/src/botan/build/include/botan/dl_group.h

Source
/*
* Discrete Logarithm Group
* (C) 1999-2008,2018 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#ifndef BOTAN_DL_PARAM_H_
#define BOTAN_DL_PARAM_H_

#include <botan/bigint.h>

namespace Botan {

class Montgomery_Params;
class DL_Group_Data;

enum class DL_Group_Source {
   Builtin,
   RandomlyGenerated,
   ExternalSource,
};

/**
* The DL group encoding format variants.
*/
enum class DL_Group_Format {
   ANSI_X9_42,
   ANSI_X9_57,
   PKCS_3,

   DSA_PARAMETERS = ANSI_X9_57,
   DH_PARAMETERS = ANSI_X9_42,
   ANSI_X9_42_DH_PARAMETERS = ANSI_X9_42,
   PKCS3_DH_PARAMETERS = PKCS_3
};

/**
* This class represents discrete logarithm groups. It holds a prime
* modulus p, a generator g, and (optionally) a prime q which is a
* factor of (p-1). In most cases g generates the order-q subgroup.
*/
class BOTAN_PUBLIC_API(2,0) DL_Group final
   {
   public:
      /**
      * Determine the prime creation for DL groups.
      */
      enum PrimeType { Strong, Prime_Subgroup, DSA_Kosherizer };

      using Format = DL_Group_Format;

      /**
      * Construct a DL group with uninitialized internal value.
      * Use this constructor is you wish to set the groups values
      * from a DER or PEM encoded group.
      */
      DL_Group() = default;

      /**
      * Construct a DL group that is registered in the configuration.
      * @param name the name of the group, for example "modp/ietf/3072"
      *
      * @warning This constructor also accepts PEM inputs. This behavior is
      * deprecated and will be removed in a future major release. Instead
      * use DL_Group_from_PEM function
      */
      explicit DL_Group(const std::string& name);

      /*
      * Read a PEM representation
      */
      static DL_Group DL_Group_from_PEM(const std::string& pem);

      /**
      * Create a new group randomly.
      * @param rng the random number generator to use
      * @param type specifies how the creation of primes p and q shall
      * be performed. If type=Strong, then p will be determined as a
      * safe prime, and q will be chosen as (p-1)/2. If
      * type=Prime_Subgroup and qbits = 0, then the size of q will be
      * determined according to the estimated difficulty of the DL
      * problem. If type=DSA_Kosherizer, DSA primes will be created.
      * @param pbits the number of bits of p
      * @param qbits the number of bits of q. Leave it as 0 to have
      * the value determined according to pbits.
      */
      DL_Group(RandomNumberGenerator& rng, PrimeType type,
               size_t pbits, size_t qbits = 0);

      /**
      * Create a DSA group with a given seed.
      * @param rng the random number generator to use
      * @param seed the seed to use to create the random primes
      * @param pbits the desired bit size of the prime p
      * @param qbits the desired bit size of the prime q.
      */
      DL_Group(RandomNumberGenerator& rng,
               const std::vector<uint8_t>& seed,
               size_t pbits = 1024, size_t qbits = 0);

      /**
      * Create a DL group.
      * @param p the prime p
      * @param g the base g
      */
      DL_Group(const BigInt& p, const BigInt& g);

      /**
      * Create a DL group.
      * @param p the prime p
      * @param q the prime q
      * @param g the base g
      */
      DL_Group(const BigInt& p, const BigInt& q, const BigInt& g);

      /**
      * Decode a BER-encoded DL group param
      */
      DL_Group(const uint8_t ber[], size_t ber_len, DL_Group_Format format);

      /**
      * Decode a BER-encoded DL group param
      */
      template<typename Alloc>
         DL_Group(const std::vector<uint8_t, Alloc>& ber, DL_Group_Format format) :
         DL_Group(ber.data(), ber.size(), format) {}

      /**
      * Get the prime p.
      * @return prime p
      */
      const BigInt& get_p() const;

      /**
      * Get the prime q, returns zero if q is not used
      * @return prime q
      */
      const BigInt& get_q() const;

      /**
      * Get the base g.
      * @return base g
      */
      const BigInt& get_g() const;

      /**
      * Perform validity checks on the group.
      * @param rng the rng to use
      * @param strong whether to perform stronger by lengthier tests
      * @return true if the object is consistent, false otherwise
      */
      bool verify_group(RandomNumberGenerator& rng, bool strong = true) const;

      /**
      * Verify a public element, ie check if y = g^x for some x.
      *
      * This is not a perfect test. It verifies that 1 < y < p and (if q is set)
      * that y is in the subgroup of size q.
      */
      bool verify_public_element(const BigInt& y) const;

      /**
      * Verify a pair of elements y = g^x
      *
      * This verifies that 1 < x,y < p and that y=g^x mod p
      */
      bool verify_element_pair(const BigInt& y, const BigInt& x) const;

      /**
      * Encode this group into a string using PEM encoding.
      * @param format the encoding format
      * @return string holding the PEM encoded group
      */
      std::string PEM_encode(DL_Group_Format format) const;

      /**
      * Encode this group into a string using DER encoding.
      * @param format the encoding format
      * @return string holding the DER encoded group
      */
      std::vector<uint8_t> DER_encode(DL_Group_Format format) const;

      /**
      * Reduce an integer modulo p
      * @return x % p
      */
      BigInt mod_p(const BigInt& x) const;

      /**
      * Multiply and reduce an integer modulo p
      * @return (x*y) % p
      */
      BigInt multiply_mod_p(const BigInt& x, const BigInt& y) const;

      /**
      * Return the inverse of x mod p
      */
      BigInt inverse_mod_p(const BigInt& x) const;

      /**
      * Reduce an integer modulo q
      * Throws if q is unset on this DL_Group
      * @return x % q
      */
      BigInt mod_q(const BigInt& x) const;

      /**
      * Multiply and reduce an integer modulo q
      * Throws if q is unset on this DL_Group
      * @return (x*y) % q
      */
      BigInt multiply_mod_q(const BigInt& x, const BigInt& y) const;

      /**
      * Multiply and reduce an integer modulo q
      * Throws if q is unset on this DL_Group
      * @return (x*y*z) % q
      */
      BigInt multiply_mod_q(const BigInt& x, const BigInt& y, const BigInt& z) const;

      /**
      * Square and reduce an integer modulo q
      * Throws if q is unset on this DL_Group
      * @return (x*x) % q
      */
      BigInt square_mod_q(const BigInt& x) const;

      /**
      * Return the inverse of x mod q
      * Throws if q is unset on this DL_Group
      */
      BigInt inverse_mod_q(const BigInt& x) const;

      /**
      * Modular exponentiation
      *
      * @warning this function leaks the size of x via the number of
      * loop iterations. Use the version taking the maximum size to
      * avoid this.
      *
      * @return (g^x) % p
      */
      BigInt power_g_p(const BigInt& x) const;

      /**
      * Modular exponentiation
      * @param x the exponent
      * @param max_x_bits x is assumed to be at most this many bits long.
      *
      * @return (g^x) % p
      */
      BigInt power_g_p(const BigInt& x, size_t max_x_bits) const;

      /**
      * Modular exponentiation
      * @param b the base
      * @param x the exponent
      * @param max_x_bits x is assumed to be at most this many bits long.
      *
      * @return (b^x) % p
      */
      BigInt power_b_p(const BigInt& b, const BigInt& x, size_t max_x_bits) const;

      /**
      * Multi-exponentiate
      * Return (g^x * y^z) % p
      */
      BigInt multi_exponentiate(const BigInt& x, const BigInt& y, const BigInt& z) const;

      /**
      * Return parameters for Montgomery reduction/exponentiation mod p
      */
      std::shared_ptr<const Montgomery_Params> monty_params_p() const;

      /**
      * Return the size of p in bits
      * Same as get_p().bits()
      */
      size_t p_bits() const;

      /**
      * Return the size of p in bytes
      * Same as get_p().bytes()
      */
      size_t p_bytes() const;

      /**
      * Return the size of q in bits
      * Same as get_q().bits()
      * Throws if q is unset
      */
      size_t q_bits() const;

      /**
      * Return the size of q in bytes
      * Same as get_q().bytes()
      * Throws if q is unset
      */
      size_t q_bytes() const;

      /**
      * Return size in bits of a secret exponent
      *
      * This attempts to balance between the attack costs of NFS
      * (which depends on the size of the modulus) and Pollard's rho
      * (which depends on the size of the exponent).
      *
      * It may vary over time for a particular group, if the attack
      * costs change.
      */
      size_t exponent_bits() const;

      /**
      * Return an estimate of the strength of this group against
      * discrete logarithm attacks (eg NFS). Warning: since this only
      * takes into account known attacks it is by necessity an
      * overestimate of the actual strength.
      */
      size_t estimated_strength() const;

      /**
      * Decode a DER/BER encoded group into this instance.
      * @param ber a vector containing the DER/BER encoded group
      * @param format the format of the encoded group
      *
      * @warning avoid this. Instead use the DL_Group constructor
      */
      void BER_decode(const std::vector<uint8_t>& ber, DL_Group_Format format);

      DL_Group_Source source() const;

      /*
      * For internal use only
      */
      static std::shared_ptr<DL_Group_Data> DL_group_info(const std::string& name);

   private:
      static std::shared_ptr<DL_Group_Data> load_DL_group_info(const char* p_str,
                                                               const char* q_str,
                                                               const char* g_str);

      static std::shared_ptr<DL_Group_Data> load_DL_group_info(const char* p_str,
                                                               const char* g_str);

      static std::shared_ptr<DL_Group_Data>
         BER_decode_DL_group(const uint8_t data[], size_t data_len,
                             DL_Group_Format format,
                             DL_Group_Source source);

      const DL_Group_Data& data() const;
      std::shared_ptr<DL_Group_Data> m_data;
   };

}

#endif

Coverage Report

Created: 2021-02-21 07:20

Line	Count	Source
1		/*
2		* Discrete Logarithm Group
3		* (C) 1999-2008,2018 Jack Lloyd
4		*
5		* Botan is released under the Simplified BSD License (see license.txt)
6		*/
7
8		#ifndef BOTAN_DL_PARAM_H_
9		#define BOTAN_DL_PARAM_H_
10
11		#include <botan/bigint.h>
12
13		namespace Botan {
14
15		class Montgomery_Params;
16		class DL_Group_Data;
17
18		enum class DL_Group_Source {
19		Builtin,
20		RandomlyGenerated,
21		ExternalSource,
22		};
23
24		/**
25		* The DL group encoding format variants.
26		*/
27		enum class DL_Group_Format {
28		ANSI_X9_42,
29		ANSI_X9_57,
30		PKCS_3,
31
32		DSA_PARAMETERS = ANSI_X9_57,
33		DH_PARAMETERS = ANSI_X9_42,
34		ANSI_X9_42_DH_PARAMETERS = ANSI_X9_42,
35		PKCS3_DH_PARAMETERS = PKCS_3
36		};
37
38		/**
39		* This class represents discrete logarithm groups. It holds a prime
40		* modulus p, a generator g, and (optionally) a prime q which is a
41		* factor of (p-1). In most cases g generates the order-q subgroup.
42		*/
43		class BOTAN_PUBLIC_API(2,0) DL_Group final
44		{
45		public:
46		/**
47		* Determine the prime creation for DL groups.
48		*/
49		enum PrimeType { Strong, Prime_Subgroup, DSA_Kosherizer };
50
51		using Format = DL_Group_Format;
52
53		/**
54		* Construct a DL group with uninitialized internal value.
55		* Use this constructor is you wish to set the groups values
56		* from a DER or PEM encoded group.
57		*/
58	218	DL_Group() = default;
59
60		/**
61		* Construct a DL group that is registered in the configuration.
62		* @param name the name of the group, for example "modp/ietf/3072"
63		*
64		* @warning This constructor also accepts PEM inputs. This behavior is
65		* deprecated and will be removed in a future major release. Instead
66		* use DL_Group_from_PEM function
67		*/
68		explicit DL_Group(const std::string& name);
69
70		/*
71		* Read a PEM representation
72		*/
73		static DL_Group DL_Group_from_PEM(const std::string& pem);
74
75		/**
76		* Create a new group randomly.
77		* @param rng the random number generator to use
78		* @param type specifies how the creation of primes p and q shall
79		* be performed. If type=Strong, then p will be determined as a
80		* safe prime, and q will be chosen as (p-1)/2. If
81		* type=Prime_Subgroup and qbits = 0, then the size of q will be
82		* determined according to the estimated difficulty of the DL
83		* problem. If type=DSA_Kosherizer, DSA primes will be created.
84		* @param pbits the number of bits of p
85		* @param qbits the number of bits of q. Leave it as 0 to have
86		* the value determined according to pbits.
87		*/
88		DL_Group(RandomNumberGenerator& rng, PrimeType type,
89		size_t pbits, size_t qbits = 0);
90
91		/**
92		* Create a DSA group with a given seed.
93		* @param rng the random number generator to use
94		* @param seed the seed to use to create the random primes
95		* @param pbits the desired bit size of the prime p
96		* @param qbits the desired bit size of the prime q.
97		*/
98		DL_Group(RandomNumberGenerator& rng,
99		const std::vector<uint8_t>& seed,
100		size_t pbits = 1024, size_t qbits = 0);
101
102		/**
103		* Create a DL group.
104		* @param p the prime p
105		* @param g the base g
106		*/
107		DL_Group(const BigInt& p, const BigInt& g);
108
109		/**
110		* Create a DL group.
111		* @param p the prime p
112		* @param q the prime q
113		* @param g the base g
114		*/
115		DL_Group(const BigInt& p, const BigInt& q, const BigInt& g);
116
117		/**
118		* Decode a BER-encoded DL group param
119		*/
120		DL_Group(const uint8_t ber[], size_t ber_len, DL_Group_Format format);
121
122		/**
123		* Decode a BER-encoded DL group param
124		*/
125		template<typename Alloc>
126		DL_Group(const std::vector<uint8_t, Alloc>& ber, DL_Group_Format format) :
127	260	DL_Group(ber.data(), ber.size(), format) {}
128
129		/**
130		* Get the prime p.
131		* @return prime p
132		*/
133		const BigInt& get_p() const;
134
135		/**
136		* Get the prime q, returns zero if q is not used
137		* @return prime q
138		*/
139		const BigInt& get_q() const;
140
141		/**
142		* Get the base g.
143		* @return base g
144		*/
145		const BigInt& get_g() const;
146
147		/**
148		* Perform validity checks on the group.
149		* @param rng the rng to use
150		* @param strong whether to perform stronger by lengthier tests
151		* @return true if the object is consistent, false otherwise
152		*/
153		bool verify_group(RandomNumberGenerator& rng, bool strong = true) const;
154
155		/**
156		* Verify a public element, ie check if y = g^x for some x.
157		*
158		* This is not a perfect test. It verifies that 1 < y < p and (if q is set)
159		* that y is in the subgroup of size q.
160		*/
161		bool verify_public_element(const BigInt& y) const;
162
163		/**
164		* Verify a pair of elements y = g^x
165		*
166		* This verifies that 1 < x,y < p and that y=g^x mod p
167		*/
168		bool verify_element_pair(const BigInt& y, const BigInt& x) const;
169
170		/**
171		* Encode this group into a string using PEM encoding.
172		* @param format the encoding format
173		* @return string holding the PEM encoded group
174		*/
175		std::string PEM_encode(DL_Group_Format format) const;
176
177		/**
178		* Encode this group into a string using DER encoding.
179		* @param format the encoding format
180		* @return string holding the DER encoded group
181		*/
182		std::vector<uint8_t> DER_encode(DL_Group_Format format) const;
183
184		/**
185		* Reduce an integer modulo p
186		* @return x % p
187		*/
188		BigInt mod_p(const BigInt& x) const;
189
190		/**
191		* Multiply and reduce an integer modulo p
192		* @return (x*y) % p
193		*/
194		BigInt multiply_mod_p(const BigInt& x, const BigInt& y) const;
195
196		/**
197		* Return the inverse of x mod p
198		*/
199		BigInt inverse_mod_p(const BigInt& x) const;
200
201		/**
202		* Reduce an integer modulo q
203		* Throws if q is unset on this DL_Group
204		* @return x % q
205		*/
206		BigInt mod_q(const BigInt& x) const;
207
208		/**
209		* Multiply and reduce an integer modulo q
210		* Throws if q is unset on this DL_Group
211		* @return (x*y) % q
212		*/
213		BigInt multiply_mod_q(const BigInt& x, const BigInt& y) const;
214
215		/**
216		* Multiply and reduce an integer modulo q
217		* Throws if q is unset on this DL_Group
218		* @return (xyz) % q
219		*/
220		BigInt multiply_mod_q(const BigInt& x, const BigInt& y, const BigInt& z) const;
221
222		/**
223		* Square and reduce an integer modulo q
224		* Throws if q is unset on this DL_Group
225		* @return (x*x) % q
226		*/
227		BigInt square_mod_q(const BigInt& x) const;
228
229		/**
230		* Return the inverse of x mod q
231		* Throws if q is unset on this DL_Group
232		*/
233		BigInt inverse_mod_q(const BigInt& x) const;
234
235		/**
236		* Modular exponentiation
237		*
238		* @warning this function leaks the size of x via the number of
239		* loop iterations. Use the version taking the maximum size to
240		* avoid this.
241		*
242		* @return (g^x) % p
243		*/
244		BigInt power_g_p(const BigInt& x) const;
245
246		/**
247		* Modular exponentiation
248		* @param x the exponent
249		* @param max_x_bits x is assumed to be at most this many bits long.
250		*
251		* @return (g^x) % p
252		*/
253		BigInt power_g_p(const BigInt& x, size_t max_x_bits) const;
254
255		/**
256		* Modular exponentiation
257		* @param b the base
258		* @param x the exponent
259		* @param max_x_bits x is assumed to be at most this many bits long.
260		*
261		* @return (b^x) % p
262		*/
263		BigInt power_b_p(const BigInt& b, const BigInt& x, size_t max_x_bits) const;
264
265		/**
266		* Multi-exponentiate
267		* Return (g^x * y^z) % p
268		*/
269		BigInt multi_exponentiate(const BigInt& x, const BigInt& y, const BigInt& z) const;
270
271		/**
272		* Return parameters for Montgomery reduction/exponentiation mod p
273		*/
274		std::shared_ptr<const Montgomery_Params> monty_params_p() const;
275
276		/**
277		* Return the size of p in bits
278		* Same as get_p().bits()
279		*/
280		size_t p_bits() const;
281
282		/**
283		* Return the size of p in bytes
284		* Same as get_p().bytes()
285		*/
286		size_t p_bytes() const;
287
288		/**
289		* Return the size of q in bits
290		* Same as get_q().bits()
291		* Throws if q is unset
292		*/
293		size_t q_bits() const;
294
295		/**
296		* Return the size of q in bytes
297		* Same as get_q().bytes()
298		* Throws if q is unset
299		*/
300		size_t q_bytes() const;
301
302		/**
303		* Return size in bits of a secret exponent
304		*
305		* This attempts to balance between the attack costs of NFS
306		* (which depends on the size of the modulus) and Pollard's rho
307		* (which depends on the size of the exponent).
308		*
309		* It may vary over time for a particular group, if the attack
310		* costs change.
311		*/
312		size_t exponent_bits() const;
313
314		/**
315		* Return an estimate of the strength of this group against
316		* discrete logarithm attacks (eg NFS). Warning: since this only
317		* takes into account known attacks it is by necessity an
318		* overestimate of the actual strength.
319		*/
320		size_t estimated_strength() const;
321
322		/**
323		* Decode a DER/BER encoded group into this instance.
324		* @param ber a vector containing the DER/BER encoded group
325		* @param format the format of the encoded group
326		*
327		* @warning avoid this. Instead use the DL_Group constructor
328		*/
329		void BER_decode(const std::vector<uint8_t>& ber, DL_Group_Format format);
330
331		DL_Group_Source source() const;
332
333		/*
334		* For internal use only
335		*/
336		static std::shared_ptr<DL_Group_Data> DL_group_info(const std::string& name);
337
338		private:
339		static std::shared_ptr<DL_Group_Data> load_DL_group_info(const char* p_str,
340		const char* q_str,
341		const char* g_str);
342
343		static std::shared_ptr<DL_Group_Data> load_DL_group_info(const char* p_str,
344		const char* g_str);
345
346		static std::shared_ptr<DL_Group_Data>
347		BER_decode_DL_group(const uint8_t data[], size_t data_len,
348		DL_Group_Format format,
349		DL_Group_Source source);
350
351		const DL_Group_Data& data() const;
352		std::shared_ptr<DL_Group_Data> m_data;
353		};
354
355		}
356
357		#endif