#include <stdio.h>
#include <openssl/evp.h>
#include <unistd.h>
#include <assert.h>
#include <string.h>


int main(int argc, char* argv[]) {
    EVP_CIPHER_CTX* context = EVP_CIPHER_CTX_new();

    int salt_size = 8;
    unsigned char salt[salt_size];
    fread(salt, sizeof(unsigned char), salt_size, stdin);
    fread(salt, sizeof(unsigned char), salt_size, stdin);

    //unsigned char preamble[16];
    //read(STDIN_FILENO, preamble, sizeof(preamble));
    //unsigned char salt[8];
    //memcpy(salt, preamble + 8, sizeof(salt));

    printf("INPUT : %s\n", salt);
    fflush(stdout);

    unsigned char key[32];
    unsigned char init_value[16];
    EVP_BytesToKey(EVP_aes_256_cbc(), EVP_sha256(), salt, argv[1], strlen(argv[1]), 1, key, init_value);
    EVP_DecryptInit(context, EVP_aes_256_cbc(), key, init_value);

    int buff_size = EVP_CIPHER_CTX_block_size(context);
    unsigned char buffer[buff_size];
    int readed = fread((void*)buffer, sizeof(unsigned char), buff_size, stdin);

    int out_size = EVP_CIPHER_CTX_block_size(context);
    unsigned char out[out_size];
    int written;

    while(readed > 0 || written > 0) {
        assert(EVP_DecryptUpdate(context, out, &written, buffer, readed) > 0);
        //printf("%d\n", written);
        fflush(stdout);
        printf("%.*s", written, out);
        //fwrite((void*)out, sizeof(unsigned char), written, stdout);
        fflush(stdout);
        //printf("here");
        readed = fread((void*)buffer, sizeof(unsigned char), buff_size, stdin);
    }

    EVP_DecryptFinal(context, out, &written);

    printf("%.*s", written, out);
    fflush(stdout);
    EVP_CIPHER_CTX_free(context);
}