ddh_multi.h File Reference

DDH multi input scheme. More...

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Data Structures
struct	cfe_ddh_multi
struct	cfe_ddh_multi_sec_key
struct	cfe_ddh_multi_fe_key
struct	cfe_ddh_multi_enc

Typedefs
typedef struct cfe_ddh_multi	cfe_ddh_multi
typedef struct cfe_ddh_multi_sec_key	cfe_ddh_multi_sec_key
typedef struct cfe_ddh_multi_fe_key	cfe_ddh_multi_fe_key
typedef struct cfe_ddh_multi_enc	cfe_ddh_multi_enc

Functions
cfe_error	cfe_ddh_multi_init (cfe_ddh_multi *m, size_t slots, size_t l, size_t modulus_len, mpz_t bound)
cfe_error	cfe_ddh_multi_precomp_init (cfe_ddh_multi *m, size_t slots, size_t l, size_t modulus_len, mpz_t bound)
void	cfe_ddh_multi_free (cfe_ddh_multi *m)
void	cfe_ddh_multi_copy (cfe_ddh_multi *res, cfe_ddh_multi *m)
void	cfe_ddh_multi_enc_init (cfe_ddh_multi_enc *e, cfe_ddh_multi *m)
void	cfe_ddh_multi_enc_free (cfe_ddh_multi_enc *e)
void	cfe_ddh_multi_sec_key_free (cfe_ddh_multi_sec_key *key)
void	cfe_ddh_multi_fe_key_free (cfe_ddh_multi_fe_key *key)
void	cfe_ddh_multi_master_keys_init (cfe_mat *mpk, cfe_ddh_multi_sec_key *msk, cfe_ddh_multi *m)
void	cfe_ddh_multi_fe_key_init (cfe_ddh_multi_fe_key *key, cfe_ddh_multi *m)
void	cfe_ddh_multi_ciphertext_init (cfe_vec *ciphertext, cfe_ddh_multi_enc *e)
void	cfe_ddh_multi_generate_master_keys (cfe_mat *mpk, cfe_ddh_multi_sec_key *msk, cfe_ddh_multi *m)
cfe_error	cfe_ddh_multi_derive_fe_key (cfe_ddh_multi_fe_key *res, cfe_ddh_multi *m, cfe_ddh_multi_sec_key *msk, cfe_mat *y)
cfe_error	cfe_ddh_multi_encrypt (cfe_vec *ciphertext, cfe_ddh_multi_enc *e, cfe_vec *x, cfe_vec *pub_key, cfe_vec *otp)
cfe_error	cfe_ddh_multi_decrypt (mpz_t res, cfe_ddh_multi *m, cfe_mat *ciphertext, cfe_ddh_multi_fe_key *key, cfe_mat *y)

Detailed Description

DDH multi input scheme.

Typedef Documentation

cfe_ddh_multi

typedef struct cfe_ddh_multi cfe_ddh_multi

cfe_ddh_multi represents a multi input variant of the underlying DDH scheme.

cfe_ddh_multi_sec_key

typedef struct cfe_ddh_multi_sec_key cfe_ddh_multi_sec_key

cfe_ddh_multi_sec_key is a secret key for DDH multi input scheme.

cfe_ddh_multi_fe_key

typedef struct cfe_ddh_multi_fe_key cfe_ddh_multi_fe_key

cfe_ddh_multi_fe_key is a functional encryption key for DDH multi input scheme.

cfe_ddh_multi_enc

typedef struct cfe_ddh_multi_enc cfe_ddh_multi_enc

cfe_ddh_multi_enc represents a single encryptor for the ddh_multi scheme.

Function Documentation

cfe_ddh_multi_init()

cfe_error cfe_ddh_multi_init	(	cfe_ddh_multi *	m,
		size_t	slots,
		size_t	l,
		size_t	modulus_len,
		mpz_t	bound
	)

Configures a new instance of the scheme. It accepts the number of slots (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
slots	The number of slots (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_ddh_multi_precomp_init()

cfe_error cfe_ddh_multi_precomp_init	(	cfe_ddh_multi *	m,
		size_t	slots,
		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 slots (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
slots	The number of slots (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_ddh_multi_free()

void cfe_ddh_multi_free

(

cfe_ddh_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_ddh_multi struct)

cfe_ddh_multi_copy()

void cfe_ddh_multi_copy	(	cfe_ddh_multi *	res,
		cfe_ddh_multi *	m
	)

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

Parameters

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

cfe_ddh_multi_enc_init()

void cfe_ddh_multi_enc_init	(	cfe_ddh_multi_enc *	e,
		cfe_ddh_multi *	m
	)

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

Parameters

e	A pointer to an uninitialized struct representing the encryptor for the scheme.
m	A pointer to an instance of the scheme (initialized cfe_ddh_multi struct)

cfe_ddh_multi_enc_free()

void cfe_ddh_multi_enc_free

(

cfe_ddh_multi_enc *

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_ddh_multi_enc struct)

cfe_ddh_multi_sec_key_free()

void cfe_ddh_multi_sec_key_free

(

cfe_ddh_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_ddh_multi_sec_key struct

cfe_ddh_multi_fe_key_free()

void cfe_ddh_multi_fe_key_free

(

cfe_ddh_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_ddh_multi_fe_key struct

cfe_ddh_multi_master_keys_init()

void cfe_ddh_multi_master_keys_init	(	cfe_mat *	mpk,
		cfe_ddh_multi_sec_key *	msk,
		cfe_ddh_multi *	m
	)

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

Parameters

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

cfe_ddh_multi_fe_key_init()

void cfe_ddh_multi_fe_key_init	(	cfe_ddh_multi_fe_key *	key,
		cfe_ddh_multi *	m
	)

Initializes the struct which represents the functional encryption key.

Parameters

key	A pointer to an uninitialized cfe_dhh_multi_fe_key struct
m	A pointer to an instance of the scheme (initialized cfe_ddh_multi struct)

cfe_ddh_multi_ciphertext_init()

void cfe_ddh_multi_ciphertext_init	(	cfe_vec *	ciphertext,
		cfe_ddh_multi_enc *	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_ddh_multi_enc struct)

cfe_ddh_multi_generate_master_keys()

void cfe_ddh_multi_generate_master_keys	(	cfe_mat *	mpk,
		cfe_ddh_multi_sec_key *	msk,
		cfe_ddh_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_ddh_multi_sec_key struct (master secret key will be stored here)
m	A pointer to an instance of the scheme (initialized cfe_ddh_multi struct)

cfe_ddh_multi_derive_fe_key()

cfe_error cfe_ddh_multi_derive_fe_key	(	cfe_ddh_multi_fe_key *	res,
		cfe_ddh_multi *	m,
		cfe_ddh_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

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

Returns

Error code

cfe_ddh_multi_encrypt()

cfe_error cfe_ddh_multi_encrypt	(	cfe_vec *	ciphertext,
		cfe_ddh_multi_enc *	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_ddh_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_ddh_multi_decrypt()

cfe_error cfe_ddh_multi_decrypt	(	mpz_t	res,
		cfe_ddh_multi *	m,
		cfe_mat *	ciphertext,
		cfe_ddh_multi_fe_key *	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_ddh_multi struct)
ciphertext	A pointer to the matrix comprised of encrypted vectors
key	A pointer to the functional encryption key
y	A pointer to the matrix comprised of plaintext vectors

Returns

Error code