hmMJQxi7

1#include "rsa.h"
2#include <math.h>
3//проверка: простое ли число
4bool isPrime(unsigned short value)
5{
6	if (value == 1)
7		return false;
8
9	if (value == 2)
10		return true;
11
12	if (value % 2 == 0)
13		return false;
14
15	bool result = true;
16	for (int i = 3; i <= sqrt((float)value); i++)
17	{
18		if (value % i == 0)
19			result = false;
20	}
21
22	return result;
23}
24//получение НОД
25unsigned short getGreatestCommonDivider(unsigned short firstNumber, unsigned short secondNumber)
26{
27	while (secondNumber != 0)
28	{
29		int temp = firstNumber % secondNumber;
30		firstNumber = secondNumber;
31		secondNumber = temp;
32	}
33	return firstNumber;
34}
35//вычисление мультипликативного инверсного
36unsigned short getMultiplyInverse(unsigned short value, unsigned short mod)
37{
38    int a = mod;
39	int b = value;
40	int x0 = 1, x1 = 0;
41	int y0 = 0, y1 = 1;
42
43	while (b > 1)
44	{
45		int q = a / b;
46		int temp = a % b;
47		int x2 = x0 - q * x1;
48		int y2 = y0 - q * y1;
49		a = b;
50		b = temp;
51		x0 = x1;
52		x1 = x2;
53		y0 = y1;
54		y1 = y2;
55	}
56
57	if (y1 < 0)
58		y1 += mod;
59
60	return y1;
61}
62//вычисление закрытого ключа
63unsigned short getKey(unsigned short p, unsigned short q, unsigned short key)
64{
65	unsigned short eilerR = (p - 1) * (q - 1);
66	return getMultiplyInverse(key, eilerR);
67}
68//быстрое возведение в степень
69int getFastExp(unsigned long long value, unsigned short power, unsigned short mod)
70{
71	unsigned long long result = 1;
72	while (power != 0)
73	{
74		while (power % 2 == 0)
75		{
76			power = power / 2;
77			value = (value * value) % mod;
78		}
79		power -= 1;
80		result = (result * value) % mod;
81	}
82
83	return result;
84}
85//поиск делителя
86unsigned short getDivider(unsigned short value)
87{
88	if (value == 1)
89		return 1;
90
91	unsigned short result = 2;
92	while (!(value % result == 0 && isPrime(value / result) && isPrime(result)) && result <= value / 2)
93	{
94		result++;
95	}
96
97	if (result > value / 2)
98		result = value;
99
100	return result;
101}
102//шифрование 
103unsigned short getCipher(unsigned short value, unsigned short p, unsigned short q, unsigned short secretKey)
104{
105	unsigned short r = p * q;
106	unsigned short publicKey = getKey(p, q, secretKey);
107	return getFastExp(value, publicKey, r);
108}
109//дешифрование
110unsigned short getPlain(unsigned short value, unsigned short r, unsigned short key)
111{
112	return getFastExp(value, key, r);
113}