com.h

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#ifndef COM_H__
#define COM_H__
#include "string.h"
#include "hash.h"
#include "prg.h"
typedef char Com[20];
typedef block Decom[1];

class Commitment{ public:
    Hash h;
    PRG prg;
    void commit(Decom decom, Com com, const void * message, int nbytes) {
        prg.random_block(decom, 1);
        h.reset();
        h.put_block(decom, 1);
        h.put(message, nbytes);
        h.digest(com);
    }

    bool open(Decom decom, Com com, const void * message, int nbytes) {
        h.reset();
        h.put_block(decom, 1);
        h.put(message, nbytes);
        Com res;
        h.digest(res);
        return strncmp(com, res, Hash::DIGEST_SIZE)==0;
    }
};
#endif// COM_H__