13230468750

Committed 09 Feb 2025 11:07PM UTC coverage: 91.651% (-0.008%) from 91.659%

Build # 13230468750

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Pull #4647

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Commit Message

Merge 8b67be1f1 into 7deaa69bb

Pull Request Pull Request #4647: Avoid using mem_ops.h or assert.h in public headers

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95.0

/src/lib/pubkey/dsa/dsa.cpp

/*
* DSA
* (C) 1999-2010,2014,2016,2023 Jack Lloyd
* (C) 2016 René Korthaus
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/dsa.h>

#include <botan/assert.h>
#include <botan/internal/divide.h>
#include <botan/internal/dl_scheme.h>
#include <botan/internal/keypair.h>
#include <botan/internal/pk_ops_impl.h>

#if defined(BOTAN_HAS_RFC6979_GENERATOR)
   #include <botan/internal/rfc6979.h>
#endif

namespace Botan {

std::optional<size_t> DSA_PublicKey::_signature_element_size_for_DER_encoding() const {
   return m_public_key->group().q_bytes();
}

size_t DSA_PublicKey::estimated_strength() const {
   return m_public_key->estimated_strength();
}

size_t DSA_PublicKey::key_length() const {
   return m_public_key->p_bits();
}

const BigInt& DSA_PublicKey::get_int_field(std::string_view field) const {
   return m_public_key->get_int_field(algo_name(), field);
}

AlgorithmIdentifier DSA_PublicKey::algorithm_identifier() const {
   return AlgorithmIdentifier(object_identifier(), m_public_key->group().DER_encode(DL_Group_Format::ANSI_X9_57));
}

std::vector<uint8_t> DSA_PublicKey::raw_public_key_bits() const {
   return m_public_key->public_key_as_bytes();
}

std::vector<uint8_t> DSA_PublicKey::public_key_bits() const {
   return m_public_key->DER_encode();
}

bool DSA_PublicKey::check_key(RandomNumberGenerator& rng, bool strong) const {
   return m_public_key->check_key(rng, strong);
}

std::unique_ptr<Private_Key> DSA_PublicKey::generate_another(RandomNumberGenerator& rng) const {
   return std::make_unique<DSA_PrivateKey>(rng, m_public_key->group());
}

DSA_PublicKey::DSA_PublicKey(const AlgorithmIdentifier& alg_id, std::span<const uint8_t> key_bits) {
   m_public_key = std::make_shared<DL_PublicKey>(alg_id, key_bits, DL_Group_Format::ANSI_X9_57);

   BOTAN_ARG_CHECK(m_public_key->group().has_q(), "Q parameter must be set for DSA");
}

DSA_PublicKey::DSA_PublicKey(const DL_Group& group, const BigInt& y) {
   m_public_key = std::make_shared<DL_PublicKey>(group, y);

   BOTAN_ARG_CHECK(m_public_key->group().has_q(), "Q parameter must be set for DSA");
}

DSA_PrivateKey::DSA_PrivateKey(RandomNumberGenerator& rng, const DL_Group& group) {
   BOTAN_ARG_CHECK(group.has_q(), "Q parameter must be set for DSA");

   m_private_key = std::make_shared<DL_PrivateKey>(group, rng);
   m_public_key = m_private_key->public_key();
}

DSA_PrivateKey::DSA_PrivateKey(const DL_Group& group, const BigInt& x) {
   BOTAN_ARG_CHECK(group.has_q(), "Q parameter must be set for DSA");

   m_private_key = std::make_shared<DL_PrivateKey>(group, x);
   m_public_key = m_private_key->public_key();
}

DSA_PrivateKey::DSA_PrivateKey(const AlgorithmIdentifier& alg_id, std::span<const uint8_t> key_bits) {
   m_private_key = std::make_shared<DL_PrivateKey>(alg_id, key_bits, DL_Group_Format::ANSI_X9_57);
   m_public_key = m_private_key->public_key();

   BOTAN_ARG_CHECK(m_private_key->group().has_q(), "Q parameter must be set for DSA");
}

bool DSA_PrivateKey::check_key(RandomNumberGenerator& rng, bool strong) const {
   if(!m_private_key->check_key(rng, strong)) {
      return false;
   }

   if(m_private_key->private_key() >= m_private_key->group().get_q()) {
      return false;
   }

   return KeyPair::signature_consistency_check(rng, *this, "SHA-256");
}

secure_vector<uint8_t> DSA_PrivateKey::private_key_bits() const {
   return m_private_key->DER_encode();
}

secure_vector<uint8_t> DSA_PrivateKey::raw_private_key_bits() const {
   return m_private_key->raw_private_key_bits();
}

const BigInt& DSA_PrivateKey::get_int_field(std::string_view field) const {
   return m_private_key->get_int_field(algo_name(), field);
}

std::unique_ptr<Public_Key> DSA_PrivateKey::public_key() const {
   // can't use make_unique here due to private constructor
   return std::unique_ptr<DSA_PublicKey>(new DSA_PublicKey(m_public_key));
}

namespace {

/**
* Object that can create a DSA signature
*/
class DSA_Signature_Operation final : public PK_Ops::Signature_with_Hash {
   public:
      DSA_Signature_Operation(const std::shared_ptr<const DL_PrivateKey>& key,
                              std::string_view emsa,
                              RandomNumberGenerator& rng) :
            PK_Ops::Signature_with_Hash(emsa), m_key(key) {
         m_b = BigInt::random_integer(rng, 2, m_key->group().get_q());
         m_b_inv = m_key->group().inverse_mod_q(m_b);
      }

      size_t signature_length() const override { return 2 * m_key->group().q_bytes(); }

      std::vector<uint8_t> raw_sign(std::span<const uint8_t> msg, RandomNumberGenerator& rng) override;

      AlgorithmIdentifier algorithm_identifier() const override;

   private:
      std::shared_ptr<const DL_PrivateKey> m_key;
      BigInt m_b, m_b_inv;
};

AlgorithmIdentifier DSA_Signature_Operation::algorithm_identifier() const {
   const std::string full_name = "DSA/" + hash_function();
   const OID oid = OID::from_string(full_name);
   return AlgorithmIdentifier(oid, AlgorithmIdentifier::USE_EMPTY_PARAM);
}

std::vector<uint8_t> DSA_Signature_Operation::raw_sign(std::span<const uint8_t> msg, RandomNumberGenerator& rng) {
   const DL_Group& group = m_key->group();
   const BigInt& q = group.get_q();

   BigInt m = BigInt::from_bytes_with_max_bits(msg.data(), msg.size(), group.q_bits());

   if(m >= q) {
      m -= q;
   }

#if defined(BOTAN_HAS_RFC6979_GENERATOR)
   BOTAN_UNUSED(rng);
   const BigInt k = generate_rfc6979_nonce(m_key->private_key(), q, m, this->rfc6979_hash_function());
#else
   const BigInt k = BigInt::random_integer(rng, 1, q);
#endif

   const BigInt k_inv = group.inverse_mod_q(group.mod_q(m_b * k)) * m_b;

   /*
   * It may not be strictly necessary for the reduction (g^k mod p) mod q to be
   * const time, since r is published as part of the signature, and deriving
   * anything useful about k from g^k mod p would seem to require computing a
   * discrete logarithm.
   *
   * However it only increases the cost of signatures by about 7-10%, and DSA is
   * only for legacy use anyway so we don't care about the performance so much.
   */
   const BigInt r = ct_modulo(group.power_g_p(k, group.q_bits()), group.get_q());

   /*
   * Blind the input message and compute x*r+m as (x*r*b + m*b)/b
   */
   m_b = group.square_mod_q(m_b);
   m_b_inv = group.square_mod_q(m_b_inv);

   m = group.multiply_mod_q(m_b, m);
   const BigInt xr = group.multiply_mod_q(m_b, m_key->private_key(), r);

   const BigInt s = group.multiply_mod_q(m_b_inv, k_inv, group.mod_q(xr + m));

   // With overwhelming probability, a bug rather than actual zero r/s
   if(r.is_zero() || s.is_zero()) {
      throw Internal_Error("Computed zero r/s during DSA signature");
   }

   return unlock(BigInt::encode_fixed_length_int_pair(r, s, q.bytes()));
}

/**
* Object that can verify a DSA signature
*/
class DSA_Verification_Operation final : public PK_Ops::Verification_with_Hash {
   public:
      DSA_Verification_Operation(const std::shared_ptr<const DL_PublicKey>& key, std::string_view emsa) :
            PK_Ops::Verification_with_Hash(emsa), m_key(key) {}

      DSA_Verification_Operation(const std::shared_ptr<const DL_PublicKey>& key, const AlgorithmIdentifier& alg_id) :
            PK_Ops::Verification_with_Hash(alg_id, "DSA"), m_key(key) {}

      bool verify(std::span<const uint8_t> input, std::span<const uint8_t> sig) override;

   private:
      std::shared_ptr<const DL_PublicKey> m_key;
};

bool DSA_Verification_Operation::verify(std::span<const uint8_t> input, std::span<const uint8_t> sig) {
   const auto group = m_key->group();

   const BigInt& q = group.get_q();
   const size_t q_bytes = q.bytes();

   if(sig.size() != 2 * q_bytes) {
      return false;
   }

   BigInt r(sig.first(q_bytes));
   BigInt s(sig.last(q_bytes));

   if(r == 0 || r >= q || s == 0 || s >= q) {
      return false;
   }

   BigInt i = BigInt::from_bytes_with_max_bits(input.data(), input.size(), group.q_bits());
   if(i >= q) {
      i -= q;
   }

   s = group.inverse_mod_q(s);

   const BigInt sr = group.multiply_mod_q(s, r);
   const BigInt si = group.multiply_mod_q(s, i);

   s = group.multi_exponentiate(si, m_key->public_key(), sr);

   // s is too big for Barrett, and verification doesn't need to be const-time
   return (s % group.get_q() == r);
}

}  // namespace

std::unique_ptr<PK_Ops::Verification> DSA_PublicKey::create_verification_op(std::string_view params,
                                                                            std::string_view provider) const {
   if(provider == "base" || provider.empty()) {
      return std::make_unique<DSA_Verification_Operation>(this->m_public_key, params);
   }
   throw Provider_Not_Found(algo_name(), provider);
}

std::unique_ptr<PK_Ops::Verification> DSA_PublicKey::create_x509_verification_op(
   const AlgorithmIdentifier& signature_algorithm, std::string_view provider) const {
   if(provider == "base" || provider.empty()) {
      return std::make_unique<DSA_Verification_Operation>(this->m_public_key, signature_algorithm);
   }

   throw Provider_Not_Found(algo_name(), provider);
}

std::unique_ptr<PK_Ops::Signature> DSA_PrivateKey::create_signature_op(RandomNumberGenerator& rng,
                                                                       std::string_view params,
                                                                       std::string_view provider) const {
   if(provider == "base" || provider.empty()) {
      return std::make_unique<DSA_Signature_Operation>(this->m_private_key, params, rng);
   }
   throw Provider_Not_Found(algo_name(), provider);
}

}  // namespace Botan

1	/*
2	* DSA
3	* (C) 1999-2010,2014,2016,2023 Jack Lloyd
4	* (C) 2016 René Korthaus
5	*
6	* Botan is released under the Simplified BSD License (see license.txt)
7	*/
8
9	#include <botan/dsa.h>
10
11	#include <botan/assert.h>
12	#include <botan/internal/divide.h>
13	#include <botan/internal/dl_scheme.h>
14	#include <botan/internal/keypair.h>
15	#include <botan/internal/pk_ops_impl.h>
16
17	#if defined(BOTAN_HAS_RFC6979_GENERATOR)
18	#include <botan/internal/rfc6979.h>
19	#endif
20
21	namespace Botan {
22
23	std::optional<size_t> DSA_PublicKey::_signature_element_size_for_DER_encoding() const {	488✔
24	return m_public_key->group().q_bytes();	488✔
25	}
26
27	size_t DSA_PublicKey::estimated_strength() const {	28✔
28	return m_public_key->estimated_strength();	28✔
29	}
30
31	size_t DSA_PublicKey::key_length() const {	1✔
32	return m_public_key->p_bits();	1✔
33	}
34
35	const BigInt& DSA_PublicKey::get_int_field(std::string_view field) const {	8✔
36	return m_public_key->get_int_field(algo_name(), field);	8✔
37	}
38
39	AlgorithmIdentifier DSA_PublicKey::algorithm_identifier() const {	93✔
40	return AlgorithmIdentifier(object_identifier(), m_public_key->group().DER_encode(DL_Group_Format::ANSI_X9_57));	186✔
41	}
42
43	std::vector<uint8_t> DSA_PublicKey::raw_public_key_bits() const {	1✔
44	return m_public_key->public_key_as_bytes();	1✔
45	}
46
47	std::vector<uint8_t> DSA_PublicKey::public_key_bits() const {	68✔
48	return m_public_key->DER_encode();	68✔
49	}
50
51	bool DSA_PublicKey::check_key(RandomNumberGenerator& rng, bool strong) const {	7✔
52	return m_public_key->check_key(rng, strong);	7✔
53	}
54
55	std::unique_ptr<Private_Key> DSA_PublicKey::generate_another(RandomNumberGenerator& rng) const {	1✔
56	return std::make_unique<DSA_PrivateKey>(rng, m_public_key->group());	2✔
57	}
58
59	DSA_PublicKey::DSA_PublicKey(const AlgorithmIdentifier& alg_id, std::span<const uint8_t> key_bits) {	234✔
60	m_public_key = std::make_shared<DL_PublicKey>(alg_id, key_bits, DL_Group_Format::ANSI_X9_57);	234✔
61
62	BOTAN_ARG_CHECK(m_public_key->group().has_q(), "Q parameter must be set for DSA");	121✔
63	}	234✔
64
65	DSA_PublicKey::DSA_PublicKey(const DL_Group& group, const BigInt& y) {	5✔
66	m_public_key = std::make_shared<DL_PublicKey>(group, y);	5✔
67
68	BOTAN_ARG_CHECK(m_public_key->group().has_q(), "Q parameter must be set for DSA");	5✔
69	}	5✔
70
71	DSA_PrivateKey::DSA_PrivateKey(RandomNumberGenerator& rng, const DL_Group& group) {	21✔
72	BOTAN_ARG_CHECK(group.has_q(), "Q parameter must be set for DSA");	21✔
73
74	m_private_key = std::make_shared<DL_PrivateKey>(group, rng);	21✔
75	m_public_key = m_private_key->public_key();	21✔
76	}	21✔
77
78	DSA_PrivateKey::DSA_PrivateKey(const DL_Group& group, const BigInt& x) {	325✔
79	BOTAN_ARG_CHECK(group.has_q(), "Q parameter must be set for DSA");	325✔
80
81	m_private_key = std::make_shared<DL_PrivateKey>(group, x);	325✔
82	m_public_key = m_private_key->public_key();	325✔
83	}	325✔
84
85	DSA_PrivateKey::DSA_PrivateKey(const AlgorithmIdentifier& alg_id, std::span<const uint8_t> key_bits) {	316✔
86	m_private_key = std::make_shared<DL_PrivateKey>(alg_id, key_bits, DL_Group_Format::ANSI_X9_57);	316✔
87	m_public_key = m_private_key->public_key();	57✔
88
89	BOTAN_ARG_CHECK(m_private_key->group().has_q(), "Q parameter must be set for DSA");	57✔
90	}	316✔
91
92	bool DSA_PrivateKey::check_key(RandomNumberGenerator& rng, bool strong) const {	5✔
93	if(!m_private_key->check_key(rng, strong)) {	5✔
94	return false;
95	}
96
97	if(m_private_key->private_key() >= m_private_key->group().get_q()) {	5✔
98	return false;
99	}
100
101	return KeyPair::signature_consistency_check(rng, *this, "SHA-256");	5✔
102	}
103
104	secure_vector<uint8_t> DSA_PrivateKey::private_key_bits() const {	33✔
105	return m_private_key->DER_encode();	33✔
106	}
107
108	secure_vector<uint8_t> DSA_PrivateKey::raw_private_key_bits() const {	×
109	return m_private_key->raw_private_key_bits();	×
110	}
111
112	const BigInt& DSA_PrivateKey::get_int_field(std::string_view field) const {	10✔
113	return m_private_key->get_int_field(algo_name(), field);	10✔
114	}
115
116	std::unique_ptr<Public_Key> DSA_PrivateKey::public_key() const {	336✔
117	// can't use make_unique here due to private constructor
118	return std::unique_ptr<DSA_PublicKey>(new DSA_PublicKey(m_public_key));	336✔
119	}
120
121	namespace {
122
123	/**
124	* Object that can create a DSA signature
125	*/
126	class DSA_Signature_Operation final : public PK_Ops::Signature_with_Hash {	×
127	public:
128	DSA_Signature_Operation(const std::shared_ptr<const DL_PrivateKey>& key,	69✔
129	std::string_view emsa,
130	RandomNumberGenerator& rng) :	69✔
131	PK_Ops::Signature_with_Hash(emsa), m_key(key) {	69✔
132	m_b = BigInt::random_integer(rng, 2, m_key->group().get_q());	138✔
133	m_b_inv = m_key->group().inverse_mod_q(m_b);	138✔
134	}	69✔
135
136	size_t signature_length() const override { return 2 * m_key->group().q_bytes(); }	23✔
137
138	std::vector<uint8_t> raw_sign(std::span<const uint8_t> msg, RandomNumberGenerator& rng) override;
139
140	AlgorithmIdentifier algorithm_identifier() const override;
141
142	private:
143	std::shared_ptr<const DL_PrivateKey> m_key;
144	BigInt m_b, m_b_inv;
145	};
146
147	AlgorithmIdentifier DSA_Signature_Operation::algorithm_identifier() const {	37✔
148	const std::string full_name = "DSA/" + hash_function();	74✔
149	const OID oid = OID::from_string(full_name);	37✔
150	return AlgorithmIdentifier(oid, AlgorithmIdentifier::USE_EMPTY_PARAM);	37✔
151	}	37✔
152
153	std::vector<uint8_t> DSA_Signature_Operation::raw_sign(std::span<const uint8_t> msg, RandomNumberGenerator& rng) {	79✔
154	const DL_Group& group = m_key->group();	79✔
155	const BigInt& q = group.get_q();	79✔
156
157	BigInt m = BigInt::from_bytes_with_max_bits(msg.data(), msg.size(), group.q_bits());	79✔
158
159	if(m >= q) {	79✔
160	m -= q;	29✔
161	}
162
163	#if defined(BOTAN_HAS_RFC6979_GENERATOR)
164	BOTAN_UNUSED(rng);	79✔
165	const BigInt k = generate_rfc6979_nonce(m_key->private_key(), q, m, this->rfc6979_hash_function());	79✔
166	#else
167	const BigInt k = BigInt::random_integer(rng, 1, q);
168	#endif
169
170	const BigInt k_inv = group.inverse_mod_q(group.mod_q(m_b * k)) * m_b;	79✔
171
172	/*
173	* It may not be strictly necessary for the reduction (g^k mod p) mod q to be
174	* const time, since r is published as part of the signature, and deriving
175	* anything useful about k from g^k mod p would seem to require computing a
176	* discrete logarithm.
177	*
178	* However it only increases the cost of signatures by about 7-10%, and DSA is
179	* only for legacy use anyway so we don't care about the performance so much.
180	*/
181	const BigInt r = ct_modulo(group.power_g_p(k, group.q_bits()), group.get_q());	79✔
182
183	/*
184	* Blind the input message and compute xr+m as (xrb + mb)/b
185	*/
186	m_b = group.square_mod_q(m_b);	79✔
187	m_b_inv = group.square_mod_q(m_b_inv);	79✔
188
189	m = group.multiply_mod_q(m_b, m);	79✔
190	const BigInt xr = group.multiply_mod_q(m_b, m_key->private_key(), r);	79✔
191
192	const BigInt s = group.multiply_mod_q(m_b_inv, k_inv, group.mod_q(xr + m));	79✔
193
194	// With overwhelming probability, a bug rather than actual zero r/s
195	if(r.is_zero() \|\| s.is_zero()) {	158✔
196	throw Internal_Error("Computed zero r/s during DSA signature");	×
197	}
198
199	return unlock(BigInt::encode_fixed_length_int_pair(r, s, q.bytes()));	237✔
200	}	79✔
201
202	/**
203	* Object that can verify a DSA signature
204	*/
205	class DSA_Verification_Operation final : public PK_Ops::Verification_with_Hash {	×
206	public:
207	DSA_Verification_Operation(const std::shared_ptr<const DL_PublicKey>& key, std::string_view emsa) :	336✔
208	PK_Ops::Verification_with_Hash(emsa), m_key(key) {}	336✔
209
210	DSA_Verification_Operation(const std::shared_ptr<const DL_PublicKey>& key, const AlgorithmIdentifier& alg_id) :	80✔
211	PK_Ops::Verification_with_Hash(alg_id, "DSA"), m_key(key) {}	80✔
212
213	bool verify(std::span<const uint8_t> input, std::span<const uint8_t> sig) override;
214
215	private:
216	std::shared_ptr<const DL_PublicKey> m_key;
217	};
218
219	bool DSA_Verification_Operation::verify(std::span<const uint8_t> input, std::span<const uint8_t> sig) {	7,241✔
220	const auto group = m_key->group();	7,241✔
221
222	const BigInt& q = group.get_q();	7,241✔
223	const size_t q_bytes = q.bytes();	7,241✔
224
225	if(sig.size() != 2 * q_bytes) {	7,241✔
226	return false;
227	}
228
229	BigInt r(sig.first(q_bytes));	7,241✔
230	BigInt s(sig.last(q_bytes));	7,241✔
231
232	if(r == 0 \|\| r >= q \|\| s == 0 \|\| s >= q) {	27,901✔
233	return false;	406✔
234	}
235
236	BigInt i = BigInt::from_bytes_with_max_bits(input.data(), input.size(), group.q_bits());	6,835✔
237	if(i >= q) {	6,835✔
238	i -= q;	1,297✔
239	}
240
241	s = group.inverse_mod_q(s);	6,835✔
242
243	const BigInt sr = group.multiply_mod_q(s, r);	6,835✔
244	const BigInt si = group.multiply_mod_q(s, i);	6,835✔
245
246	s = group.multi_exponentiate(si, m_key->public_key(), sr);	6,835✔
247
248	// s is too big for Barrett, and verification doesn't need to be const-time
249	return (s % group.get_q() == r);	13,670✔
250	}	14,482✔
251
252	} // namespace
253
254	std::unique_ptr<PK_Ops::Verification> DSA_PublicKey::create_verification_op(std::string_view params,	1,311✔
255	std::string_view provider) const {
256	if(provider == "base" \|\| provider.empty()) {	1,637✔
257	return std::make_unique<DSA_Verification_Operation>(this->m_public_key, params);	336✔
258	}
259	throw Provider_Not_Found(algo_name(), provider);	1,950✔
260	}
261
262	std::unique_ptr<PK_Ops::Verification> DSA_PublicKey::create_x509_verification_op(	80✔
263	const AlgorithmIdentifier& signature_algorithm, std::string_view provider) const {
264	if(provider == "base" \|\| provider.empty()) {	80✔
265	return std::make_unique<DSA_Verification_Operation>(this->m_public_key, signature_algorithm);	80✔
266	}
267
268	throw Provider_Not_Found(algo_name(), provider);	×
269	}
270
271	std::unique_ptr<PK_Ops::Signature> DSA_PrivateKey::create_signature_op(RandomNumberGenerator& rng,	132✔
272	std::string_view params,
273	std::string_view provider) const {
274	if(provider == "base" \|\| provider.empty()) {	154✔
275	return std::make_unique<DSA_Signature_Operation>(this->m_private_key, params, rng);	69✔
276	}
277	throw Provider_Not_Found(algo_name(), provider);	126✔
278	}
279
280	} // namespace Botan

randombit / botan / 13230468750

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