int expmod(int a, int e, int n) {
if (a > n)
return expmod((a % n), e, n);
else if (e == 1)
return (a % n);
else if (e == 0)
return 1;
else if (a == 0)
return 0;
else if (e % 2 == 0)
return expmod(a * a, e / 2, n);
else
return (expmod(a, e - 1, n) * a) % n;
}
ll expmod(ll b, ll e, ll m) { //O(log b)
if (!e)
return 1;
ll q = expmod(b, e / 2, m);
q = mulmod(q, q, m);
return e % 2 ? mulmod(b, q, m) : q;
}
int RSA::is_prime_san(int p[MAX])
{
int i, a[MAX], t[MAX], s[MAX], o[MAX];
for (i = 0; i<MAX; i++)
s[i] = o[i] = a[i] = t[i] = 0;
t[0] = 1;
t[MAX - 1] = 1;
a[0] = 2;// { 2,3,5,7 }
a[MAX - 1] = 1;
sub(p, t, s);
expmod(a, s, p, o);
if (cmp(o, t) != 0)
{
return 0;
}
a[0] = 3;
for (i = 0; i<MAX; i++) o[i] = 0;
expmod(a, s, p, o);
if (cmp(o, t) != 0)
{
return 0;
}
a[0] = 5;
for (i = 0; i<MAX; i++) o[i] = 0;
expmod(a, s, p, o);
if (cmp(o, t) != 0)
{
return 0;
}
a[0] = 7;
for (i = 0; i<MAX; i++) o[i] = 0;
expmod(a, s, p, o);
if (cmp(o, t) != 0)
{
return 0;
}
return 1;
}
bool es_primo_prob(ll n, int a) {
if (n == a)
return true;
ll s = 0, d = n - 1;
while (d % 2 == 0)
s++, d /= 2;
ll x = expmod(a, d, n);
if ((x == 1) || (x + 1 == n))
return true;
for (int i = 0; i < s-1; ++i) {
x = mulmod(x, x, n);
if (x == 1)
return false;
if (x + 1 == n)
return true;
}
return false;
}
/*!
* @param[in] d,n为私钥，由函数RSAKey()产生
* @param[in] text为密文，对应加密函数，密文的格式为string
* @return[string] 解密之后的明文采用string进行存储
* @pre \e 进行解密的过程中进行了数据类型的转换
* @see e，d，n & text
*/
string RSA::tdecrypto(int d[MAX], int n[MAX], string text)
{
struct slink *h, *p1, *p2;
char ch;
int i, j, k, c, count, temp;
i = 0;
j = 3;
count = 0;
h = p1 = p2 = (struct slink *)malloc(LEN);
int kk;
for (kk = 0; kk < text.length(); kk++)
{
ch = text.at(kk);
c = ch;
if (j == 3)
{
p1->bignum[MAX - 2] = c;
j--;
}
else if (j == 2)
{
temp = c - 48;
j--;
}
else if (j == 1)
{
p1->bignum[MAX - 1] = temp * 10 + c - 48;
j--;
}
else if (j == 0)
{
p1->bignum[i] = c - 48;
i++;
if (i == p1->bignum[MAX - 1])
{
i = 0;
j = 3;
count++;
if (count == 1)
h = p1;
else p2->next = p1;
p2 = p1;
p1 = (struct slink *)malloc(LEN);
}
}
}
p2->next = NULL;
p2 = (struct slink *)malloc(LEN);
p1 = h;
k = 0;
string res;
if (h != NULL)/*/temp为暂存ASIIC码的int值*/
do
{
for (i = 0; i<MAX; i++)
p2->bignum[i] = 0;
expmod(p1->bignum, d, n, p2->bignum);
temp = p2->bignum[0] + p2->bignum[1] * 10 + p2->bignum[2] * 100;
if ((p2->bignum[MAX - 2]) == '0')
{
temp = 0 - temp;
}/*/转化为正确的ASIIC码，如-78-96形成汉字 */
ch = temp;/* str[k]--->ch */
res += ch;
k++;
p1 = p1->next;
p2 = (struct slink *)malloc(LEN);
} while (p1 != NULL);
return res;
}
/*!
* @param[in] e，n为随机产生的公钥，利用公钥进行加密
* @param[in] text为明文，明文以char*的格式存储
* @return[string] 返回值为加密成功之后的密文，采用string类型进行存储
* @pre \e 进行加密的过程中进行了数据类型的转换
* @see e，d，n & text
*/
string RSA::tencrypto(int e[MAX], int n[MAX], char* text)/*//对有需要的文件进行加密*/
{
int i, k, count, temp, c;
char ch;
struct slink *p, *p1, *p2;
struct slink *h;
h = p = p1 = p2 = (struct slink *)malloc(LEN);
h = NULL;
if (text == NULL)
{
return NULL;
}
count = 0;
int j;
for (j = 0; j < strlen(text); j++)
{
ch = text[j];
c = ch;
k = 0;
if (c<0)
{
c = abs(c);/*/把负数取正并且做一个标记*/
p1->bignum[MAX - 2] = '0';
}
else
{
p1->bignum[MAX - 2] = '1';
}
while (c / 10 != 0)
{
temp = c % 10;
c = c / 10;
p1->bignum[k] = temp;
k++;
}
p1->bignum[k] = c;
p1->bignum[MAX - 1] = k + 1;
count = count + 1;
if (count == 1)
h = p1;
else p2->next = p1;
p2 = p1;
p1 = (struct slink *)malloc(LEN);
}
p2->next = NULL;
string res;
p = p1 = (struct slink *)malloc(LEN);
p = h;
if (h != NULL)
do
{
expmod(p->bignum, e, n, p1->bignum);
ch = p1->bignum[MAX - 2];
res += ch;
if ((p1->bignum[MAX - 1] / 10) == 0)/*/判断p1->bignum[99]的是否大于十；*/
{
ch = 0 + 48;
res += ch;
ch = p1->bignum[MAX - 1] + 48;
res += ch;
}
else
{
ch = p1->bignum[MAX - 1] / 10 + 48;
res += ch;
ch = p1->bignum[MAX - 1] % 10 + 48;
res += ch;
}
for (i = 0; i<p1->bignum[MAX - 1]; i++)
{
ch = p1->bignum[i] + 48;
res += ch;
}
p = p->next;
p1 = (struct slink *)malloc(LEN);
} while (p != NULL);
return res;
}
int main() {
uint32_t b, p, m;
while (std::cin >> b >> p >> m) {
std::cout << expmod(b, p, m) << std::endl;
}
}
