cryptocb.h

Functions

	Name
int	wc_CryptoCb_RegisterDevice(int devId, CryptoDevCallbackFunc cb, void * ctx) This function registers a unique device identifier (devID) and callback function for offloading crypto operations to external hardware such as Key Store, Secure Element, HSM, PKCS11 or TPM.
void	wc_CryptoCb_UnRegisterDevice(int devId) This function un_registers a unique device identifier (devID) callback function.
int	wc_CryptoCb_DefaultDevID(void ) This function returns the default device ID for crypto callbacks. This is useful when you want to get the device ID that was set as the default for the library.
void	wc_CryptoCb_SetDeviceFindCb(CryptoDevCallbackFind cb) This function sets a callback for finding crypto devices. The callback is invoked when a device ID needs to be resolved to a device context. This is useful for dynamic device management.
void	wc_CryptoCb_InfoString(wc_CryptoInfo * info) This function converts a wc_CryptoInfo structure to a human-readable string for debugging purposes. The string is printed to stdout and describes the cryptographic operation being performed.

Functions Documentation

function wc_CryptoCb_RegisterDevice

int wc_CryptoCb_RegisterDevice(
    int devId,
    CryptoDevCallbackFunc cb,
    void * ctx
)

This function registers a unique device identifier (devID) and callback function for offloading crypto operations to external hardware such as Key Store, Secure Element, HSM, PKCS11 or TPM.

Parameters:

devId any unique value, not -2 (INVALID_DEVID)
cb a callback function with prototype: typedef int (CryptoDevCallbackFunc)(int devId, wc_CryptoInfo info, void* ctx);

See:

Return:

CRYPTOCB_UNAVAILABLE to fallback to using software crypto
0 for success
negative value for failure

For STSAFE with Crypto Callbacks example see wolfcrypt/src/port/st/stsafe.c and the wolfSSL_STSAFE_CryptoDevCb function.

For TPM based crypto callbacks example see the wolfTPM2_CryptoDevCb function in wolfTPM src/tpm2_wrap.c

Example

#include <wolfssl/wolfcrypt/settings.h>
#include <wolfssl/wolfcrypt/cryptocb.h>
static int myCryptoCb_Func(int devId, wc_CryptoInfo* info, void* ctx)
{
    int ret = CRYPTOCB_UNAVAILABLE;

    if (info->algo_type == WC_ALGO_TYPE_PK) {
    #ifndef NO_RSA
        if (info->pk.type == WC_PK_TYPE_RSA) {
            switch (info->pk.rsa.type) {
                case RSA_PUBLIC_ENCRYPT:
                case RSA_PUBLIC_DECRYPT:
                    // RSA public op
                    ret = wc_RsaFunction(
                        info->pk.rsa.in, info->pk.rsa.inLen,
                        info->pk.rsa.out, info->pk.rsa.outLen,
                        info->pk.rsa.type, info->pk.rsa.key,
                        info->pk.rsa.rng);
                    break;
                case RSA_PRIVATE_ENCRYPT:
                case RSA_PRIVATE_DECRYPT:
                    // RSA private op
                    ret = wc_RsaFunction(
                        info->pk.rsa.in, info->pk.rsa.inLen,
                        info->pk.rsa.out, info->pk.rsa.outLen,
                        info->pk.rsa.type, info->pk.rsa.key,
                        info->pk.rsa.rng);
                    break;
            }
        }
    #endif
    #ifdef HAVE_ECC
        if (info->pk.type == WC_PK_TYPE_ECDSA_SIGN) {
            // ECDSA
            ret = wc_ecc_sign_hash(
                info->pk.eccsign.in, info->pk.eccsign.inlen,
                info->pk.eccsign.out, info->pk.eccsign.outlen,
                info->pk.eccsign.rng, info->pk.eccsign.key);
        }
    #endif
    #ifdef HAVE_ED25519
        if (info->pk.type == WC_PK_TYPE_ED25519_SIGN) {
            // ED25519 sign
            ret = wc_ed25519_sign_msg_ex(
                info->pk.ed25519sign.in, info->pk.ed25519sign.inLen,
                info->pk.ed25519sign.out, info->pk.ed25519sign.outLen,
                info->pk.ed25519sign.key, info->pk.ed25519sign.type,
                info->pk.ed25519sign.context,
                info->pk.ed25519sign.contextLen);
        }
    #endif
    }
    return ret;
}

int devId = 1;
wc_CryptoCb_RegisterDevice(devId, myCryptoCb_Func, &myCtx);
wolfSSL_CTX_SetDevId(ctx, devId);

function wc_CryptoCb_UnRegisterDevice

void wc_CryptoCb_UnRegisterDevice(
    int devId
)

This function un-registers a unique device identifier (devID) callback function.

Parameters:

devId any unique value, not -2 (INVALID_DEVID)

See:

Return: none No returns.

Example

wc_CryptoCb_UnRegisterDevice(devId);
devId = INVALID_DEVID;
wolfSSL_CTX_SetDevId(ctx, devId);

function wc_CryptoCb_DefaultDevID

int wc_CryptoCb_DefaultDevID(
    void 
)

This function returns the default device ID for crypto callbacks. This is useful when you want to get the device ID that was set as the default for the library.

See:

Return: The default device ID, or INVALID_DEVID if no default is set.

Example

int devId = wc_CryptoCb_DefaultDevID();
if (devId != INVALID_DEVID) {
    // default device ID is set
}

function wc_CryptoCb_SetDeviceFindCb

void wc_CryptoCb_SetDeviceFindCb(
    CryptoDevCallbackFind cb
)

This function sets a callback for finding crypto devices. The callback is invoked when a device ID needs to be resolved to a device context. This is useful for dynamic device management.

Parameters:

cb callback function with prototype: typedef void (CryptoDevCallbackFind)(int devId);

See: wc_CryptoCb_RegisterDevice

Return: none No returns.

Example

void* myDeviceFindCb(int devId) {
    // lookup device context by ID
    return deviceContext;
}

wc_CryptoCb_SetDeviceFindCb(myDeviceFindCb);

function wc_CryptoCb_InfoString

void wc_CryptoCb_InfoString(
    wc_CryptoInfo * info
)

This function converts a wc_CryptoInfo structure to a human-readable string for debugging purposes. The string is printed to stdout and describes the cryptographic operation being performed.

Parameters:

info pointer to the wc_CryptoInfo structure to convert

See: wc_CryptoCb_RegisterDevice

Return: none No returns.

Example

int myCryptoCb(int devId, wc_CryptoInfo* info, void* ctx) {
    // print debug info about the operation
    wc_CryptoCb_InfoString(info);

    // handle the operation
    return CRYPTOCB_UNAVAILABLE;
}

Source code


int  wc_CryptoCb_RegisterDevice(int devId, CryptoDevCallbackFunc cb, void* ctx);

void wc_CryptoCb_UnRegisterDevice(int devId);

int wc_CryptoCb_DefaultDevID(void);

void wc_CryptoCb_SetDeviceFindCb(CryptoDevCallbackFind cb);

void wc_CryptoCb_InfoString(wc_CryptoInfo* info);

Updated on 2026-01-05 at 01:19:55 +0000