Simple Quantum Sha1

quantum_sha.cpp

//THis is an implementation for a quantum simulator showing that sha1 iterations are computable and reversible with no global ancillary bits and one *local* 
//ancillary register that is uncomputed per iteration.  This iteration is only 5 bits, of course, for space.

#include<qcpp/QRegister.h>
#include<qcpp/QMachine.h>

uint32_t msha1_computeF(int i,QRegister& B,QRegister& C,QRegister& D,QRegister& F)
{
	static const uint32_t k[4]=[0x5A827999,0x6ED9EBA1,0x8F1BBCDC,0xCA62C1D6]
	switch(i/20)
	{
	case 0:
	{
		//F=(B and C) xor ((not B) and D)
		F^=B & C; //Toffoli gates
		B=~B; //invert B
		F^=B & D;
		B=~B; //invert B back.
		break;
	}
	case 1:
	{
		F^=B;
		F^=C;
		F^=D;
		break;
	}
	case 2:
	{
		//F=(b And C) xor (B and D) xor (C and D);
		F^=B & C;  //Toffoli gates
		F^=B & D;
		F^=C & D;
		break;
	}
	case 3:
	{
		F^=B;
		F^=C;
		F^=D;
		break;
	}
	};
	return k[i/20];
}

void msha1_uncomputeF(int i,QRegister& B,QRegister& C,QRegister& D,QRegister& F)
{
	static const uint32_t k[4]=[0x5A827999,0x6ED9EBA1,0x8F1BBCDC,0xCA62C1D6]
	switch(i/20)
	{
	case 0:
	{
		//F=(B and C) xor ((not B) and D)
		B=~B; //invert B back.
		F^=B & D;
		B=~B; //invert B
		F^=B & C; //Toffoli gates
		break;
	}
	case 1:
	{
		F^=D;
		F^=C;
		F^=B;
		break;
	}
	case 2:
	{
		//F=(b And C) xor (B and D) xor (C and D);
		F^=C & D;
		F^=B & D;
		F^=B & C;  //Toffoli gates
		break;
	}
	case 3:
	{
		F^=D;
		F^=C;
		F^=B;
		break;
	}
	};
	return k[i/20];
}

void msha1_iterate_forwards(int i,unsigned char w_i,
	QRegister& A,QRegister& B,
	QRegister& C,QRegister& D,
	QRegister& E,QRegister& F)
{
	uint32_t k=msha1_computeF(i,B,C,D,F);

	//Compute TEMP variable
	A <<= 5;
	F+=A;
	F+=E;
	F+=k;
	F+=w_i;
	A >>=5;

	QMachine& m=A.machine;
	QRegister all(m,{0:30});
	//Rotate globally (reversible)
	/*
	F=E
	E=D
	D=C
	C=B
	B=A
	A=F */
	all <<=5;

	F-=A; //F=oldE-(B left 5)-computedf-k-w[i]-oldE
	B <<=5;
	F+=B;
	B >>=5; //F=computedf-k-w[i]
	F+=k;
	F+=w[i];  //F=computedf
	
	msha1_uncomputeF(i,C,D,E,F);
		//F=0; rest of state is correct for one iteration.
}
QRegister minisha1(QMachine& m,unsigned char w[80])
{

	QRegister 	A(m,{0,1,2,3,4}),
			B(m,{5,6,7,8,9}),
			C(m,{10,11,12,13,14}),
			D(m,{16,17,18,19,20}),
			E(m,{21,22,23,24,25})
			F(m,{26,27,28,29,30});
	QRegister outhash(m,
		{0,1,2,3,4,5,6,7,8,9,10
		,11,12,13,14,15,16,17,18,19,20,
		21,22,23,24,25,26,27,28,29,30});
			
	A ^= 0x67452301 & 0x1F;
	B ^= 0xEFCDAB89 & 0x1F;
	C ^= 0x98BADCFE & 0x1F;
	D ^= 0x10325476 & 0x1F;
	E ^= 0xC3D2E1F0 & 0x1F;
	F ^= 0;
	
	for(int i=0;i<80;i++)
	{
		iterate_forwards(i,w[i],A,B,C,D,E,F);
	}
	
	//output is Hash value is A|B|C|D|E
	//Set A
	return outhash;
}

int main()
{
	QMachine m(30);
	cout << measure(minisha1(m));
}