How to resolve the "EVP_DecryptFInal_ex: bad decrypt" during file decryption
I have the following query.Could any one please suggest me a solution.
I'm working on encryption and decryption of file for first time.
I have encrypted file through command prompt using the command:
openssl enc -aes-256-cbc -in file.txt -out file.enc -k "key value" -iv "iv value"
I have to decrypt it programmatically. So I have written the program for it, but it is throwing the following error:
./exe_file enc_file_directory
...
error: 06065064: digital envelope routines: EVP_DecryptFInal_ex: bad decrypt: evp_enc.c
The program below takes input as directory path and search for encrypted file ".enc" and try to decrypt it read into buffer.
Code:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <dirent.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <openssl/evp.h>
#include <openssl/err.h>
#include <openssl/conf.h>
#include <libxml/globals.h>
void handleErrors(char *msg)
{
{
ERR_print_errors_fp(stderr);
printf("%s", msg);
abort();
}
}
void freeMemory(char *mem)
{
if (NULL != mem)
{
free(mem);
mem = NULL;
}
}
/* Function to decrypt the XML files */
int decryptXML(unsigned char *indata, unsigned char *outdata, int fsize)
{
int outlen1 = 0, outlen2 = 0;
unsigned char iv[] = "b63e541bc9ece19a1339df4f8720dcc3";
unsigned char ckey[] = "70bbc518c57acca2c2001694648c40ddaf19e3b4fe1376ad656de8887a0a5ec2" ;
if (NULL == indata)
{
printf ("input data is empty\n");
return 0;
}
if (0 >= fsize)
{
printf ("file size is zero\n");
return 0;
}
outdata = (char *) malloc (sizeof (char) * fsize * 2);
EVP_CIPHER_CTX ctx;
EVP_CIPHER_CTX_init(&ctx);
if (! EVP_DecryptInit_ex (&ctx, EVP_aes_256_cbc(), NULL, ckey, iv))
{
EVP_CIPHER_CTX_cleanup(&ctx);
handleErrors("DInit");
}
if (! EVP_DecryptUpdate (&ctx, outdata, &outlen1, indata, fsize))
{
EVP_CIPHER_CTX_cleanup(&ctx);
handleErrors("DUpdate");
}
if (! EVP_DecryptFinal_ex (&ctx, outdata + outlen1, &outlen2))
{
EVP_CIPHER_CTX_cleanup(&ctx);
handleErrors("DFinal");
}
EVP_CIPHER_CTX_cleanup(&ctx);
return outlen1+outlen2;
}
int isDirectory(char *path)
{
DIR *dir = NULL;
FILE *fin = NULL, *fout = NULL;
int enc_len = 0, dec_len = 0, fsize = 0, ksize = 0;
unsigned char *indata = NULL, *outdata = NULL;
char buff[BUFFER_SIZE], file_path[BUFFER_SIZE], cur_dir[BUFFER_SIZE];
struct dirent *in_dir;
struct stat s;
if (NULL == (dir = opendir(path)))
{
printf ("ERROR: Failed to open the directory %s\n", path);
perror("cannot open.");
exit(1);
}
while (NULL != (in_dir = readdir(dir)))
{
if (!strcmp (in_dir->d_name, ".") || !strcmp(in_dir->d_name, ".."))
continue;
sprintf (buff, "%s/%s", path, in_dir->d_name);
if (-1 == stat(buff, &s))
{
perror("stat");
exit(1);
}
if (S_ISDIR(s.st_mode))
{
isDirectory(buff);
}
else
{
strcpy(file_path, buff);
if (strstr(file_path, ".enc"))
{
/* File to be decrypted */
fout = fopen(file_path,"rb");
fseek (fout, 0L, SEEK_END);
fsize = ftell(fout);
fseek (fout, 0L, SEEK_SET);
indata = (char*)malloc(fsize);
fread (indata, sizeof(char), fsize, fout);
if (NULL == fout)
{
perror("Cannot open enc file: ");
return 1;
}
dec_len = decryptXML (indata, outdata, fsize);
outdata[dec_len] = '\0';
printf ("%s\n", outdata);
fclose (fin);
fclose (fout);
}
}
}
closedir(dir);
freeMemory(outdata);
freeMemory(indata);
return 1;
}
int main(int argc, char *argv[])
{
int result;
if (argc != 2)
{
printf ("Usage: <executable> path_of_the_files\n");
return -1;
}
ERR_load_crypto_strings();
OpenSSL_add_all_algorithms();
OPENSSL_config(NULL);
/* Checking for the directory existance */
result = isDirectory(argv[1]);
EVP_cleanup();
ERR_free_strings();
if (0 == result)
return 1;
else
return 0;
}
Thank you.
