/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,
};

/**
* 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 };

      /**
      * The DL group encoding format variants.
      */
      enum 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
      };

      /**
      * 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, Format format);

      /**
      * Decode a BER-encoded DL group param
      */
      template<typename Alloc>
         DL_Group(const std::vector<uint8_t, Alloc>& ber, 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(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(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;

      /**
      * 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, 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: 2020-11-21 08:34

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		* This class represents discrete logarithm groups. It holds a prime
26		* modulus p, a generator g, and (optionally) a prime q which is a
27		* factor of (p-1). In most cases g generates the order-q subgroup.
28		*/
29		class BOTAN_PUBLIC_API(2,0) DL_Group final
30		{
31		public:
32		/**
33		* Determine the prime creation for DL groups.
34		*/
35		enum PrimeType { Strong, Prime_Subgroup, DSA_Kosherizer };
36
37		/**
38		* The DL group encoding format variants.
39		*/
40		enum Format {
41		ANSI_X9_42,
42		ANSI_X9_57,
43		PKCS_3,
44
45		DSA_PARAMETERS = ANSI_X9_57,
46		DH_PARAMETERS = ANSI_X9_42,
47		ANSI_X9_42_DH_PARAMETERS = ANSI_X9_42,
48		PKCS3_DH_PARAMETERS = PKCS_3
49		};
50
51		/**
52		* Construct a DL group with uninitialized internal value.
53		* Use this constructor is you wish to set the groups values
54		* from a DER or PEM encoded group.
55		*/
56	6.59k	DL_Group() = default;
57
58		/**
59		* Construct a DL group that is registered in the configuration.
60		* @param name the name of the group, for example "modp/ietf/3072"
61		*
62		* @warning This constructor also accepts PEM inputs. This behavior is
63		* deprecated and will be removed in a future major release. Instead
64		* use DL_Group_from_PEM function
65		*/
66		explicit DL_Group(const std::string& name);
67
68		/*
69		* Read a PEM representation
70		*/
71		static DL_Group DL_Group_from_PEM(const std::string& pem);
72
73		/**
74		* Create a new group randomly.
75		* @param rng the random number generator to use
76		* @param type specifies how the creation of primes p and q shall
77		* be performed. If type=Strong, then p will be determined as a
78		* safe prime, and q will be chosen as (p-1)/2. If
79		* type=Prime_Subgroup and qbits = 0, then the size of q will be
80		* determined according to the estimated difficulty of the DL
81		* problem. If type=DSA_Kosherizer, DSA primes will be created.
82		* @param pbits the number of bits of p
83		* @param qbits the number of bits of q. Leave it as 0 to have
84		* the value determined according to pbits.
85		*/
86		DL_Group(RandomNumberGenerator& rng, PrimeType type,
87		size_t pbits, size_t qbits = 0);
88
89		/**
90		* Create a DSA group with a given seed.
91		* @param rng the random number generator to use
92		* @param seed the seed to use to create the random primes
93		* @param pbits the desired bit size of the prime p
94		* @param qbits the desired bit size of the prime q.
95		*/
96		DL_Group(RandomNumberGenerator& rng,
97		const std::vector<uint8_t>& seed,
98		size_t pbits = 1024, size_t qbits = 0);
99
100		/**
101		* Create a DL group.
102		* @param p the prime p
103		* @param g the base g
104		*/
105		DL_Group(const BigInt& p, const BigInt& g);
106
107		/**
108		* Create a DL group.
109		* @param p the prime p
110		* @param q the prime q
111		* @param g the base g
112		*/
113		DL_Group(const BigInt& p, const BigInt& q, const BigInt& g);
114
115		/**
116		* Decode a BER-encoded DL group param
117		*/
118		DL_Group(const uint8_t ber[], size_t ber_len, Format format);
119
120		/**
121		* Decode a BER-encoded DL group param
122		*/
123		template<typename Alloc>
124		DL_Group(const std::vector<uint8_t, Alloc>& ber, Format format) :
125	225	DL_Group(ber.data(), ber.size(), format) {}
126
127		/**
128		* Get the prime p.
129		* @return prime p
130		*/
131		const BigInt& get_p() const;
132
133		/**
134		* Get the prime q, returns zero if q is not used
135		* @return prime q
136		*/
137		const BigInt& get_q() const;
138
139		/**
140		* Get the base g.
141		* @return base g
142		*/
143		const BigInt& get_g() const;
144
145		/**
146		* Perform validity checks on the group.
147		* @param rng the rng to use
148		* @param strong whether to perform stronger by lengthier tests
149		* @return true if the object is consistent, false otherwise
150		*/
151		bool verify_group(RandomNumberGenerator& rng, bool strong = true) const;
152
153		/**
154		* Verify a public element, ie check if y = g^x for some x.
155		*
156		* This is not a perfect test. It verifies that 1 < y < p and (if q is set)
157		* that y is in the subgroup of size q.
158		*/
159		bool verify_public_element(const BigInt& y) const;
160
161		/**
162		* Verify a pair of elements y = g^x
163		*
164		* This verifies that 1 < x,y < p and that y=g^x mod p
165		*/
166		bool verify_element_pair(const BigInt& y, const BigInt& x) const;
167
168		/**
169		* Encode this group into a string using PEM encoding.
170		* @param format the encoding format
171		* @return string holding the PEM encoded group
172		*/
173		std::string PEM_encode(Format format) const;
174
175		/**
176		* Encode this group into a string using DER encoding.
177		* @param format the encoding format
178		* @return string holding the DER encoded group
179		*/
180		std::vector<uint8_t> DER_encode(Format format) const;
181
182		/**
183		* Reduce an integer modulo p
184		* @return x % p
185		*/
186		BigInt mod_p(const BigInt& x) const;
187
188		/**
189		* Multiply and reduce an integer modulo p
190		* @return (x*y) % p
191		*/
192		BigInt multiply_mod_p(const BigInt& x, const BigInt& y) const;
193
194		/**
195		* Return the inverse of x mod p
196		*/
197		BigInt inverse_mod_p(const BigInt& x) const;
198
199		/**
200		* Reduce an integer modulo q
201		* Throws if q is unset on this DL_Group
202		* @return x % q
203		*/
204		BigInt mod_q(const BigInt& x) const;
205
206		/**
207		* Multiply and reduce an integer modulo q
208		* Throws if q is unset on this DL_Group
209		* @return (x*y) % q
210		*/
211		BigInt multiply_mod_q(const BigInt& x, const BigInt& y) const;
212
213		/**
214		* Multiply and reduce an integer modulo q
215		* Throws if q is unset on this DL_Group
216		* @return (xyz) % q
217		*/
218		BigInt multiply_mod_q(const BigInt& x, const BigInt& y, const BigInt& z) const;
219
220		/**
221		* Square and reduce an integer modulo q
222		* Throws if q is unset on this DL_Group
223		* @return (x*x) % q
224		*/
225		BigInt square_mod_q(const BigInt& x) const;
226
227		/**
228		* Return the inverse of x mod q
229		* Throws if q is unset on this DL_Group
230		*/
231		BigInt inverse_mod_q(const BigInt& x) const;
232
233		/**
234		* Modular exponentiation
235		*
236		* @warning this function leaks the size of x via the number of
237		* loop iterations. Use the version taking the maximum size to
238		* avoid this.
239		*
240		* @return (g^x) % p
241		*/
242		BigInt power_g_p(const BigInt& x) const;
243
244		/**
245		* Modular exponentiation
246		* @param x the exponent
247		* @param max_x_bits x is assumed to be at most this many bits long.
248		*
249		* @return (g^x) % p
250		*/
251		BigInt power_g_p(const BigInt& x, size_t max_x_bits) const;
252
253		/**
254		* Multi-exponentiate
255		* Return (g^x * y^z) % p
256		*/
257		BigInt multi_exponentiate(const BigInt& x, const BigInt& y, const BigInt& z) const;
258
259		/**
260		* Return parameters for Montgomery reduction/exponentiation mod p
261		*/
262		std::shared_ptr<const Montgomery_Params> monty_params_p() const;
263
264		/**
265		* Return the size of p in bits
266		* Same as get_p().bits()
267		*/
268		size_t p_bits() const;
269
270		/**
271		* Return the size of p in bytes
272		* Same as get_p().bytes()
273		*/
274		size_t p_bytes() const;
275
276		/**
277		* Return the size of q in bits
278		* Same as get_q().bits()
279		* Throws if q is unset
280		*/
281		size_t q_bits() const;
282
283		/**
284		* Return the size of q in bytes
285		* Same as get_q().bytes()
286		* Throws if q is unset
287		*/
288		size_t q_bytes() const;
289
290		/**
291		* Return size in bits of a secret exponent
292		*
293		* This attempts to balance between the attack costs of NFS
294		* (which depends on the size of the modulus) and Pollard's rho
295		* (which depends on the size of the exponent).
296		*
297		* It may vary over time for a particular group, if the attack
298		* costs change.
299		*/
300		size_t exponent_bits() const;
301
302		/**
303		* Return an estimate of the strength of this group against
304		* discrete logarithm attacks (eg NFS). Warning: since this only
305		* takes into account known attacks it is by necessity an
306		* overestimate of the actual strength.
307		*/
308		size_t estimated_strength() const;
309
310		/**
311		* Decode a DER/BER encoded group into this instance.
312		* @param ber a vector containing the DER/BER encoded group
313		* @param format the format of the encoded group
314		*
315		* @warning avoid this. Instead use the DL_Group constructor
316		*/
317		void BER_decode(const std::vector<uint8_t>& ber, Format format);
318
319		DL_Group_Source source() const;
320
321		/*
322		* For internal use only
323		*/
324		static std::shared_ptr<DL_Group_Data> DL_group_info(const std::string& name);
325
326		private:
327		static std::shared_ptr<DL_Group_Data> load_DL_group_info(const char* p_str,
328		const char* q_str,
329		const char* g_str);
330
331		static std::shared_ptr<DL_Group_Data> load_DL_group_info(const char* p_str,
332		const char* g_str);
333
334		static std::shared_ptr<DL_Group_Data>
335		BER_decode_DL_group(const uint8_t data[], size_t data_len,
336		DL_Group::Format format,
337		DL_Group_Source source);
338
339		const DL_Group_Data& data() const;
340		std::shared_ptr<DL_Group_Data> m_data;
341		};
342
343		}
344
345		#endif