tech13-1.c

#include <openssl/evp.h>
#include <openssl/sha.h>
#include <stdio.h>
#include <string.h>

enum { MAX_SIZE = 4096 };
enum ErrorCodes {SUCCESS, BAD_ARG };

int main(int argc, char* argv[])
{

    if (argc - 1 < 1 ) {
        return BAD_ARG;
    }

    unsigned char data[MAX_SIZE] = "";

    int num_read = 0;

    num_read = fread(data, sizeof(data[0]), MAX_SIZE, stdin);


    unsigned char key[32], iv[32];

    unsigned char* password = (unsigned char*)argv[1];
    size_t pass_len = strlen(argv[1]);


    EVP_BytesToKey(
        EVP_aes_256_cbc(),
        EVP_sha256(),
        data + 8,
        password,
        pass_len,
        1,
        key,
        iv);

    
    printf("Salt=");
    for (size_t i = 0; i < 8; ++i) {
        printf("%02x", (data + 8)[i]);
    }
    printf("!\n");

    printf("key=");
    for (size_t i = 0; i < 32; ++i) {
        printf("%02x", (key)[i]);
    }
    printf("!\n");

    printf("iv=");
    for (size_t i = 0; i < 32; ++i) {
        printf("%02x", (iv)[i]);
    }
    printf("!\n");

    return 0;

    EVP_CIPHER_CTX* ctx = EVP_CIPHER_CTX_new();

    int len = 0;
    int plaintext_len = 0;

    unsigned char plaintext[MAX_SIZE] = "";

    EVP_DecryptInit_ex(ctx, EVP_aes_256_cbc(), NULL, key, iv);
    //EVP_CIPHER_CTX_set_key_length(ctx, EVP_MAX_KEY_LENGTH);

    EVP_DecryptUpdate(ctx, plaintext, &len, data, num_read); 

    EVP_DecryptFinal_ex(ctx, plaintext + len, &len);
    plaintext_len += len;

    EVP_CIPHER_CTX_free(ctx);

}