strange i think it has something to do with me using "rb" and "wb" instead
of "r" and "w"...
On Fri, Aug 16, 2013 at 2:14 AM, Ztatik Light <ztatik.li...@gmail.com>wrote:
> So, I'm having a really weird issue... i'm trying simple file
> encryption/decryption with BIO_*, but if the encrypted file is in a
> subdirectory.. i get garbage data,
>
> I'll post the code i'm using, with a brief elaboration on how i'm using it
> and what behaviour i'm getting:
>
> ///////////////////////////////
>
> /*
>>
>> Example of ssl read and write to a file
>>
>>
>>> gcc ssl_write_read.c -lssl
>>
>> ./a.out
>>
>>
>>>
>>> */
>>
>>
>>>
>>>
>>> #include <openssl/bio.h>
>>
>> #include <openssl/err.h>
>>
>> #include <openssl/rand.h>
>>
>> #include <openssl/ssl.h>
>>
>> #include <openssl/x509v3.h>
>>
>>
>>> int read_whole_file( char* filename, char** data ){
>>
>> FILE* file = fopen( filename, "rb" );
>>
>> fseek( file, 0, SEEK_END );
>>
>> long fileSize = ftell( file );
>>
>> rewind( file );
>>
>> *data = malloc( fileSize );
>>
>> fread( *data, fileSize, 1, file );
>>
>> fclose( file );
>>
>> return fileSize;
>>
>> }
>>
>> void encrypt_file( char* filename ){
>>
>> char new_filename[strlen( filename + 4 )];
>>
>> strcpy( new_filename, filename );
>>
>> strcat( new_filename, ".enc" );
>>
>> char* data;
>>
>> int fileSize = read_whole_file( filename, &data );
>>
>> write_data( new_filename, data, fileSize, (unsigned char*)"mykey" );
>>
>> free( data );
>>
>> }
>>
>>
>>> int write_data(const char *filename, char *out, int len, unsigned char
>>> *key)
>>
>> {
>>
>> int total, written;
>>
>> BIO *cipher, *buffer, *file;
>>
>>
>>
>> /* Create a buffered file BIO for writing */
>>
>> file = BIO_new_file(filename, "wb");
>>
>> if (!file)
>>
>> return 0;
>>
>>
>>
>> /* Create a buffering filter BIO to buffer writes to the file */
>>
>> buffer = BIO_new(BIO_f_buffer( ));
>>
>>
>>
>> /* Create a base64 encoding filter BIO */
>>
>> // b64 = BIO_new(BIO_f_base64( ));
>>
>>
>>
>> /* Create the cipher filter BIO and set the key. The last parameter of
>>
>> BIO_set_cipher is 1 for encryption and 0 for decryption */
>>
>> cipher = BIO_new(BIO_f_cipher( ));
>>
>> BIO_set_cipher(cipher, EVP_des_ede3_cbc( ), key, NULL, 1);
>>
>>
>>
>> /* Assemble the BIO chain to be in the order cipher-b64-buffer-file */
>>
>> // BIO_push(cipher, b64);
>>
>> // BIO_push(b64, buffer);
>>
>> BIO_push(cipher,buffer);
>>
>> BIO_push(buffer, file);
>>
>>
>>> /* This loop writes the data to the file. It checks for errors as if
>>> the
>>
>> underlying file were non-blocking */
>>
>> for (total = 0; total < len; total += written)
>>
>> {
>>
>> if ((written = BIO_write(cipher, out + total, len - total)) <= 0)
>>
>> {
>>
>> if (BIO_should_retry(cipher))
>>
>> {
>>
>> written = 0;
>>
>> continue;
>>
>> }
>>
>> break;
>>
>> }
>>
>> }
>>
>>
>>
>> /* Ensure all of our data is pushed all the way to the file */
>>
>> BIO_flush(cipher);
>>
>>
>>
>> BIO_free_all(cipher);
>>
>> }
>>
>>
>>> BIO* decrypt_open( const char *filename, unsigned char *key ){
>>
>> int total, written;
>>
>> BIO *cipher, *buffer, *file;
>>
>> //char *b = malloc(len);
>>
>>
>>
>> /* Create a buffered file BIO for reading */
>>
>> file = BIO_new_file(filename, "rb");
>>
>> if (!file)
>>
>> return 0;
>>
>>
>>
>> /* Create a buffering filter BIO to buffer writes to the file */
>>
>> buffer = BIO_new(BIO_f_buffer( ));
>>
>>
>>
>> /* Create a base64 encoding filter BIO */
>>
>> // b64 = BIO_new(BIO_f_base64( ));
>>
>>
>>
>> /* Create the cipher filter BIO and set the key. The last parameter of
>>
>> BIO_set_cipher is 1 for encryption and 0 for decryption */
>>
>> cipher = BIO_new(BIO_f_cipher( ));
>>
>> BIO_set_cipher(cipher, EVP_des_ede3_cbc( ), key, NULL, 0);
>>
>>
>>
>> /* Assemble the BIO chain to be in the order cipher-b64-buffer-file */
>>
>> // BIO_push(cipher, b64);
>>
>> // BIO_push(b64, buffer);
>>
>> BIO_push(cipher,buffer);
>>
>> BIO_push(buffer, file);
>>
>> return cipher;
>>
>> }
>>
>> char* decrypt_read( BIO* cipher, int len, char* b ){
>>
>> int total, written;
>>
>>
>>> // char b[len + 1];
>>
>> for (total = 0; total < len; total += written)
>>
>> {
>>
>> if ((written = BIO_read(cipher, b, len - total)) <= 0)
>>
>> {
>>
>> if (BIO_should_retry(cipher))
>>
>> {
>>
>> written = 0;
>>
>> continue;
>>
>> }
>>
>> break;
>>
>> }
>>
>> }
>>
>>
>>
>> b[total] = '\0';
>>
>>
>>
>> return b;
>>
>> }
>>
>>
>>> int main(void)
>>
>> {
>>
>> //chdir("subdirectory");
>>
>> char *file_="test.txt";
>>
>> char* data = "howdy\n";
>>
>> write_data( file_, data, strlen(data), "mykey");
>>
>>
>>> BIO* cipher = decrypt_open( file_, (unsigned char*)"mykey" );
>>
>> char b[999999];
>>
>> decrypt_read( cipher, 999999, b );
>>
>> BIO_flush( cipher );
>>
>> BIO_free_all( cipher );
>>
>> printf(">%s\n",b);
>>
>>
>>> //char* test="plain.txt";
>>
>> //encrypt_file(test);
>>
>>
>>> }
>>
>>
> ///////////////////////////////////////////////////////////
>
> 1. So, first run creates and writes encrypted file "test.txt" and then
> decrypts and prints out the contents, "howdy",
>
> 2. Now, comment out line 141 // write_data( ... re-run to verify "howdy",
> works fine
>
> 3. make directory "temp", move "test.txt" into "temp" and change line 139
> to reflect that: char *file_="temp/test.txt";.. re-run - I get no results ??
>
> 4. Even more weird: change line 139 back to just "test.txt", and replace
> file_ on line 143 with "temp/test.txt" ... so it reads: BIO* cipher =
> decrypt_open( "temp/test.txt", (unsigned char*)"mykey" ); // re-run... now
> it works again all of a sudden. BUT - if you comment out line 139 // char
> *file_="test.txt";.... then it doesn't work again? Even though *file_ isn't
> being used???
>
