Algorithms - ECC

Functions
WOLFSSL_API int	wc_ecc_make_key (WC_RNG *rng, int keysize, ecc_key *key)
	This function generates a new ecc_key and stores it in key.
WOLFSSL_API int	wc_ecc_make_key_ex (WC_RNG *rng, int keysize, ecc_key *key, int curve_id)
	This function generates a new ecc_key and stores it in key.
WOLFSSL_API int	wc_ecc_check_key (ecc_key *key)
	Perform sanity checks on ecc key validity.
WOLFSSL_API int	wc_ecc_shared_secret (ecc_key *private_key, ecc_key *public_key, byte *out, word32 *outlen)
	This function generates a new secret key using a local private key and a received public key. It stores this shared secret key in the buffer out and updates outlen to hold the number of bytes written to the output buffer.
WOLFSSL_API int	wc_ecc_shared_secret_ex (ecc_key *private_key, ecc_point *point, byte *out, word32 *outlen)
	Create an ECC shared secret between private key and public point.
WOLFSSL_API int	wc_ecc_sign_hash (const byte *in, word32 inlen, byte *out, word32 *outlen, WC_RNG *rng, ecc_key *key)
	This function signs a message digest using an ecc_key object to guarantee authenticity.
WOLFSSL_API int	wc_ecc_sign_hash_ex (const byte *in, word32 inlen, WC_RNG *rng, ecc_key *key, mp_int *r, mp_int *s)
	Sign a message digest.
WOLFSSL_API int	wc_ecc_verify_hash (const byte *sig, word32 siglen, const byte *hash, word32 hashlen, int *stat, ecc_key *key)
	This function verifies the ECC signature of a hash to ensure authenticity. It returns the answer through stat, with 1 corresponding to a valid signature, and 0 corresponding to an invalid signature.
WOLFSSL_API int	wc_ecc_init (ecc_key *key)
	This function initializes an ecc_key object for future use with message verification or key negotiation.
WOLFSSL_API int	wc_ecc_free (ecc_key *key)
	This function frees an ecc_key object after it has been used.
WOLFSSL_API void	wc_ecc_fp_free (void)
	This function frees the fixed-point cache, which can be used with ecc to speed up computation times. To use this functionality, FP_ECC (fixed-point ecc), should be defined.
WOLFSSL_API int	wc_ecc_is_valid_idx (int n)
	Checks if an ECC idx is valid.
WOLFSSL_API ecc_point *	wc_ecc_new_point (void)
	Allocate a new ECC point.
WOLFSSL_API void	wc_ecc_del_point (ecc_point *p)
	Free an ECC point from memory.
WOLFSSL_API int	wc_ecc_copy_point (ecc_point *p, ecc_point *r)
	Copy the value of one point to another one.
WOLFSSL_API int	wc_ecc_cmp_point (ecc_point *a, ecc_point *b)
	Compare the value of a point with another one.
WOLFSSL_API int	wc_ecc_point_is_at_infinity (ecc_point *p)
	Checks if a point is at infinity. Returns 1 if point is at infinity, 0 if not, < 0 on error.
WOLFSSL_API int	wc_ecc_mulmod (mp_int *k, ecc_point *G, ecc_point *R, mp_int *a, mp_int *modulus, int map)
	Perform ECC Fixed Point multiplication.
WOLFSSL_API int	wc_ecc_export_x963 (ecc_key *, byte *out, word32 *outLen)
	This function exports the ECC key from the ecc_key structure, storing the result in out. The key will be stored in ANSI X9.63 format. It stores the bytes written to the output buffer in outLen.
WOLFSSL_API int	wc_ecc_export_x963_ex (ecc_key *, byte *out, word32 *outLen, int compressed)
	This function exports the ECC key from the ecc_key structure, storing the result in out. The key will be stored in ANSI X9.63 format. It stores the bytes written to the output buffer in outLen. This function allows the additional option of compressing the certificate through the compressed parameter. When this parameter is true, the key will be stored in ANSI X9.63 compressed format.
WOLFSSL_API int	wc_ecc_import_x963 (const byte *in, word32 inLen, ecc_key *key)
	This function imports a public ECC key from a buffer containing the key stored in ANSI X9.63 format. This function will handle both compressed and uncompressed keys, as long as compressed keys are enabled at compile time through the HAVE_COMP_KEY option.
WOLFSSL_API int	wc_ecc_rs_to_sig (const char *r, const char *s, byte *out, word32 *outlen)
	This function converts the R and S portions of an ECC signature into a DER-encoded ECDSA signature. This function also stores the length written to the output buffer, out, in outlen.
WOLFSSL_API int	wc_ecc_import_raw (ecc_key *key, const char *qx, const char *qy, const char *d, const char *curveName)
	This function fills an ecc_key structure with the raw components of an ECC signature.
WOLFSSL_API int	wc_ecc_export_private_only (ecc_key *key, byte *out, word32 *outLen)
	This function exports only the private key from an ecc_key structure. It stores the private key in the buffer out, and sets the bytes written to this buffer in outLen.
WOLFSSL_API int	wc_ecc_export_point_der (const int curve_idx, ecc_point *point, byte *out, word32 *outLen)
	Export point to der.
WOLFSSL_API int	wc_ecc_import_point_der (byte *in, word32 inLen, const int curve_idx, ecc_point *point)
	Import point from der format.
WOLFSSL_API int	wc_ecc_size (ecc_key *key)
	This function returns the key size of an ecc_key structure in octets.
WOLFSSL_API int	wc_ecc_sig_size_calc (int sz)
	This function returns the worst case size for an ECC signature, given by: (keySz * 2) + SIG_HEADER_SZ + ECC_MAX_PAD_SZ. The actual signature size can be computed with wc_ecc_sign_hash.
WOLFSSL_API int	wc_ecc_sig_size (ecc_key *key)
	This function returns the worst case size for an ECC signature, given by: (keySz * 2) + SIG_HEADER_SZ + ECC_MAX_PAD_SZ. The actual signature size can be computed with wc_ecc_sign_hash.
WOLFSSL_API ecEncCtx *	wc_ecc_ctx_new (int flags, WC_RNG *rng)
	This function allocates and initializes space for a new ECC context object to allow secure message exchange with ECC.
WOLFSSL_API void	wc_ecc_ctx_free (ecEncCtx *)
	This function frees the ecEncCtx object used for encrypting and decrypting messages.
WOLFSSL_API int	wc_ecc_ctx_reset (ecEncCtx *, WC_RNG *)
	This function resets an ecEncCtx structure to avoid having to free and allocate a new context object.
WOLFSSL_API const byte *	wc_ecc_ctx_get_own_salt (ecEncCtx *)
	This function returns the salt of an ecEncCtx object. This function should only be called when the ecEncCtx's state is ecSRV_INIT or ecCLI_INIT.
WOLFSSL_API int	wc_ecc_ctx_set_peer_salt (ecEncCtx *, const byte *salt)
	This function sets the peer salt of an ecEncCtx object.
WOLFSSL_API int	wc_ecc_ctx_set_info (ecEncCtx *, const byte *info, int sz)
	This function can optionally be called before or after wc_ecc_ctx_set_peer_salt. It sets optional information for an ecEncCtx object.
WOLFSSL_API int	wc_ecc_encrypt (ecc_key *privKey, ecc_key *pubKey, const byte *msg, word32 msgSz, byte *out, word32 *outSz, ecEncCtx *ctx)
	This function encrypts the given input message from msg to out. This function takes an optional ctx object as parameter. When supplied, encryption proceeds based on the ecEncCtx's encAlgo, kdfAlgo, and macAlgo. If ctx is not supplied, processing completes with the default algorithms, ecAES_128_CBC, ecHKDF_SHA256 and ecHMAC_SHA256. This function requires that the messages are padded according to the encryption type specified by ctx.
WOLFSSL_API int	wc_ecc_decrypt (ecc_key *privKey, ecc_key *pubKey, const byte *msg, word32 msgSz, byte *out, word32 *outSz, ecEncCtx *ctx)
	This function decrypts the ciphertext from msg to out. This function takes an optional ctx object as parameter. When supplied, encryption proceeds based on the ecEncCtx's encAlgo, kdfAlgo, and macAlgo. If ctx is not supplied, processing completes with the default algorithms, ecAES_128_CBC, ecHKDF_SHA256 and ecHMAC_SHA256. This function requires that the messages are padded according to the encryption type specified by ctx.

Detailed Description

Function Documentation

wc_ecc_check_key()

WOLFSSL_API int wc_ecc_check_key

(

ecc_key *

key

)

Perform sanity checks on ecc key validity.

Returns

MP_OKAY Success, key is OK.

BAD_FUNC_ARG Returns if key is NULL.

ECC_INF_E Returns if wc_ecc_point_is_at_infinity returns 1.

Parameters

key	Pointer to key to check.

Example

ecc_key key;
WC_WC_RNG rng;
int check_result;
wc_ecc_init(&key);
wc_InitRng(&rng);
wc_ecc_make_key(&rng, 32, &key);
check_result = wc_ecc_check_key(&key);
 
if (check_result == MP_OKAY)
{
    // key check succeeded
}
else
{
    // key check failed
}

See also

wc_ecc_point_is_at_infinity

wc_ecc_cmp_point()

WOLFSSL_API int wc_ecc_cmp_point	(	ecc_point *	a,
		ecc_point *	b )

Compare the value of a point with another one.

Returns

BAD_FUNC_ARG One or both arguments are NULL.

MP_EQ The points are equal.

ret Either MP_LT or MP_GT and signifies that the points are not equal.

Parameters

a	First point to compare.
b	Second point to compare.

Example

ecc_point* point;
ecc_point* point_to_compare;
int cmp_result;
 
point = wc_ecc_new_point();
point_to_compare = wc_ecc_new_point();
cmp_result = wc_ecc_cmp_point(point, point_to_compare);
if (cmp_result == BAD_FUNC_ARG)
{
    // arguments are invalid
}
else if (cmp_result == MP_EQ)
{
    // Points are equal
}
else
{
    // Points are not equal
}

See also

wc_ecc_new_point

wc_ecc_del_point

wc_ecc_copy_point

Compare the value of a point with an other one a The point to compare b The other point to compare

return MP_EQ if equal, MP_LT/MP_GT if not, < 0 in case of error

wc_ecc_copy_point()

WOLFSSL_API int wc_ecc_copy_point	(	ecc_point *	p,
		ecc_point *	r )

Copy the value of one point to another one.

Returns

ECC_BAD_ARG_E Error thrown when p or r is null.

MP_OKAY Point copied successfully

ret Error from internal functions. Can be...

Parameters

p	The point to copy.
r	The created point.

Example

ecc_point* point;
ecc_point* copied_point;
int copy_return;
 
point = wc_ecc_new_point();
copy_return = wc_ecc_copy_point(point, copied_point);
if (copy_return != MP_OKAY)
{
    // Handle error
}

See also

wc_ecc_new_point

wc_ecc_cmp_point

wc_ecc_del_point

Copy the value of a point to an other one p The point to copy r The created point

wc_ecc_ctx_free()

WOLFSSL_API void wc_ecc_ctx_free

(

ecEncCtx *

ctx

)

This function frees the ecEncCtx object used for encrypting and decrypting messages.

Returns

none Returns.

Parameters

ctx	pointer to the ecEncCtx object to free

Example

ecEncCtx* ctx;
WC_WC_RNG rng;
wc_InitRng(&rng);
ctx = wc_ecc_ctx_new(REQ_RESP_CLIENT, &rng);
// do secure communication
...
wc_ecc_ctx_free(&ctx);

See also

wc_ecc_ctx_new

wc_ecc_ctx_get_own_salt()

WOLFSSL_API const byte * wc_ecc_ctx_get_own_salt

(

ecEncCtx *

ctx

)

This function returns the salt of an ecEncCtx object. This function should only be called when the ecEncCtx's state is ecSRV_INIT or ecCLI_INIT.

Returns

Success On success, returns the ecEncCtx salt

NULL Returned if the ecEncCtx object is NULL, or the ecEncCtx's state is not ecSRV_INIT or ecCLI_INIT. In the latter two cases, this function also sets the ecEncCtx's state to ecSRV_BAD_STATE or ecCLI_BAD_STATE, respectively

Parameters

ctx	pointer to the ecEncCtx object from which to get the salt

Example

ecEncCtx* ctx;
WC_WC_RNG rng;
const byte* salt;
wc_InitRng(&rng);
ctx = wc_ecc_ctx_new(REQ_RESP_CLIENT, &rng);
salt = wc_ecc_ctx_get_own_salt(&ctx);
if(salt == NULL) {
    // error getting salt
}

See also

wc_ecc_ctx_new

wc_ecc_ctx_set_peer_salt

wc_ecc_ctx_new()

WOLFSSL_API ecEncCtx * wc_ecc_ctx_new	(	int	flags,
		WC_RNG *	rng )

This function allocates and initializes space for a new ECC context object to allow secure message exchange with ECC.

Returns

Success On successfully generating a new ecEncCtx object, returns a pointer to that object

NULL Returned if the function fails to generate a new ecEncCtx object

Parameters

flags	indicate whether this is a server or client context Options are: REQ_RESP_CLIENT, and REQ_RESP_SERVER
rng	pointer to a RNG object with which to generate a salt

Example

ecEncCtx* ctx;
WC_WC_RNG rng;
wc_InitRng(&rng);
ctx = wc_ecc_ctx_new(REQ_RESP_CLIENT, &rng);
if(ctx == NULL) {
    // error generating new ecEncCtx object
}

See also

wc_ecc_encrypt

wc_ecc_decrypt

wc_ecc_ctx_reset()

WOLFSSL_API int wc_ecc_ctx_reset	(	ecEncCtx *	ctx,
		WC_RNG *	rng )

This function resets an ecEncCtx structure to avoid having to free and allocate a new context object.

Returns

0 Returned if the ecEncCtx structure is successfully reset

BAD_FUNC_ARG Returned if either rng or ctx is NULL

RNG_FAILURE_E Returned if there is an error generating a new salt for the ECC object

Parameters

ctx	pointer to the ecEncCtx object to reset
rng	pointer to an RNG object with which to generate a new salt

Example

ecEncCtx* ctx;
WC_WC_RNG rng;
wc_InitRng(&rng);
ctx = wc_ecc_ctx_new(REQ_RESP_CLIENT, &rng);
// do secure communication
...
wc_ecc_ctx_reset(&ctx, &rng);
// do more secure communication

See also

wc_ecc_ctx_new

wc_ecc_ctx_set_info()

WOLFSSL_API int wc_ecc_ctx_set_info	(	ecEncCtx *	ctx,
		const byte *	info,
		int	sz )

This function can optionally be called before or after wc_ecc_ctx_set_peer_salt. It sets optional information for an ecEncCtx object.

Returns

0 Returned upon successfully setting the information for the ecEncCtx object.

BAD_FUNC_ARG Returned if the given ecEncCtx object is NULL, the input info is NULL or it's size is invalid

Parameters

ctx	pointer to the ecEncCtx for which to set the info
info	pointer to a buffer containing the info to set
sz	size of the info buffer

Example

ecEncCtx* ctx;
byte info[] = { initialize with information };
// initialize ctx, get salt,
if(wc_ecc_ctx_set_info(&ctx, info, sizeof(info))) {
    // error setting info
}

See also

wc_ecc_ctx_new

wc_ecc_ctx_set_peer_salt()

WOLFSSL_API int wc_ecc_ctx_set_peer_salt	(	ecEncCtx *	ctx,
		const byte *	salt )

This function sets the peer salt of an ecEncCtx object.

Returns

0 Returned upon successfully setting the peer salt for the ecEncCtx object.

BAD_FUNC_ARG Returned if the given ecEncCtx object is NULL or has an invalid protocol, or if the given salt is NULL

BAD_ENC_STATE_E Returned if the ecEncCtx's state is ecSRV_SALT_GET or ecCLI_SALT_GET. In the latter two cases, this function also sets the ecEncCtx's state to ecSRV_BAD_STATE or ecCLI_BAD_STATE, respectively

Parameters

ctx	pointer to the ecEncCtx for which to set the salt
salt	pointer to the peer's salt

Example

ecEncCtx* cliCtx, srvCtx;
WC_WC_RNG rng;
const byte* cliSalt, srvSalt;
int ret;
 
wc_InitRng(&rng);
cliCtx = wc_ecc_ctx_new(REQ_RESP_CLIENT, &rng);
srvCtx = wc_ecc_ctx_new(REQ_RESP_SERVER, &rng);
 
cliSalt = wc_ecc_ctx_get_own_salt(&cliCtx);
srvSalt = wc_ecc_ctx_get_own_salt(&srvCtx);
ret = wc_ecc_ctx_set_peer_salt(&cliCtx, srvSalt);

See also

wc_ecc_ctx_get_own_salt

wc_ecc_decrypt()

WOLFSSL_API int wc_ecc_decrypt	(	ecc_key *	privKey,
		ecc_key *	pubKey,
		const byte *	msg,
		word32	msgSz,
		byte *	out,
		word32 *	outSz,
		ecEncCtx *	ctx )

This function decrypts the ciphertext from msg to out. This function takes an optional ctx object as parameter. When supplied, encryption proceeds based on the ecEncCtx's encAlgo, kdfAlgo, and macAlgo. If ctx is not supplied, processing completes with the default algorithms, ecAES_128_CBC, ecHKDF_SHA256 and ecHMAC_SHA256. This function requires that the messages are padded according to the encryption type specified by ctx.

Returns

0 Returned upon successfully decrypting the input message

BAD_FUNC_ARG Returned if privKey, pubKey, msg, msgSz, out, or outSz are NULL, or the ctx object specifies an unsupported encryption type

BAD_ENC_STATE_E Returned if the ctx object given is in a state that is not appropriate for decryption

BUFFER_E Returned if the supplied output buffer is too small to store the decrypted plaintext

MEMORY_E Returned if there is an error allocating memory for the shared secret key

Parameters

privKey	pointer to the ecc_key object containing the private key to use for decryption
pubKey	pointer to the ecc_key object containing the public key of the peer with whom one wishes to communicate
msg	pointer to the buffer holding the ciphertext to decrypt
msgSz	size of the buffer to decrypt
out	pointer to the buffer in which to store the decrypted plaintext
outSz	pointer to a word32 object containing the available size in the out buffer. Upon successfully decrypting the ciphertext, holds the number of bytes written to the output buffer
ctx	Optional: pointer to an ecEncCtx object specifying different decryption algorithms to use

Example

byte cipher[] = { initialize with
ciphertext to decrypt. Ensure padded to block size };
byte plain[sizeof(cipher)];
word32 plainSz = sizeof(plain);
int ret;
ecc_key cli, serv;
// initialize cli with private key
// initialize serv with received public key
ecEncCtx* cliCtx, servCtx;
// initialize cliCtx and servCtx
// exchange salts
ret = wc_ecc_decrypt(&cli, &serv, cipher, sizeof(cipher),
plain, &plainSz, cliCtx);
 
if(ret != 0) {
    // error decrypting message
}

See also

Wc_ecc_encrypt

wc_ecc_del_point()

WOLFSSL_API void wc_ecc_del_point

(

ecc_point *

p

)

Free an ECC point from memory.

Returns

none No returns.

Parameters

p	The point to free.

Example

ecc_point* point;
point = wc_ecc_new_point();
if (point == NULL)
{
    // Handle point creation error
}
// Do stuff with point
wc_ecc_del_point(point);

See also

wc_ecc_new_point

wc_ecc_cmp_point

wc_ecc_copy_point

Free an ECC point from memory p The point to free

wc_ecc_encrypt()

WOLFSSL_API int wc_ecc_encrypt	(	ecc_key *	privKey,
		ecc_key *	pubKey,
		const byte *	msg,
		word32	msgSz,
		byte *	out,
		word32 *	outSz,
		ecEncCtx *	ctx )

This function encrypts the given input message from msg to out. This function takes an optional ctx object as parameter. When supplied, encryption proceeds based on the ecEncCtx's encAlgo, kdfAlgo, and macAlgo. If ctx is not supplied, processing completes with the default algorithms, ecAES_128_CBC, ecHKDF_SHA256 and ecHMAC_SHA256. This function requires that the messages are padded according to the encryption type specified by ctx.

Returns

0 Returned upon successfully encrypting the input message

BAD_FUNC_ARG Returned if privKey, pubKey, msg, msgSz, out, or outSz are NULL, or the ctx object specifies an unsupported encryption type

BAD_ENC_STATE_E Returned if the ctx object given is in a state that is not appropriate for encryption

BUFFER_E Returned if the supplied output buffer is too small to store the encrypted ciphertext

MEMORY_E Returned if there is an error allocating memory for the shared secret key

Parameters

privKey	pointer to the ecc_key object containing the private key to use for encryption
pubKey	pointer to the ecc_key object containing the public key of the peer with whom one wishes to communicate
msg	pointer to the buffer holding the message to encrypt
msgSz	size of the buffer to encrypt
out	pointer to the buffer in which to store the encrypted ciphertext
outSz	pointer to a word32 object containing the available size in the out buffer. Upon successfully encrypting the message, holds the number of bytes written to the output buffer
ctx	Optional: pointer to an ecEncCtx object specifying different encryption algorithms to use

Example

byte msg[] = { initialize with msg to encrypt. Ensure padded to block size };
byte out[sizeof(msg)];
word32 outSz = sizeof(out);
int ret;
ecc_key cli, serv;
// initialize cli with private key
// initialize serv with received public key
 
ecEncCtx* cliCtx, servCtx;
// initialize cliCtx and servCtx
// exchange salts
ret = wc_ecc_encrypt(&cli, &serv, msg, sizeof(msg), out, &outSz, cliCtx);
if(ret != 0) {
    // error encrypting message
}

See also

wc_ecc_decrypt

wc_ecc_export_point_der()

WOLFSSL_API int wc_ecc_export_point_der	(	const int	curve_idx,
		ecc_point *	point,
		byte *	out,
		word32 *	outLen )

Export point to der.

Returns

0 Returned on success.

ECC_BAD_ARG_E Returns if curve_idx is less than 0 or invalid. Also returns when

LENGTH_ONLY_E outLen is set but nothing else.

BUFFER_E Returns if outLen is less than 1 + 2 * the curve size.

MEMORY_E Returns if there is a problem allocating memory.

Parameters

curve_idx	Index of the curve used from ecc_sets.
point	Point to export to der.
out	Destination for the output.
outLen	Maxsize allowed for output, destination for final size of output

Example

int curve_idx;
ecc_point* point;
byte out[];
word32 outLen;
wc_ecc_export_point_der(curve_idx, point, out, &outLen);

See also

wc_ecc_import_point_der

wc_ecc_export_private_only()

WOLFSSL_API int wc_ecc_export_private_only	(	ecc_key *	key,
		byte *	out,
		word32 *	outLen )

This function exports only the private key from an ecc_key structure. It stores the private key in the buffer out, and sets the bytes written to this buffer in outLen.

Returns

0 Returned upon successfully exporting the private key

ECC_BAD_ARG_E Returned if any of the input values evaluate to NULL

MEMORY_E Returned if there is an error initializing space to store the parameters of the ecc_key

ASN_PARSE_E Returned if the input curveName is not defined in ecc_sets

MP_INIT_E may be returned if there is an error processing the input parameters

MP_READ_E may be returned if there is an error processing the input parameters

MP_CMP_E may be returned if there is an error processing the input parameters

MP_INVMOD_E may be returned if there is an error processing the input parameters

MP_EXPTMOD_E may be returned if there is an error processing the input parameters

MP_MOD_E may be returned if there is an error processing the input parameters

MP_MUL_E may be returned if there is an error processing the input parameters

MP_ADD_E may be returned if there is an error processing the input parameters

MP_MULMOD_E may be returned if there is an error processing the input parameters

MP_TO_E may be returned if there is an error processing the input parameters

MP_MEM may be returned if there is an error processing the input parameters

Parameters

key	pointer to an ecc_key structure from which to export the private key
out	pointer to the buffer in which to store the private key
outLen	pointer to a word32 object with the size available in out. Set with the number of bytes written to out after successfully exporting the private key

Example

int ret;
ecc_key key;
// initialize key, make key
 
char priv[ECC_KEY_SIZE];
word32 privSz = sizeof(priv);
ret = wc_ecc_export_private_only(&key, priv, &privSz);
if ( ret != 0) {
    // error exporting private key
}

See also

wc_ecc_import_private_key

wc_ecc_export_x963()

WOLFSSL_API int wc_ecc_export_x963	(	ecc_key *	key,
		byte *	out,
		word32 *	outLen )

This function exports the ECC key from the ecc_key structure, storing the result in out. The key will be stored in ANSI X9.63 format. It stores the bytes written to the output buffer in outLen.

Returns

0 Returned on successfully exporting the ecc_key

LENGTH_ONLY_E Returned if the output buffer evaluates to NULL, but the other two input parameters are valid. Indicates that the function is only returning the length required to store the key

ECC_BAD_ARG_E Returned if any of the input parameters are NULL, or the key is unsupported (has an invalid index)

BUFFER_E Returned if the output buffer is too small to store the ecc key. If the output buffer is too small, the size needed will be returned in outLen

MEMORY_E Returned if there is an error allocating memory with XMALLOC

MP_INIT_E may be returned if there is an error processing the ecc_key

MP_READ_E may be returned if there is an error processing the ecc_key

MP_CMP_E may be returned if there is an error processing the ecc_key

MP_INVMOD_E may be returned if there is an error processing the ecc_key

MP_EXPTMOD_E may be returned if there is an error processing the ecc_key

MP_MOD_E may be returned if there is an error processing the ecc_key

MP_MUL_E may be returned if there is an error processing the ecc_key

MP_ADD_E may be returned if there is an error processing the ecc_key

MP_MULMOD_E may be returned if there is an error processing the ecc_key

MP_TO_E may be returned if there is an error processing the ecc_key

MP_MEM may be returned if there is an error processing the ecc_key

Parameters

key	pointer to the ecc_key object to export
out	pointer to the buffer in which to store the ANSI X9.63 formatted key
outLen	size of the output buffer. On successfully storing the key, will hold the bytes written to the output buffer

Example

int ret;
byte buff[1024];
word32 buffSz = sizeof(buff);
 
ecc_key key;
// initialize key, make key
ret = wc_ecc_export_x963(&key, buff, &buffSz);
if ( ret != 0) {
    // error exporting key
}

See also

wc_ecc_export_x963_ex

wc_ecc_import_x963

wc_ecc_export_x963_ex()

WOLFSSL_API int wc_ecc_export_x963_ex	(	ecc_key *	key,
		byte *	out,
		word32 *	outLen,
		int	compressed )

This function exports the ECC key from the ecc_key structure, storing the result in out. The key will be stored in ANSI X9.63 format. It stores the bytes written to the output buffer in outLen. This function allows the additional option of compressing the certificate through the compressed parameter. When this parameter is true, the key will be stored in ANSI X9.63 compressed format.

Returns

0 Returned on successfully exporting the ecc_key

NOT_COMPILED_IN Returned if the HAVE_COMP_KEY was not enabled at compile time, but the key was requested in compressed format

LENGTH_ONLY_E Returned if the output buffer evaluates to NULL, but the other two input parameters are valid. Indicates that the function is only returning the length required to store the key

ECC_BAD_ARG_E Returned if any of the input parameters are NULL, or the key is unsupported (has an invalid index)

BUFFER_E Returned if the output buffer is too small to store the ecc key. If the output buffer is too small, the size needed will be returned in outLen

MEMORY_E Returned if there is an error allocating memory with XMALLOC

MP_INIT_E may be returned if there is an error processing the ecc_key

MP_READ_E may be returned if there is an error processing the ecc_key

MP_CMP_E may be returned if there is an error processing the ecc_key

MP_INVMOD_E may be returned if there is an error processing the ecc_key

MP_EXPTMOD_E may be returned if there is an error processing the ecc_key

MP_MOD_E may be returned if there is an error processing the ecc_key

MP_MUL_E may be returned if there is an error processing the ecc_key

MP_ADD_E may be returned if there is an error processing the ecc_key

MP_MULMOD_E may be returned if there is an error processing the ecc_key

MP_TO_E may be returned if there is an error processing the ecc_key

MP_MEM may be returned if there is an error processing the ecc_key

Parameters

key	pointer to the ecc_key object to export
out	pointer to the buffer in which to store the ANSI X9.63 formatted key
outLen	size of the output buffer. On successfully storing the key, will hold the bytes written to the output buffer
compressed	indicator of whether to store the key in compressed format. 1==compressed, 0==uncompressed

Example

int ret;
byte buff[1024];
word32 buffSz = sizeof(buff);
ecc_key key;
// initialize key, make key
ret = wc_ecc_export_x963_ex(&key, buff, &buffSz, 1);
if ( ret != 0) {
    // error exporting key
}

See also

wc_ecc_export_x963

wc_ecc_import_x963

wc_ecc_fp_free()

WOLFSSL_API void wc_ecc_fp_free

(

void

)

This function frees the fixed-point cache, which can be used with ecc to speed up computation times. To use this functionality, FP_ECC (fixed-point ecc), should be defined.

Returns

none No returns.

Parameters

none	No parameters.

Example

ecc_key key;
// initialize key and perform secure exchanges
...
 
wc_ecc_fp_free();

See also

wc_ecc_free

Free the Fixed Point cache

wc_ecc_free()

WOLFSSL_API int wc_ecc_free

(

ecc_key *

key

)

This function frees an ecc_key object after it has been used.

Returns

int integer returned indicating wolfSSL error or success status.

Parameters

key	pointer to the ecc_key object to free

Example

// initialize key and perform secure exchanges
...
wc_ecc_free(&key);

See also

wc_ecc_init

Free an ECC key from memory key The key you wish to free

wc_ecc_import_point_der()

WOLFSSL_API int wc_ecc_import_point_der	(	byte *	in,
		word32	inLen,
		const int	curve_idx,
		ecc_point *	point )

Import point from der format.

Returns

ECC_BAD_ARG_E Returns if any arguments are null or if inLen is even.

MEMORY_E Returns if there is an error initializing

NOT_COMPILED_IN Returned if HAVE_COMP_KEY is not true and in is a compressed cert

MP_OKAY Successful operation.

Parameters

in	der buffer to import point from.
inLen	Length of der buffer.
curve_idx	Index of curve.
point	Destination for point.

Example

byte in[];
word32 inLen;
int curve_idx;
ecc_point* point;
wc_ecc_import_point_der(in, inLen, curve_idx, point);

See also

wc_ecc_export_point_der

wc_ecc_import_raw()

WOLFSSL_API int wc_ecc_import_raw	(	ecc_key *	key,
		const char *	qx,
		const char *	qy,
		const char *	d,
		const char *	curveName )

This function fills an ecc_key structure with the raw components of an ECC signature.

Returns

0 Returned upon successfully importing into the ecc_key structure

ECC_BAD_ARG_E Returned if any of the input values evaluate to NULL

MEMORY_E Returned if there is an error initializing space to store the parameters of the ecc_key

ASN_PARSE_E Returned if the input curveName is not defined in ecc_sets

MP_INIT_E may be returned if there is an error processing the input parameters

MP_READ_E may be returned if there is an error processing the input parameters

MP_CMP_E may be returned if there is an error processing the input parameters

MP_INVMOD_E may be returned if there is an error processing the input parameters

MP_EXPTMOD_E may be returned if there is an error processing the input parameters

MP_MOD_E may be returned if there is an error processing the input parameters

MP_MUL_E may be returned if there is an error processing the input parameters

MP_ADD_E may be returned if there is an error processing the input parameters

MP_MULMOD_E may be returned if there is an error processing the input parameters

MP_TO_E may be returned if there is an error processing the input parameters

MP_MEM may be returned if there is an error processing the input parameters

Parameters

key	pointer to an ecc_key structure to fill
qx	pointer to a buffer containing the x component of the base point as an ASCII hex string
qy	pointer to a buffer containing the y component of the base point as an ASCII hex string
d	pointer to a buffer containing the private key as an ASCII hex string
curveName	pointer to a string containing the ECC curve name, as found in ecc_sets

Example

int ret;
ecc_key key;
wc_ecc_init(&key);
 
char qx[] = { initialize with x component of base point };
char qy[] = { initialize with y component of base point };
char d[]  = { initialize with private key };
ret = wc_ecc_import_raw(&key,qx, qy, d, "ECC-256");
if ( ret != 0) {
    // error initializing key with given inputs
}

See also

wc_ecc_import_private_key

Import raw ECC key key The destination ecc_key structure qx x component of the public key, as ASCII hex string qy y component of the public key, as ASCII hex string d private key, as ASCII hex string, optional if importing public key only curveName ECC curve name, from ecc_sets[] return MP_OKAY on success

wc_ecc_import_x963()

WOLFSSL_API int wc_ecc_import_x963	(	const byte *	in,
		word32	inLen,
		ecc_key *	key )

This function imports a public ECC key from a buffer containing the key stored in ANSI X9.63 format. This function will handle both compressed and uncompressed keys, as long as compressed keys are enabled at compile time through the HAVE_COMP_KEY option.

Returns

0 Returned on successfully importing the ecc_key

NOT_COMPILED_IN Returned if the HAVE_COMP_KEY was not enabled at compile time, but the key is stored in compressed format

ECC_BAD_ARG_E Returned if in or key evaluate to NULL, or the inLen is even (according to the x9.63 standard, the key must be odd)

MEMORY_E Returned if there is an error allocating memory

ASN_PARSE_E Returned if there is an error parsing the ECC key; may indicate that the ECC key is not stored in valid ANSI X9.63 format

IS_POINT_E Returned if the public key exported is not a point on the ECC curve

MP_INIT_E may be returned if there is an error processing the ecc_key

MP_READ_E may be returned if there is an error processing the ecc_key

MP_CMP_E may be returned if there is an error processing the ecc_key

MP_INVMOD_E may be returned if there is an error processing the ecc_key

MP_EXPTMOD_E may be returned if there is an error processing the ecc_key

MP_MOD_E may be returned if there is an error processing the ecc_key

MP_MUL_E may be returned if there is an error processing the ecc_key

MP_ADD_E may be returned if there is an error processing the ecc_key

MP_MULMOD_E may be returned if there is an error processing the ecc_key

MP_TO_E may be returned if there is an error processing the ecc_key

MP_MEM may be returned if there is an error processing the ecc_key

Parameters

in	pointer to the buffer containing the ANSI x9.63 formatted ECC key
inLen	length of the input buffer
key	pointer to the ecc_key object in which to store the imported key

Example

int ret;
byte buff[] = { initialize with ANSI X9.63 formatted key };
 
ecc_key pubKey;
wc_ecc_init(&pubKey);
 
ret = wc_ecc_import_x963(buff, sizeof(buff), &pubKey);
if ( ret != 0) {
    // error importing key
}

See also

wc_ecc_export_x963

wc_ecc_import_private_key

wc_ecc_init()

WOLFSSL_API int wc_ecc_init

(

ecc_key *

key

)

This function initializes an ecc_key object for future use with message verification or key negotiation.

Returns

0 Returned upon successfully initializing the ecc_key object

MEMORY_E Returned if there is an error allocating memory

Parameters

key	pointer to the ecc_key object to initialize

Example

ecc_key key;
wc_ecc_init(&key);

See also

wc_ecc_make_key

wc_ecc_free

wc_ecc_is_valid_idx()

WOLFSSL_API int wc_ecc_is_valid_idx

(

int

n

)

Checks if an ECC idx is valid.

Returns

1 Return if valid.

0 Return if not valid.

Parameters

n	The idx number to check.

Example

ecc_key key;
WC_WC_RNG rng;
int is_valid;
wc_ecc_init(&key);
wc_InitRng(&rng);
wc_ecc_make_key(&rng, 32, &key);
is_valid = wc_ecc_is_valid_idx(key.idx);
if (is_valid == 1)
{
    // idx is valid
}
else if (is_valid == 0)
{
    // idx is not valid
}

See also

none

Returns whether an ECC idx is valid or not n The idx number to check return 1 if valid, 0 if not

wc_ecc_make_key()

WOLFSSL_API int wc_ecc_make_key	(	WC_RNG *	rng,
		int	keysize,
		ecc_key *	key )

This function generates a new ecc_key and stores it in key.

Returns

0 Returned on success.

ECC_BAD_ARG_E Returned if rng or key evaluate to NULL

BAD_FUNC_ARG Returned if the specified key size is not in the correct range of supported keys

MEMORY_E Returned if there is an error allocating memory while computing the ecc key

MP_INIT_E may be returned if there is an error while computing the ecc key

MP_READ_E may be returned if there is an error while computing the ecc key

MP_CMP_E may be returned if there is an error while computing the ecc key

MP_INVMOD_E may be returned if there is an error while computing the ecc key

MP_EXPTMOD_E may be returned if there is an error while computing the ecc key

MP_MOD_E may be returned if there is an error while computing the ecc key

MP_MUL_E may be returned if there is an error while computing the ecc key

MP_ADD_E may be returned if there is an error while computing the ecc key

MP_MULMOD_E may be returned if there is an error while computing the ecc key

MP_TO_E may be returned if there is an error while computing the ecc key

MP_MEM may be returned if there is an error while computing the ecc key

Parameters

rng	pointer to an initialized RNG object with which to generate the key
keysize	desired length for the ecc_key
key	pointer to the ecc_key for which to generate a key

Example

ecc_key key;
wc_ecc_init(&key);
WC_WC_RNG rng;
wc_InitRng(&rng);
wc_ecc_make_key(&rng, 32, &key); // initialize 32 byte ecc key

See also

wc_ecc_init

wc_ecc_shared_secret

Make a new ECC key rng An active RNG state keysize The keysize for the new key (in octets from 20 to 65 bytes) key [out] Destination of the newly created key return MP_OKAY if successful, upon error all allocated memory will be freed

wc_ecc_make_key_ex()

WOLFSSL_API int wc_ecc_make_key_ex	(	WC_RNG *	rng,
		int	keysize,
		ecc_key *	key,
		int	curve_id )

This function generates a new ecc_key and stores it in key.

Returns

0 Returned on success.

ECC_BAD_ARG_E Returned if rng or key evaluate to NULL

BAD_FUNC_ARG Returned if the specified key size is not in the correct range of supported keys

MEMORY_E Returned if there is an error allocating memory while computing the ecc key

MP_INIT_E may be returned if there is an error while computing the ecc key

MP_READ_E may be returned if there is an error while computing the ecc key

MP_CMP_E may be returned if there is an error while computing the ecc key

MP_INVMOD_E may be returned if there is an error while computing the ecc key

MP_EXPTMOD_E may be returned if there is an error while computing the ecc key

MP_MOD_E may be returned if there is an error while computing the ecc key

MP_MUL_E may be returned if there is an error while computing the ecc key

MP_ADD_E may be returned if there is an error while computing the ecc key

MP_MULMOD_E may be returned if there is an error while computing the ecc key

MP_TO_E may be returned if there is an error while computing the ecc key

MP_MEM may be returned if there is an error while computing the ecc key

Parameters

key	Pointer to store the created key.
keysize	size of key to be created in bytes, set based on curveId
rng	Rng to be used in key creation
curve_id	Curve to use for key

Example

ecc_key key;
int ret;
WC_WC_RNG rng;
wc_ecc_init(&key);
wc_InitRng(&rng);
int curveId = ECC_SECP521R1;
int keySize = wc_ecc_get_curve_size_from_id(curveId);
ret = wc_ecc_make_key_ex(&rng, keySize, &key, curveId);
if (ret != MP_OKAY) {
    // error handling
}

See also

wc_ecc_make_key

wc_ecc_get_curve_size_from_id

wc_ecc_mulmod()

WOLFSSL_API int wc_ecc_mulmod	(	mp_int *	k,
		ecc_point *	G,
		ecc_point *	R,
		mp_int *	a,
		mp_int *	modulus,
		int	map )

Perform ECC Fixed Point multiplication.

Returns

MP_OKAY Returns on successful operation.

MP_INIT_E Returned if there is an error initializing an integer for use with the multiple precision integer (mp_int) library.

Parameters

k	The multiplicand.
G	Base point to multiply.
R	Destination of product.
modulus	The modulus for the curve.
map	If non-zero maps the point back to affine coordinates, otherwise it's left in jacobian-montgomery form.

Example

ecc_point* base;
ecc_point* destination;
// Initialize points
base = wc_ecc_new_point();
destination = wc_ecc_new_point();
// Setup other arguments
mp_int multiplicand;
mp_int modulus;
int map;

See also

none

ECC Fixed Point mulmod global k The multiplicand G Base point to multiply R [out] Destination of product a ECC curve parameter a modulus The modulus for the curve map [boolean] If non-zero maps the point back to affine coordinates, otherwise it's left in jacobian-montgomery form return MP_OKAY if successful

wc_ecc_new_point()

WOLFSSL_API ecc_point * wc_ecc_new_point

(

void

)

Allocate a new ECC point.

Returns

p A newly allocated point.

NULL Returns NULL on error.

Parameters

none	No parameters.

Example

ecc_point* point;
point = wc_ecc_new_point();
if (point == NULL)
{
    // Handle point creation error
}
// Do stuff with point

See also

wc_ecc_del_point

wc_ecc_cmp_point

wc_ecc_copy_point

Allocate a new ECC point return A newly allocated point or NULL on error

wc_ecc_point_is_at_infinity()

WOLFSSL_API int wc_ecc_point_is_at_infinity

(

ecc_point *

p

)

Checks if a point is at infinity. Returns 1 if point is at infinity, 0 if not, < 0 on error.

Returns

1 p is at infinity.

0 p is not at infinity.

<0 Error.

Parameters

p	The point to check.

Example

ecc_point* point;
int is_infinity;
point = wc_ecc_new_point();
 
is_infinity = wc_ecc_point_is_at_infinity(point);
if (is_infinity < 0)
{
    // Handle error
}
else if (is_infinity == 0)
{
    // Point is not at infinity
}
else if (is_infinity == 1)
{
    // Point is at infinity
}

See also

wc_ecc_new_point

wc_ecc_del_point

wc_ecc_cmp_point

wc_ecc_copy_point

wc_ecc_rs_to_sig()

WOLFSSL_API int wc_ecc_rs_to_sig	(	const char *	r,
		const char *	s,
		byte *	out,
		word32 *	outlen )

This function converts the R and S portions of an ECC signature into a DER-encoded ECDSA signature. This function also stores the length written to the output buffer, out, in outlen.

Returns

0 Returned on successfully converting the signature

ECC_BAD_ARG_E Returned if any of the input parameters evaluate to NULL, or if the input buffer is not large enough to hold the DER-encoded ECDSA signature

MP_INIT_E may be returned if there is an error processing the ecc_key

MP_READ_E may be returned if there is an error processing the ecc_key

MP_CMP_E may be returned if there is an error processing the ecc_key

MP_INVMOD_E may be returned if there is an error processing the ecc_key

MP_EXPTMOD_E may be returned if there is an error processing the ecc_key

MP_MOD_E may be returned if there is an error processing the ecc_key

MP_MUL_E may be returned if there is an error processing the ecc_key

MP_ADD_E may be returned if there is an error processing the ecc_key

MP_MULMOD_E may be returned if there is an error processing the ecc_key

MP_TO_E may be returned if there is an error processing the ecc_key

MP_MEM may be returned if there is an error processing the ecc_key

Parameters

r	pointer to the buffer containing the R portion of the signature as a string
s	pointer to the buffer containing the S portion of the signature as a string
out	pointer to the buffer in which to store the DER-encoded ECDSA signature
outlen	length of the output buffer available. Will store the bytes written to the buffer after successfully converting the signature to ECDSA format

Example

int ret;
ecc_key key;
// initialize key, generate R and S
 
char r[] = { initialize with R };
char s[] = { initialize with S };
byte sig[wc_ecc_sig_size(key)];
// signature size will be 2 * ECC key size + ~10 bytes for ASN.1 overhead
word32 sigSz = sizeof(sig);
ret = wc_ecc_rs_to_sig(r, s, sig, &sigSz);
if ( ret != 0) {
    // error converting parameters to signature
}

See also

wc_ecc_sign_hash

wc_ecc_sig_size

Convert ECC R,S to signature r R component of signature s S component of signature out DER-encoded ECDSA signature outlen [in/out] output buffer size, output signature size return MP_OKAY on success

wc_ecc_shared_secret()

WOLFSSL_API int wc_ecc_shared_secret	(	ecc_key *	private_key,
		ecc_key *	public_key,
		byte *	out,
		word32 *	outlen )

This function generates a new secret key using a local private key and a received public key. It stores this shared secret key in the buffer out and updates outlen to hold the number of bytes written to the output buffer.

Returns

0 Returned upon successfully generating a shared secret key

BAD_FUNC_ARG Returned if any of the input parameters evaluate to NULL

ECC_BAD_ARG_E Returned if the type of the private key given as argument, private_key, is not ECC_PRIVATEKEY, or if the public and private key types (given by ecc->dp) are not equivalent

MEMORY_E Returned if there is an error generating a new ecc point

BUFFER_E Returned if the generated shared secret key is too long to store in the provided buffer

MP_INIT_E may be returned if there is an error while computing the shared key

MP_READ_E may be returned if there is an error while computing the shared key

MP_CMP_E may be returned if there is an error while computing the shared key

MP_INVMOD_E may be returned if there is an error while computing the shared key

MP_EXPTMOD_E may be returned if there is an error while computing the shared key

MP_MOD_E may be returned if there is an error while computing the shared key

MP_MUL_E may be returned if there is an error while computing the shared key

MP_ADD_E may be returned if there is an error while computing the shared key

MP_MULMOD_E may be returned if there is an error while computing the shared key

MP_TO_E may be returned if there is an error while computing the shared key

MP_MEM may be returned if there is an error while computing the shared key

Parameters

private_key	pointer to the ecc_key structure containing the local private key
public_key	pointer to the ecc_key structure containing the received public key
out	pointer to an output buffer in which to store the generated shared secret key
outlen	pointer to the word32 object containing the length of the output buffer. Will be overwritten with the length written to the output buffer upon successfully generating a shared secret key

Example

ecc_key priv, pub;
WC_WC_RNG rng;
byte secret[1024]; // can hold 1024 byte shared secret key
word32 secretSz = sizeof(secret);
int ret;
 
wc_InitRng(&rng); // initialize rng
wc_ecc_init(&priv); // initialize key
wc_ecc_make_key(&rng, 32, &priv); // make public/private key pair
// receive public key, and initialise into pub
ret = wc_ecc_shared_secret(&priv, &pub, secret, &secretSz);
// generate secret key
if ( ret != 0 ) {
    // error generating shared secret key
}

See also

wc_ecc_init

wc_ecc_make_key

Create an ECC shared secret between two keys private_key The private ECC key (heap hint based off of private key) public_key The public key out [out] Destination of the shared secret Conforms to EC-DH from ANSI X9.63 outlen [in/out] The max size and resulting size of the shared secret return MP_OKAY if successful

wc_ecc_shared_secret_ex()

WOLFSSL_API int wc_ecc_shared_secret_ex	(	ecc_key *	private_key,
		ecc_point *	point,
		byte *	out,
		word32 *	outlen )

Create an ECC shared secret between private key and public point.

Returns

MP_OKAY Indicates success.

BAD_FUNC_ARG Error returned when any arguments are null.

ECC_BAD_ARG_E Error returned if private_key->type is not ECC_PRIVATEKEY or private_key->idx fails to validate.

BUFFER_E Error when outlen is too small.

MEMORY_E Error to create a new point.

MP_VAL possible when an initialization failure occurs.

MP_MEM possible when an initialization failure occurs.

Parameters

private_key	The private ECC key.
point	The point to use (public key).
out	Output destination of the shared secret. Conforms to EC-DH from ANSI X9.63.
outlen	Input the max size and output the resulting size of the shared secret.

Example

ecc_key key;
ecc_point* point;
byte shared_secret[];
int secret_size;
int result;
 
point = wc_ecc_new_point();
 
result = wc_ecc_shared_secret_ex(&key, point,
&shared_secret, &secret_size);
 
if (result != MP_OKAY)
{
    // Handle error
}

See also

wc_ecc_verify_hash_ex

Create an ECC shared secret between private key and public point private_key The private ECC key (heap hint based on private key) point The point to use (public key) out [out] Destination of the shared secret Conforms to EC-DH from ANSI X9.63 outlen [in/out] The max size and resulting size of the shared secret return MP_OKAY if successful

wc_ecc_sig_size()

WOLFSSL_API int wc_ecc_sig_size

(

ecc_key *

key

)

This function returns the worst case size for an ECC signature, given by: (keySz * 2) + SIG_HEADER_SZ + ECC_MAX_PAD_SZ. The actual signature size can be computed with wc_ecc_sign_hash.

Returns

Success Given a valid key, returns the maximum signature size, in octets

0 Returned if the given key is NULL

Parameters

key	pointer to an ecc_key structure for which to get the signature size

Example

int sigSz;
ecc_key key;
// initialize key, make key
 
sigSz = wc_ecc_sig_size(&key);
if ( sigSz == 0) {
    // error determining sig size
}

See also

wc_ecc_sign_hash

wc_ecc_sig_size_calc

wc_ecc_sig_size_calc()

WOLFSSL_API int wc_ecc_sig_size_calc

(

int

sz

)

This function returns the worst case size for an ECC signature, given by: (keySz * 2) + SIG_HEADER_SZ + ECC_MAX_PAD_SZ. The actual signature size can be computed with wc_ecc_sign_hash.

Returns

returns the maximum signature size, in octets

Parameters

key

size

Example

int sigSz = wc_ecc_sig_size_calc(32);
if ( sigSz == 0) {
    // error determining sig size
}

See also

wc_ecc_sign_hash

wc_ecc_sig_size

wc_ecc_sign_hash()

WOLFSSL_API int wc_ecc_sign_hash	(	const byte *	in,
		word32	inlen,
		byte *	out,
		word32 *	outlen,
		WC_RNG *	rng,
		ecc_key *	key )

This function signs a message digest using an ecc_key object to guarantee authenticity.

Returns

0 Returned upon successfully generating a signature for the message digest

BAD_FUNC_ARG Returned if any of the input parameters evaluate to NULL, or if the output buffer is too small to store the generated signature

ECC_BAD_ARG_E Returned if the input key is not a private key, or if the ECC OID is invalid

RNG_FAILURE_E Returned if the rng cannot successfully generate a satisfactory key

MP_INIT_E may be returned if there is an error while computing the message signature

MP_READ_E may be returned if there is an error while computing the message signature

MP_CMP_E may be returned if there is an error while computing the message signature

MP_INVMOD_E may be returned if there is an error while computing the message signature

MP_EXPTMOD_E may be returned if there is an error while computing the message signature

MP_MOD_E may be returned if there is an error while computing the message signature

MP_MUL_E may be returned if there is an error while computing the message signature

MP_ADD_E may be returned if there is an error while computing the message signature

MP_MULMOD_E may be returned if there is an error while computing the message signature

MP_TO_E may be returned if there is an error while computing the message signature

MP_MEM may be returned if there is an error while computing the message signature

Parameters

in	pointer to the buffer containing the message hash to sign
inlen	length of the message hash to sign
out	buffer in which to store the generated signature
outlen	max length of the output buffer. Will store the bytes written to out upon successfully generating a message signature
key	pointer to a private ECC key with which to generate the signature

Example

ecc_key key;
WC_WC_RNG rng;
int ret, sigSz;
 
byte sig[512]; // will hold generated signature
sigSz = sizeof(sig);
byte digest[] = { // initialize with message hash };
wc_InitRng(&rng); // initialize rng
wc_ecc_init(&key); // initialize key
wc_ecc_make_key(&rng, 32, &key); // make public/private key pair
ret = wc_ecc_sign_hash(digest, sizeof(digest), sig, &sigSz, &key);
if ( ret != 0 ) {
    // error generating message signature
}

See also

wc_ecc_verify_hash

Sign a message digest in The message digest to sign inlen The length of the digest out [out] The destination for the signature outlen [in/out] The max size and resulting size of the signature key A private ECC key return MP_OKAY if successful

wc_ecc_sign_hash_ex()

int wc_ecc_sign_hash_ex	(	const byte *	in,
		word32	inlen,
		WC_RNG *	rng,
		ecc_key *	key,
		mp_int *	r,
		mp_int *	s )

Sign a message digest.

Returns

MP_OKAY Returned upon successfully generating a signature for the message digest

ECC_BAD_ARG_E Returned if the input key is not a private key, or if the ECC IDX is invalid, or if any of the input parameters evaluate to NULL, or if the output buffer is too small to store the generated signature

RNG_FAILURE_E Returned if the rng cannot successfully generate a satisfactory key

MP_INIT_E may be returned if there is an error while computing the message signature

MP_READ_E may be returned if there is an error while computing the message signature

MP_CMP_E may be returned if there is an error while computing the message signature

MP_INVMOD_E may be returned if there is an error while computing the message signature

MP_EXPTMOD_E may be returned if there is an error while computing the message signature

MP_MOD_E may be returned if there is an error while computing the message signature

MP_MUL_E may be returned if there is an error while computing the message signature

MP_ADD_E may be returned if there is an error while computing the message signature

MP_MULMOD_E may be returned if there is an error while computing the message signature

MP_TO_E may be returned if there is an error while computing the message signature

MP_MEM may be returned if there is an error while computing the message signature

Parameters

in	The message digest to sign.
inlen	The length of the digest.
rng	Pointer to WC_RNG struct.
key	A private ECC key.
r	The destination for r component of the signature.
s	The destination for s component of the signature.

Example

ecc_key key;
WC_WC_WC_RNG rng;
int ret, sigSz;
mp_int r; // destination for r component of signature.
mp_int s; // destination for s component of signature.
 
byte sig[512]; // will hold generated signature
sigSz = sizeof(sig);
byte digest[] = { initialize with message hash };
wc_InitRng(&rng); // initialize rng
wc_ecc_init(&key); // initialize key
wc_ecc_make_key(&rng, 32, &key); // make public/private key pair
ret = wc_ecc_sign_hash_ex(digest, sizeof(digest), &rng, &key, &r, &s);
 
if ( ret != MP_OKAY ) {
    // error generating message signature
}

See also

wc_ecc_verify_hash_ex

Sign a message digest in The message digest to sign inlen The length of the digest key A private ECC key r [out] The destination for r component of the signature s [out] The destination for s component of the signature return MP_OKAY if successful

wc_ecc_size()

WOLFSSL_API int wc_ecc_size

(

ecc_key *

key

)

This function returns the key size of an ecc_key structure in octets.

Returns

Given a valid key, returns the key size in octets

0 Returned if the given key is NULL

Parameters

key	pointer to an ecc_key structure for which to get the key size

Example

int keySz;
ecc_key key;
// initialize key, make key
keySz = wc_ecc_size(&key);
if ( keySz == 0) {
    // error determining key size
}

See also

wc_ecc_make_key

wc_ecc_verify_hash()

WOLFSSL_API int wc_ecc_verify_hash	(	const byte *	sig,
		word32	siglen,
		const byte *	hash,
		word32	hashlen,
		int *	res,
		ecc_key *	key )

This function verifies the ECC signature of a hash to ensure authenticity. It returns the answer through stat, with 1 corresponding to a valid signature, and 0 corresponding to an invalid signature.

Returns

0 Returned upon successfully performing the signature verification. Note: This does not mean that the signature is verified. The authenticity information is stored instead in stat

BAD_FUNC_ARG Returned any of the input parameters evaluate to NULL

MEMORY_E Returned if there is an error allocating memory

MP_INIT_E may be returned if there is an error while computing the message signature

MP_READ_E may be returned if there is an error while computing the message signature

MP_CMP_E may be returned if there is an error while computing the message signature

MP_INVMOD_E may be returned if there is an error while computing the message signature

MP_EXPTMOD_E may be returned if there is an error while computing the message signature

MP_MOD_E may be returned if there is an error while computing the message signature

MP_MUL_E may be returned if there is an error while computing the message signature

MP_ADD_E may be returned if there is an error while computing the message signature

MP_MULMOD_E may be returned if there is an error while computing the message signature

MP_TO_E may be returned if there is an error while computing the message signature

MP_MEM may be returned if there is an error while computing the message signature

Parameters

sig	pointer to the buffer containing the signature to verify
siglen	length of the signature to verify
hash	pointer to the buffer containing the hash of the message verified
hashlen	length of the hash of the message verified
stat	pointer to the result of the verification. 1 indicates the message was successfully verified
key	pointer to a public ECC key with which to verify the signature

Example

ecc_key key;
int ret, verified = 0;
 
byte sig[1024] { initialize with received signature };
byte digest[] = { initialize with message hash };
// initialize key with received public key
ret = wc_ecc_verify_hash(sig, sizeof(sig), digest,sizeof(digest),
&verified, &key);
if ( ret != 0 ) {
    // error performing verification
} else if ( verified == 0 ) {
    // the signature is invalid
}

See also

wc_ecc_sign_hash

wc_ecc_verify_hash_ex

Verify an ECC signature sig The signature to verify siglen The length of the signature (octets) hash The hash (message digest) that was signed hashlen The length of the hash (octets) res Result of signature, 1==valid, 0==invalid key The corresponding public ECC key return MP_OKAY if successful (even if the signature is not valid)