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+// nbtheory.h - written and placed in the public domain by Wei Dai
+
+#ifndef CRYPTOPP_NBTHEORY_H
+#define CRYPTOPP_NBTHEORY_H
+
+#include "integer.h"
+#include "algparam.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+// obtain pointer to small prime table and get its size
+CRYPTOPP_DLL const word16 * CRYPTOPP_API GetPrimeTable(unsigned int &size);
+
+// ************ primality testing ****************
+
+// generate a provable prime
+CRYPTOPP_DLL Integer CRYPTOPP_API MaurerProvablePrime(RandomNumberGenerator &rng, unsigned int bits);
+CRYPTOPP_DLL Integer CRYPTOPP_API MihailescuProvablePrime(RandomNumberGenerator &rng, unsigned int bits);
+
+CRYPTOPP_DLL bool CRYPTOPP_API IsSmallPrime(const Integer &p);
+
+// returns true if p is divisible by some prime less than bound
+// bound not be greater than the largest entry in the prime table
+CRYPTOPP_DLL bool CRYPTOPP_API TrialDivision(const Integer &p, unsigned bound);
+
+// returns true if p is NOT divisible by small primes
+CRYPTOPP_DLL bool CRYPTOPP_API SmallDivisorsTest(const Integer &p);
+
+// These is no reason to use these two, use the ones below instead
+CRYPTOPP_DLL bool CRYPTOPP_API IsFermatProbablePrime(const Integer &n, const Integer &b);
+CRYPTOPP_DLL bool CRYPTOPP_API IsLucasProbablePrime(const Integer &n);
+
+CRYPTOPP_DLL bool CRYPTOPP_API IsStrongProbablePrime(const Integer &n, const Integer &b);
+CRYPTOPP_DLL bool CRYPTOPP_API IsStrongLucasProbablePrime(const Integer &n);
+
+// Rabin-Miller primality test, i.e. repeating the strong probable prime test
+// for several rounds with random bases
+CRYPTOPP_DLL bool CRYPTOPP_API RabinMillerTest(RandomNumberGenerator &rng, const Integer &w, unsigned int rounds);
+
+// primality test, used to generate primes
+CRYPTOPP_DLL bool CRYPTOPP_API IsPrime(const Integer &p);
+
+// more reliable than IsPrime(), used to verify primes generated by others
+CRYPTOPP_DLL bool CRYPTOPP_API VerifyPrime(RandomNumberGenerator &rng, const Integer &p, unsigned int level = 1);
+
+class CRYPTOPP_DLL PrimeSelector
+{
+public:
+ const PrimeSelector *GetSelectorPointer() const {return this;}
+ virtual bool IsAcceptable(const Integer &candidate) const =0;
+};
+
+// use a fast sieve to find the first probable prime in {x | p<=x<=max and x%mod==equiv}
+// returns true iff successful, value of p is undefined if no such prime exists
+CRYPTOPP_DLL bool CRYPTOPP_API FirstPrime(Integer &p, const Integer &max, const Integer &equiv, const Integer &mod, const PrimeSelector *pSelector);
+
+CRYPTOPP_DLL unsigned int CRYPTOPP_API PrimeSearchInterval(const Integer &max);
+
+CRYPTOPP_DLL AlgorithmParameters CRYPTOPP_API MakeParametersForTwoPrimesOfEqualSize(unsigned int productBitLength);
+
+// ********** other number theoretic functions ************
+
+inline Integer GCD(const Integer &a, const Integer &b)
+ {return Integer::Gcd(a,b);}
+inline bool RelativelyPrime(const Integer &a, const Integer &b)
+ {return Integer::Gcd(a,b) == Integer::One();}
+inline Integer LCM(const Integer &a, const Integer &b)
+ {return a/Integer::Gcd(a,b)*b;}
+inline Integer EuclideanMultiplicativeInverse(const Integer &a, const Integer &b)
+ {return a.InverseMod(b);}
+
+// use Chinese Remainder Theorem to calculate x given x mod p and x mod q, and u = inverse of p mod q
+CRYPTOPP_DLL Integer CRYPTOPP_API CRT(const Integer &xp, const Integer &p, const Integer &xq, const Integer &q, const Integer &u);
+
+// if b is prime, then Jacobi(a, b) returns 0 if a%b==0, 1 if a is quadratic residue mod b, -1 otherwise
+// check a number theory book for what Jacobi symbol means when b is not prime
+CRYPTOPP_DLL int CRYPTOPP_API Jacobi(const Integer &a, const Integer &b);
+
+// calculates the Lucas function V_e(p, 1) mod n
+CRYPTOPP_DLL Integer CRYPTOPP_API Lucas(const Integer &e, const Integer &p, const Integer &n);
+// calculates x such that m==Lucas(e, x, p*q), p q primes, u=inverse of p mod q
+CRYPTOPP_DLL Integer CRYPTOPP_API InverseLucas(const Integer &e, const Integer &m, const Integer &p, const Integer &q, const Integer &u);
+
+inline Integer ModularExponentiation(const Integer &a, const Integer &e, const Integer &m)
+ {return a_exp_b_mod_c(a, e, m);}
+// returns x such that x*x%p == a, p prime
+CRYPTOPP_DLL Integer CRYPTOPP_API ModularSquareRoot(const Integer &a, const Integer &p);
+// returns x such that a==ModularExponentiation(x, e, p*q), p q primes,
+// and e relatively prime to (p-1)*(q-1)
+// dp=d%(p-1), dq=d%(q-1), (d is inverse of e mod (p-1)*(q-1))
+// and u=inverse of p mod q
+CRYPTOPP_DLL Integer CRYPTOPP_API ModularRoot(const Integer &a, const Integer &dp, const Integer &dq, const Integer &p, const Integer &q, const Integer &u);
+
+// find r1 and r2 such that ax^2 + bx + c == 0 (mod p) for x in {r1, r2}, p prime
+// returns true if solutions exist
+CRYPTOPP_DLL bool CRYPTOPP_API SolveModularQuadraticEquation(Integer &r1, Integer &r2, const Integer &a, const Integer &b, const Integer &c, const Integer &p);
+
+// returns log base 2 of estimated number of operations to calculate discrete log or factor a number
+CRYPTOPP_DLL unsigned int CRYPTOPP_API DiscreteLogWorkFactor(unsigned int bitlength);
+CRYPTOPP_DLL unsigned int CRYPTOPP_API FactoringWorkFactor(unsigned int bitlength);
+
+// ********************************************************
+
+//! generator of prime numbers of special forms
+class CRYPTOPP_DLL PrimeAndGenerator
+{
+public:
+ PrimeAndGenerator() {}
+ // generate a random prime p of the form 2*q+delta, where delta is 1 or -1 and q is also prime
+ // Precondition: pbits > 5
+ // warning: this is slow, because primes of this form are harder to find
+ PrimeAndGenerator(signed int delta, RandomNumberGenerator &rng, unsigned int pbits)
+ {Generate(delta, rng, pbits, pbits-1);}
+ // generate a random prime p of the form 2*r*q+delta, where q is also prime
+ // Precondition: qbits > 4 && pbits > qbits
+ PrimeAndGenerator(signed int delta, RandomNumberGenerator &rng, unsigned int pbits, unsigned qbits)
+ {Generate(delta, rng, pbits, qbits);}
+
+ void Generate(signed int delta, RandomNumberGenerator &rng, unsigned int pbits, unsigned qbits);
+
+ const Integer& Prime() const {return p;}
+ const Integer& SubPrime() const {return q;}
+ const Integer& Generator() const {return g;}
+
+private:
+ Integer p, q, g;
+};
+
+NAMESPACE_END
+
+#endif