wolfssl/doc/dox_comments/header_files/ecc.h

/*!
    \ingroup ECC

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

    \return 0 Returned on success.
    \return ECC_BAD_ARG_E Returned if rng or key evaluate to NULL
    \return BAD_FUNC_ARG Returned if the specified key size is not in the
    correct range of supported keys
    \return MEMORY_E Returned if there is an error allocating memory while
    computing the ecc key
    \return MP_INIT_E may be returned if there is an error while computing
    the ecc key
    \return MP_READ_E may be returned if there is an error while computing
    the ecc key
    \return MP_CMP_E may be returned if there is an error while computing the
    ecc key
    \return MP_INVMOD_E may be returned if there is an error while computing
    the ecc key
    \return MP_EXPTMOD_E may be returned if there is an error while computing
    the ecc key
    \return MP_MOD_E may be returned if there is an error while computing the
    ecc key
    \return MP_MUL_E may be returned if there is an error while computing the
    ecc key
    \return MP_ADD_E may be returned if there is an error while computing the
    ecc key
    \return MP_MULMOD_E may be returned if there is an error while computing
    the ecc key
    \return MP_TO_E may be returned if there is an error while computing the
    ecc key
    \return MP_MEM may be returned if there is an error while computing the
    ecc key

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

    _Example_
    \code
    ecc_key key;
    wc_ecc_init(&key);
    WC_RNG rng;
    wc_InitRng(&rng);
    wc_ecc_make_key(&rng, 32, &key); // initialize 32 byte ecc key
    \endcode

    \sa wc_ecc_init
    \sa wc_ecc_shared_secret
*/

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

/*!
    \ingroup ECC

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

    \return 0 Returned on success.
    \return ECC_BAD_ARG_E Returned if rng or key evaluate to NULL
    \return BAD_FUNC_ARG Returned if the specified key size is not in the
    correct range of supported keys
    \return MEMORY_E Returned if there is an error allocating memory while
    computing the ecc key
    \return MP_INIT_E may be returned if there is an error while computing
    the ecc key
    \return MP_READ_E may be returned if there is an error while computing
    the ecc key
    \return MP_CMP_E may be returned if there is an error while computing the
    ecc key
    \return MP_INVMOD_E may be returned if there is an error while computing
    the ecc key
    \return MP_EXPTMOD_E may be returned if there is an error while computing
    the ecc key
    \return MP_MOD_E may be returned if there is an error while computing the
    ecc key
    \return MP_MUL_E may be returned if there is an error while computing the
    ecc key
    \return MP_ADD_E may be returned if there is an error while computing the
    ecc key
    \return MP_MULMOD_E may be returned if there is an error while computing
    the ecc key
    \return MP_TO_E may be returned if there is an error while computing the
    ecc key
    \return MP_MEM may be returned if there is an error while computing the
    ecc key

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

    _Example_
    \code
    ecc_key key;
    int ret;
    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
    }

    \endcode

    \sa wc_ecc_make_key
    \sa wc_ecc_get_curve_size_from_id
*/

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

/*!
    \ingroup ECC

    \brief Perform sanity checks on ecc key validity.

    \return MP_OKAY Success, key is OK.
    \return BAD_FUNC_ARG Returns if key is NULL.
    \return ECC_INF_E Returns if wc_ecc_point_is_at_infinity returns 1.

    \param key Pointer to key to check.

    _Example_
    \code
    ecc_key key;
    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
    }
    \endcode

    \sa wc_ecc_point_is_at_infinity
*/

int wc_ecc_check_key(ecc_key* key);

/*!
    \ingroup ECC

    \brief This function frees an ecc_key key after it has been used.


    \param key pointer to the ecc_key structure to free

    _Example_
    \code
    // initialize key and perform ECC operations
    ...
    wc_ecc_key_free(&key);
    \endcode

    \sa wc_ecc_key_new
    \sa wc_ecc_init_ex
*/

void wc_ecc_key_free(ecc_key* key);

/*!
    \ingroup ECC

    \brief 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.

    \return 0 Returned upon successfully generating a shared secret key
    \return BAD_FUNC_ARG Returned if any of the input parameters evaluate to
    NULL
    \return 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
    \return MEMORY_E Returned if there is an error generating a new ecc point
    \return BUFFER_E Returned if the generated shared secret key is too long
    to store in the provided buffer
    \return MP_INIT_E may be returned if there is an error while computing the
    shared key
    \return MP_READ_E may be returned if there is an error while computing the
    shared key
    \return MP_CMP_E may be returned if there is an error while computing the
    shared key
    \return MP_INVMOD_E may be returned if there is an error while computing
    the shared key
    \return MP_EXPTMOD_E may be returned if there is an error while computing
    the shared key
    \return MP_MOD_E may be returned if there is an error while computing the
    shared key
    \return MP_MUL_E may be returned if there is an error while computing the
    shared key
    \return MP_ADD_E may be returned if there is an error while computing the
    shared key
    \return MP_MULMOD_E may be returned if there is an error while computing
    the shared key
    \return MP_TO_E may be returned if there is an error while computing the
    shared key
    \return MP_MEM may be returned if there is an error while computing the
    shared key

    \param private_key pointer to the ecc_key structure containing the local
    private key
    \param public_key pointer to the ecc_key structure containing the received
    public key
    \param out pointer to an output buffer in which to store the generated
    shared secret key
    \param 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_
    \code
    ecc_key priv, pub;
    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
    }
    \endcode

    \sa wc_ecc_init
    \sa wc_ecc_make_key
*/

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

/*!
    \ingroup ECC

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

    \return MP_OKAY Indicates success.
    \return BAD_FUNC_ARG Error returned when any arguments are null.
    \return ECC_BAD_ARG_E Error returned if private_key->type is not
    ECC_PRIVATEKEY or private_key->idx fails to validate.
    \return BUFFER_E Error when outlen is too small.
    \return MEMORY_E Error to create a new point.
    \return MP_VAL possible when an initialization failure occurs.
    \return MP_MEM possible when an initialization failure occurs.

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

    _Example_
    \code
    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
    }
    \endcode

    \sa wc_ecc_verify_hash_ex
*/

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

/*!
    \ingroup ECC

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

    \return 0 Returned upon successfully generating a signature for the
    message digest
    \return 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
    \return ECC_BAD_ARG_E Returned if the input key is not a private key, or
    if the ECC OID is invalid
    \return RNG_FAILURE_E Returned if the rng cannot successfully generate a
    satisfactory key
    \return MP_INIT_E may be returned if there is an error while computing
    the message signature
    \return MP_READ_E may be returned if there is an error while computing
    the message signature
    \return MP_CMP_E may be returned if there is an error while computing the
    message signature
    \return MP_INVMOD_E may be returned if there is an error while computing
    the message signature
    \return MP_EXPTMOD_E may be returned if there is an error while computing
    the message signature
    \return MP_MOD_E may be returned if there is an error while computing the
    message signature
    \return MP_MUL_E may be returned if there is an error while computing the
    message signature
    \return MP_ADD_E may be returned if there is an error while computing the
    message signature
    \return MP_MULMOD_E may be returned if there is an error while computing
    the message signature
    \return MP_TO_E may be returned if there is an error while computing the
    message signature
    \return MP_MEM may be returned if there is an error while computing the
    message signature

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

    _Example_
    \code
    ecc_key key;
    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
    }
    \endcode

    \sa wc_ecc_verify_hash
*/

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

/*!
    \ingroup ECC

    \brief Sign a message digest.

    \return MP_OKAY Returned upon successfully generating a signature for the
    message digest
    \return 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
    \return RNG_FAILURE_E Returned if the rng cannot successfully generate a
    satisfactory key
    \return MP_INIT_E may be returned if there is an error while computing the
    message signature
    \return MP_READ_E may be returned if there is an error while computing the
    message signature
    \return MP_CMP_E may be returned if there is an error while computing the
    message signature
    \return MP_INVMOD_E may be returned if there is an error while computing
    the message signature
    \return MP_EXPTMOD_E may be returned if there is an error while computing
    the message signature
    \return MP_MOD_E may be returned if there is an error while computing the
    message signature
    \return MP_MUL_E may be returned if there is an error while computing the
    message signature
    \return MP_ADD_E may be returned if there is an error while computing the
    message signature
    \return MP_MULMOD_E may be returned if there is an error while computing
    the message signature
    \return MP_TO_E may be returned if there is an error while computing the
    message signature
    \return MP_MEM may be returned if there is an error while computing the
    message signature

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

    _Example_
    \code
    ecc_key key;
    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
    mp_init(&r); // initialize r component
    mp_init(&s); // initialize s component
    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
    }
    \endcode

    \sa wc_ecc_verify_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);

/*!
    \ingroup ECC

    \brief 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.

    \return 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
    \return BAD_FUNC_ARG Returned any of the input parameters evaluate to NULL
    \return MEMORY_E Returned if there is an error allocating memory
    \return MP_INIT_E  may be returned if there is an error while computing
    the message signature
    \return MP_READ_E  may be returned if there is an error while computing
    the message signature
    \return MP_CMP_E  may be returned if there is an error while computing
    the message signature
    \return MP_INVMOD_E  may be returned if there is an error while computing
    the message signature
    \return MP_EXPTMOD_E  may be returned if there is an error while
    computing the message signature
    \return MP_MOD_E  may be returned if there is an error while computing
    the message signature
    \return MP_MUL_E  may be returned if there is an error while computing
    the message signature
    \return MP_ADD_E  may be returned if there is an error while computing
    the message signature
    \return MP_MULMOD_E  may be returned if there is an error while computing
    the message signature
    \return MP_TO_E  may be returned if there is an error while computing the
    message signature
    \return MP_MEM may be returned if there is an error while computing the
    message signature

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

    _Example_
    \code
    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
    }
    \endcode

    \sa wc_ecc_sign_hash
    \sa wc_ecc_verify_hash_ex
*/

int wc_ecc_verify_hash(const byte* sig, word32 siglen, const byte* hash,
                    word32 hashlen, int* stat, ecc_key* key);

/*!
    \ingroup ECC

    \brief Verify an ECC signature.  Result is written to stat.
    1 is valid, 0 is invalid.
    Note: Do not use the return value to test for valid.  Only use stat.

    \return MP_OKAY If successful (even if the signature is not valid)
    \return ECC_BAD_ARG_E Returns if arguments are null or if
    key-idx is invalid.
    \return MEMORY_E Error allocating ints or points.

    \param r The signature R component to verify
    \param s The signature S component to verify
    \param hash The hash (message digest) that was signed
    \param hashlen The length of the hash (octets)
    \param stat Result of signature, 1==valid, 0==invalid
    \param key The corresponding public ECC key

    _Example_
    \code
    mp_int r;
    mp_int s;
    int stat;
    byte hash[] = { Some hash }
    ecc_key key;

    if(wc_ecc_verify_hash_ex(&r, &s, hash, hashlen, &stat, &key) == MP_OKAY)
    {
        // Check stat
    }
    \endcode

    \sa wc_ecc_verify_hash
*/

int wc_ecc_verify_hash_ex(mp_int *r, mp_int *s, const byte* hash,
                          word32 hashlen, int* stat, ecc_key* key);

/*!
    \ingroup ECC

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

    \return 0 Returned upon successfully initializing the ecc_key object
    \return MEMORY_E Returned if there is an error allocating memory

    \param key pointer to the ecc_key object to initialize

    _Example_
    \code
    ecc_key key;
    wc_ecc_init(&key);
    \endcode

    \sa wc_ecc_make_key
    \sa wc_ecc_free
*/

int wc_ecc_init(ecc_key* key);

/*!
    \ingroup ECC

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

    \return 0 Returned upon successfully initializing the ecc_key object
    \return MEMORY_E Returned if there is an error allocating memory

    \param key pointer to the ecc_key object to initialize
    \param heap pointer to a heap identifier
    \param devId ID to use with crypto callbacks or async hardware. Set to INVALID_DEVID (-2) if not used

    _Example_
    \code
    ecc_key key;
    wc_ecc_init_ex(&key, heap, devId);
    \endcode

    \sa wc_ecc_make_key
    \sa wc_ecc_free
    \sa wc_ecc_init
*/

int wc_ecc_init_ex(ecc_key* key, void* heap, int devId);

/*!
    \ingroup ECC

    \brief This function uses a user defined heap and allocates space for the
    key structure.

    \return 0 Returned upon successfully initializing the ecc_key object
    \return MEMORY_E Returned if there is an error allocating memory


    _Example_
    \code
    wc_ecc_key_new(&heap);
    \endcode

    \sa wc_ecc_make_key
    \sa wc_ecc_key_free
    \sa wc_ecc_init
*/

ecc_key* wc_ecc_key_new(void* heap);

/*!
    \ingroup ECC

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

    \return int integer returned indicating wolfSSL error or success status.

    \param key pointer to the ecc_key object to free

    _Example_
    \code
    // initialize key and perform secure exchanges
    ...
    wc_ecc_free(&key);
    \endcode

    \sa wc_ecc_init
*/

int wc_ecc_free(ecc_key* key);

/*!
    \ingroup ECC

    \brief 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. Threaded applications should
    call this function before exiting the thread.

    \return none No returns.

    \param none No parameters.

    _Example_
    \code
    ecc_key key;
    // initialize key and perform secure exchanges
    ...

    wc_ecc_fp_free();
    \endcode

    \sa wc_ecc_free
*/

void wc_ecc_fp_free(void);

/*!
    \ingroup ECC

    \brief Checks if an ECC idx is valid.

    \return 1 Return if valid.
    \return 0 Return if not valid.

    \param n The idx number to check.

    _Example_
    \code
    ecc_key key;
    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
    }
    \endcode

    \sa none
*/

int wc_ecc_is_valid_idx(int n);

/*!
    \ingroup ECC

    \brief Allocate a new ECC point.

    \return p A newly allocated point.
    \return NULL Returns NULL on error.

    \param none No parameters.

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

    \sa wc_ecc_del_point
    \sa wc_ecc_cmp_point
    \sa wc_ecc_copy_point
*/

ecc_point* wc_ecc_new_point(void);

/*!
    \ingroup ECC

    \brief Free an ECC point from memory.

    \return none No returns.

    \param p The point to free.

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

    \sa wc_ecc_new_point
    \sa wc_ecc_cmp_point
    \sa wc_ecc_copy_point
*/

void wc_ecc_del_point(ecc_point* p);

/*!
    \ingroup ECC

    \brief Copy the value of one point to another one.

    \return ECC_BAD_ARG_E Error thrown when p or r is null.
    \return MP_OKAY Point copied successfully
    \return ret Error from internal functions.  Can be...

    \param p The point to copy.
    \param r The created point.

    _Example_
    \code
    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
    }
    \endcode

    \sa wc_ecc_new_point
    \sa wc_ecc_cmp_point
    \sa wc_ecc_del_point
*/

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

/*!
    \ingroup ECC

    \brief Compare the value of a point with another one.

    \return BAD_FUNC_ARG One or both arguments are NULL.
    \return MP_EQ The points are equal.
    \return ret Either MP_LT or MP_GT and signifies that the
    points are not equal.

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

    _Example_
    \code
    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
    }
    \endcode

    \sa wc_ecc_new_point
    \sa wc_ecc_del_point
    \sa wc_ecc_copy_point
*/

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

/*!
    \ingroup ECC

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

    \return 1 p is at infinity.
    \return 0 p is not at infinity.
    \return <0 Error.

    \param p The point to check.

    _Example_
    \code
    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
    }
    \endcode

    \sa wc_ecc_new_point
    \sa wc_ecc_del_point
    \sa wc_ecc_cmp_point
    \sa wc_ecc_copy_point
*/

int wc_ecc_point_is_at_infinity(ecc_point *p);

/*!
    \ingroup ECC

    \brief Perform ECC Fixed Point multiplication.

    \return MP_OKAY Returns on successful operation.
    \return MP_INIT_E Returned if there is an error initializing an integer
    for use with the multiple precision integer (mp_int) library.

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

    _Example_
    \code
    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;
    \endcode

    \sa none
*/

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

/*!
    \ingroup ECC

    \brief 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.

    \return 0 Returned on successfully exporting the ecc_key
    \return 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
    \return ECC_BAD_ARG_E Returned if any of the input parameters are NULL,
    or the key is unsupported (has an invalid index)
    \return 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
    \return MEMORY_E Returned if there is an error allocating memory with
    XMALLOC
    \return MP_INIT_E may be returned if there is an error processing the
    ecc_key
    \return MP_READ_E may be returned if there is an error processing the
    ecc_key
    \return MP_CMP_E may be returned if there is an error processing the
    ecc_key
    \return MP_INVMOD_E may be returned if there is an error processing the
    ecc_key
    \return MP_EXPTMOD_E may be returned if there is an error processing the
    ecc_key
    \return MP_MOD_E may be returned if there is an error processing the
    ecc_key
    \return MP_MUL_E may be returned if there is an error processing the
    ecc_key
    \return MP_ADD_E may be returned if there is an error processing the
    ecc_key
    \return MP_MULMOD_E may be returned if there is an error processing the
    ecc_key
    \return MP_TO_E may be returned if there is an error processing the ecc_key
    \return MP_MEM may be returned if there is an error processing the ecc_key

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

    _Example_
    \code
    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
    }
    \endcode

    \sa wc_ecc_export_x963_ex
    \sa wc_ecc_import_x963
*/

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

/*!
    \ingroup ECC

    \brief 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.

    \return 0 Returned on successfully exporting the ecc_key
    \return NOT_COMPILED_IN Returned if the HAVE_COMP_KEY was not enabled at
    compile time, but the key was requested in compressed format
    \return 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
    \return ECC_BAD_ARG_E Returned if any of the input parameters are NULL, or
    the key is unsupported (has an invalid index)
    \return 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
    \return MEMORY_E Returned if there is an error allocating memory with
    XMALLOC
    \return MP_INIT_E may be returned if there is an error processing the
    ecc_key
    \return MP_READ_E may be returned if there is an error processing the
    ecc_key
    \return MP_CMP_E may be returned if there is an error processing the
    ecc_key
    \return MP_INVMOD_E may be returned if there is an error processing the
    ecc_key
    \return MP_EXPTMOD_E may be returned if there is an error processing
    the ecc_key
    \return MP_MOD_E may be returned if there is an error processing the
    ecc_key
    \return MP_MUL_E may be returned if there is an error processing the
    ecc_key
    \return MP_ADD_E may be returned if there is an error processing the
    ecc_key
    \return MP_MULMOD_E may be returned if there is an error processing
    the ecc_key
    \return MP_TO_E may be returned if there is an error processing the ecc_key
    \return MP_MEM may be returned if there is an error processing the ecc_key

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

    _Example_
    \code
    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
    }
    \endcode

    \sa wc_ecc_export_x963
    \sa wc_ecc_import_x963
*/

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

/*!
    \ingroup ECC

    \brief 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.

    \return 0 Returned on successfully importing the ecc_key
    \return NOT_COMPILED_IN Returned if the HAVE_COMP_KEY was not enabled at
    compile time, but the key is stored in compressed format
    \return 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)
    \return MEMORY_E Returned if there is an error allocating memory
    \return 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
    \return IS_POINT_E Returned if the public key exported is not a point
    on the ECC curve
    \return MP_INIT_E may be returned if there is an error processing the
    ecc_key
    \return MP_READ_E may be returned if there is an error processing the
    ecc_key
    \return MP_CMP_E may be returned if there is an error processing the
    ecc_key
    \return MP_INVMOD_E may be returned if there is an error processing the
    ecc_key
    \return MP_EXPTMOD_E may be returned if there is an error processing the
    ecc_key
    \return MP_MOD_E may be returned if there is an error processing the
    ecc_key
    \return MP_MUL_E may be returned if there is an error processing the
    ecc_key
    \return MP_ADD_E may be returned if there is an error processing the
    ecc_key
    \return MP_MULMOD_E may be returned if there is an error processing the
    ecc_key
    \return MP_TO_E may be returned if there is an error processing the ecc_key
    \return MP_MEM may be returned if there is an error processing the ecc_key

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

    _Example_
    \code
    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
    }
    \endcode

    \sa wc_ecc_export_x963
    \sa wc_ecc_import_private_key
*/

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

/*!
    \ingroup ECC

    \brief This function imports a public/private ECC key pair from a buffer
    containing the raw private key, and a second buffer containing the ANSI
    X9.63 formatted public key. 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.

    \return 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
    \return 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)
    \return MEMORY_E Returned if there is an error allocating memory
    \return 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
    \return IS_POINT_E Returned if the public key exported is not a point
    on the ECC curve
    \return MP_INIT_E may be returned if there is an error processing the
    ecc_key
    \return MP_READ_E may be returned if there is an error processing the
    ecc_key
    \return MP_CMP_E may be returned if there is an error processing the
    ecc_key
    \return MP_INVMOD_E may be returned if there is an error processing
    the ecc_key
    \return MP_EXPTMOD_E may be returned if there is an error processing
    the ecc_key
    \return MP_MOD_E may be returned if there is an error processing the
    ecc_key
    \return MP_MUL_E may be returned if there is an error processing the
    ecc_key
    \return MP_ADD_E may be returned if there is an error processing the
    ecc_key
    \return MP_MULMOD_E may be returned if there is an error processing
    the ecc_key
    \return MP_TO_E may be returned if there is an error processing the ecc_key
    \return MP_MEM may be returned if there is an error processing the ecc_key

    \param priv pointer to the buffer containing the raw private key
    \param privSz size of the private key buffer
    \param pub pointer to the buffer containing the ANSI x9.63 formatted ECC
    public key
    \param pubSz length of the public key input buffer
    \param key pointer to the ecc_key object in which to store the imported
    private/public key pair

    _Example_
    \code
    int ret;
    byte pub[] = { initialize with ANSI X9.63 formatted key };
    byte priv[] = { initialize with the raw private key };

    ecc_key key;
    wc_ecc_init(&key);
    ret = wc_ecc_import_private_key(priv, sizeof(priv), pub, sizeof(pub),
    &key);
    if ( ret != 0) {
    	// error importing key
    }
    \endcode

    \sa wc_ecc_export_x963
    \sa wc_ecc_import_private_key
*/

int wc_ecc_import_private_key(const byte* priv, word32 privSz, const byte* pub,
                           word32 pubSz, ecc_key* key);

/*!
    \ingroup ECC

    \brief 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.

    \return 0 Returned on successfully converting the signature
    \return 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
    \return MP_INIT_E may be returned if there is an error processing
    the ecc_key
    \return MP_READ_E may be returned if there is an error processing
    the ecc_key
    \return MP_CMP_E may be returned if there is an error processing
    the ecc_key
    \return MP_INVMOD_E may be returned if there is an error processing
    the ecc_key
    \return MP_EXPTMOD_E may be returned if there is an error processing
    the ecc_key
    \return MP_MOD_E may be returned if there is an error processing the
    ecc_key
    \return MP_MUL_E may be returned if there is an error processing the
    ecc_key
    \return MP_ADD_E may be returned if there is an error processing the
    ecc_key
    \return MP_MULMOD_E may be returned if there is an error processing
    the ecc_key
    \return MP_TO_E may be returned if there is an error processing the ecc_key
    \return MP_MEM may be returned if there is an error processing the ecc_key

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

    _Example_
    \code
    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
    }
    \endcode

    \sa wc_ecc_sign_hash
    \sa wc_ecc_sig_size
*/

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

/*!
    \ingroup ECC

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

    \return 0 Returned upon successfully importing into the ecc_key structure
    \return ECC_BAD_ARG_E Returned if any of the input values evaluate to NULL
    \return MEMORY_E Returned if there is an error initializing space to
    store the parameters of the ecc_key
    \return ASN_PARSE_E Returned if the input curveName is not defined
    in ecc_sets
    \return MP_INIT_E may be returned if there is an error processing the
    input parameters
    \return MP_READ_E may be returned if there is an error processing the
    input parameters
    \return MP_CMP_E may be returned if there is an error processing the
    input parameters
    \return MP_INVMOD_E may be returned if there is an error processing the
    input parameters
    \return MP_EXPTMOD_E may be returned if there is an error processing the
    input parameters
    \return MP_MOD_E may be returned if there is an error processing the
    input parameters
    \return MP_MUL_E may be returned if there is an error processing the
    input parameters
    \return MP_ADD_E may be returned if there is an error processing the
    input parameters
    \return MP_MULMOD_E may be returned if there is an error processing
    the input parameters
    \return MP_TO_E may be returned if there is an error processing the
    input parameters
    \return MP_MEM may be returned if there is an error processing the
    input parameters

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

    _Example_
    \code
    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
    }
    \endcode

    \sa wc_ecc_import_private_key
*/

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

/*!
    \ingroup ECC

    \brief 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.

    \return 0 Returned upon successfully exporting the private key
    \return ECC_BAD_ARG_E Returned if any of the input values evaluate to NULL
    \return MEMORY_E Returned if there is an error initializing space
    to store the parameters of the ecc_key
    \return ASN_PARSE_E Returned if the input curveName is not defined
    in ecc_sets
    \return MP_INIT_E may be returned if there is an error processing
    the input parameters
    \return MP_READ_E may be returned if there is an error processing the
    input parameters
    \return MP_CMP_E may be returned if there is an error processing the
    input parameters
    \return MP_INVMOD_E may be returned if there is an error processing
    the input parameters
    \return MP_EXPTMOD_E may be returned if there is an error processing
    the input parameters
    \return MP_MOD_E may be returned if there is an error processing the
    input parameters
    \return MP_MUL_E may be returned if there is an error processing the
    input parameters
    \return MP_ADD_E may be returned if there is an error processing the
    input parameters
    \return MP_MULMOD_E may be returned if there is an error processing
    the input parameters
    \return MP_TO_E may be returned if there is an error processing the
    input parameters
    \return MP_MEM may be returned if there is an error processing the
    input parameters

    \param key pointer to an ecc_key structure from which to export the
    private key
    \param out pointer to the buffer in which to store the private key
    \param 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_
    \code
    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
    }
    \endcode

    \sa wc_ecc_import_private_key
*/

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

/*!
    \ingroup ECC

    \brief Export point to der.

    \return 0 Returned on success.
    \return ECC_BAD_ARG_E Returns if curve_idx is less than 0 or
    invalid.  Also returns when
    \return LENGTH_ONLY_E outLen is set but nothing else.
    \return BUFFER_E Returns if outLen is less than 1 + 2 * the curve size.
    \return MEMORY_E Returns if there is a problem allocating memory.

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

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

    \sa wc_ecc_import_point_der
*/

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

/*!
    \ingroup ECC

    \brief Import point from der format.

    \return ECC_BAD_ARG_E Returns if any arguments are null or if
    inLen is even.
    \return MEMORY_E Returns if there is an error initializing
    \return NOT_COMPILED_IN Returned if HAVE_COMP_KEY is not true
    and in is a compressed cert
    \return MP_OKAY Successful operation.

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

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

    \sa wc_ecc_export_point_der
*/

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

/*!
    \ingroup ECC

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

    \return Given a valid key, returns the key size in octets
    \return 0 Returned if the given key is NULL

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

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

    \sa wc_ecc_make_key
*/

int wc_ecc_size(ecc_key* key);

/*!
    \ingroup ECC

    \brief 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.

    \return returns the maximum signature
    size, in octets

    \param key size

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

    \sa wc_ecc_sign_hash
    \sa wc_ecc_sig_size
*/

int wc_ecc_sig_size_calc(int sz);


/*!
    \ingroup ECC

    \brief 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.

    \return Success Given a valid key, returns the maximum signature
    size, in octets
    \return 0 Returned if the given key is NULL

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

    _Example_
    \code
    int sigSz;
    ecc_key key;
    // initialize key, make key

    sigSz = wc_ecc_sig_size(&key);
    if ( sigSz == 0) {
        // error determining sig size
    }
    \endcode

    \sa wc_ecc_sign_hash
    \sa wc_ecc_sig_size_calc
*/

int wc_ecc_sig_size(ecc_key* key);


/*!
    \ingroup ECC

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

    \return Success On successfully generating a new ecEncCtx object,
    returns a pointer to that object
    \return NULL Returned if the function fails to generate a new
    ecEncCtx object

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

    _Example_
    \code
    ecEncCtx* ctx;
    WC_RNG rng;
    wc_InitRng(&rng);
    ctx = wc_ecc_ctx_new(REQ_RESP_CLIENT, &rng);
    if(ctx == NULL) {
        // error generating new ecEncCtx object
    }
    \endcode

    \sa wc_ecc_encrypt
    \sa wc_ecc_encrypt_ex
    \sa wc_ecc_decrypt
*/

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

/*!
    \ingroup ECC

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

    \return none Returns.

    \param ctx pointer to the ecEncCtx object to free

    _Example_
    \code
    ecEncCtx* ctx;
    WC_RNG rng;
    wc_InitRng(&rng);
    ctx = wc_ecc_ctx_new(REQ_RESP_CLIENT, &rng);
    // do secure communication
    ...
    wc_ecc_ctx_free(&ctx);
    \endcode

    \sa wc_ecc_ctx_new
*/

void wc_ecc_ctx_free(ecEncCtx*);

/*!
    \ingroup ECC

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

    \return 0 Returned if the ecEncCtx structure is successfully reset
    \return BAD_FUNC_ARG Returned if either rng or ctx is NULL
    \return RNG_FAILURE_E Returned if there is an error generating a
    new salt for the ECC object

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

    _Example_
    \code
    ecEncCtx* ctx;
    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
    \endcode

    \sa wc_ecc_ctx_new
*/

int wc_ecc_ctx_reset(ecEncCtx* ctx, WC_RNG* rng);  /* reset for use again w/o alloc/free */

/*!
    \ingroup ECC

    \brief This function can optionally be called after
    wc_ecc_ctx_new. It sets the encryption, KDF, and MAC algorithms
    into an ecEncCtx object.

    \return 0 Returned upon successfully setting the information
    for the ecEncCtx object.
    \return BAD_FUNC_ARG Returned if the given ecEncCtx object is
    NULL.

    \param ctx pointer to the ecEncCtx for which to set the info
    \param encAlgo encryption algorithm to use.
    \param kdfAlgo KDF algorithm to use.
    \param macAlgo MAC algorithm to use.

    _Example_
    \code
    ecEncCtx* ctx;
    // initialize ctx
    if(wc_ecc_ctx_set_algo(&ctx, ecAES_128_CTR, ecHKDF_SHA256, ecHMAC_SHA256))) {
	    // error setting info
    }
    \endcode

    \sa wc_ecc_ctx_new
*/

int wc_ecc_ctx_set_algo(ecEncCtx* ctx, byte encAlgo, byte kdfAlgo,
    byte macAlgo);

/*!
    \ingroup ECC

    \brief 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.

    \return Success On success, returns the ecEncCtx salt
    \return 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

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

    _Example_
    \code
    ecEncCtx* ctx;
    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
    }
    \endcode

    \sa wc_ecc_ctx_new
    \sa wc_ecc_ctx_set_peer_salt
    \sa wc_ecc_ctx_set_kdf_salt
*/

const byte* wc_ecc_ctx_get_own_salt(ecEncCtx*);

/*!
    \ingroup ECC

    \brief This function sets the peer salt of an ecEncCtx object.

    \return 0 Returned upon successfully setting the peer salt for the
    ecEncCtx object.
    \return BAD_FUNC_ARG Returned if the given ecEncCtx object is NULL
    or has an invalid protocol, or if the given salt is NULL
    \return 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

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

    _Example_
    \code
    ecEncCtx* cliCtx, srvCtx;
    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);
    \endcode

    \sa wc_ecc_ctx_get_own_salt
    \sa wc_ecc_ctx_set_kdf_salt
*/

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

/*!
    \ingroup ECC

    \brief This function sets the salt pointer and length to use with KDF
    into the ecEncCtx object.

    \return 0 Returned upon successfully setting the salt for the
    ecEncCtx object.
    \return BAD_FUNC_ARG Returned if the given ecEncCtx object is NULL
    or if the given salt is NULL and length is not NULL.

    \param ctx pointer to the ecEncCtx for which to set the salt
    \param salt pointer to salt buffer
    \param len length salt in bytes

    _Example_
    \code
    ecEncCtx* srvCtx;
    WC_RNG rng;
    byte cliSalt[] = { fixed salt data };
    word32 cliSaltLen = (word32)sizeof(cliSalt);
    int ret;

    wc_InitRng(&rng);
    cliCtx = wc_ecc_ctx_new(REQ_RESP_SERVER, &rng);

    ret = wc_ecc_ctx_set_kdf_salt(&cliCtx, cliSalt, cliSaltLen);
    \endcode

    \sa wc_ecc_ctx_get_own_salt
    \sa wc_ecc_ctx_get_peer_salt
*/

int wc_ecc_ctx_set_kdf_salt(ecEncCtx* ctx, const byte* salt, word32 len);

/*!
    \ingroup ECC

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

    \return 0 Returned upon successfully setting the information
    for the ecEncCtx object.
    \return BAD_FUNC_ARG Returned if the given ecEncCtx object is
    NULL, the input info is NULL or it's size is invalid

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

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

    \sa wc_ecc_ctx_new
*/

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

/*!
    \ingroup ECC

    \brief 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.

    \return 0 Returned upon successfully encrypting the input message
    \return BAD_FUNC_ARG Returned if privKey, pubKey, msg, msgSz, out,
    or outSz are NULL, or the ctx object specifies an unsupported
    encryption type
    \return BAD_ENC_STATE_E Returned if the ctx object given is in a
    state that is not appropriate for encryption
    \return BUFFER_E Returned if the supplied output buffer is too
    small to store the encrypted ciphertext
    \return MEMORY_E Returned if there is an error allocating memory
    for the shared secret key

    \param privKey pointer to the ecc_key object containing the
    private key to use for encryption
    \param pubKey pointer to the ecc_key object containing the public
    key of the peer with whom one wishes to communicate
    \param msg pointer to the buffer holding the message to encrypt
    \param msgSz size of the buffer to encrypt
    \param out pointer to the buffer in which to store the encrypted
    ciphertext
    \param 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
    \param ctx Optional: pointer to an ecEncCtx object specifying different
    encryption algorithms to use

    _Example_
    \code
    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
    }
    \endcode

    \sa wc_ecc_encrypt_ex
    \sa wc_ecc_decrypt
*/

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

/*!
    \ingroup ECC

    \brief 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.

    \return 0 Returned upon successfully encrypting the input message
    \return BAD_FUNC_ARG Returned if privKey, pubKey, msg, msgSz, out,
    or outSz are NULL, or the ctx object specifies an unsupported
    encryption type
    \return BAD_ENC_STATE_E Returned if the ctx object given is in a
    state that is not appropriate for encryption
    \return BUFFER_E Returned if the supplied output buffer is too
    small to store the encrypted ciphertext
    \return MEMORY_E Returned if there is an error allocating memory
    for the shared secret key

    \param privKey pointer to the ecc_key object containing the
    private key to use for encryption
    \param pubKey pointer to the ecc_key object containing the public
    key of the peer with whom one wishes to communicate
    \param msg pointer to the buffer holding the message to encrypt
    \param msgSz size of the buffer to encrypt
    \param out pointer to the buffer in which to store the encrypted
    ciphertext
    \param 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
    \param ctx Optional: pointer to an ecEncCtx object specifying different
    encryption algorithms to use
    \param compressed Public key field is to be output in compressed format.

    _Example_
    \code
    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_ex(&cli, &serv, msg, sizeof(msg), out, &outSz, cliCtx,
        1);
    if(ret != 0) {
    	// error encrypting message
    }
    \endcode

    \sa wc_ecc_encrypt
    \sa wc_ecc_decrypt
*/

int wc_ecc_encrypt_ex(ecc_key* privKey, ecc_key* pubKey, const byte* msg,
    word32 msgSz, byte* out, word32* outSz, ecEncCtx* ctx, int compressed);

/*!
    \ingroup ECC

    \brief 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.

    \return 0 Returned upon successfully decrypting the input message
    \return BAD_FUNC_ARG Returned if privKey, pubKey, msg, msgSz, out,
    or outSz are NULL, or the ctx object specifies an unsupported
    encryption type
    \return BAD_ENC_STATE_E Returned if the ctx object given is in
    a state that is not appropriate for decryption
    \return BUFFER_E Returned if the supplied output buffer is too
    small to store the decrypted plaintext
    \return MEMORY_E Returned if there is an error allocating memory
    for the shared secret key

    \param privKey pointer to the ecc_key object containing the private
    key to use for decryption
    \param pubKey pointer to the ecc_key object containing the public
    key of the peer with whom one wishes to communicate
    \param msg pointer to the buffer holding the ciphertext to decrypt
    \param msgSz size of the buffer to decrypt
    \param out pointer to the buffer in which to store the decrypted plaintext
    \param 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
    \param ctx Optional: pointer to an ecEncCtx object specifying
    different decryption algorithms to use

    _Example_
    \code
    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
    }
    \endcode

    \sa wc_ecc_encrypt
    \sa wc_ecc_encrypt_ex
*/

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


/*!
    \ingroup ECC

    \brief Enable ECC support for non-blocking operations. Supported for
        Single Precision (SP) math with the following build options:
            WOLFSSL_SP_NONBLOCK
            WOLFSSL_SP_SMALL
            WOLFSSL_SP_NO_MALLOC
            WC_ECC_NONBLOCK

    \return 0 Returned upon successfully setting the callback context the input message

    \param key pointer to the ecc_key object
    \param ctx pointer to ecc_nb_ctx_t structure with stack data cache for SP

    _Example_
    \code
    int ret;
    ecc_key ecc;
    ecc_nb_ctx_t nb_ctx;

    ret = wc_ecc_init(&ecc);
    if (ret == 0) {
        ret = wc_ecc_set_nonblock(&ecc, &nb_ctx);
        if (ret == 0) {
            do {
                ret = wc_ecc_verify_hash_ex(
                    &r, &s,       // r/s as mp_int
                    hash, hashSz, // computed hash digest
                    &verify_res,  // verification result 1=success
                    &key
                );

                // TODO: Real-time work can be called here
            } while (ret == FP_WOULDBLOCK);
        }
        wc_ecc_free(&key);
    }
    \endcode
*/
int wc_ecc_set_nonblock(ecc_key *key, ecc_nb_ctx_t* ctx);