1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
| #include <iostream>
#include <vector>
using namespace std;
class RSA {
public:
RSA() {}
void generateKeys() {
// Generate two prime numbers, p and q.
p = generatePrime();
q = generatePrime();
// Calculate the modulus, n.
n = p * q;
// Calculate the public exponent, e.
e = rand() % (p - 1) + 1;
// Calculate the private exponent, d.
d = modInverse(e, (p - 1) * (q - 1));
}
string encrypt(string message) {
// Convert the message to a number.
int messageNumber = stoi(message);
// Encrypt the message using the public exponent, e.
int encryptedNumber = pow(messageNumber, e) % n;
// Convert the encrypted number back to a string.
string encryptedMessage = to_string(encryptedNumber);
return encryptedMessage;
}
string decrypt(string encryptedMessage) {
// Convert the encrypted message to a number.
int encryptedNumber = stoi(encryptedMessage);
// Decrypt the message using the private exponent, d.
int decryptedNumber = pow(encryptedNumber, d) % n;
// Convert the decrypted number back to a string.
string decryptedMessage = to_string(decryptedNumber);
return decryptedMessage;
}
private:
int p;
int q;
int n;
int e;
int d;
int generatePrime() {
// Generate a random number between 2 and 1000.
int number = rand() % 1000 + 2;
// Check if the number is prime.
bool isPrime = true;
for (int i = 2; i < number; i++) {
if (number % i == 0) {
isPrime = false;
break;
}
}
// If the number is prime, return it.
if (isPrime) {
return number;
}
// Otherwise, generate another number.
return generatePrime();
}
int modInverse(int a, int m) {
// This function returns the modular inverse of a modulo m.
// Initialize the result to 1.
int result = 1;
// While a is not 0, do the following:
while (a != 0) {
// Calculate the remainder of a divided by m.
int remainder = a % m;
// Calculate the modular inverse of the remainder.
int inverse = modInverse(remainder, m);
// Multiply the result by the inverse.
result = result * inverse % m;
// Subtract the remainder from a.
a = a - remainder;
}
return result;
}
};
int main() {
// Create an RSA object.
RSA rsa;
// Generate the public and private keys.
rsa.generateKeys();
// Print the public and private keys.
cout << "Public key: " << rsa.e << " " << rsa.n << endl;
cout << "Private key: " << rsa.d << " " << rsa.n << endl;
// Encrypt a message.
string message = "Hello, world!";
string encryptedMessage = rsa.encrypt(message);
// Decrypt the message.
string decryptedMessage = rsa.decrypt(encryptedMessage);
// Print the encrypted and decrypted messages.
cout << "Encrypted message: " << encryptedMessage << endl;
cout << "Decrypted message: " << decryptedMessage << endl;
return 0;
} |
