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

int encrypt(char a, int r1, int r2){
    int t;
    r1 = r1 & 0xff;
    r2 = r2 & 7;
    printf("encrypt(%x, %x, %x)\n",a,r1,r2);
    t = a ^ r1;
    printf("t: %x\n",t);
    return ((t << r2)|(t >> (8-r2)));
}

int decrypt(int a, int r1, int r2){
    int t;
    r1 = r1 & 0xff;
    r2 = r2 & 7;
    a = a&0xff;
    // printf("decrypt(%x, %x, %x)\n",a,r1,r2);
    t = ((a << (8-r2))|(a >>r2)) & 0xff;
    // printf("t: %x\n",t);
    return t ^ r1;
}

int main(void) {
    uint seed;
    int r1,r2, enc, dec;
    FILE *enc_file;
    size_t size;

    // seed = 0x63d17786;
    // srand(seed);
    // r1 = rand();
    // r2 = rand();
    // //printf("%x", r);
    enc_file = fopen("flag.enc.bak","rb");
    fseek(enc_file,0L,SEEK_END);
    size = ftell(enc_file)-4;
    char buffer[size+1];
    printf("size: %x\n", size);
    fseek(enc_file,0L,SEEK_SET);
    fread(&seed, 4, 1, enc_file);
    srand(seed);
    printf("seed: %x\n", seed);
    // buffer = malloc(2);
    // fseek(enc_file, 0, SEEK_END);
    // size = ftell(enc_file);
    // fseek(enc_file, sizeof(seed), SEEK_SET);
        // fread(buffer, 1, 1, enc_file);
    fread(&buffer, size, 1, enc_file);
    fclose(enc_file);
    printf("buffer: ");
    for (int i = 0; i < size; i++){
        printf("%2x",buffer[i]&0xff);
    }
    printf("\n");
    for (int i = 0; i < size; i++){

        r1 = rand();
        r2 = rand();
        // // enc = encrypt('A',r1,r2);
        // // printf("enc: %x\n", enc);

        dec = decrypt(buffer[i],r1,r2);
        printf("%c", dec);
    }
    return 0;
}