lwe.h File Reference

LWE scheme. More...

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Data Structures
struct	cfe_lwe

Typedefs
typedef struct cfe_lwe	cfe_lwe

Functions
cfe_error	cfe_lwe_init (cfe_lwe *s, size_t l, mpz_t bound_x, mpz_t bound_y, size_t n)
void	cfe_lwe_sec_key_init (cfe_mat *SK, cfe_lwe *s)
void	cfe_lwe_generate_sec_key (cfe_mat *SK, cfe_lwe *s)
void	cfe_lwe_pub_key_init (cfe_mat *PK, cfe_lwe *s)
cfe_error	cfe_lwe_generate_pub_key (cfe_mat *PK, cfe_lwe *s, cfe_mat *SK)
void	cfe_lwe_fe_key_init (cfe_vec *sk_y, cfe_lwe *s)
cfe_error	cfe_lwe_derive_fe_key (cfe_vec *sk_y, cfe_lwe *s, cfe_mat *SK, cfe_vec *y)
void	cfe_lwe_ciphertext_init (cfe_vec *ct, cfe_lwe *s)
cfe_error	cfe_lwe_encrypt (cfe_vec *ct, cfe_lwe *s, cfe_vec *x, cfe_mat *PK)
cfe_error	cfe_lwe_decrypt (mpz_t res, cfe_lwe *s, cfe_vec *c, cfe_vec *sk_y, cfe_vec *y)
void	cfe_lwe_free (cfe_lwe *s)

Detailed Description

LWE scheme.

Typedef Documentation

cfe_lwe

typedef struct cfe_lwe cfe_lwe

cfe_lwe represents common properties of the scheme.

Function Documentation

cfe_lwe_init()

cfe_error cfe_lwe_init	(	cfe_lwe *	s,
		size_t	l,
		mpz_t	bound_x,
		mpz_t	bound_y,
		size_t	n
	)

Configures a new instance of the scheme. Security parameters are generated so that they satisfy theoretical bounds provided in the phd thesis Functional Encryption for Inner-Product Evaluations, see Section 8.3.1 in https://www.di.ens.fr/~fbourse/publications/Thesis.pdf

Parameters

s	A pointer to an uninitialized struct representing the scheme
l	The length of input vectors
bound_x	The bound by which coordinates of the encrypted vectors are bounded
bound_y	The bound by which coordinates of the inner product vectors are bounded
n	The security parameter of the scheme

Returns

Error code

cfe_lwe_sec_key_init()

void cfe_lwe_sec_key_init	(	cfe_mat *	SK,
		cfe_lwe *	s
	)

Initializes the matrix which represents the secret key.

Parameters

SK	A pointer to an uninitialized matrix
s	A pointer to an instance of the scheme (initialized cfe_lwe struct)

cfe_lwe_generate_sec_key()

void cfe_lwe_generate_sec_key	(	cfe_mat *	SK,
		cfe_lwe *	s
	)

Generates a private secret key for the scheme.

Parameters

SK	A pointer to a matrix (master secret key will be stored here)
s	A pointer to an instance of the scheme (initialized cfe_lwe struct)

cfe_lwe_pub_key_init()

void cfe_lwe_pub_key_init	(	cfe_mat *	PK,
		cfe_lwe *	s
	)

Initializes the matrix which represents the public key.

Parameters

PK	A pointer to an uninitialized matrix
s	A pointer to an instance of the scheme (initialized cfe_lwe struct)

cfe_lwe_generate_pub_key()

cfe_error cfe_lwe_generate_pub_key	(	cfe_mat *	PK,
		cfe_lwe *	s,
		cfe_mat *	SK
	)

Generates a public key for the scheme.

Parameters

PK	A pointer to a matrix (public key will be stored here)
s	A pointer to an instance of the scheme (initialized cfe_lwe struct)
SK	A pointer to an initialized matrix representing the secret key.

Returns

Error code

cfe_lwe_fe_key_init()

void cfe_lwe_fe_key_init	(	cfe_vec *	sk_y,
		cfe_lwe *	s
	)

Initializes the vector which represents the functional encryption key.

Parameters

sk_y	A pointer to an uninitialized vector
s	A pointer to an instance of the scheme (initialized cfe_lwe struct)

cfe_lwe_derive_fe_key()

cfe_error cfe_lwe_derive_fe_key	(	cfe_vec *	sk_y,
		cfe_lwe *	s,
		cfe_mat *	SK,
		cfe_vec *	y
	)

Takes master secret key and inner product vector, and returns the functional encryption key.

Parameters

sk_y	A pointer to a vector (the functional encryption key will be stored here)
SK	A pointer to the master secret key
s	A pointer to an instance of the scheme (initialized cfe_lwe struct)
y	A pointer to the inner product vector

Returns

Error code

cfe_lwe_ciphertext_init()

void cfe_lwe_ciphertext_init	(	cfe_vec *	ct,
		cfe_lwe *	s
	)

Initializes the vector which represents the ciphertext.

Parameters

ct	A pointer to an uninitialized vector
s	A pointer to an instance of the scheme (initialized cfe_lwe struct)

cfe_lwe_encrypt()

cfe_error cfe_lwe_encrypt	(	cfe_vec *	ct,
		cfe_lwe *	s,
		cfe_vec *	x,
		cfe_mat *	PK
	)

Encrypts input vector x with the provided master public key.

Parameters

ct	A pointer to a vector (the resulting ciphertext will be stored here)
s	A pointer to an instance of the scheme (initialized cfe_lwe struct)
x	A pointer to the input vector
PK	A pointer to the matrix representing the public key.

Returns

Error code

cfe_lwe_decrypt()

cfe_error cfe_lwe_decrypt	(	mpz_t	res,
		cfe_lwe *	s,
		cfe_vec *	c,
		cfe_vec *	sk_y,
		cfe_vec *	y
	)

Accepts the encrypted vector x, functional encryption key, and a plaintext vector. It returns the inner product. If decryption failed, an error is returned.

Parameters

res	The result of the decryption (the value will be stored here)
s	A pointer to an instance of the scheme (initialized cfe_lwe struct)
c	A pointer to the ciphertext vector
sk_y	The functional encryption key
y	A pointer to the inner product vector

Returns

Error code

cfe_lwe_free()

void cfe_lwe_free

(

cfe_lwe *

s

)

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

Parameters

s	A pointer to an instance of the scheme (initialized cfe_lwe struct)