Signature API

Functions
WOLFSSL_API int	wc_SignatureGetSize (enum wc_SignatureType sig_type, const void *key, word32 key_len)
	This function returns the maximum size of the resulting signature. More...
WOLFSSL_API int	wc_SignatureVerify (enum wc_HashType hash_type, enum wc_SignatureType sig_type, const byte *data, word32 data_len, const byte *sig, word32 sig_len, const void *key, word32 key_len)
	This function validates a signature by hashing the data and using the resulting hash and key to verify the signature. More...
WOLFSSL_API int	wc_SignatureGenerate (enum wc_HashType hash_type, enum wc_SignatureType sig_type, const byte *data, word32 data_len, byte *sig, word32 *sig_len, const void *key, word32 key_len, WC_RNG *rng)
	This function generates a signature from the data using a key. It first creates a hash of the data then signs the hash using the key. More...

Detailed Description

Function Documentation

wc_SignatureGenerate()

WOLFSSL_API int wc_SignatureGenerate	(	enum wc_HashType	hash_type,
		enum wc_SignatureType	sig_type,
		const byte *	data,
		word32	data_len,
		byte *	sig,
		word32 *	sig_len,
		const void *	key,
		word32	key_len,
		WC_RNG *	rng
	)

This function generates a signature from the data using a key. It first creates a hash of the data then signs the hash using the key.

Returns

0 Success

SIG_TYPE_E -231, signature type not enabled/ available

BAD_FUNC_ARG -173, bad function argument provided

BUFFER_E -132, output buffer too small or input too large.

Parameters

hash_type	A hash type from the “enum wc_HashType” such as “WC_HASH_TYPE_SHA256”.
sig_type	A signature type enum value such as WC_SIGNATURE_TYPE_ECC or WC_SIGNATURE_TYPE_RSA.
data	Pointer to buffer containing the data to hash.
data_len	Length of the data buffer.
sig	Pointer to buffer to output signature.
sig_len	Length of the signature output buffer.
key	Pointer to a key structure such as ecc_key or RsaKey.
key_len	Size of the key structure.
rng	Pointer to an initialized RNG structure.

Example

int ret;
WC_RNG rng;
ecc_key eccKey;

wc_InitRng(&rng);
wc_ecc_init(&eccKey);

// Generate key
ret = wc_ecc_make_key(&rng, 32, &eccKey);

// Get signature length and allocate buffer
sigLen = wc_SignatureGetSize(sig_type, &eccKey, sizeof(eccKey));
sigBuf = malloc(sigLen);

// Perform signature verification using public key
ret = wc_SignatureGenerate(
    WC_HASH_TYPE_SHA256, WC_SIGNATURE_TYPE_ECC,
    fileBuf, fileLen,
    sigBuf, &sigLen,
    &eccKey, sizeof(eccKey),
    &rng);
printf("Signature Generation: %s
(%d)\n", (ret == 0) ? "Pass" : "Fail", ret);

free(sigBuf);
wc_ecc_free(&eccKey);
wc_FreeRng(&rng);

See also

wc_SignatureGetSize

wc_SignatureVerify

wc_SignatureGetSize()

WOLFSSL_API int wc_SignatureGetSize	(	enum wc_SignatureType	sig_type,
		const void *	key,
		word32	key_len
	)

This function returns the maximum size of the resulting signature.

Returns

Returns SIG_TYPE_E if sig_type is not supported. Returns BAD_FUNC_ARG if sig_type was invalid. A positive return value indicates the maximum size of a signature.

Parameters

sig_type	A signature type enum value such as WC_SIGNATURE_TYPE_ECC or WC_SIGNATURE_TYPE_RSA.
key	Pointer to a key structure such as ecc_key or RsaKey.
key_len	Size of the key structure.

Example

// Get signature length
enum wc_SignatureType sig_type = WC_SIGNATURE_TYPE_ECC;
ecc_key eccKey;
word32 sigLen;
wc_ecc_init(&eccKey);
sigLen = wc_SignatureGetSize(sig_type, &eccKey, sizeof(eccKey));
if (sigLen > 0) {
    // Success
}

See also

wc_HashGetDigestSize

wc_SignatureGenerate

wc_SignatureVerify

wc_SignatureVerify()

WOLFSSL_API int wc_SignatureVerify	(	enum wc_HashType	hash_type,
		enum wc_SignatureType	sig_type,
		const byte *	data,
		word32	data_len,
		const byte *	sig,
		word32	sig_len,
		const void *	key,
		word32	key_len
	)

This function validates a signature by hashing the data and using the resulting hash and key to verify the signature.

Returns

0 Success

SIG_TYPE_E -231, signature type not enabled/ available

BAD_FUNC_ARG -173, bad function argument provided

BUFFER_E -132, output buffer too small or input too large.

Parameters

hash_type	A hash type from the “enum wc_HashType” such as “WC_HASH_TYPE_SHA256”.
sig_type	A signature type enum value such as WC_SIGNATURE_TYPE_ECC or WC_SIGNATURE_TYPE_RSA.
data	Pointer to buffer containing the data to hash.
data_len	Length of the data buffer.
sig	Pointer to buffer to output signature.
sig_len	Length of the signature output buffer.
key	Pointer to a key structure such as ecc_key or RsaKey.
key_len	Size of the key structure.

Example

int ret;
ecc_key eccKey;

// Import the public key
wc_ecc_init(&eccKey);
ret = wc_ecc_import_x963(eccPubKeyBuf, eccPubKeyLen, &eccKey);
// Perform signature verification using public key
ret = wc_SignatureVerify(
WC_HASH_TYPE_SHA256, WC_SIGNATURE_TYPE_ECC,
fileBuf, fileLen,
sigBuf, sigLen,
&eccKey, sizeof(eccKey));
printf("Signature Verification: %s
(%d)\n", (ret == 0) ? "Pass" : "Fail", ret);
wc_ecc_free(&eccKey);

See also

wc_SignatureGetSize

wc_SignatureGenerate