C++ encryption

SUBMITTED BY: Guest

DATE: Jan. 16, 2014, 11:34 a.m.

FORMAT: C++

SIZE: 3.5 kB

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  1. A great code about encryption
  3. #include <stdio.h>
  4. #include <sys/types.h>
  5. #include <sys/stat.h>
  6. #include <fcntl.h>
  8. #define cypherbits 256 /* encryption strength in bits */
  9. #define cypher cypherbits/(sizeof(int)*8)
  10. int seed[cypher];
  11. void modseed() {
  12. int x;
  13. for(x=1;x<cypher;x++)seed[x]=seed[x]*0x81772012+seed[x]+0x49122035+seed[x+1];
  14. for(x=1;x<cypher;x++)seed[0]=seed[0]^seed[x];
  15. }
  16. int seedsum() {
  17. int n,x;
  18. n=0x80379251;
  19. for(x=0;x<cypher;x++)n=n^seed[x];
  20. return((n>>24)^((n>>16)&255)^((n>>8)&255)^(n&255));
  21. }
  22. char strequ(char *s1,char *s2) {
  23. int p;
  24. p=0;
  25. while((s1[p]==s2[p])&&(s1[p]!=0)&&(s2[p]!=0))p++;
  26. if(s1[p]==s2[p])return(1); else return(0);
  27. }
  28. int main(int argc,char *argv[]) {
  29. char
  30. banner[]="\x43\x6f\x64\x65\x64\x20\x62\x79\x20\x50\x72\x61\x76\x65\x65\x6e\x61"
  31. "\x20\x6f\x66\x20\x49\x6e\x64\x69\x61"
  33. "\x20\x28\x70\x76\x6e\x63\x61\x64\x40\x6b\x72\x65\x63\x2e\x65\x72\x6e\x65\x74\x2e\x69\x6e\x29";
  34. char buf[2048];
  35. int p,r,l,i,t,s,x;
  36. char b,c,pct,lpct;
  37. FILE *infile=NULL,*outfile=NULL;
  38. fprintf(stderr, "%s\n", banner);
  39. if(argc!=4){
  40. fprintf(stderr,"use: %s <infile> <outfile> <key>\n",argv[0]);
  41. return -1;
  42. }
  43. if(strequ(argv[1],"stdin"))infile=stdin; else
  44. if((infile=fopen(argv[1],"r"))==NULL){
  45. fprintf(stderr,"failed to open %s\n",argv[1]);
  46. return -1;
  47. }
  48. if(strequ(argv[2],"stdout"))outfile=stdout; else
  49. if((outfile=fopen(argv[2],"w"))==NULL){
  50. fprintf(stderr,"failed to create %s\n",argv[2]);
  51. return -1;
  52. }
  53. if(infile!=stdin) {
  54. fseek(infile,0,SEEK_END);
  55. l=ftell(infile);
  56. rewind(infile);
  57. } else l=0;
  58. s=l;
  59. t=0;
  60. pct=0;
  61. if(l<1)fprintf(stderr,"Encrypting data.. (%d bit cypher)\n",cypher*sizeof(int)*8);
  62. else fprintf(stderr,"Encrypting %d bytes.. (%d bit cypher)\n",l,cypher*sizeof(int)*8);
  63. /* bzero(seed,sizeof(seed)); */
  64. modseed();
  65. p=0;
  66. while(argv[3][p]!=0){
  67. modseed();
  68. seed[0]=seed[0]+argv[3][p];
  69. modseed();
  70. p++;
  71. }
  72. i=0;
  73. if(l>0){
  74. fputc('[',stderr);
  75. x=(l/sizeof(buf));
  76. if(l-x*sizeof(buf)!=0)x+=1;
  77. if(x>38)x=38;
  78. for(p=0;p<x;p++) fputc(32,stderr);
  79. fputc(']',stderr);
  80. fputc(13,stderr);
  81. fputc('[',stderr);
  82. fflush(stderr);
  83. }
  84. c=1;
  85. while(c){
  86. r=fread(&buf,1,sizeof(buf),infile);
  87. if(r>0) {
  88. t+=r;
  89. if(l>0){
  90. lpct=pct;
  91. pct=t/(l/x);
  92. if(pct>lpct) {
  93. fputc(88+32*i,stderr);
  94. fflush(stderr);
  95. i=1-i;
  96. }
  97. } else {
  98. fputc(88+32*i,stderr);
  99. fflush(stderr);
  100. i=1-i;
  101. }
  102. p=0;
  103. while(p<r) {
  104. modseed();
  105. buf[p]=buf[p]^seedsum();
  106. p++;
  107. }
  108. if(fwrite(&buf,1,r,outfile)!=r) {
  109. fprintf(stderr,"\nerror writing data\n");
  110. return -1;
  111. }
  112. } else c=0;
  113. }
  114. if(l>0)fputc(']',stderr);
  115. fprintf(stderr,"\nDone. Wrote %d bytes.\n",t);
  116. }
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