Kriptografiyaning matematik asosi(rsa) shifrlash algoritmi

RC4 printsipi uch bosqichga bo'lingan:
1. S va T ni ishga tushiring
uchun i = 0 dan 255 gacha
S [i] = i;
T [i] = K [imodkeylen];
2. Dastlabki tartibga solish S
uchun i = 0 dan 255 gacha
j = (j + S [i] + T [i]) mod256;
almashtirish (S [i], S [j]);
3. Asosiy oqimni yaratish
for r = 0 to len do // r - oddiy matn uzunligi, r bayt
i = (i + 1) mod 256;
j = (j + S [i]) mod 256;
almashtirish (S [i], S [j]);
t = (S [i] + S [j]) mod 256;
k [r] = S [t];
RC4 shifrlash va dekodlashning C++ dasturi quyida keltirilgan:

1. 
   class RC4 {
   
2. 
   public:
   
3. 
   RC4(int kl):keylen(kl) {
   
4. 
   srand((unsigned)time(NULL));
   
5. 
   for (int i = 0; i
   
6. 
   int tmp=rand()%256;
   
7. 
   K.push_back(char(tmp));
   
8. 
   }
   
9. 
   }
   
10. 
    
    
11. 
    void encryption(const string &,const string &,const string &);
    
12. 
    
13. 
    private:
    
14. 
    unsigned char S [256];
    
15. 
    unsigned char T [256];
    
16. 
    int keylen;
    
17. 
    vector K;
    
18. 
    vector k;
    
19. 
    };
    
20. 
    void RC4::keyStream(int len) {
    
21. 
    initial();
    
22. 
    rangeS();
    
23. 
    
24. 
    int i=0,j=0,t;
    
25. 
    while(len--){
    
26. 
    i=(i+1)%256;
    
27. 
    j=(j+S[i])%256;
    
28. 
    
29. 
    S[i]=S[i]+S[j];
    
30. 
    S[j]=S[i]-S[j];
    
31. 
    S[i]=S[i]-S[j];
    
32. 
    
33. 
    t=(S[i]+S[j])%256;
    
34. 
    k.push_back(S[t]);
    
35. 
    }
    
36. 
    }
    
37. 
    void RC4::encryption(const string &plaintext,const string &ks,const string &ciphertext) {
    
38. 
    ifstream in;
    
39. 
    ofstream out,outks;
    
40. 
    
41. 
    in.open(plaintext);
    
42. 
    in.seekg(0,ios::end);
    
43. 
    int lenFile=in.tellg();
    
44. 
    in.seekg(0, ios::beg);
    
45. 
    
46. 
    void initial() {
    
47. 
    for(int i=0;i<256;++i){
    
48. 
    S[i]=i;
    
49. 
    T[i]=K[i%keylen];
    
50. 
    }
    
51. 
    }
    
52. 
    
    
53. 
    void rangeS() {
    
54. 
    int j=0;
    
55. 
    for(int i=0;i<256;++i){
    
56. 
    j=(j+S[i]+T[i])%256;
    
57. 
    S[i]=S[i]+S[j];
    
58. 
    S[j]=S[i]-S[j];
    
59. 
    S[i]=S[i]-S[j];
    
60. 
    }
    
61. 
    }
    
62. 
    
    
63. 
    void keyStream(int len);
    
64. 
    
65. 
    keyStream(lenFile);
    
66. 
    outks.open(ks);
    
67. 
    for(int i=0;i
    
68. 
    outks<<(k[i]);
    
69. 
    }
    
70. 
    outks.close();
    
71. 
    
72. 
    unsigned char *bits=new unsigned char[lenFile];
    
73. 
    in.read((char *)bits,lenFile);
    
74. 
    in.close();
    
75. 
    
76. 
    
77. 
    out.open(ciphertext);
    
78. 
    for(int i=0;i
    
79. 
    out<<(unsigned char)(bits[i]^k[i]);
    
80. 
    }
    
81. 
    out.close();
    
82. 
    
83. 
    delete []bits;
    
84. 
    }