Functions
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_typeA hash type from the “enum wc_HashType” such as “WC_HASH_TYPE_SHA256”.
sig_typeA signature type enum value such as WC_SIGNATURE_TYPE_ECC or WC_SIGNATURE_TYPE_RSA.
dataPointer to buffer containing the data to hash.
data_lenLength of the data buffer.
sigPointer to buffer to output signature.
sig_lenLength of the signature output buffer.
keyPointer to a key structure such as ecc_key or RsaKey.
key_lenSize of the key structure.
rngPointer 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
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_typeA signature type enum value such as WC_SIGNATURE_TYPE_ECC or WC_SIGNATURE_TYPE_RSA.
keyPointer to a key structure such as ecc_key or RsaKey.
key_lenSize 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_typeA hash type from the “enum wc_HashType” such as “WC_HASH_TYPE_SHA256”.
sig_typeA signature type enum value such as WC_SIGNATURE_TYPE_ECC or WC_SIGNATURE_TYPE_RSA.
dataPointer to buffer containing the data to hash.
data_lenLength of the data buffer.
sigPointer to buffer to output signature.
sig_lenLength of the signature output buffer.
keyPointer to a key structure such as ecc_key or RsaKey.
key_lenSize 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
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