DecryptFinal

This function must be called to finish a decryption operation. It can be used for either discovering the target buffer length, or for actually performing the operation.

If the target buffer address, tgt, is NULL, then the variable pointed to by plen is updated to contain the length of the output that is required to perform the operation.

If the target buffer address is not NULL, and the mode is padded mode, the final block is decrypted and the padding bytes are removed before they are placed in the tgt buffer. If there is not exactly one block of data in the buffer, an error is returned.

Synopsis

#include “fmciphobj.h”
int (*DecryptFinal)(struct CipherObj * ctx,
void * tgt, unsigned int tlength, unsigned int * plen);

Parameter	Description
ctx	The address of a cipher object instance.
tgt	The address of the output buffer. It may be set to NULL for output buffer length estimation.
tlength	Total number of bytes available in the output buffer.
plen	Address of a variable that will receive the number of bytes placed in the target buffer. This variable must not be NULL.

Return Value

0: Operation completed successfully.

Otherwise: There was an error.

Comments

This function finalizes the decryption context. DecInit() must be called again to decrypt more data, even when the key is the same.