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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3.  
  4. long long P, Q, E, D;
  5.  
  6. long long ExtendedGCD(long long A, long long B, long long *C, long long *D)
  7. {
  8. 	long long I;
  9. 	long long J;
  10. 	if (A%B == 0)
  11. 	{
  12. 		(*C) = 0;
  13. 		(*D) = 1;
  14. 		return B;
  15. 	}
  16. 	else
  17. 	{
  18. 		I = ExtendedGCD(B, A%B, C, D);
  19. 		J = (*C);
  20. 		(*C) = (*D);
  21. 		(*D) = (*D)*(-A / B) + J;
  22. 		return I;
  23. 	}
  24. }
  25.  
  26. void GenerateKeys()
  27. {
  28. 	long long I, J;
  29. 	P = 944659;
  30. 	P = 10007;
  31. 	Q = 817907;
  32. 	Q = 10009;
  33. 	E = 65537;
  34. 	ExtendedGCD((P - 1)*(Q - 1), E, &I, &J);
  35. 	while (J <= 0)
  36. 		J += (P - 1)*(Q - 1);
  37. 	D = J;
  38. }
  39.  
  40. long long ExponentBySquaring(long long V, long long Exp)
  41. {
  42. 	long long I;
  43. 	if (Exp == 0)
  44. 	{
  45. 		return 1;
  46. 	}
  47. 	else if (Exp == 1)
  48. 	{
  49. 		return V % (P*Q);
  50. 	}
  51. 	else
  52. 	{
  53. 		if (Exp % 2 == 0)
  54. 		{
  55. 			I = ExponentBySquaring(V, Exp / 2);
  56. 			I = ((I % (P*Q)) * (I % (P*Q))) % (P*Q);
  57. 		}
  58. 		else
  59. 		{
  60. 			I = ExponentBySquaring(V, Exp / 2);
  61. 			I = ((((I % (P*Q)) * (I % (P*Q))) % (P*Q))*(V % (P*Q))) % (P * Q);
  62. 		}
  63. 		return I % (P*Q);
  64. 	}
  65. }
  66.  
  67.  
  68.  
  69. long long MyEncrypt(long long M)
  70. {
  71. 	return ExponentBySquaring(M, E);
  72. }
  73.  
  74. long long MyDecrypt(long long C)
  75. {
  76. 	return ExponentBySquaring(C, D);
  77. }
  78.  
  79. int main()
  80. {
  81. 	GenerateKeys();
  82. 	printf("%lld\n", MyDecrypt(MyEncrypt(65)));
  83. 	while (getchar() != 'q')
  84. 	{
  85.  
  86. 	}
  87. 	return 0;
  88. }
  89.  
Time limit exceeded #stdin #stdout 5s 3348KB
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https://ideone.com/DpRAIU
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
public

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