linux 加密解密文件小程序

代码见下面，编译之后就可以用；建议放在bash下，或者添加环境变量。

使用方法：encrypt <文件名>。两次输入密码。加密密码与解密密码不一致解码后就不是原文件了！

#include <stdio.h>
#include <stdlib.h>
#include <string.h>   

int decrypt(FILE *in,FILE *out);
int encrypt(FILE *in,FILE *out);
int passlen;
char pass[105],passa[105];

int main(int argc,char **argv)
{
    if(argc != 2)
    {
        printf("\n请输入文件名进行加密或者解密!\n");
        printf("    encrypt <inputfile>\n\n");
        exit(0);
    }
    while(1)
    {
        printf("Enter password:");
        system("stty -icanon");
        system("stty -echo");
        scanf("%s",pass);
        system("stty icanon");
        system("stty echo");
        printf("\nEnter password again:");
        system("stty -icanon");
        system("stty -echo");
        scanf("%s",passa);
        system("stty icanon");
        system("stty echo");
        if(strcmp(pass,passa)==0) break;
        printf("\nPassword is inconsistent\n");
    }
    printf("\n");
    FILE *in = fopen(argv[1],"rb");
    FILE *out = fopen("encrypt-tmp","w");
    passlen=strlen(pass);
    char code=0xAA;
    for(int i=0;i<passlen;i++) pass[i]=pass[i]^code;
    if(in == NULL || out == NULL)
    {
        fprintf(stderr,"%s\n","open file error!");
        exit(1);
    }
    encrypt(in,out);
    fclose(in);
    fclose(out);
    remove(argv[1]);
    rename("encrypt-tmp",argv[1]);
    return 0;
}
int encrypt(FILE *in,FILE *out)
{
    if(in == NULL || out == NULL)
    {
        fprintf(stderr,"%s\n","file error!\n");
        return -1;
    }  

    char hex;
    int i=0;
    while(fread(&hex,1,1,in))
    {
        char s=pass[i];
        hex = hex^s;
        fwrite(&hex,1,1,out);
        i++;
        i%=passlen;
    }
    return 0;
}