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/*
* copyright: 2014-2015
* name : Francis Banyikwa
* email: mhogomchungu@gmail.com
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifdef __cplusplus
extern "C" {
#endif
#include <sys/types.h>
/*
* This data structure hold result of the operation.
*/
typedef struct{
void * buffer ;
size_t length ;
}crypt_buffer_result ;
typedef struct crypt_buffer_ctx_1 * crypt_buffer_ctx ;
/*
* create crypt buffer_context object.
* The same context object can be used for both encryption and decryption.
* 1 is returned on success.
* 0 is returned on error.
*/
int crypt_buffer_init( crypt_buffer_ctx * ctx,const void * password,size_t passphrase_size ) ;
/*
* destroy crypt_buffer context object when done with it.
*/
void crypt_buffer_uninit( crypt_buffer_ctx * ctx ) ;
/*
* This routine takes a block of data and encrypts it
* The first argument is for internal use of the library and it is to be reused between encryption/decryption operations.
* 1 is returned on success.
* 0 is returned on error.
*/
int crypt_buffer_encrypt( crypt_buffer_ctx ctx,const void * buffer,u_int32_t buffer_size,crypt_buffer_result * r ) ;
/*
* This routine takes a block of data encrypted by crypt_buffer_encrypt() decrypt it.
* The first argument is for internal use of the library and it is to be reused between encryption/decryption operations.
*
* 1 is returned on success.
* 0 is returned on error.
*/
int crypt_buffer_decrypt( crypt_buffer_ctx ctx,const void * buffer,u_int32_t buffer_size,crypt_buffer_result * r ) ;
/*
* example use case using a complete workable program is below.
*/
#if 0
#include "crypt_buffer.h"
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
static void * _buffer ;
static size_t _buffer_size ;
static void sendData( const void * buffer,size_t buffer_size )
{
_buffer = malloc( buffer_size ) ;
_buffer = memcpy( _buffer,buffer,buffer_size ) ;
_buffer_size = buffer_size ;
}
static void receiveEncryptedDataFromSomeWhere( void ** buffer,size_t * buffer_size )
{
*buffer = _buffer ;
*buffer_size = _buffer_size ;
}
static void consumeDecryptedReceivedData( const void * buffer,size_t buffer_size )
{
const char * x = buffer ;
size_t i ;
char e ;
for( i = 0 ; i < buffer_size ; i++ ){
e = *( x + i ) ;
printf( "%c",e ) ;
}
printf( "\n" ) ;
}
static void encryptAndSendData( crypt_buffer_ctx ctx,const void * data,size_t data_size )
{
crypt_buffer_result r ;
if( crypt_buffer_encrypt( ctx,data,data_size,&r ) ){
/*
* encryption succeeded,simulate sending encrypted data somewhere
*/
sendData( r.buffer,r.length ) ;
}
}
void decryptReceivedDataAndConsumeIt( crypt_buffer_ctx ctx,const void * cipher_text_data,size_t cipher_text_data_size )
{
crypt_buffer_result r ;
if( crypt_buffer_decrypt( ctx,cipher_text_data,cipher_text_data_size,&r ) ){
/*
* decryption succeeded,
*/
/*
* This function simulates using of now decrypted data
*/
consumeDecryptedReceivedData( r.buffer,r.length ) ;
}
}
int main( int argc,char * argv[] )
{
/*
* data to be encrypted before sending it somewhere.
*/
const char * data = "works as expected" ;
size_t data_size = strlen( data ) ;
/*
* key to be used for encryption and decryption
*/
const char * key = "xyz" ;
size_t key_size = strlen( key ) ;
void * cipher_buffer ;
size_t cipher_buffer_size ;
crypt_buffer_ctx ctx ;
/*
* we dont need these two arguments
*/
if( argc && argv ){;}
_buffer = NULL ;
if( crypt_buffer_init( &ctx,key,key_size ) ){
/*
* This function simulates encrypting data and sending it somewhere
*/
encryptAndSendData( ctx,data,data_size ) ;
/*
* This function simulates receiving encrypted data.
*/
receiveEncryptedDataFromSomeWhere( &cipher_buffer,&cipher_buffer_size ) ;
/*
* This function simulates data decryption received from somewhere.
* Notice the same context is used for encryption and decryption
*/
decryptReceivedDataAndConsumeIt( ctx,cipher_buffer,cipher_buffer_size ) ;
crypt_buffer_uninit( &ctx ) ;
/*
* clean up after simulation ;
*/
free( _buffer ) ;
return 0 ;
}else{
return 1 ;
}
}
#endif
#ifdef __cplusplus
}
#endif
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