Skip to content

Algorithms - ECC

Functions

Name
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.
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.
int wc_ecc_check_key(ecc_key * key)
Perform sanity checks on ecc key validity.
void wc_ecc_key_free(ecc_key * key)
This function frees an ecc_key key after it has been used.
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.
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.
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.
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.
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.
int wc_ecc_verify_hash_ex(mp_int * r, mp_int * s, const byte * hash, word32 hashlen, int * stat, ecc_key * key)
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.
int wc_ecc_init(ecc_key * key)
This function initializes an ecc_key object for future use with message verification or key negotiation.
int wc_ecc_init_ex(ecc_key * key, void * heap, int devId)
This function initializes an ecc_key object for future use with message verification or key negotiation.
ecc_key * wc_ecc_key_new(void * heap)
This function uses a user defined heap and allocates space for the key structure.
int wc_ecc_free(ecc_key * key)
This function frees an ecc_key object after it has been used.
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. Threaded applications should call this function before exiting the thread.
int wc_ecc_is_valid_idx(int n)
Checks if an ECC idx is valid.
ecc_point * wc_ecc_new_point(void )
Allocate a new ECC point.
void wc_ecc_del_point(ecc_point * p)
Free an ECC point from memory.
int wc_ecc_copy_point(ecc_point * p, ecc_point * r)
Copy the value of one point to another one.
int wc_ecc_cmp_point(ecc_point * a, ecc_point * b)
Compare the value of a point with another one.
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.
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.
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.
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.
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.
int wc_ecc_import_private_key(const byte * priv, word32 privSz, const byte * pub, word32 pubSz, ecc_key * key)
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.
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.
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.
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.
int wc_ecc_export_point_der(const int curve_idx, ecc_point * point, byte * out, word32 * outLen)
Export point to der.
int wc_ecc_import_point_der(byte * in, word32 inLen, const int curve_idx, ecc_point * point)
Import point from der format.
int wc_ecc_size(ecc_key * key)
This function returns the key size of an ecc_key structure in octets.
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.
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.
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.
void wc_ecc_ctx_free(ecEncCtx * )
This function frees the ecEncCtx object used for encrypting and decrypting messages.
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.
int wc_ecc_ctx_set_algo(ecEncCtx * ctx, byte encAlgo, byte kdfAlgo, byte macAlgo)
This function can optionally be called after wc_ecc_ctx_new. It sets the encryption, KDF, and MAC algorithms into an ecEncCtx object.
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.
int wc_ecc_ctx_set_peer_salt(ecEncCtx * ctx, const byte * salt)
This function sets the peer salt of an ecEncCtx object.
int wc_ecc_ctx_set_kdf_salt(ecEncCtx * ctx, const byte * salt, word32 len)
This function sets the salt pointer and length to use with KDF into the ecEncCtx object.
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.
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.
int wc_ecc_encrypt_ex(ecc_key * privKey, ecc_key * pubKey, const byte * msg, word32 msgSz, byte * out, word32 * outSz, ecEncCtx * ctx, int compressed)
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.
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.
int wc_ecc_set_nonblock(ecc_key * key, ecc_nb_ctx_t * ctx)
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.

Functions Documentation

function wc_ecc_make_key

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.

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

See:

Return:

  • 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

Example

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

function wc_ecc_make_key_ex

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.

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

See:

Return:

  • 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

Example

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
}

function wc_ecc_check_key

int wc_ecc_check_key(
    ecc_key * key
)

Perform sanity checks on ecc key validity.

Parameters:

  • key Pointer to key to check.

See: wc_ecc_point_is_at_infinity

Return:

  • 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.

Example

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
}

function wc_ecc_key_free

void wc_ecc_key_free(
    ecc_key * key
)

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

Parameters:

  • key pointer to the ecc_key structure to free

See:

Example

// initialize key and perform ECC operations
...
wc_ecc_key_free(&key);

function wc_ecc_shared_secret

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.

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

See:

Return:

  • 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

Example

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
}

function wc_ecc_shared_secret_ex

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.

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.

See: wc_ecc_verify_hash_ex

Return:

  • 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.

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
}

function wc_ecc_sign_hash

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.

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

See: wc_ecc_verify_hash

Return:

  • 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

Example

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
}

function 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.

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.

See: wc_ecc_verify_hash_ex

Return:

  • 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

Example

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
}

function wc_ecc_verify_hash

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.

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

See:

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
  • 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

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
}

function wc_ecc_verify_hash_ex

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

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.

Parameters:

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

See: wc_ecc_verify_hash

Return:

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

Example

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
}

function wc_ecc_init

int wc_ecc_init(
    ecc_key * key
)

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

Parameters:

  • key pointer to the ecc_key object to initialize

See:

Return:

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

Example

ecc_key key;
wc_ecc_init(&key);

function wc_ecc_init_ex

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

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

Parameters:

  • key pointer to the ecc_key object to initialize
  • devId ID to use with async hardware
  • heap pointer to a heap identifier

See:

Return:

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

Example

ecc_key key;
wc_ecc_init_ex(&key, heap, devId);

function wc_ecc_key_new

ecc_key * wc_ecc_key_new(
    void * heap
)

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

See:

Return:

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

Example

wc_ecc_key_new(&heap);

function wc_ecc_free

int wc_ecc_free(
    ecc_key * key
)

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

Parameters:

  • key pointer to the ecc_key object to free

See: wc_ecc_init

Return: int integer returned indicating wolfSSL error or success status.

Example

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

function wc_ecc_fp_free

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

Parameters:

  • none No parameters.

See: wc_ecc_free

Return: none No returns.

Example

ecc_key key;
// initialize key and perform secure exchanges
...

wc_ecc_fp_free();

function wc_ecc_is_valid_idx

int wc_ecc_is_valid_idx(
    int n
)

Checks if an ECC idx is valid.

Parameters:

  • n The idx number to check.

See: none

Return:

  • 1 Return if valid.
  • 0 Return if not valid.

Example

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
}

function wc_ecc_new_point

ecc_point * wc_ecc_new_point(
    void 
)

Allocate a new ECC point.

Parameters:

  • none No parameters.

See:

Return:

  • p A newly allocated point.
  • NULL Returns NULL on error.

Example

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

function wc_ecc_del_point

void wc_ecc_del_point(
    ecc_point * p
)

Free an ECC point from memory.

Parameters:

  • p The point to free.

See:

Return: none No returns.

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);

function wc_ecc_copy_point

int wc_ecc_copy_point(
    ecc_point * p,
    ecc_point * r
)

Copy the value of one point to another one.

Parameters:

  • p The point to copy.
  • r The created point.

See:

Return:

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

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
}

function wc_ecc_cmp_point

int wc_ecc_cmp_point(
    ecc_point * a,
    ecc_point * b
)

Compare the value of a point with another one.

Parameters:

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

See:

Return:

  • 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.

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
}

function wc_ecc_point_is_at_infinity

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.

Parameters:

  • p The point to check.

See:

Return:

  • 1 p is at infinity.
  • 0 p is not at infinity.
  • <0 Error.

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
}

function wc_ecc_mulmod

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.

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.

See: none

Return:

  • 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.

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;

function wc_ecc_export_x963

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.

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

See:

Return:

  • 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

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
}

function wc_ecc_export_x963_ex

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.

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

See:

Return:

  • 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

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
}

function wc_ecc_import_x963

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.

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

See:

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
  • 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

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
}

function wc_ecc_import_private_key

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

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.

Parameters:

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

See:

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
  • 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

Example

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
}

function wc_ecc_rs_to_sig

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.

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

See:

Return:

  • 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

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
}

function wc_ecc_import_raw

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.

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

See: wc_ecc_import_private_key

Return:

  • 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

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
}

function wc_ecc_export_private_only

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.

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

See: wc_ecc_import_private_key

Return:

  • 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

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
}

function wc_ecc_export_point_der

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

Export point to der.

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

See: wc_ecc_import_point_der

Return:

  • 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.

Example

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

function wc_ecc_import_point_der

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

Import point from der format.

Parameters:

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

See: wc_ecc_export_point_der

Return:

  • 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.

Example

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

function wc_ecc_size

int wc_ecc_size(
    ecc_key * key
)

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

Parameters:

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

See: wc_ecc_make_key

Return:

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

Example

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

function wc_ecc_sig_size_calc

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.

Parameters:

  • key size

See:

Return: returns the maximum signature size, in octets

Example

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

function wc_ecc_sig_size

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.

Parameters:

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

See:

Return:

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

Example

int sigSz;
ecc_key key;
// initialize key, make key

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

function wc_ecc_ctx_new

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.

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

See:

Return:

  • 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

Example

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
}

function wc_ecc_ctx_free

void wc_ecc_ctx_free(
    ecEncCtx * 
)

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

Parameters:

  • ctx pointer to the ecEncCtx object to free

See: wc_ecc_ctx_new

Return: none Returns.

Example

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);

function wc_ecc_ctx_reset

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.

Parameters:

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

See: wc_ecc_ctx_new

Return:

  • 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

Example

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

function wc_ecc_ctx_set_algo

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

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

Parameters:

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

See: wc_ecc_ctx_new

Return:

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

Example

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

function wc_ecc_ctx_get_own_salt

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.

Parameters:

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

See:

Return:

  • 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

Example

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
}

function wc_ecc_ctx_set_peer_salt

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

This function sets the peer salt of an ecEncCtx object.

Parameters:

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

See:

Return:

  • 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

Example

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);

function wc_ecc_ctx_set_kdf_salt

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

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

Parameters:

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

See:

Return:

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

Example

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);

function wc_ecc_ctx_set_info

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.

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

See: wc_ecc_ctx_new

Return:

  • 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

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
}

function wc_ecc_encrypt

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.

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

See:

Return:

  • 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

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
}

function wc_ecc_encrypt_ex

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

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.

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
  • compressed Public key field is to be output in compressed format.

See:

Return:

  • 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

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

function wc_ecc_decrypt

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.

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

See:

Return:

  • 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

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
}

function wc_ecc_set_nonblock

int wc_ecc_set_nonblock(
    ecc_key * key,
    ecc_nb_ctx_t * ctx
)

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.

Parameters:

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

Return: 0 Returned upon successfully setting the callback context the input message

Example

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);
}

Updated on 2022-12-09 at 08:30:47 +0000