int main(){
bignum valor, aux, total;
int n, f, i, bill = 1;
char str[MAXDIGITS];
scanf("%d %d", &n, &f);
while( n ) {
scanf("%s", &str );
stringToBignum( str, &valor );
for( i = 1; i < n; i++ ){
scanf("%s", &str );
stringToBignum( str, &aux );
add_bignum( &valor, &aux, &total );
valor = total;
}
printf("Bill #%d costs ", bill++ );
print_bignum( &valor );
sprintf( str, "%d", f );
stringToBignum( str, &aux );
divide_bignum( &valor, &aux, &total );
printf(": each friend should pay ");
print_bignum(&total);
printf("\n\n");
scanf("%d %d", &n, &f);
}
return 0;
}
void subtract_bignum(bignum *a, bignum *b, bignum *c)
{
int borrow, v, i;
if ((a->signbit == MINUS) || (b->signbit == MINUS)) {
b->signbit = -1 * b->signbit;
add_bignum(a, b, c);
b->signbit = -1 * b->signbit;
return;
}
if (compare_bignum(a, b) == PLUS) {
subtract_bignum(b, a, c);
c->signbit = MINUS;
return;
}
c->lastdigit = max(a->lastdigit, b->lastdigit);
borrow = 0;
for (i = 0; i <= c->lastdigit; i++) {
v = (a->digits[i] - borrow - b->digits[i]);
if (a->digits[i] > 0)
borrow = 0;
if (v < 0) {
v = v + 10;
borrow = 1;
}
c->digits[i] = (char) v % 10;
}
zero_justify(c);
}
/** Test Function */
int main( )
{
bignum n1, n2, n3, zero;
// Instantiate string buffers for big numbers a and b
char* a = calloc( MAXDIGITS, sizeof( char ) );
char* b = calloc( MAXDIGITS, sizeof( char ) );
// Get big numbers a and b as strings
printf( "a = " );
fgets( a, MAXDIGITS, stdin );
printf( "b = " );
fgets( b, MAXDIGITS, stdin );
// Remove the newline character (if present) from string buffers
char* nl;
if( ( nl = strchr( a, '\n' ) ) != NULL ) *nl = '\0';
if( ( nl = strchr( b, '\n' ) ) != NULL ) *nl = '\0';
// Create a and b big number instances via the string buffers
string_to_bignum( a, &n1 );
string_to_bignum( b, &n2 );
// Test addition
add_bignum( &n1, &n2, &n3 );
printf( "a + b = " );
print_bignum( &n3 );
// Test comparison
int comparison = compare_bignum( &n1, &n2 );
printf( "a %s b\n", comparison == 0 ? "==" : ( comparison < 0 ? ">" : "<" ) );
// Test subtraction
subtract_bignum( &n1, &n2, &n3 );
printf( "a - b = " );
print_bignum( &n3 );
// Test multiplication
multiply_bignum( &n1, &n2, &n3 );
printf( "a * b = " );
print_bignum( &n3 );
// Test division
int_to_bignum( 0, &zero );
if( compare_bignum( &zero, &n2 ) == 0 )
{
printf( "a / b = NaN\n" );
}
else
{
divide_bignum( &n1, &n2, &n3 );
printf( "a / b = " );
print_bignum( &n3 );
}
return 0;
}
void multiply_bignum(bignum *a, bignum *b, bignum *c)
{
bignum row, tmp;
int i, j;
initialize_bignum(c);
row = *a;
for (i = 0; i <= b->lastdigit; i++) {
for (j = 1; j <= b->digits[i]; j++) {
add_bignum(c, &row, &tmp);
*c = tmp;
}
digit_shift(&row, 1);
}
c->signbit = a->signbit * b->signbit;
zero_justify(c);
}
/** Subtracts big numbers; i.e. c = a - b */
void subtract_bignum( bignum* a, bignum* b, bignum* c )
{
int borrow; /* has anything been borrowed? */
int v; /* placeholder digit */
int i; /* counter */
initialize_bignum( c );
if( ( a->signbit == MINUS ) || ( b->signbit == MINUS ) )
{
b->signbit = -1 * b->signbit;
add_bignum( a, b, c );
b->signbit = -1 * b->signbit;
return;
}
if( compare_bignum( a, b ) == PLUS )
{
subtract_bignum( b, a, c );
c->signbit = MINUS;
return;
}
c->lastdigit = max( a->lastdigit, b->lastdigit );
borrow = 0;
for( i = 0; i <= ( c->lastdigit ); i++ )
{
v = ( a->digits[ i ] - borrow - b->digits[ i ] );
if( a->digits[ i ] > 0)
{
borrow = 0;
}
if( v < 0 )
{
v = v + 10;
borrow = 1;
}
c->digits[ i ] = ( char ) v % 10;
}
zero_justify( c );
}
int main(int argc, char ** argv)
{
int j, n; // n == num_digits
char * dummy_str;
bignum_t f1, f2, f3, pow_ten, ten;
if(argc < 2)
{
printf("Usage: %s num_digits\n"
"warning: using num_digits = 1000\n", argv[0]);
n = 1000;
}
else
n = atoi(argv[1]);
init_bignum(&f1);
init_bignum(&f2);
init_bignum(&f3);
init_bignum(&pow_ten);
init_bignum(&ten);
ulong_to_bignum(&ten, 10);
pow_bignum(&pow_ten, &ten, n - 1);
// n digits + a small buffer
dummy_str = malloc(n + 2);
ulong_to_bignum(&f1, 1);
ulong_to_bignum(&f2, 1);
for(j = 3; ; j++)
{
copy_bignum(&f3, &f2);
add_bignum(&f3, &f1);
// if the current_fibonacci_number >= 10**n, then we're done
if(ge_bignum(&f3, &pow_ten))
break;
swap_bignum(&f1, &f2);
swap_bignum(&f2, &f3);
}
printf("First term in Fibonacci sequence to contain %d digits: F_%d\n", n, j);
free(dummy_str);
return 0;
}
void multiply_bignum(bignum *a, bignum *b, bignum *c) {
bignum row; /* represent shifted row */
bignum tmp; /* placeholder bignum */
int i,j; /* counters */
initialize_bignum(c);
row = *a;
for(i = 0; i <= b->lastdigit; i++) {
for(j = 1; j <= b->digits[i]; j++) {
add_bignum(c,&row,&tmp);
*c = tmp;
}
digit_shift(&row,1);
}
c->signbit = a->signbit * b->signbit;
zero_justify(c);
}
int main(void) {
int a,b;
bignum n1,n2,n3,zero;
while (scanf("%d %d",&a,&b) != EOF) {
printf("a = %d b = %d\n",a,b);
int_to_bignum(a,&n1);
int_to_bignum(b,&n2);
add_bignum(&n1,&n2,&n3);
printf("addition -- ");
print_bignum(&n3);
printf("compare_bignum a ? b = %d\n",compare_bignum(&n1, &n2));
subtract_bignum(&n1,&n2,&n3);
printf("subtraction -- ");
print_bignum(&n3);
multiply_bignum(&n1,&n2,&n3);
printf("multiplication -- ");
print_bignum(&n3);
int_to_bignum(0,&zero);
if(compare_bignum(&zero, &n2) == 0)
printf("division -- NaN \n");
else {
divide_bignum(&n1,&n2,&n3);
printf("division -- ");
print_bignum(&n3);
}
printf("--------------------------\n");
}
return 0;
}
/** Generate a new key.
* \param id The name to embed in the key.
* \return The newly generated key, containing public and private data.
* \sa gale_crypto_public() */
struct gale_group gale_crypto_generate(struct gale_text id) {
RSA *rsa = NULL;
int bits = gale_text_to_number(gale_var(G_("GALE_AUTH_BITS")));
struct gale_group output = gale_group_empty();
struct gale_fragment frag;
if (0 == bits) bits = 768; /* default value */
if (bits < 512) {
gale_alert(GALE_WARNING,G_("expanding key size to 512"),0);
bits = 512;
}
crypto_i_seed();
gale_alert(GALE_NOTICE,G_("generating key, please wait..."),0);
rsa = RSA_generate_key(bits,RSA_F4,NULL,NULL);
assert(NULL != rsa);
frag.type = frag_text;
frag.name = G_("key.id");
frag.value.text = id;
gale_group_add(&output,frag);
frag.type = frag_number;
frag.name = G_("rsa.bits");
frag.value.number = bits;
gale_group_add(&output,frag);
add_bignum(&output,G_("rsa.modulus"),GALE_RSA_MODULUS_LEN,1,rsa->n);
add_bignum(&output,G_("rsa.exponent"),GALE_RSA_MODULUS_LEN,1,rsa->e);
add_bignum(&output,G_("rsa.private.exponent"),
GALE_RSA_MODULUS_LEN,1,rsa->d);
add_bignum(&output,G_("rsa.private.prime"),
GALE_RSA_PRIME_LEN,2,rsa->p,rsa->q);
add_bignum(&output,G_("rsa.private.prime.exponent"),
GALE_RSA_PRIME_LEN,2,rsa->dmp1,rsa->dmq1);
add_bignum(&output,G_("rsa.private.coefficient"),
GALE_RSA_PRIME_LEN,1,rsa->iqmp);
if (NULL != rsa) RSA_free(rsa);
return output;
}