NAME

SYNOPSIS

void asn1_long_half(li)
asn1_long *li;

void asn1_long_add(li1, li2, li3)
asn1_long *li1, *li2, *li3;

void asn1_long_sub(li1, li2, li3)
asn1_long *li1, *li2, *li3;

void asn1_long_mul(li1, li2, li3)
asn1_long *li1, *li2, *li3;

void asn1_long_div(li1, li2, li3)
asn1_long *li1, *li2, *li3;

void asn1_long_modulo(r, n, i, po)
asn1_long *r, *n, *i;
int po;

ASN1_LONG_ITEM asn1_long_mod_small(li, l)
asn1_long *li;
ASN1_LONG_ITEM l;

void asn1_long_power_modulo(X, Y, N, r)
asn1_long *X, *Y, *N, *r;

void asn1_long_2powN(li, n)
asn1_long *li;
int n;

int asn1_long_gcd(A, B, GCD, I)
asn1_long *A, *B, *GCD, *I;

DESCRIPTION

These routines perform arithmetic on integers of arbitrary length. The integers are stored using the defined type asn1_long (see asn1_long(9x)) :

• asn1_long_half() divides a long integer by two.
• asn1_long_add(), asn1_long_sub() and asn1_long_mult() assign to their third arguments the sum, difference, and product, respectively, of their first two arguments. The firth argument should be freed.
• asn1_long_div() assigns the quotient and remainder,respectively, to its third and fourth arguments.
• asn1_long_modulo() reduces r to its value modulo n.
  i is an auxiliary number, such that : n*i - 2**p + r, where r < n.
  po is the expression of the exponent p divided by the number of bits in a long integer.
• asn1_long_mod_small() computes li modulo n, where n is a "small" integer.
• asn1_long_power_modulo() computes X power Y modulo N, returning it in r.
• asn1_long_2powN() computes two power n, returning it in the first argument.
• asn1_long_gcd() computes the greatest common divisor of the first two arguments, returning it in the third argument. The first two arguments are nonnegative long integers, with A greatest or equal than B. If GCD is equal to one, i.e the first two numbers are prime, the its also returns I such as : "B*I - 1 mod A."
  This routine returns 1 if the numbers are prime, 0 otherwise.

"SEE ALSO"