#include "cryptwrapper.h"

void mycryptwrapper_init(){

    /* Version check should be the very first call because it
    makes sure that important subsystems are initialized.
    #define NEED_LIBGCRYPT_VERSION to the minimum required version. */
    if (!gcry_check_version (NEED_LIBGCRYPT_VERSION))
    {
        fprintf (stderr, "libgcrypt is too old (need %s, have %s)\n",
                 NEED_LIBGCRYPT_VERSION, gcry_check_version (NULL));
        exit (2);
    }

    /* Disable secure memory.  */
    gcry_control (GCRYCTL_DISABLE_SECMEM, 0);

    /* ... If required, other initialization goes here.  */

    /* Tell Libgcrypt that initialization has completed. */
    gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);

    HASH_SIZE = gcry_md_get_algo_dlen(algo);

}

void  mycryptwrapper_print(const void * buf, size_t len){
    for (size_t i = 0; i< len; i++){
        printf("%02x ", ((uint8_t*)buf)[i]);
    }
    printf("\n");
}

int check_sha256_tag(uint8_t * ptr, size_t file_len){
    uint8_t * calc_hash = malloc(HASH_SIZE);
    gcry_md_hash_buffer(algo,calc_hash,ptr,file_len-HASH_SIZE);
    /*printf("hash\n");
    mycryptwrapper_print(calc_hash,32);
    printf("HASH in file:\n");
    for (int i = 0 ; i< HASH_SIZE; i++){
        printf("%02x ", ptr[file_len+i-HASH_SIZE]);
    }
    printf("file:\n%s",(char* )ptr);
*/
    for (int i=0 ; i< HASH_SIZE; i++){
        //printf("%02x ", calc_hash[i]);
        if (calc_hash[i] != ptr[i+file_len-HASH_SIZE]){
            free(calc_hash);
           // printf("no match\n");
            return 0;
        }
    }


    return 1;

}