int deserialize_mpi(gcry_mpi_t *x, enum disp_format df, const char *buf,
int inlen)
{
switch(df) {
case DF_BIN:
gcry_mpi_scan(x, GCRYMPI_FMT_USG, buf, inlen, NULL);
gcry_mpi_set_flag(*x, GCRYMPI_FLAG_SECURE);
break;
case DF_COMPACT:
case DF_BASE36:
do {
const char *digits = get_digits(df);
unsigned int digit_count = get_digit_count(df);
char *d;
int i;
*x = gcry_mpi_snew(0);
for(i = 0; i < inlen; i++) {
if (! (d = memchr(digits, buf[i], digit_count))) {
gcry_mpi_release(*x);
return 0;
}
gcry_mpi_mul_ui(*x, *x, digit_count);
gcry_mpi_add_ui(*x, *x, d - digits);
}
} while (0);
break;
default:
assert(0);
}
return 1;
}
void serialize_mpi(char *outbuf, int outlen, enum disp_format df,
const gcry_mpi_t x)
{
switch(df) {
case DF_BIN: do {
int len = (gcry_mpi_get_nbits(x) + 7) / 8;
assert(len <= outlen);
memset(outbuf, 0, outlen - len);
gcry_mpi_print(GCRYMPI_FMT_USG, (unsigned char*)outbuf + (outlen - len),
len, NULL, x);
} while (0);
break;
case DF_COMPACT:
case DF_BASE36: do {
const char *digits = get_digits(df);
unsigned int digit_count = get_digit_count(df);
gcry_mpi_t base, Q, R;
int i;
base = gcry_mpi_set_ui(NULL, digit_count);
Q = gcry_mpi_copy(x);
R = gcry_mpi_snew(0);
for(i = outlen - 1; i >= 0; i--) {
unsigned char digit = 0;
gcry_mpi_div(Q, R, Q, base, 0);
gcry_mpi_print(GCRYMPI_FMT_USG, &digit, 1, NULL, R);
assert(digit < digit_count);
outbuf[i] = digits[digit];
}
assert(! gcry_mpi_cmp_ui(Q, 0));
gcry_mpi_release(base);
gcry_mpi_release(Q);
gcry_mpi_release(R);
} while(0);
break;
default:
assert(0);
}
}
int main()
{
int result = 1;
int index = 1;
int positive_integer=1;
for(int new_pos = 0; index < LIMIT; positive_integer++)
{
int prev_pos = new_pos;
new_pos += get_digit_count(positive_integer);
if(index >= prev_pos+1 && index <= new_pos)
{
result *= get_digit_at_pos(index-prev_pos,positive_integer);
index = index*10;
}
}
cout << result << endl;
return 0;
}
int get_serialization_len(const gcry_mpi_t x, enum disp_format df)
{
int res;
switch(df) {
case DF_BIN:
res = (gcry_mpi_get_nbits(x) + 7) / 8;
break;
case DF_BASE36:
case DF_COMPACT:
do {
gcry_mpi_t base, Q;
base = gcry_mpi_set_ui(NULL, get_digit_count(df));
Q = gcry_mpi_copy(x);
for(res = 0; gcry_mpi_cmp_ui(Q, 0); res++)
gcry_mpi_div(Q, NULL, Q, base, 0);
gcry_mpi_release(base);
gcry_mpi_release(Q);
} while (0);
break;
default:
assert(0);
}
return res;
}
