void bii_binarymodpow_powerof2(bigint *dest, bigint base, bigint exp, uint32_t modpow){
//if the modulus is a power of 2, division and modular arithmetic is very fast.
if(modpow==0){
bigint_setval32(dest, 0);
return;
}
bigint res, B, E, tmp1;
bigint_init(&res);
bigint_init(&B);
bigint_init(&E);
bigint_init(&tmp1);
bigint_setval32(&res,1);
bigint_getsigbits(&B,base, modpow);
bigint_setval(&E, exp);
while(!bigint_isval(E,0)){
if(bigint_parity(E)==1){
bigint_multiply(&tmp1, res, B);
bigint_getsigbits(&res, tmp1, modpow);
}
bigint_rightshift(&E,1);
bigint_multiply(&tmp1, B,B);
bigint_getsigbits(&B,tmp1,modpow);
}
bigint_setval(dest, res);
bigint_free(&res);
bigint_free(&B);
bigint_free(&E);
bigint_free(&tmp1);
}
void bii_monproduct(bigint *dest, bigint abar, bigint bbar, bigint n, bigint nprime, uint32_t rpow){
bigint t, m, u, tmp1, tmp2;
bigint_init(&t);
bigint_init(&m);
bigint_init(&u);
bigint_init(&tmp1);
bigint_init(&tmp2);
bigint_multiply(&t, abar, bbar);
bigint_multiply(&tmp1, t, nprime);
bigint_getsigbits(&m, tmp1, rpow);
bigint_multiply(&tmp1, m,n);
bigint_add(&u,t,tmp1);
bigint_rightshift(&u,rpow);
if(bigint_cmp(u,n)>=0) bigint_subtract(dest,u,n);
else bigint_setval(dest, u);
bigint_free(&t);
bigint_free(&m);
bigint_free(&u);
bigint_free(&tmp1);
bigint_free(&tmp2);
}
/* Allocates some memory for a brainfuck program */
Memory *make_memory(void) {
int i;
Memory *mem;
mem = malloc(sizeof(Memory));
mem->mp = 0;
if(wrap) {
/* memory cells are unsigned char */
mem->pos_mem = malloc(INIT_MEM_SIZE);
mem->pos_len = INIT_MEM_SIZE;
memset(mem->pos_mem, 0, INIT_MEM_SIZE);
mem->neg_mem = malloc(INIT_MEM_SIZE);
mem->neg_len = INIT_MEM_SIZE;
memset(mem->neg_mem, 0, INIT_MEM_SIZE);
} else {
/* memory cells are bigint */
mem->pos_mem = malloc(INIT_MEM_SIZE * sizeof(bigint));
mem->pos_len = INIT_MEM_SIZE;
/* we have to cast to "bigint *" here for the pointer arithmetic to work */
for(i = 0; i < mem->pos_len; i++) bigint_init((bigint *)mem->pos_mem + i);
mem->neg_mem = malloc(INIT_MEM_SIZE * sizeof(bigint));
mem->neg_len = INIT_MEM_SIZE;
for(i = 0; i < mem->neg_len; i++) bigint_init((bigint *)mem->neg_mem + i);
}
return mem;
}
int bii_test_modexp(void){
bigint dest, base, exp, mod;
bigint_init(&dest);
bigint_init(&base);
bigint_init(&exp);
bigint_init(&mod);
bigint_setval32(&base, 375);
bigint_setval32(&exp, 249);
bigint_setval32(&mod, 388);
buf = calloc(1, sizeof(char));
bigint_modexp(&dest, base, exp, mod);
if(!bigint_isval(dest, 175)){
printf("Failed.\n");
return 1;
}
bigint_setval32(&base,2);
bigint_setvalhex(&mod, "444291e51b3ea5fd16673e95674b01e7b");
//bigint_setval32(&mod, 0x25);
bigint_setvalrand(&exp, 400);
bigint_modequals(&exp,mod);
bigint_tohex(base,&buf);
printf("modexp(%s, ",buf);
bigint_tohex(exp, &buf);
printf("%s, ", buf);
bigint_tohex(mod, &buf);
printf("%s)\n ", buf);
fflush(stdout);
bigint_modexp(&dest, base, exp, mod);
printf("done.\n");fflush(stdout);
bigint_tohex(base,&buf);
printf("%s",buf);
printf(" ** ");
bigint_tohex(exp, &buf);
printf("%s", buf);
printf(" %% ");
bigint_tohex(mod, &buf);
printf("%s == ", buf);
bigint_tohex(dest, &buf);
printf("%s\n", buf);
free(buf);
return 0;
}
int bigint_multiply(bigint_s *dst, bigint_s *a, bigint_s *b) {
if (!dst || !a || !b || !dst->bytes || !a->bytes || !b->bytes) return BIGINT_INVALID_ARGUMENT;
if (a->bytes_alloced != b->bytes_alloced) return BIGINT_DIFFRENT_SIZE; // TODO: allow different sizes (padding)
uint32_t buffer_size = dst->bytes_alloced;
/*
* multiply two big numbers (in columns with carry)
* assuming that:
* (b-number) first row
* x (a-number) second row
* -------------
* result
*/
bool add = false;
for (uint32_t i = 0; i < a->bytes_used; i++) { // second row on paper
bigint_s tmp;
bigint_init(&tmp);
uint32_t k = i;
uint16_t rest = 0, carry = 0;
for (uint32_t j = 0; j < b->bytes_used; j++) {
uint16_t result = (uint16_t) a->bytes[i] * (uint16_t) b->bytes[j] + carry;
carry = result/BIGINT_BASE;
rest = result % BIGINT_BASE;
if (k >= buffer_size) return BIGINT_OUT_OF_MEMORY;
tmp.bytes[k++] = (uint8_t) rest;
}
if (k >= buffer_size) return BIGINT_OUT_OF_MEMORY;
if (carry > 0) tmp.bytes[k++] = (uint8_t) carry;
tmp.bytes_used = k;
if (!add) {
bigint_swap(dst, &tmp);
add = true;
} else {
bigint_s r;
bigint_init(&r);
int rr = bigint_add(&r, dst, &tmp);
if (rr != BIGINT_OK) return rr;
bigint_swap(dst, &r);
bigint_free(&r);
}
while (dst->bytes_used > 0 && dst->bytes[dst->bytes_used - 1] == 0) { dst->bytes_used--; } // sometimes result is prefixed with zeros, cutting them off
bigint_free(&tmp);
}
return BIGINT_OK;
}
/** Multiply two big integers.
*
* The big integers @a a and @a b are multiplied and the result is stored in
* @a dest.
*
* @param a First factor.
* @param b Second factor.
* @param dest Destination bigint.
*/
void bigint_mul(bigint_t *a, bigint_t *b, bigint_t *dest)
{
size_t idx;
bigint_t dprod;
bigint_t sum;
bigint_t tmp;
#ifdef DEBUG_BIGINT_TRACE
printf("Multiply bigints.\n");
#endif
bigint_init(&sum, 0);
for (idx = 0; idx < b->length; ++idx) {
bigint_shift_mul_dig(a, b->digit[idx], idx, &dprod);
bigint_add(&dprod, &sum, &tmp);
bigint_destroy(&dprod);
bigint_destroy(&sum);
bigint_shallow_copy(&tmp, &sum);
}
if (b->negative)
sum.negative = !sum.negative;
bigint_shallow_copy(&sum, dest);
}
/** Get value of big integer.
*
* Allows to obtain the value of big integer, provided that it fits
* into a small integer.
*
* @param bigint Bigint to obtain value from.
* @param dval Place to store value.
* @return EOK on success, ELIMIT if bigint is too big to fit
* to @a dval.
*/
int bigint_get_value_int(bigint_t *bigint, int *dval)
{
bigint_t vval, diff;
size_t idx;
int val;
bool_t zf;
#ifdef DEBUG_BIGINT_TRACE
printf("Get int value of bigint.\n");
#endif
val = 0;
for (idx = 0; idx < bigint->length; ++idx) {
val = val * BIGINT_BASE + bigint->digit[idx];
}
if (bigint->negative)
val = - val;
/* If the value did not fit @c val now contains garbage. Verify. */
bigint_init(&vval, val);
bigint_sub(bigint, &vval, &diff);
zf = bigint_is_zero(&diff);
bigint_destroy(&vval);
bigint_destroy(&diff);
/* If the difference is not zero, the verification failed. */
if (zf != b_true)
return EINVAL;
*dval = val;
return EOK;
}
int bii_test_egcd(void){
bigint a;
bigint b;
bigint c;
bigint x;
bigint y;
bigint_initrand(&a, 128);
bigint_initrand(&b, 128);
bigint_initrand(&c, 64);
bigint_init(&x);
bigint_init(&y);
do{
bigint_egcd(a,b,c,&x,&y);
}while(bigint_isval(x,0) && bigint_isval(y,0));
bigint_timesequals(&x,a);
bigint_timesequals(&y,b);
bigint_minusequals(&c,x);
bigint_minusequals(&c,y);
if(!bigint_isval(c,0)){
printf("egcd failed.\n");
return 1;
}
bigint_setval32(&a,4);
bigint_setval32(&b,3);
bigint_setval32(&c,1);
bigint_egcd(a,b,c,&x,&y);
if(!bigint_isval(x,1) || !(bigint_isval(y,1) && y.sign == BII_NEG)){
printf("egcd(4,3,1) failed.\n");
return 1;
}
bigint_free(&a);
bigint_free(&b);
bigint_free(&c);
bigint_free(&x);
bigint_free(&y);
return 0;
}
/* Returns a pointer to the current cell of memory in mem. Sorts out the
growing of memory where necessary */
static inline void *get_cell(Memory *memory) {
int i;
int *len;
void **mem;
int mp;
/* positive or negative address? */
if(memory->mp >= 0) {
len = &(memory->pos_len);
mp = memory->mp;
mem = &(memory->pos_mem);
} else {
if(noneg) {
fprintf(stderr, "%s: negative memory, perhaps you need to stop using "
"the --no-negative option or fix a memory leak in your "
"program.\n",
program_name);
stop_program = 1;
return NULL;
}
len = &(memory->neg_len);
mp = -memory->mp;
mem = &(memory->neg_mem);
}
/* check that mp is within range */
if(maxmem && mp > maxmem) {
fprintf(stderr, "%s: memory overflow, perhaps you need to adjust the "
"--max-mem option or fix a memory leak in your program.\n",
program_name);
stop_program = 1;
return NULL;
}
/* double the size of memory until we are within range */
while(mp >= *len) {
if(wrap) {
*mem = realloc(*mem, *len * 2);
memset(*mem + *len, 0, *len);
} else {
*mem = realloc(*mem, *len * 2 * sizeof(bigint));
/* the cast is to make the pointer arithmetic happy */
for(i = 0; i < *len; i++) bigint_init((bigint *)*mem + *len + i);
}
*len *= 2;
}
if(wrap) return *mem + mp;
else return *(bigint **)mem + mp;
}
void bii_modexpodd(bigint *dest, bigint a, bigint e, bigint n){
/*
* Modular exponentiation, returns a**e mod n
* Uses the Mongtomery Product algorithm to speed up a standard repeated-squaring routine
*/
bigint r, nprime, tmp1, tmp2, abar, xbar;
bigint_init(&r);
bigint_init(&nprime);
bigint_init(&tmp1);
bigint_init(&tmp2);
bigint_init(&abar);
bigint_init(&xbar);
//r is the least power of 2 which is larger than n.
bigint_setval32(&r,1);
uint32_t rpow = bii_sigbits(n)-1;
bigint_leftshift(&r, rpow);
if(bigint_cmp(r,n)==-1){
bigint_leftshift(&r,1);
rpow++;
}
//r * r^{-1} - n*n' = 1. Use the euclidean algorithm to find n'.
bigint_setval32(&tmp1, 1);
bigint_egcd(r,n, tmp1, &tmp2, &nprime);
bigint_setpos(&nprime);
//abar = a * r mod n
bigint_multiply(&tmp1,a,r);
bigint_divide(&tmp2,&abar,tmp1,n);
bigint_divide(&tmp1,&xbar,r,n);
fflush(stdout);
for(int i = bii_sigbits(e)-1; i>=0; i--){
bii_monproduct(&tmp1, xbar, xbar, n, nprime, rpow);
bigint_setval(&xbar, tmp1);
bigint_setval(&tmp2,e);
bigint_rightshift(&tmp2,i);
if(bigint_parity(tmp2)==1){
bii_monproduct(&tmp1,abar,xbar,n,nprime,rpow);
bigint_setval(&xbar,tmp1);
}
}
bigint_setval32(&tmp1, 1);
bii_monproduct(dest, xbar, tmp1, n, nprime, rpow);
bigint_free(&r);
bigint_free(&nprime);
bigint_free(&tmp1);
bigint_free(&tmp2);
bigint_free(&abar);
bigint_free(&xbar);
}
/* Read input to the current cell */
void input(Memory *mem) {
void *cell;
bigint input;
int c;
char buf[1024];
char *p;
if(!(cell = get_cell(mem))) return;
if(chario) {
/* character io */
fflush(stdout);
c = fgetc(stdin);
if(c == EOF) goto handle_eof;
else {
if(wrap) *(unsigned char *)cell = c;
else bigint_from_int(cell, c);
}
} else {
/* number io */
bigint_init(&input);
/* use bigint for input even if we're reading to wrapping cells */
do {
if(prompt) {
fprintf(stderr, "Input: ");
fflush(stderr);
}
if(!(fgets(buf, 1024, stdin))) goto handle_eof;
if((p = strchr(buf, '\n'))) *p = '\0';
} while(bigint_from_string(&input, buf) == BIGINT_ILLEGAL_PARAM);
if(wrap) *(unsigned char *)cell = bigint_to_int(&input);
else bigint_copy(cell, &input);
bigint_release(&input);
}
return;
handle_eof:
if(strcasecmp(eof_value, "nochange") != 0) {
bigint_from_string(cell, eof_value);
}
}
/**
* Perform modular exponentiation of big integers
*
* @v base0 Element 0 of big integer base
* @v modulus0 Element 0 of big integer modulus
* @v exponent0 Element 0 of big integer exponent
* @v result0 Element 0 of big integer to hold result
* @v size Number of elements in base, modulus, and result
* @v exponent_size Number of elements in exponent
* @v tmp Temporary working space
*/
void bigint_mod_exp_raw ( const bigint_element_t *base0,
const bigint_element_t *modulus0,
const bigint_element_t *exponent0,
bigint_element_t *result0,
unsigned int size, unsigned int exponent_size,
void *tmp ) {
const bigint_t ( size ) __attribute__ (( may_alias )) *base =
( ( const void * ) base0 );
const bigint_t ( size ) __attribute__ (( may_alias )) *modulus =
( ( const void * ) modulus0 );
const bigint_t ( exponent_size ) __attribute__ (( may_alias ))
*exponent = ( ( const void * ) exponent0 );
bigint_t ( size ) __attribute__ (( may_alias )) *result =
( ( void * ) result0 );
size_t mod_multiply_len = bigint_mod_multiply_tmp_len ( modulus );
struct {
bigint_t ( size ) base;
bigint_t ( exponent_size ) exponent;
uint8_t mod_multiply[mod_multiply_len];
} *temp = tmp;
static const uint8_t start[1] = { 0x01 };
memcpy ( &temp->base, base, sizeof ( temp->base ) );
memcpy ( &temp->exponent, exponent, sizeof ( temp->exponent ) );
bigint_init ( result, start, sizeof ( start ) );
while ( ! bigint_is_zero ( &temp->exponent ) ) {
if ( bigint_bit_is_set ( &temp->exponent, 0 ) ) {
bigint_mod_multiply ( result, &temp->base, modulus,
result, temp->mod_multiply );
}
bigint_ror ( &temp->exponent );
bigint_mod_multiply ( &temp->base, &temp->base, modulus,
&temp->base, temp->mod_multiply );
}
}
void bigint_egcd(bigint a, bigint b, bigint c, bigint *x, bigint *y){
bigint r0, r1, r2, s1, s2, t1, t2, q, r, tmp1, tmp2;
int revflag = 0;
bigint_init(&r0);
bigint_init(&r1);
bigint_init(&r2);
bigint_init(&s1);
bigint_init(&s2);
bigint_init(&t1);
bigint_init(&t2);
bigint_init(&q);
bigint_init(&r);
bigint_init(&tmp1);
bigint_init(&tmp2);
if(bigint_cmp(a,b)==-1){
revflag = 1;
bigint_setval(&r0, b);
bigint_setval(&r1, a);
} else{
bigint_setval(&r0, a);
bigint_setval(&r1, b);
}
bigint_divide(&q,&r2,r0,r1);
bigint_setval32(&s1, 0);
bigint_setval32(&s2, 1);
bigint_setval32(&t1, 1);
bigint_setval(&t2, q);
bigint_negate(&t2);
if(bigint_isval(r2,0)){
bigint_divide(&tmp1,&tmp2,c,b);
if(bigint_isval(tmp2,0)){
if(revflag == 0){
bigint_setval32(x,0);
bigint_setval(y,tmp1);
return;
}
bigint_setval(x,tmp1);
bigint_setval32(y,0);
return;
}
bigint_setval32(x,0);
bigint_setval32(y,0);
return;
}
while(!bigint_isval(r2,0)){
bigint_divide(&q,&r,r1,r2);
bigint_setval(&r1, r2);
bigint_setval(&r2, r);
bigint_multiply(&tmp1,s2,q);
bigint_subtract(&tmp2,s1,tmp1);
bigint_setval(&s1, s2);
bigint_setval(&s2, tmp2);
bigint_multiply(&tmp1,t2,q);
bigint_subtract(&tmp2,t1,tmp1);
bigint_setval(&t1, t2);
bigint_setval(&t2, tmp2);
}
bigint_divide(&q,&r,c,r1);
if(!bigint_isval(r,0)){
bigint_setval32(x,0);
bigint_setval32(y,0);
return;
}
if(revflag==1){
bigint_setval(&tmp1, s1);
bigint_setval(&s1, t1);
bigint_setval(&t1, tmp1);
}
if(s1.sign == BII_NEG){
bigint_setval(&tmp1, s1);
bigint_setpos(&tmp1);
bigint_divide(&tmp2,&r,tmp1,b);
bigint_setval(&tmp1, tmp2);
if(!bigint_isval(r,0)) bigint_incr(&tmp1);
bigint_multiply(&tmp2,tmp1,b);
bigint_plusequals(&s1,tmp2);
bigint_multiply(&tmp2,tmp1,a);
bigint_minusequals(&t1,tmp2);
}
bigint_multiply(x,q,s1);
bigint_multiply(y,q,t1);
bigint_free(&r0);
bigint_free(&r1);
bigint_free(&r2);
bigint_free(&s1);
bigint_free(&s2);
bigint_free(&t1);
bigint_free(&t2);
bigint_free(&q);
bigint_free(&r);
bigint_free(&tmp1);
bigint_free(&tmp2);
}
void bii_modexpeven(bigint *dest, bigint a, bigint e, bigint n){
/*
* Returns a**e mod n for the case when n is even.
* This algorithm is from the paper:
* Montgomery reduction with even modulus
* Koc,C.K.
* IEE Proceedings - Computers and Digital Techniques(1994),141(5):314
* http://dx.doi.org/10.1049/ip-cdt:19941291
*/
bigint q, j, A, E, x1, x2, y, qinv, tmp1, tmp2;
bigint_init(&q);
bigint_init(&j);
bigint_init(&A);
bigint_init(&E);
bigint_init(&x1);
bigint_init(&x2);
bigint_init(&y);
bigint_init(&qinv);
bigint_init(&tmp1);
bigint_init(&tmp2);
//n = q * (2**jpow)
bigint_setval(&q,n);
uint32_t jpow = 0;
bigint_setval32(&j,1);
while(bigint_parity(q)==0){
bigint_rightshift(&q,1);
bigint_leftshift(&j,1);
jpow++;
}
bigint_divide(&tmp1,&A,a,q);
bii_modexpodd(&x1, A, e, q);
bigint_getsigbits(&A,a,jpow);
bigint_getsigbits(&E, e, jpow-1);
bii_binarymodpow_powerof2(&x2,A,E,jpow);
bigint_setval32(&tmp1, 1);
bigint_egcd(q,j,tmp1, &qinv,&tmp2);
bigint_subtract(&tmp1,x2,x1);
bigint_multiply(&tmp2,tmp1,qinv);
bigint_divide(&tmp1,&y,tmp2,j);
bigint_multiply(&tmp1,q,y);
bigint_add(dest,x1,tmp1);
bigint_free(&q);
bigint_free(&j);
bigint_free(&A);
bigint_free(&E);
bigint_free(&x1);
bigint_free(&x2);
bigint_free(&y);
bigint_free(&qinv);
bigint_free(&tmp1);
bigint_free(&tmp2);
}
