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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, char** argv) {
// We need a file to encrypt
if (argc != 2) {
fprintf(stderr, "Usage: encrypt <file>");
return EXIT_FAILURE;
}
// Now lets open that file
FILE* file = fopen(argv[1], "r");
if (file == NULL) {
fprintf(stderr, "No file specified\n");
return EXIT_FAILURE;
}
// Now we need the passphrase. Get it
char *passphrase = malloc(256);
do {
printf("Enter Passphrase: ");
if (fgets(passphrase, 255, stdin) == NULL) {
fclose(file);
fprintf(stderr, "Read error or end of file");
return EXIT_FAILURE;
}
} while (strlen(passphrase) <= 0);
// And a temporary file to hold the encrypted data
char tpath[] = "SimCr.XXXXXX";
int tempfd = mkstemp(tpath);
FILE* temp = fdopen(tempfd, "w");
// Now we encrypt!
int passlen = strlen(passphrase) - 1;
int c,j=0;
while ((c=fgetc(file)) != EOF) {
if (j == passlen) {
fputc(c ^ passphrase[0], temp);
j=1;
} else {
fputc(c ^ passphrase[j], temp);
j++;
}
}
// Close the files
fflush(temp);
fclose(temp);
fclose(file);
// Move the file back
if (rename(tpath, argv[1]) != 0) {
fprintf(stderr, "Your encrypted file is located in %s.", tpath);
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}
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