blumshub.cpp

各种加密算法的集合

 #include "pch.h" 
#include "blumshub.h" 
 
NAMESPACE_BEGIN(CryptoPP) 
 
PublicBlumBlumShub::PublicBlumBlumShub(const Integer &n, const Integer &seed) 
	: modn(n), 
	  maxBits(BitPrecision(n.BitCount())-1) 
{ 
	current = modn.Square(modn.Square(seed)); 
	bitsLeft = maxBits; 
} 
 
unsigned int PublicBlumBlumShub::GetBit() 
{ 
	if (bitsLeft==0) 
	{ 
		current = modn.Square(current); 
		bitsLeft = maxBits; 
	} 
 
	return current.GetBit(--bitsLeft); 
} 
 
byte PublicBlumBlumShub::GetByte() 
{ 
	byte b=0; 
	for (int i=0; i<8; i++) 
		b = (b << 1) | PublicBlumBlumShub::GetBit(); 
	return b; 
} 
 
BlumBlumShub::BlumBlumShub(const Integer &p, const Integer &q, const Integer &seed) 
	: PublicBlumBlumShub(p*q, seed), 
	  p(p), q(q), 
	  x0(modn.Square(seed)) 
{ 
} 
 
void BlumBlumShub::Seek(unsigned long index) 
{ 
	Integer e = a_exp_b_mod_c (2, ((index*8) / maxBits + 1), (p-1)*(q-1)); 
	current = modn.Exponentiate(x0, e); 
	bitsLeft = maxBits - int((index*8) % maxBits); 
} 
 
NAMESPACE_END