mr_small smul(mr_small x,mr_small y,mr_small n)
{ /* returns x*y mod n */
mr_small r;
#ifdef MR_ITANIUM
mr_small tm;
#endif
#ifdef MR_WIN64
mr_small tm;
#endif
#ifdef MR_FP
mr_small dres;
#endif
#ifndef MR_NOFULLWIDTH
if (n==0)
{ /* Assume n=2^MIRACL */
muldvd(x,y,(mr_small)0,&r);
return r;
}
#endif
x=MR_REMAIN(x,n);
y=MR_REMAIN(y,n);
muldiv(x,y,(mr_small)0,n,&r);
return r;
}
mr_small invers(mr_small x,mr_small y)
{ /* returns inverse of x mod y */
mr_small r,s,q,t,p;
#ifdef MR_FP
mr_small dres;
#endif
BOOL pos;
if (y!=0) x=MR_REMAIN(x,y);
r=1;
s=0;
p=y;
pos=TRUE;
#ifndef MR_NOFULLWIDTH
if (p==0)
{ /* if modulus is 0, assume its actually 2^MIRACL */
if (x==1) return (mr_small)1;
t=r; r=s; s=t;
p=x;
q=muldvm((mr_small)1,(mr_small)0,p,&t);
t=r+s*q; r=s; s=t;
t=0-p*q; x=p; p=t;
}
#endif
while (p!=0)
{ /* main euclidean loop */
q=MR_DIV(x,p);
t=r+s*q; r=s; s=t;
t=x-p*q; x=p; p=t;
pos=!pos;
}
if (!pos) r=y-r;
return r;
}
void frand(_MIPD_ flash x)
{ /* generates random flash number 0<x<1 */
int i;
#ifdef MR_FP
mr_small dres;
#endif
#ifdef MR_OS_THREADS
miracl *mr_mip=get_mip();
#endif
if (mr_mip->ERNUM) return;
MR_IN(46)
zero(mr_mip->w6);
mr_mip->w6->len=mr_mip->nib;
for (i=0;i<mr_mip->nib;i++)
{ /* generate a full width random number */
if (mr_mip->base==0) mr_mip->w6->w[i]=brand(_MIPPO_ );
else mr_mip->w6->w[i]=MR_REMAIN(brand(_MIPPO_ ),mr_mip->base);
}
mr_mip->check=OFF;
bigrand(_MIPP_ mr_mip->w6,mr_mip->w5);
mr_mip->check=ON;
mround(_MIPP_ mr_mip->w5,mr_mip->w6,x);
MR_OUT
}
void strong_bigrand(_MIPD_ csprng *rng,big w,big x)
{
int i, m;
mr_small r;
unsigned int ran;
unsigned int ch;
#ifdef MR_OS_THREADS
miracl *mr_mip=get_mip();
#endif
if (mr_mip->ERNUM) return;
MR_IN(20)
m = 0;
zero(mr_mip->w1);
do
{
m++;
mr_mip->w1->len=m;
for (r = 0, i = 0; i < sizeof(mr_small); i++) {
ch=(unsigned char)strong_rng(rng);
ran=ch;
r = (r << 8) ^ ran;
}
if (mr_mip->base==0) mr_mip->w1->w[m-1]=r;
else mr_mip->w1->w[m-1]=MR_REMAIN(r,mr_mip->base);
} while (mr_compare(mr_mip->w1,w)<0);
mr_lzero(mr_mip->w1);
divide(_MIPP_ mr_mip->w1,w,w);
copy(mr_mip->w1,x);
MR_OUT
}
void uconvert(_MIPD_ unsigned int n ,big x)
{ /* convert integer n to big number format */
int m;
#ifdef MR_FP
mr_small dres;
#endif
#ifdef MR_OS_THREADS
miracl *mr_mip=get_mip();
#endif
zero(x);
if (n==0) return;
m=0;
if (mr_mip->base==0)
{
#ifndef MR_NOFULLWIDTH
#if MR_IBITS > MIRACL
while (n>0)
{
x->w[m++]=(mr_small)(n%((mr_small)1<<(MIRACL)));
n/=((mr_small)1<<(MIRACL));
}
#else
x->w[m++]=(mr_small)n;
#endif
#endif
}
else while (n>0)
{
x->w[m++]=MR_REMAIN((mr_small)n,mr_mip->base);
n/=mr_mip->base;
}
x->len=(m);
}
mr_small spmd(mr_small x,mr_small n,mr_small m)
{ /* returns x^n mod m */
mr_small r,sx;
#ifdef MR_FP
mr_small dres;
#endif
x=MR_REMAIN(x,m);
r=0;
if (x==0) return r;
r=1;
if (n==0) return r;
sx=x;
forever
{
if (MR_REMAIN(n,2)!=0) muldiv(r,sx,(mr_small)0,m,&r);
n=MR_DIV(n,2);
if (n==0) return r;
muldiv(sx,sx,(mr_small)0,m,&sx);
}
}
int jac(mr_small x,mr_small n)
{ /* finds (x/n) as (-1)^m */
int m,k,n8,u4;
mr_small t;
#ifdef MR_FP
mr_small dres;
#endif
if (x==0)
{
if (n==1) return 1;
else return 0;
}
if (MR_REMAIN(n,2)==0) return 0;
x=MR_REMAIN(x,n);
m=0;
while(n>1)
{ /* main loop */
if (x==0) return 0;
/* extract powers of 2 */
for (k=0;MR_REMAIN(x,2)==0;k++) x=MR_DIV(x,2);
n8=(int)MR_REMAIN(n,8);
if (k%2==1) m+=(n8*n8-1)/8;
/* quadratic reciprocity */
u4=(int)MR_REMAIN(x,4);
m+=(n8-1)*(u4-1)/4;
t=n; t=MR_REMAIN(t,x);
n=x; x=t;
m%=2;
}
if (m==0) return 1;
else return (-1);
}
void lgconv(_MIPD_ long n,big x)
{ /* convert long integer to big number format - rarely needed */
int m;
mr_unsign32 s;
#ifdef MR_FP
mr_small dres;
#endif
#ifdef MR_OS_THREADS
miracl *mr_mip=get_mip();
#endif
zero(x);
if (n==0) return;
s=0;
if (n<0)
{
s=MR_MSBIT;
n=(-n);
}
m=0;
if (mr_mip->base==0)
{
#ifndef MR_NOFULLWIDTH
#if MR_LBITS > MIRACL
while (n>0)
{
x->w[m++]=(mr_small)(n%(1L<<(MIRACL)));
n/=(1L<<(MIRACL));
}
#else
x->w[m++]=(mr_small)n;
#endif
#endif
}
else while (n>0)
{
x->w[m++]=MR_REMAIN(n,mr_mip->base);
n/=mr_mip->base;
}
x->len=(m|s);
}
void dlconv(_MIPD_ mr_dltype n,big x)
{ /* convert double length integer to big number format - rarely needed */
int m;
mr_unsign32 s;
#ifdef MR_FP
mr_small dres;
#endif
#ifdef MR_OS_THREADS
miracl *mr_mip=get_mip();
#endif
zero(x);
if (n==0) return;
s=0;
if (n<0)
{
s=MR_MSBIT;
n=(-n);
}
m=0;
if (mr_mip->base==0)
{
#ifndef MR_NOFULLWIDTH
while (n>0)
{
x->w[m++]=(mr_small)(n%((mr_dltype)1<<(MIRACL)));
n/=((mr_dltype)1<<(MIRACL));
}
#endif
}
else while (n>0)
{
x->w[m++]=(mr_small)MR_REMAIN(n,mr_mip->base);
n/=mr_mip->base;
}
x->len=(m|s);
}
mr_small sqrmp(mr_small x,mr_small m)
{ /* square root mod a small prime by Shanks method *
* returns 0 if root does not exist or m not prime */
mr_small z,y,v,w,t,q;
#ifdef MR_FP
mr_small dres;
#endif
int i,e,n,r;
BOOL pp;
x=MR_REMAIN(x,m);
if (x==0) return 0;
if (x==1) return 1;
if (spmd(x,(mr_small)((m-1)/2),m)!=1) return 0; /* Legendre symbol not 1 */
if (MR_REMAIN(m,4)==3) return spmd(x,(mr_small)((m+1)/4),m); /* easy case for m=4.k+3 */
if (MR_REMAIN(m,8)==5)
{ /* also relatively easy */
t=spmd(x,(mr_small)((m-1)/4),m);
if (t==1) return spmd(x,(mr_small)((m+3)/8),m);
if (t==(mr_small)(m-1))
{
muldiv((mr_small)4,x,(mr_small)0,m,&t);
t=spmd(t,(mr_small)((m+3)/8),m);
muldiv(t,(mr_small)((m+1)/2),(mr_small)0,m,&t);
return t;
}
return 0;
}
q=m-1;
e=0;
while (MR_REMAIN(q,2)==0)
{
q=MR_DIV(q,2);
e++;
}
if (e==0) return 0; /* even m */
for (r=2;;r++)
{ /* find suitable z */
z=spmd((mr_small)r,q,m);
if (z==1) continue;
t=z;
pp=FALSE;
for (i=1;i<e;i++)
{ /* check for composite m */
if (t==(m-1)) pp=TRUE;
muldiv(t,t,(mr_small)0,m,&t);
if (t==1 && !pp) return 0;
}
if (t==(m-1)) break;
if (!pp) return 0; /* m is not prime */
}
y=z;
r=e;
v=spmd(x,(mr_small)((q+1)/2),m);
w=spmd(x,q,m);
while (w!=1)
{
t=w;
for (n=0;t!=1;n++) muldiv(t,t,(mr_small)0,m,&t);
if (n>=r) return 0;
y=spmd(y,mr_shiftbits(1,r-n-1),m);
muldiv(v,y,(mr_small)0,m,&v);
muldiv(y,y,(mr_small)0,m,&y);
muldiv(w,y,(mr_small)0,m,&w);
r=n;
}
return v;
}
int egcd(_MIPD_ big x,big y,big z)
{ /* greatest common divisor z=gcd(x,y) by Euclids *
* method using Lehmers algorithm for big numbers */
int q,r,a,b,c,d,n;
mr_small sr,m,sm;
mr_small u,v,lq,lr;
#ifdef MR_FP
mr_small dres;
#endif
big t;
#ifndef MR_GENERIC_MT
miracl *mr_mip=get_mip();
#endif
if (mr_mip->ERNUM) return 0;
MR_IN(12)
copy(x,mr_mip->w1);
copy(y,mr_mip->w2);
insign(PLUS,mr_mip->w1);
insign(PLUS,mr_mip->w2);
a=b=c=d=0;
while (size(mr_mip->w2)!=0)
{
if (b==0)
{ /* update w1 and w2 */
divide(_MIPP_ mr_mip->w1,mr_mip->w2,mr_mip->w2);
t=mr_mip->w1,mr_mip->w1=mr_mip->w2,mr_mip->w2=t; /* swap(w1,w2) */
}
else
{
premult(_MIPP_ mr_mip->w1,c,z);
premult(_MIPP_ mr_mip->w1,a,mr_mip->w1);
premult(_MIPP_ mr_mip->w2,b,mr_mip->w0);
premult(_MIPP_ mr_mip->w2,d,mr_mip->w2);
add(_MIPP_ mr_mip->w1,mr_mip->w0,mr_mip->w1);
add(_MIPP_ mr_mip->w2,z,mr_mip->w2);
}
if (mr_mip->ERNUM || size(mr_mip->w2)==0) break;
n=(int)mr_mip->w1->len;
if (mr_mip->w2->len==1)
{ /* special case if mr_mip->w2 is now small */
sm=mr_mip->w2->w[0];
#ifdef MR_FP_ROUNDING
sr=mr_sdiv(_MIPP_ mr_mip->w1,sm,mr_invert(sm),mr_mip->w1);
#else
sr=mr_sdiv(_MIPP_ mr_mip->w1,sm,mr_mip->w1);
#endif
if (sr==0)
{
copy(mr_mip->w2,mr_mip->w1);
break;
}
zero(mr_mip->w1);
mr_mip->w1->len=1;
mr_mip->w1->w[0]=sr;
while ((sr=MR_REMAIN(mr_mip->w2->w[0],mr_mip->w1->w[0]))!=0)
mr_mip->w2->w[0]=mr_mip->w1->w[0],mr_mip->w1->w[0]=sr;
break;
}
a=1;
b=0;
c=0;
d=1;
m=mr_mip->w1->w[n-1]+1;
if (mr_mip->base==0)
{
#ifndef MR_NOFULLWIDTH
if (m==0)
{
u=mr_mip->w1->w[n-1];
v=mr_mip->w2->w[n-1];
}
else
{
u=muldvm(mr_mip->w1->w[n-1],mr_mip->w1->w[n-2],m,&sr);
v=muldvm(mr_mip->w2->w[n-1],mr_mip->w2->w[n-2],m,&sr);
}
#endif
}
else
{
u=muldiv(mr_mip->w1->w[n-1],mr_mip->base,mr_mip->w1->w[n-2],m,&sr);
v=muldiv(mr_mip->w2->w[n-1],mr_mip->base,mr_mip->w2->w[n-2],m,&sr);
}
forever
{ /* work only with most significant piece */
if (((v+c)==0) || ((v+d)==0)) break;
lq=MR_DIV((u+a),(v+c));
if (lq!=MR_DIV((u+b),(v+d))) break;
if (lq>=(mr_small)(MR_TOOBIG/mr_abs(d))) break;
q=(int)lq;
r=a-q*c;
a=c;
c=r;
r=b-q*d;
b=d;
d=r;
lr=u-lq*v;
u=v;
v=lr;
}
}
copy(mr_mip->w1,z);
MR_OUT
return (size(mr_mip->w1));
}
