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118 lines
3.2 KiB
C++
118 lines
3.2 KiB
C++
// (C) 2016 University of Bristol. See License.txt
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#ifndef _Share
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#define _Share
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/* Class for holding a share of either a T or gfp element */
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#include <vector>
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#include <iostream>
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using namespace std;
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#include "Math/gfp.h"
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#include "Math/gf2n.h"
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// Forward declaration as apparently this is needed for friends in templates
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template<class T> class Share;
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template<class T> T combine(const vector< Share<T> >& S);
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template<class T> bool check_macs(const vector< Share<T> >& S,const T& key);
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template<class T>
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class Share
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{
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T a; // The share
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T mac; // Shares of the mac
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public:
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typedef T value_type;
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static int size()
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{ return 2 * T::size(); }
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static string type_string()
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{ return T::type_string(); }
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void assign(const Share<T>& S)
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{ a=S.a; mac=S.mac; }
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void assign(const char* buffer)
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{ a.assign(buffer); mac.assign(buffer + T::size()); }
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void assign_zero()
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{ a.assign_zero();
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mac.assign_zero();
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}
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Share() { assign_zero(); }
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Share(const Share<T>& S) { assign(S); }
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Share(const T& aa, int my_num, const T& alphai);
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~Share() { ; }
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Share& operator=(const Share<T>& S)
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{ if (this!=&S) { assign(S); }
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return *this;
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}
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const T& get_share() const { return a; }
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const T& get_mac() const { return mac; }
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void set_share(const T& aa) { a=aa; }
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void set_mac(const T& aa) { mac=aa; }
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/* Arithmetic Routines */
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void mul(const Share<T>& S,const T& aa);
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void mul_by_bit(const Share<T>& S,const T& aa);
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void add(const Share<T>& S,const T& aa,bool playerone,const T& alphai);
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void negate() { a.negate(); mac.negate(); }
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void sub(const Share<T>& S,const T& aa,bool playerone,const T& alphai);
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void sub(const T& aa,const Share<T>& S,bool playerone,const T& alphai);
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void add(const Share<T>& S1,const Share<T>& S2);
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void sub(const Share<T>& S1,const Share<T>& S2);
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void add(const Share<T>& S1) { add(*this,S1); }
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// Input and output from a stream
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// - Can do in human or machine only format (later should be faster)
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void output(ostream& s,bool human) const
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{ a.output(s,human); if (human) { s << " "; }
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mac.output(s,human);
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}
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void input(istream& s,bool human)
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{ a.input(s,human);
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mac.input(s,human);
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}
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/* Takes a vector of shares, one from each player and
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* determines the shared value
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* - i.e. Partially open the shares
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*/
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friend T combine<T>(const vector< Share<T> >& S);
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/* Given a set of shares, one from each player and
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* the global key, determines if the sharing is valid
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* - Mainly for test purposes
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*/
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friend bool check_macs<T>(const vector< Share<T> >& S,const T& key);
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};
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// specialized mul by bit for gf2n
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template <>
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void Share<gf2n>::mul_by_bit(const Share<gf2n>& S,const gf2n& aa);
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template <class T>
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Share<T> operator*(const T& y, const Share<T>& x) { Share<T> res; res.mul(x, y); return res; }
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template<class T>
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inline void Share<T>::add(const Share<T>& S1,const Share<T>& S2)
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{
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a.add(S1.a,S2.a);
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mac.add(S1.mac,S2.mac);
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}
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template<class T>
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inline void Share<T>::mul(const Share<T>& S,const T& aa)
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{
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a.mul(S.a,aa);
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mac.mul(S.mac,aa);
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}
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#endif
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