XML Security Library

LibXML2
LibXSLT
OpenSSL

Encrypting data.

The typical encryption process includes following steps:

Example 11. Encrypting binary data with a template.

/**
 * encrypt_file:
 * @tmpl_file:		the encryption template file name.
 * @key_file:		the Triple DES key file.
 * @data:		the binary data to encrypt.
 * @dataSize:		the binary data size.
 *
 * Encrypts binary #data using template from #tmpl_file and DES key from
 * #key_file.
 *
 * Returns 0 on success or a negative value if an error occurs.
 */
int 
encrypt_file(const char* tmpl_file, const char* key_file, const unsigned char* data, size_t dataSize) {
    xmlDocPtr doc = NULL;
    xmlNodePtr node = NULL;
    xmlSecEncCtxPtr encCtx = NULL;
    int res = -1;
    
    assert(tmpl_file);
    assert(key_file);
    assert(data);

    /* load template */
    doc = xmlParseFile(tmpl_file);
    if ((doc == NULL) || (xmlDocGetRootElement(doc) == NULL)){
	fprintf(stderr, "Error: unable to parse file \"%s\"\n", tmpl_file);
	goto done;	
    }
    
    /* find start node */
    node = xmlSecFindNode(xmlDocGetRootElement(doc), xmlSecNodeEncryptedData, xmlSecEncNs);
    if(node == NULL) {
	fprintf(stderr, "Error: start node not found in \"%s\"\n", tmpl_file);
	goto done;	
    }

    /* create encryption context, we don't need keys manager in this example */
    encCtx = xmlSecEncCtxCreate(NULL);
    if(encCtx == NULL) {
        fprintf(stderr,"Error: failed to create encryption context\n");
	goto done;
    }

    /* load DES key */
    encCtx->encKey = xmlSecKeyReadBinaryFile(xmlSecKeyDataDesId, key_file);
    if(encCtx->encKey == NULL) {
        fprintf(stderr,"Error: failed to load des key from binary file \"%s\"\n", key_file);
	goto done;
    }

    /* set key name to the file name, this is just an example! */
    if(xmlSecKeySetName(encCtx->encKey, key_file) < 0) {
    	fprintf(stderr,"Error: failed to set key name for key from \"%s\"\n", key_file);
	goto done;
    }

    /* encrypt the data */
    if(xmlSecEncCtxBinaryEncrypt(encCtx, node, data, dataSize) < 0) {
        fprintf(stderr,"Error: encryption failed\n");
    	goto done;
    }
        
    /* print encrypted data with document to stdout */
    xmlDocDump(stdout, doc);
    
    /* success */
    res = 0;

done:    
    /* cleanup */
    if(encCtx != NULL) {
	xmlSecEncCtxDestroy(encCtx);
    }
    
    if(doc != NULL) {
	xmlFreeDoc(doc); 
    }
    return(res);
}
		

Full program listing

Simple encryption template file