fhipe.h File Reference

// FHIPE represents a Function Hiding Inner Product Encryption scheme based on the paper by Kim, Lewi, Mandal, Montgomery, Roy, Wu: "Function-Hiding Inner Product Encryption is Practical". It allows to encrypt a vector x and derive a secret key based on an inner product vector y so that a deryptor can decrypt the inner product <x,y> without revealing x or y. More...

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Data Structures
struct	cfe_fhipe
struct	cfe_fhipe_sec_key
struct	cfe_fhipe_fe_key
struct	cfe_fhipe_ciphertext

Typedefs
typedef struct cfe_fhipe	cfe_fhipe
typedef struct cfe_fhipe_sec_key	cfe_fhipe_sec_key
typedef struct cfe_fhipe_fe_key	cfe_fhipe_fe_key
typedef struct cfe_fhipe_ciphertext	cfe_fhipe_ciphertext

Functions
cfe_error	cfe_fhipe_init (cfe_fhipe *c, size_t l, mpz_t bound_x, mpz_t bound_y)
void	cfe_fhipe_copy (cfe_fhipe *res, cfe_fhipe *c)
void	cfe_fhipe_free (cfe_fhipe *c)
void	cfe_fhipe_master_key_init (cfe_fhipe_sec_key *sec_key, cfe_fhipe *c)
void	cfe_fhipe_master_key_free (cfe_fhipe_sec_key *sec_key)
cfe_error	cfe_fhipe_generate_master_key (cfe_fhipe_sec_key *sec_key, cfe_fhipe *c)
void	cfe_fhipe_fe_key_init (cfe_fhipe_fe_key *fe_key, cfe_fhipe *c)
void	cfe_fhipe_fe_key_free (cfe_fhipe_fe_key *fe_key)
cfe_error	cfe_fhipe_derive_fe_key (cfe_fhipe_fe_key *fe_key, cfe_vec *y, cfe_fhipe_sec_key *sec_key, cfe_fhipe *c)
void	cfe_fhipe_ciphertext_init (cfe_fhipe_ciphertext *cipher, cfe_fhipe *c)
void	cfe_fhipe_ciphertext_free (cfe_fhipe_ciphertext *cipher)
cfe_error	cfe_fhipe_encrypt (cfe_fhipe_ciphertext *cipher, cfe_vec *x, cfe_fhipe_sec_key *sec_key, cfe_fhipe *c)
cfe_error	cfe_fhipe_decrypt (mpz_t res, cfe_fhipe_ciphertext *cipher, cfe_fhipe_fe_key *fe_key, cfe_fhipe *c)

Detailed Description

// FHIPE represents a Function Hiding Inner Product Encryption scheme based on the paper by Kim, Lewi, Mandal, Montgomery, Roy, Wu: "Function-Hiding Inner Product Encryption is Practical". It allows to encrypt a vector x and derive a secret key based on an inner product vector y so that a deryptor can decrypt the inner product <x,y> without revealing x or y.

Typedef Documentation

cfe_fhipe

typedef struct cfe_fhipe cfe_fhipe

cfe_fhipe contains the shared choice for parameters on which the functionality of the scheme depend.

cfe_fhipe_sec_key

typedef struct cfe_fhipe_sec_key cfe_fhipe_sec_key

cfe_fhipe_sec_key represents a master secret key in fhipe scheme.

cfe_fhipe_fe_key

typedef struct cfe_fhipe_fe_key cfe_fhipe_fe_key

cfe_fhipe_fe_key represents a functional encryption key in fhipe scheme.

cfe_fhipe_ciphertext

typedef struct cfe_fhipe_ciphertext cfe_fhipe_ciphertext

cfe_fhipe_ciphertext represents a ciphertext in fhipe scheme.

Function Documentation

cfe_fhipe_init()

cfe_error cfe_fhipe_init	(	cfe_fhipe *	c,
		size_t	l,
		mpz_t	bound_x,
		mpz_t	bound_y
	)

Configures a new client for the fhipe scheme. It returns an error if the bounds and length of vectors are too high.

Parameters

c	A pointer to an uninitialized struct representing the scheme
l	Length of the vectors that will be encrypted
bound_x	Bound on the inputs of the vectors that will be encrypted
bound_y	Bound on the inputs of the inner product vectors for which the functional keys will be generated.

Returns

Error code

cfe_fhipe_copy()

void cfe_fhipe_copy	(	cfe_fhipe *	res,
		cfe_fhipe *	c
	)

Reconstructs the scheme with the same configuration parameters from an already existing fhipe scheme instance.

Parameters

res	A pointer to an uninitialized cfe_fhipe struct
c	A pointer to an instance of the scheme (initialized cfe_fhipe struct)

cfe_fhipe_free()

void cfe_fhipe_free

(

cfe_fhipe *

c

)

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

Parameters

c	A pointer to an instance of the scheme (initialized cfe_fhipe struct)

cfe_fhipe_master_key_init()

void cfe_fhipe_master_key_init	(	cfe_fhipe_sec_key *	sec_key,
		cfe_fhipe *	c
	)

Initializes the struct which represents the master secret key in fhipe.

Parameters

sec_key	A pointer to an uninitialized cfe_fhipe_sec_key struct
c	A pointer to an instance of the scheme (initialized cfe_fhipe struct)

cfe_fhipe_master_key_free()

void cfe_fhipe_master_key_free

(

cfe_fhipe_sec_key *

sec_key

)

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

Parameters

sec_key

A pointer to an initialized cfe_fhipe_sec_key struct

cfe_fhipe_generate_master_key()

cfe_error cfe_fhipe_generate_master_key	(	cfe_fhipe_sec_key *	sec_key,
		cfe_fhipe *	c
	)

Generates a master secret key for the scheme. It returns an error if generating one of the parts of the secret key failed.

Parameters

sec_key	A pointer to a cfe_fhipe_sec_key struct (the master secret key will be stored here)
c	A pointer to an instance of the scheme (initialized cfe_fhipe struct)

Returns

Error code

cfe_fhipe_fe_key_init()

void cfe_fhipe_fe_key_init	(	cfe_fhipe_fe_key *	fe_key,
		cfe_fhipe *	c
	)

Initializes the struct which represents the functional encryption key in fhipe.

Parameters

fe_key	A pointer to an uninitialized cfe_fhipe_FE_key struct
c	A pointer to an instance of the scheme (initialized cfe_fhipe struct)

cfe_fhipe_fe_key_free()

void cfe_fhipe_fe_key_free

(

cfe_fhipe_fe_key *

fe_key

)

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

Parameters

fe_key

A pointer to an initialized cfe_fhipe_FE_key struct

cfe_fhipe_derive_fe_key()

cfe_error cfe_fhipe_derive_fe_key	(	cfe_fhipe_fe_key *	fe_key,
		cfe_vec *	y,
		cfe_fhipe_sec_key *	sec_key,
		cfe_fhipe *	c
	)

Takes a master secret key and input vector y, and derives the functional encryption key. In case the key could not be derived, it returns an error.

Parameters

fe_key	A pointer to a cfe_fhipe_fe_key struct (the functional encryption key will be stored here)
y	A pointer to the inner product vector
sec_key	A pointer to the master secret key
c	A pointer to an instance of the scheme (initialized cfe_fhipe struct)

Returns

Error code

cfe_fhipe_ciphertext_init()

void cfe_fhipe_ciphertext_init	(	cfe_fhipe_ciphertext *	cipher,
		cfe_fhipe *	c
	)

Initializes the struct which represents the ciphertext.

Parameters

cipher	A pointer to an uninitialized cfe_fhipe_ciphertext struct
c	A pointer to an instance of the scheme (initialized cfe_fhipe struct)

cfe_fhipe_ciphertext_free()

void cfe_fhipe_ciphertext_free

(

cfe_fhipe_ciphertext *

cipher

)

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

Parameters

cipher

A pointer to an initialized cfe_fhipe_ciphertext struct

cfe_fhipe_encrypt()

cfe_error cfe_fhipe_encrypt	(	cfe_fhipe_ciphertext *	cipher,
		cfe_vec *	x,
		cfe_fhipe_sec_key *	sec_key,
		cfe_fhipe *	c
	)

Encrypts input vector x with the provided master secret key. It returns a ciphertext struct. If encryption failed, an error is returned.

Parameters

cipher	A pointer to an initialized cfe_fhipe_ciphertext struct (the resulting ciphertext will be stored here)
x	A pointer to the plaintext vector
sec_key	A pointer to the master secret key
c	A pointer to an instance of the scheme (initialized cfe_fhipe struct)

Returns

Error code

cfe_fhipe_decrypt()

cfe_error cfe_fhipe_decrypt	(	mpz_t	res,
		cfe_fhipe_ciphertext *	cipher,
		cfe_fhipe_fe_key *	fe_key,
		cfe_fhipe *	c
	)

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

Parameters

res	The result of the decryption (the value will be stored here)
cipher	A pointer to the ciphertext vector
fe_key	The functional encryption key
c	A pointer to an instance of the scheme (initialized cfe_fhipe struct)

Returns

Error code