hcs_shares.h File Reference

This is a structure which is designed to hold a number of shares. More...

#include <gmp.h>

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Data Structures
struct	hcs_shares
	Stores a number of shares, with flags indicating if they are currently to be counted. More...

Functions
hcs_shares *	hcs_init_shares (unsigned long size)
	Initialise a hcs_shares and return a pointer to the newly created structure. More...
void	hcs_set_share (hcs_shares *hs, mpz_t value, unsigned long index)
	Set a share value for the server given by id index. More...
void	hcs_set_flag (hcs_shares *hs, unsigned long index)
	Set the flag on hs at index. More...
void	hcs_clear_flag (hcs_shares *hs, unsigned long index)
	Clear the flag on hs at index. More...
void	hcs_toggle_flag (hcs_shares *hs, unsigned long index)
	Toggle the flag on hs at index. More...
int	hcs_tst_flag (hcs_shares *hs, unsigned long index)
	Test if the server given by index is to be counted. More...
void	hcs_free_shares (hcs_shares *hs)
	Frees a hcs_shares and all associated memory. More...

Detailed Description

This is a structure which is designed to hold a number of shares.

It can be thought of as an array of mpz_t values, each with a corresponding bit which signals if the particular value of the share should be counted when combining shares. This is used by all threshold encryption schemes.

The rationale for this is that one may want to test a number of different combinations of shares, and setting a flag simplifies this process.

Function Documentation

hcs_shares* hcs_init_shares

(

unsigned long

size

)

Initialise a hcs_shares and return a pointer to the newly created structure.

Parameters

size	The number of shares this hcs_shares should store

Returns

A pointer to an initialised hcs_shares, NULL on allocation failure

void hcs_set_share	(	hcs_shares *	hs,
		mpz_t	value,
		unsigned long	index
	)

Set a share value for the server given by id index.

index should be less than hs->size. It is up to the caller to enforce this. The owner of this hs should have a mapping of server id's to indices, as it is required by a number of other functions involved in threshold system.

Parameters

hs	A pointer to an initialised hcs_shares
value	Share stored in an mpz_t variable
index	Index of the server to store this share in

void hcs_set_flag	(	hcs_shares *	hs,
		unsigned long	index
	)

Set the flag on hs at index.

This share will then be counted by any share combinining functions that are subsequently called.

Parameters

hs	A pointer to an initialised hcs_shares
index	Index of the server to set

void hcs_clear_flag	(	hcs_shares *	hs,
		unsigned long	index
	)

Clear the flag on hs at index.

This share will NOT be counted by any share combining functions that are subsequently called.

Parameters

hs	A pointer to an initialised hcs_shares
index	Index of the server to clear

void hcs_toggle_flag	(	hcs_shares *	hs,
		unsigned long	index
	)

Toggle the flag on hs at index.

Parameters

hs	A pointer to an initialised hcs_shares
index	Index of the server to clear

int hcs_tst_flag	(	hcs_shares *	hs,
		unsigned long	index
	)

Test if the server given by index is to be counted.

Parameters

hs	A pointer to an initialised hcs_shares
index	Index of the server to clear

Returns

non-zero if flag is set, 0 otherwise

void hcs_free_shares

(

hcs_shares *

hs

)

Frees a hcs_shares and all associated memory.

Parameters

hs	A pointer to an initialised hcs_shares