damgard_multi.h File Reference

Damgard multi input scheme. More...

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Data Structures
struct	cfe_damgard_multi
struct	cfe_damgard_multi_sec_key
struct	cfe_damgard_multi_fe_key
struct	cfe_damgard_multi_client

Typedefs
typedef struct cfe_damgard_multi	cfe_damgard_multi
typedef struct cfe_damgard_multi_sec_key	cfe_damgard_multi_sec_key
typedef struct cfe_damgard_multi_fe_key	cfe_damgard_multi_fe_key
typedef struct cfe_damgard_multi_client	cfe_damgard_multi_client

Functions
cfe_error	cfe_damgard_multi_init (cfe_damgard_multi *m, size_t num_clients, size_t l, size_t modulus_len, mpz_t bound)
cfe_error	cfe_damgard_multi_precomp_init (cfe_damgard_multi *m, size_t num_clients, size_t l, size_t modulus_len, mpz_t bound)
void	cfe_damgard_multi_free (cfe_damgard_multi *m)
void	cfe_damgard_multi_copy (cfe_damgard_multi *res, cfe_damgard_multi *m)
void	cfe_damgard_multi_client_init (cfe_damgard_multi_client *e, cfe_damgard_multi *m)
void	cfe_damgard_multi_client_free (cfe_damgard_multi_client *e)
void	cfe_damgard_multi_sec_key_free (cfe_damgard_multi_sec_key *key)
void	cfe_damgard_multi_fe_key_free (cfe_damgard_multi_fe_key *key)
void	cfe_damgard_multi_master_keys_init (cfe_mat *mpk, cfe_damgard_multi_sec_key *msk, cfe_damgard_multi *m)
void	cfe_damgard_multi_generate_master_keys (cfe_mat *mpk, cfe_damgard_multi_sec_key *msk, cfe_damgard_multi *m)
void	cfe_damgard_multi_fe_key_init (cfe_damgard_multi_fe_key *fe_key, cfe_damgard_multi *m)
cfe_error	cfe_damgard_multi_derive_fe_key (cfe_damgard_multi_fe_key *fe_key, cfe_damgard_multi *m, cfe_damgard_multi_sec_key *msk, cfe_mat *y)
void	cfe_damgard_multi_ciphertext_init (cfe_vec *ciphertext, cfe_damgard_multi_client *e)
cfe_error	cfe_damgard_multi_encrypt (cfe_vec *ciphertext, cfe_damgard_multi_client *e, cfe_vec *x, cfe_vec *pub_key, cfe_vec *otp)
cfe_error	cfe_damgard_multi_decrypt (mpz_t res, cfe_damgard_multi *m, cfe_vec *ciphertext, cfe_damgard_multi_fe_key *fe_key, cfe_mat *y)

Detailed Description

Damgard multi input scheme.

Typedef Documentation

cfe_damgard_multi

typedef struct cfe_damgard_multi cfe_damgard_multi

cfe_damgard_multi represents a multi input variant of the underlying Damgard scheme.

cfe_damgard_multi_sec_key

typedef struct cfe_damgard_multi_sec_key cfe_damgard_multi_sec_key

cfe_damgard_multi_sec_key is a secret key for Damgard multi input scheme.

cfe_damgard_multi_fe_key

typedef struct cfe_damgard_multi_fe_key cfe_damgard_multi_fe_key

cfe_damgard_multi_fe_key is a functional encryption key for Damgard multi input scheme.

cfe_damgard_multi_client

typedef struct cfe_damgard_multi_client cfe_damgard_multi_client

cfe_damgard_multi_client represents a single encryptor for the damgard_multi scheme.

Function Documentation

cfe_damgard_multi_init()

cfe_error cfe_damgard_multi_init	(	cfe_damgard_multi *	m,
		size_t	num_clients,
		size_t	l,
		size_t	modulus_len,
		mpz_t	bound
	)

Configures a new instance of the scheme. It accepts the number of clients (encryptors), the length of input vectors l, the bit length of the modulus (we are operating in the Z_p group), and a bound by which coordinates of input vectors are bounded.

Parameters

m	A pointer to an uninitialized struct representing the scheme
num_clients	The number of clients (encryptors)
l	The length of input vectors
modulus_len	The bit length of the modulus (we are operating in the Z_p group)
bound	The bound by which coordinates of input vectors are bounded.

Returns

Error code

cfe_damgard_multi_precomp_init()

cfe_error cfe_damgard_multi_precomp_init	(	cfe_damgard_multi *	m,
		size_t	num_clients,
		size_t	l,
		size_t	modulus_len,
		mpz_t	bound
	)

Configures a new instance of the scheme based on precomputed prime numbers and generators. It accepts the number of clients (encryptors), the length of input vectors l, the bit length of the modulus (we are operating in the Z_p group), and a bound by which coordinates of input vectors are bounded.

Parameters

m	A pointer to an uninitialized struct representing the scheme
num_clients	The number of clients (encryptors)
l	The length of input vectors
modulus_len	The bit length of the modulus (we are operating in the Z_p group)
bound	The bound by which coordinates of input vectors are bounded.

Returns

Error code

cfe_damgard_multi_free()

void cfe_damgard_multi_free

(

cfe_damgard_multi *

m

)

Frees the memory occupied by the struct members. It does not free memory occupied by the struct itself.

Parameters

m	A pointer to an instance of the scheme (initialized cfe_damgard_multi struct)

cfe_damgard_multi_copy()

void cfe_damgard_multi_copy	(	cfe_damgard_multi *	res,
		cfe_damgard_multi *	m
	)

Reconstructs the scheme with the same configuration parameters from an already existing Damgard multi input scheme instance.

Parameters

res	A pointer to an uninitialized damgard_multi struct
m	A pointer to an instance of the scheme (initialized cfe_damgard_multi struct)

cfe_damgard_multi_client_init()

void cfe_damgard_multi_client_init	(	cfe_damgard_multi_client *	e,
		cfe_damgard_multi *	m
	)

Takes configuration parameters of a scheme instance, and instantiates a new cfe_damgard_multi_client.

Parameters

e	A pointer to an uninitialized struct representing a client for the scheme.
m	A pointer to an instance of the scheme (initialized cfe_damgard_multi struct)

cfe_damgard_multi_client_free()

void cfe_damgard_multi_client_free

(

cfe_damgard_multi_client *

e

)

Frees the memory occupied by the struct members. It does not free memory occupied by the struct itself.

Parameters

e	A pointer to an instance of the encryptor (initialized cfe_damgard_multi_client struct)

cfe_damgard_multi_sec_key_free()

void cfe_damgard_multi_sec_key_free

(

cfe_damgard_multi_sec_key *

key

)

Frees the memory occupied by the struct members. It does not free memory occupied by the struct itself.

Parameters

key	A pointer to an initialized cfe_damgard_multi_sec_key struct

cfe_damgard_multi_fe_key_free()

void cfe_damgard_multi_fe_key_free

(

cfe_damgard_multi_fe_key *

key

)

Frees the memory occupied by the struct members. It does not free memory occupied by the struct itself.

Parameters

key	A pointer to an initialized cfe_damgard_multi_fe_key struct

cfe_damgard_multi_master_keys_init()

void cfe_damgard_multi_master_keys_init	(	cfe_mat *	mpk,
		cfe_damgard_multi_sec_key *	msk,
		cfe_damgard_multi *	m
	)

Initializes the structs which represent the master public key and master secret key.

Parameters

mpk	A pointer to an uninitialized matrix
msk	A pointer to an uninitialized cfe_damgard_multi_sec_key struct
m	A pointer to an instance of the scheme (initialized cfe_damgard_multi struct)

cfe_damgard_multi_generate_master_keys()

void cfe_damgard_multi_generate_master_keys	(	cfe_mat *	mpk,
		cfe_damgard_multi_sec_key *	msk,
		cfe_damgard_multi *	m
	)

Generates a matrix comprised of master public keys and a struct encapsulating master secret keys for the scheme. It returns an error in case master keys could not be generated.

Parameters

mpk	A pointer to a matrix (master public key will be stored here)
msk	A pointer to a cfe_damgard_multi_sec_key struct (master secret key will be stored here)
m	A pointer to an instance of the scheme (initialized cfe_damgard_multi struct)

cfe_damgard_multi_fe_key_init()

void cfe_damgard_multi_fe_key_init	(	cfe_damgard_multi_fe_key *	fe_key,
		cfe_damgard_multi *	m
	)

Initializes the struct which represents the functional encryption key.

Parameters

fe_key	A pointer to an uninitialized cfe_damgard_multi_fe_key struct
m	A pointer to an instance of the scheme (initialized cfe_damgard_multi struct)

cfe_damgard_multi_derive_fe_key()

cfe_error cfe_damgard_multi_derive_fe_key	(	cfe_damgard_multi_fe_key *	fe_key,
		cfe_damgard_multi *	m,
		cfe_damgard_multi_sec_key *	msk,
		cfe_mat *	y
	)

Takes master secret key and a matrix y comprised of input vectors, and returns the functional encryption key. In case the key could not be derived, it returns an error.

Parameters

fe_key	A pointer to a cfe_damgard_multi_fe_key struct (the functional encryption key will be stored here)
m	A pointer to an instance of the scheme (initialized cfe_damgard_multi struct)
msk	A pointer to the master secret key
y	A pointer to the matrix comprised of input vectors

Returns

Error code

cfe_damgard_multi_ciphertext_init()

void cfe_damgard_multi_ciphertext_init	(	cfe_vec *	ciphertext,
		cfe_damgard_multi_client *	e
	)

Initializes the vector which represents the ciphertext.

Parameters

ciphertext	A pointer to an uninitialized vector
e	A pointer to an instance of the encryptor (initialized cfe_damgard_multi_enc struct)

cfe_damgard_multi_encrypt()

cfe_error cfe_damgard_multi_encrypt	(	cfe_vec *	ciphertext,
		cfe_damgard_multi_client *	e,
		cfe_vec *	x,
		cfe_vec *	pub_key,
		cfe_vec *	otp
	)

Generates a ciphertext from the input vector x with the provided public key and one-time pad otp (which is a part of the secret key). It returns the ciphertext vector. If encryption failed, an error is returned.

Parameters

ciphertext	A pointer to a vector (the resulting ciphertext will be stored here)
e	A pointer to an instance of the encryptor (initialized cfe_damgard_multi_enc struct)
x	A pointer to the input vector
pub_key	A pointer to the public key vector
otp	A pointer to the one-time pad vector

Returns

Error code

cfe_damgard_multi_decrypt()

cfe_error cfe_damgard_multi_decrypt	(	mpz_t	res,
		cfe_damgard_multi *	m,
		cfe_vec *	ciphertext,
		cfe_damgard_multi_fe_key *	fe_key,
		cfe_mat *	y
	)

Accepts the matrix cipher comprised of encrypted vectors, functional encryption key, and a matrix y comprised of plaintext vectors. It returns the sum of inner products. If decryption failed, an error is returned.

Parameters

res	The result of the decryption (the value will be stored here)
m	A pointer to an instance of the scheme (initialized cfe_damgard_multi struct)
ciphertext	An array comprised of encrypted vectors
fe_key	An functional encryption key represented as an array of the parts of functional encryption keys.
y	A pointer to the matrix comprised of plaintext inner product vectors

Returns

Error code