ISE Production Code Functions				jpeg_ise::decrypt_file(0)

NAME
jpeg_ise::decrypt_file()

SYNOPSIS
#include <ise.h>
int jpeg_ise::decrypt_file()

DESCRIPTION	
jpeg_ise::decrypt_file()
The decrypt_file method will take a jpeg_ise file and selectively decrypt the Huffman Table frames found within the file.  
If the output file already exists, the existing file will be overwritten.  Otherwise, a new file will be created for the selectively decrypted jpeg image.

PRE-CONDITIONS
The input_file_name and key ise data members must be set using either the jpeg_ise() overloaded constructor or the set_input_file_name(char* name) and set_key(char* key) functions prior to calling this method.  
This code requires that the input and output file pointers be at the head 	of the file.

POST-CONDITIONS  	
A decrypted file will be created with the name and path specified by the output_file_name data member.  
If this data member is NULL, then a default file name will be created based upon the input_file_name data member.

RETURN VALUES
An integer is returned indicating a success or failure.  
0 will indicate a success.  
1 will indicate input file is not a jpeg ise file.  
2 will indicate could not open ise file.  
3 will indicate could not create output jpeg file.  
4 will indicate could not open output jpeg file.

EXAMPLE USEAGE
// MyJpegIseObj must be of type jpeg_ise
// decrypt ise file to jpeg file
MyJpegIseObj.decrypt_file();

SEE ALSO
ise::ise(),  jpeg_ise::jpeg_ise(),  ise::set_input_file_name(),  ise::set_output_file_name(),  ise::set_key(),  jpeg_ise::encrypt_file()

TEAM ISE		Last Change:  15 April 2004
