cast<double>(this->bits()) / 3.32));	60✔
46
47	// (over-)estimate of db such that conversion_radix^db > *this
48	const size_t digit_blocks = (digit_estimate + radix_digits - 1) / radix_digits;	60✔
49
50	BigInt value = *this;	60✔
51	value.set_sign(Positive);	60✔
52
53	// Extract groups of digits into words
54	std::vector<word> digit_groups(digit_blocks);	60✔
55
56	for(size_t i = 0; i != digit_blocks; ++i) {	132✔
57	word remainder = 0;	72✔
58	ct_divide_word(value, conversion_radix, value, remainder);	72✔
59	digit_groups[i] = remainder;	72✔
60	}
61
62	BOTAN_ASSERT_NOMSG(value.is_zero());	120✔
63
64	// Extract digits from the groups
65	std::vector<uint8_t> digits(digit_blocks * radix_digits);	60✔
66
67	for(size_t i = 0; i != digit_blocks; ++i) {	132✔
68	word remainder = digit_groups[i];	72✔
69	for(size_t j = 0; j != radix_digits; ++j) {	1,440✔
70	const word new_remainder = divide_10(remainder);	1,368✔
71	const word digit = remainder - new_remainder * 10;	1,368✔
72	digits[radix_digits * i + j] = static_cast<uint8_t>(digit);	1,368✔
73	remainder = new_remainder;	1,368✔
74	}
75	}
76
77	// remove leading zeros
78	while(!digits.empty() && digits.back() == 0) {	960✔
79	digits.pop_back();	900✔
80	}
81
82	BOTAN_ASSERT_NOMSG(digit_estimate >= digits.size());	60✔
83
84	// Reverse the digits to big-endian and format to text
85	std::string s;	60✔
86	s.reserve(1 + digits.size());	60✔
87
88	if(is_negative()) {	60✔
89	s += "-";	5✔
90	}
91
92	// Reverse and convert to textual digits
93	// TODO(Botan4) use std::ranges::reverse_view here once available (need newer Clang)
94	// NOLINTNEXTLINE(modernize-loop-convert)
95	for(auto i = digits.rbegin(); i != digits.rend(); ++i) {	528✔
96	s.push_back(*i + '0'); // assumes ASCII	468✔
97	}
98
99	if(s.empty()) {	60✔
100	s += "0";	6✔
101	}
102
103	return s;	120✔
104	}	120✔
105
106	std::string BigInt::to_hex_string() const {	86✔
107	const size_t this_bytes = this->bytes();	86✔
108	std::vector<uint8_t> bits(std::max<size_t>(1, this_bytes));	145✔
109
110	if(this_bytes > 0) {	86✔
111	this->serialize_to(bits);	84✔
112	}
113
114	std::string hrep;	86✔
115	if(is_negative()) {	86✔
116	hrep += "-";	5✔
117	}
118	hrep += "0x";	86✔
119	hrep += hex_encode(bits);	172✔
120	return hrep;	86✔
121	}	86✔
122
123	/*
124	* Encode two BigInt, with leading 0s if needed, and concatenate
125	*/
126	secure_vector<uint8_t> BigInt::encode_fixed_length_int_pair(const BigInt& n1, const BigInt& n2, size_t bytes) {	97✔
127	if(n1.is_negative() \|\| n2.is_negative()) {	97✔
128	throw Encoding_Error("encode_fixed_length_int_pair: values must be positive");	×
129	}
130	if(n1.bytes() > bytes \|\| n2.bytes() > bytes) {	97✔
131	throw Encoding_Error("encode_fixed_length_int_pair: values too large to encode properly");	×
132	}
133	secure_vector<uint8_t> output(2 * bytes);	97✔
134	BufferStuffer stuffer(output);	97✔
135	n1.serialize_to(stuffer.next(bytes));	97✔
136	n2.serialize_to(stuffer.next(bytes));	97✔
137	return output;	97✔
138	}	×
139
140	BigInt BigInt::decode(std::span<const uint8_t> buf, Base base) {	46,614✔
141	if(base == Binary) {	46,614✔
142	return BigInt::from_bytes(buf);	×
143	}
144	return BigInt::decode(buf.data(), buf.size(), base);	46,614✔
145	}
146
147	/*
148	* Decode a BigInt
149	*/
150	BigInt BigInt::decode(const uint8_t buf[], size_t length, Base base) {	46,614✔
151	if(base == Binary) {	46,614✔
152	return BigInt::from_bytes(std::span{buf, length});	×
153	} else if(base == Hexadecimal) {	46,614✔
154	BigInt r;	42,347✔
155	secure_vector<uint8_t> binary;	42,347✔
156
157	if(length % 2 == 1) {	42,347✔
158	// Handle lack of leading 0
159	const char buf0_with_leading_0[2] = {'0', static_cast<char>(buf[0])};	4,219✔
160
161	binary = hex_decode_locked(buf0_with_leading_0, 2);	8,438✔
162
163	if(length > 1) {	4,219✔
164	binary += hex_decode_locked(cast_uint8_ptr_to_char(&buf[1]), length - 1, false);	6,082✔
165	}
166	} else {
167	binary = hex_decode_locked(cast_uint8_ptr_to_char(buf), length, false);	76,256✔
168	}
169
170	r.assign_from_bytes(binary);	42,347✔
171	return r;	42,347✔
172	} else if(base == Decimal) {	46,614✔
173	BigInt r;	4,267✔
174	// This could be made faster using the same trick as to_dec_string
175	for(size_t i = 0; i != length; ++i) {	382,959✔
176	const char c = buf[i];	378,692✔
177
178	if(c < '0' \|\| c > '9') {	378,692✔
179	throw Invalid_Argument("BigInt::decode: invalid decimal char");	×
180	}
181
182	const uint8_t x = c - '0';	378,692✔
183	BOTAN_ASSERT_NOMSG(x < 10);	378,692✔
184
185	r *= 10;	378,692✔
186	r += x;	378,692✔
187	}
188	return r;	4,267✔
189	} else {	4,267✔
190	throw Invalid_Argument("Unknown BigInt decoding method");	×
191	}
192	}
193
194	} // namespace Botan

randombit / botan / 21768358452

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