IoT-Safe Module

Functions
int	wolfSSL_CTX_iotsafe_enable (WOLFSSL_CTX *ctx)
	This function enables the IoT-Safe support on the given context. More...
int	wolfSSL_iotsafe_on (WOLFSSL *ssl, byte privkey_id, byte ecdh_keypair_slot, byte peer_pubkey_slot, byte peer_cert_slot)
	This function connects the IoT-Safe TLS callbacks to the given SSL session. More...
int	wolfSSL_iotsafe_on_ex (WOLFSSL *ssl, byte *privkey_id, byte *ecdh_keypair_slot, byte *peer_pubkey_slot, byte *peer_cert_slot, word16 id_size)
	This function connects the IoT-Safe TLS callbacks to the given SSL session. This is equivalent to wolfSSL_iotsafe_on except that the IDs for the IoT-SAFE slots can be passed by reference, and the length of the ID fields can be specified via the parameter "id_size". More...
void	wolfIoTSafe_SetCSIM_read_cb (wolfSSL_IOTSafe_CSIM_read_cb rf)
	Associates a read callback for the AT+CSIM commands. This input function is usually associated to a read event of a UART channel communicating with the modem. The read callback associated is global and changes for all the contexts that use IoT-safe support at the same time. More...
void	wolfIoTSafe_SetCSIM_write_cb (wolfSSL_IOTSafe_CSIM_write_cb wf)
	Associates a write callback for the AT+CSIM commands. This output function is usually associated to a write event on a UART channel communicating with the modem. The write callback associated is global and changes for all the contexts that use IoT-safe support at the same time. More...
int	wolfIoTSafe_GetRandom (unsigned char *out, word32 sz)
	Generate a random buffer of given size, using the IoT-Safe function GetRandom. This function is automatically used by the wolfCrypt RNG object. More...
int	wolfIoTSafe_GetCert (uint8_t id, unsigned char *output, unsigned long sz)
	Import a certificate stored in a file on IoT-Safe applet, and store it locally in memory. Works with one-byte file ID field. More...
int	wolfIoTSafe_GetCert_ex (uint8_t *id, uint16_t id_sz, unsigned char *output, unsigned long sz)
	Import a certificate stored in a file on IoT-Safe applet, and store it locally in memory. Equivalent to wolfIoTSafe_GetCert, except that it can be invoked with a file ID of two or more bytes. More...
int	wc_iotsafe_ecc_import_public (ecc_key *key, byte key_id)
	Import an ECC 256-bit public key, stored in the IoT-Safe applet, into an ecc_key object. More...
int	wc_iotsafe_ecc_export_public (ecc_key *key, byte key_id)
	Export an ECC 256-bit public key, from ecc_key object to a writable public-key slot into the IoT-Safe applet. More...
int	wc_iotsafe_ecc_import_public_ex (ecc_key *key, byte *key_id, word16 id_size)
	Export an ECC 256-bit public key, from ecc_key object to a writable public-key slot into the IoT-Safe applet. Equivalent to wc_iotsafe_ecc_import_public, except that it can be invoked with a key ID of two or more bytes. More...
int	wc_iotsafe_ecc_export_private (ecc_key *key, byte key_id)
	Export an ECC 256-bit key, from ecc_key object to a writable private-key slot into the IoT-Safe applet. More...
int	wc_iotsafe_ecc_export_private_ex (ecc_key *key, byte *key_id, word16 id_size)
	Export an ECC 256-bit key, from ecc_key object to a writable private-key slot into the IoT-Safe applet. Equivalent to wc_iotsafe_ecc_export_private, except that it can be invoked with a key ID of two or more bytes. More...
int	wc_iotsafe_ecc_sign_hash (byte *in, word32 inlen, byte *out, word32 *outlen, byte key_id)
	Sign a pre-computed HASH, using a private key previously stored, or pre-provisioned, in the IoT-Safe applet. More...
int	wc_iotsafe_ecc_sign_hash_ex (byte *in, word32 inlen, byte *out, word32 *outlen, byte *key_id, word16 id_size)
	Sign a pre-computed HASH, using a private key previously stored, or pre-provisioned, in the IoT-Safe applet. Equivalent to wc_iotsafe_ecc_sign_hash, except that it can be invoked with a key ID of two or more bytes. More...
int	wc_iotsafe_ecc_verify_hash (byte *sig, word32 siglen, byte *hash, word32 hashlen, int *res, byte key_id)
	Verify an ECC signature against a pre-computed HASH, using a public key previously stored, or pre-provisioned, in the IoT-Safe applet. Result is written to res. 1 is valid, 0 is invalid. Note: Do not use the return value to test for valid. Only use res. More...
int	wc_iotsafe_ecc_verify_hash_ex (byte *sig, word32 siglen, byte *hash, word32 hashlen, int *res, byte *key_id, word16 id_size)
	Verify an ECC signature against a pre-computed HASH, using a public key previously stored, or pre-provisioned, in the IoT-Safe applet. Result is written to res. 1 is valid, 0 is invalid. Note: Do not use the return value to test for valid. Only use res. Equivalent to wc_iotsafe_ecc_verify_hash, except that it can be invoked with a key ID of two or more bytes. More...
int	wc_iotsafe_ecc_gen_k (byte key_id)
	Generate an ECC 256-bit keypair and store it in a (writable) slot into the IoT-Safe applet. More...

Detailed Description

IoT-Safe (IoT-SIM Applet For Secure End-2-End Communication) is a technology that leverage the SIM as robust, scalable and standardized hardware Root of Trust to protect data communication.

IoT-Safe SSL sessions use the SIM as Hardware Security Module, offloading all the crypto public key operations and reducing the attack surface by restricting access to certificate and keys to the SIM.

IoT-Safe support can be enabled on an existing WOLFSSL_CTX context, using wolfSSL_CTX_iotsafe_enable().
Session created within the context can set the parameters for IoT-Safe key and files usage, and enable the public keys callback, with wolfSSL_iotsafe_on().

If compiled in, the module supports IoT-Safe random number generator as source of entropy for wolfCrypt.

Function Documentation

wc_iotsafe_ecc_export_private()

int wc_iotsafe_ecc_export_private	(	ecc_key *	key,
		byte	key_id
	)

Export an ECC 256-bit key, from ecc_key object to a writable private-key slot into the IoT-Safe applet.

Parameters

key	the ecc_key object containing the key to be exported
id	The key id in the IoT-Safe applet where the private key will be stored

Returns

0 upon success

< 0 in case of failure

See also

wc_iotsafe_ecc_export_private_ex

wc_iotsafe_ecc_import_public

wc_iotsafe_ecc_export_public

wc_iotsafe_ecc_export_private_ex()

int wc_iotsafe_ecc_export_private_ex	(	ecc_key *	key,
		byte *	key_id,
		word16	id_size
	)

Export an ECC 256-bit key, from ecc_key object to a writable private-key slot into the IoT-Safe applet. Equivalent to wc_iotsafe_ecc_export_private, except that it can be invoked with a key ID of two or more bytes.

Parameters

key	the ecc_key object containing the key to be exported
id	The pointer to the key id in the IoT-Safe applet where the private key will be stored
id_size	The key id size

Returns

0 upon success

< 0 in case of failure

See also

wc_iotsafe_ecc_export_private

wc_iotsafe_ecc_import_public

wc_iotsafe_ecc_export_public

wc_iotsafe_ecc_export_public()

int wc_iotsafe_ecc_export_public	(	ecc_key *	key,
		byte	key_id
	)

Export an ECC 256-bit public key, from ecc_key object to a writable public-key slot into the IoT-Safe applet.

Parameters

key	the ecc_key object containing the key to be exported
id	The key id in the IoT-Safe applet where the public key will be stored

Returns

0 upon success

< 0 in case of failure

See also

wc_iotsafe_ecc_import_public_ex

wc_iotsafe_ecc_export_private

wc_iotsafe_ecc_gen_k()

int wc_iotsafe_ecc_gen_k

(

byte

key_id

)

Generate an ECC 256-bit keypair and store it in a (writable) slot into the IoT-Safe applet.

Generate an ECC 256-bit keypair and store it in a (writable) slot into the IoT-Safe applet. Equivalent to wc_iotsafe_ecc_gen_k, except that it can be invoked with a key ID of two or more bytes.

Parameters

key_id

The id of the slot where the ECC key pair is stored in the IoT-Safe applet.

Returns

0 upon success

< 0 in case of failure.

See also

wc_iotsafe_ecc_gen_k_ex

wc_iotsafe_ecc_sign_hash

wc_iotsafe_ecc_verify_hash

Parameters

key_id	The id of the slot where the ECC key pair is stored in the IoT-Safe applet.
id_size	The key id size

Returns

0 upon success

< 0 in case of failure.

See also

wc_iotsafe_ecc_gen_k

wc_iotsafe_ecc_sign_hash_ex

wc_iotsafe_ecc_verify_hash_ex

wc_iotsafe_ecc_import_public()

int wc_iotsafe_ecc_import_public	(	ecc_key *	key,
		byte	key_id
	)

Import an ECC 256-bit public key, stored in the IoT-Safe applet, into an ecc_key object.

Parameters

key	the ecc_key object that will contain the key imported from the IoT-Safe applet
id	The key id in the IoT-Safe applet where the public key is stored

Returns

0 upon success

< 0 in case of failure

See also

wc_iotsafe_ecc_export_public

wc_iotsafe_ecc_export_private

wc_iotsafe_ecc_import_public_ex()

int wc_iotsafe_ecc_import_public_ex	(	ecc_key *	key,
		byte *	key_id,
		word16	id_size
	)

Export an ECC 256-bit public key, from ecc_key object to a writable public-key slot into the IoT-Safe applet. Equivalent to wc_iotsafe_ecc_import_public, except that it can be invoked with a key ID of two or more bytes.

Parameters

key	the ecc_key object containing the key to be exported
id	The pointer to the key id in the IoT-Safe applet where the public key will be stored
id_size	The key id size

Returns

0 upon success

< 0 in case of failure

See also

wc_iotsafe_ecc_import_public

wc_iotsafe_ecc_export_private

wc_iotsafe_ecc_sign_hash()

int wc_iotsafe_ecc_sign_hash	(	byte *	in,
		word32	inlen,
		byte *	out,
		word32 *	outlen,
		byte	key_id
	)

Sign a pre-computed HASH, using a private key previously stored, or pre-provisioned, in the IoT-Safe applet.

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
id	key id in the IoT-Safe applet for the slot containing the private key to sign the payload written to out upon successfully generating a message signature

Returns

0 upon success

< 0 in case of failure

See also

wc_iotsafe_ecc_sign_hash_ex

wc_iotsafe_ecc_verify_hash

wc_iotsafe_ecc_gen_k

wc_iotsafe_ecc_sign_hash_ex()

int wc_iotsafe_ecc_sign_hash_ex	(	byte *	in,
		word32	inlen,
		byte *	out,
		word32 *	outlen,
		byte *	key_id,
		word16	id_size
	)

Sign a pre-computed HASH, using a private key previously stored, or pre-provisioned, in the IoT-Safe applet. Equivalent to wc_iotsafe_ecc_sign_hash, except that it can be invoked with a key ID of two or more bytes.

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
id	pointer to a key id in the IoT-Safe applet for the slot containing the private key to sign the payload written to out upon successfully generating a message signature
id_size	The key id size

Returns

0 upon success

< 0 in case of failure

See also

wc_iotsafe_ecc_sign_hash

wc_iotsafe_ecc_verify_hash

wc_iotsafe_ecc_gen_k

wc_iotsafe_ecc_verify_hash()

int wc_iotsafe_ecc_verify_hash	(	byte *	sig,
		word32	siglen,
		byte *	hash,
		word32	hashlen,
		int *	res,
		byte	key_id
	)

Verify an ECC signature against a pre-computed HASH, using a public key previously stored, or pre-provisioned, in the IoT-Safe applet. Result is written to res. 1 is valid, 0 is invalid. Note: Do not use the return value to test for valid. Only use res.

Returns

0 upon success (even if the signature is not valid)

< 0 in case of failure.

Parameters

sig	buffer containing the signature to verify
hash	The hash (message digest) that was signed
hashlen	The length of the hash (octets)
res	Result of signature, 1==valid, 0==invalid
key_id	The id of the slot where the public ECC key is stored in the IoT-Safe applet

See also

wc_iotsafe_ecc_verify_hash_ex

wc_iotsafe_ecc_sign_hash

wc_iotsafe_ecc_gen_k

wc_iotsafe_ecc_verify_hash_ex()

int wc_iotsafe_ecc_verify_hash_ex	(	byte *	sig,
		word32	siglen,
		byte *	hash,
		word32	hashlen,
		int *	res,
		byte *	key_id,
		word16	id_size
	)

Verify an ECC signature against a pre-computed HASH, using a public key previously stored, or pre-provisioned, in the IoT-Safe applet. Result is written to res. 1 is valid, 0 is invalid. Note: Do not use the return value to test for valid. Only use res. Equivalent to wc_iotsafe_ecc_verify_hash, except that it can be invoked with a key ID of two or more bytes.

Returns

0 upon success (even if the signature is not valid)

< 0 in case of failure.

Parameters

sig	buffer containing the signature to verify
hash	The hash (message digest) that was signed
hashlen	The length of the hash (octets)
res	Result of signature, 1==valid, 0==invalid
key_id	The id of the slot where the public ECC key is stored in the IoT-Safe applet
id_size	The key id size

See also

wc_iotsafe_ecc_verify_hash

wc_iotsafe_ecc_sign_hash

wc_iotsafe_ecc_gen_k

wolfIoTSafe_GetCert()

int wolfIoTSafe_GetCert	(	uint8_t	id,
		unsigned char *	output,
		unsigned long	sz
	)

Import a certificate stored in a file on IoT-Safe applet, and store it locally in memory. Works with one-byte file ID field.

Parameters

id	The file id in the IoT-Safe applet where the certificate is stored
output	the buffer where the certificate will be imported
sz	the maximum size available in the buffer output

Returns

the length of the certificate imported

< 0 in case of failure

Example

#define CRT_CLIENT_FILE_ID 0x03
unsigned char cert_buffer[2048];
// Get the certificate into the buffer
cert_buffer_size = wolfIoTSafe_GetCert(CRT_CLIENT_FILE_ID, cert_buffer, 2048);
if (cert_buffer_size < 1) {
    printf("Bad cli cert\n");
    return -1;
}
printf("Loaded Client certificate from IoT-Safe, size = %lu\n", cert_buffer_size);
 
// Use the certificate buffer as identity for the TLS client context
if (wolfSSL_CTX_use_certificate_buffer(cli_ctx, cert_buffer,
            cert_buffer_size, SSL_FILETYPE_ASN1) != SSL_SUCCESS) {
    printf("Cannot load client cert\n");
    return -1;
}
printf("Client certificate successfully imported.\n");

wolfIoTSafe_GetCert_ex()

int wolfIoTSafe_GetCert_ex	(	uint8_t *	id,
		uint16_t	id_sz,
		unsigned char *	output,
		unsigned long	sz
	)

Import a certificate stored in a file on IoT-Safe applet, and store it locally in memory. Equivalent to wolfIoTSafe_GetCert, except that it can be invoked with a file ID of two or more bytes.

Parameters

id	Pointer to the file id in the IoT-Safe applet where the certificate is stored
id_sz	Size of the file id in bytes
output	the buffer where the certificate will be imported
sz	the maximum size available in the buffer output

Returns

the length of the certificate imported

< 0 in case of failure

Example

#define CRT_CLIENT_FILE_ID 0x0302
#define ID_SIZE (sizeof(word16))
unsigned char cert_buffer[2048];
word16 client_file_id = CRT_CLIENT_FILE_ID;
 
 
 
// Get the certificate into the buffer
cert_buffer_size = wolfIoTSafe_GetCert_ex(&client_file_id, ID_SIZE, cert_buffer, 2048);
if (cert_buffer_size < 1) {
    printf("Bad cli cert\n");
    return -1;
}
printf("Loaded Client certificate from IoT-Safe, size = %lu\n", cert_buffer_size);
 
// Use the certificate buffer as identity for the TLS client context
if (wolfSSL_CTX_use_certificate_buffer(cli_ctx, cert_buffer,
            cert_buffer_size, SSL_FILETYPE_ASN1) != SSL_SUCCESS) {
    printf("Cannot load client cert\n");
    return -1;
}
printf("Client certificate successfully imported.\n");

wolfIoTSafe_GetRandom()

int wolfIoTSafe_GetRandom	(	unsigned char *	out,
		word32	sz
	)

Generate a random buffer of given size, using the IoT-Safe function GetRandom. This function is automatically used by the wolfCrypt RNG object.

Parameters

out	the buffer where the random sequence of bytes is stored.
sz	the size of the random sequence to generate, in bytes

Returns

0 upon success

wolfIoTSafe_SetCSIM_read_cb()

void wolfIoTSafe_SetCSIM_read_cb

(

wolfSSL_IOTSafe_CSIM_read_cb

rf

)

Associates a read callback for the AT+CSIM commands. This input function is usually associated to a read event of a UART channel communicating with the modem. The read callback associated is global and changes for all the contexts that use IoT-safe support at the same time.

Parameters

rf	Read callback associated to a UART read event. The callback function takes two arguments (buf, len) and return the number of characters read, up to len. When a newline is encountered, the callback should return the number of characters received so far, including the newline character.

Example

// USART read function, defined elsewhere
int usart_read(char *buf, int len);
 
wolfIoTSafe_SetCSIM_read_cb(usart_read);

See also

wolfIoTSafe_SetCSIM_write_cb

wolfIoTSafe_SetCSIM_write_cb()

void wolfIoTSafe_SetCSIM_write_cb

(

wolfSSL_IOTSafe_CSIM_write_cb

wf

)

Associates a write callback for the AT+CSIM commands. This output function is usually associated to a write event on a UART channel communicating with the modem. The write callback associated is global and changes for all the contexts that use IoT-safe support at the same time.

Parameters

rf	Write callback associated to a UART write event. The callback function takes two arguments (buf, len) and return the number of characters written, up to len.

Example

// USART write function, defined elsewhere
int usart_write(const char *buf, int len);
wolfIoTSafe_SetCSIM_write_cb(usart_write);

See also

wolfIoTSafe_SetCSIM_read_cb

wolfSSL_CTX_iotsafe_enable()

int wolfSSL_CTX_iotsafe_enable

(

WOLFSSL_CTX *

ctx

)

This function enables the IoT-Safe support on the given context.

Parameters

ctx	pointer to the WOLFSSL_CTX object on which the IoT-safe support must be enabled

Returns

0 on success

WC_HW_E on hardware error

Example

WOLFSSL_CTX *ctx;
ctx = wolfSSL_CTX_new(wolfTLSv1_2_client_method());
if (!ctx)
    return NULL;
wolfSSL_CTX_iotsafe_enable(ctx);

See also

wolfSSL_iotsafe_on

wolfIoTSafe_SetCSIM_read_cb

wolfIoTSafe_SetCSIM_write_cb

wolfSSL_iotsafe_on()

int wolfSSL_iotsafe_on	(	WOLFSSL *	ssl,
		byte	privkey_id,
		byte	ecdh_keypair_slot,
		byte	peer_pubkey_slot,
		byte	peer_cert_slot
	)

This function connects the IoT-Safe TLS callbacks to the given SSL session.

This should be called to connect a SSL session to IoT-Safe applet when the ID of the slots are one-byte long. If IoT-SAFE slots have an ID of two or more bytes, wolfSSL_iotsafe_on_ex() should be used instead.

Parameters

ssl	pointer to the WOLFSSL object where the callbacks will be enabled
privkey_id	id of the iot-safe applet slot containing the private key for the host
ecdh_keypair_slot	id of the iot-safe applet slot to store the ECDH keypair
peer_pubkey_slot	id of the iot-safe applet slot to store the other endpoint's public key for ECDH
peer_cert_slot	id of the iot-safe applet slot to store the other endpoint's public key for verification

Returns

0 upon success

NOT_COMPILED_IN if HAVE_PK_CALLBACKS is disabled

BAD_FUNC_ARG if the ssl pointer is invalid

Example

// Define key ids for IoT-Safe
#define PRIVKEY_ID 0x02
#define ECDH_KEYPAIR_ID 0x03
#define PEER_PUBKEY_ID 0x04
#define PEER_CERT_ID 0x05
// Create new ssl session
WOLFSSL *ssl;
ssl = wolfSSL_new(ctx);
if (!ssl)
    return NULL;
// Enable IoT-Safe and associate key slots
ret = wolfSSL_CTX_iotsafe_enable(ctx);
if (ret == 0) {
    ret = wolfSSL_iotsafe_on(ssl, PRIVKEY_ID, ECDH_KEYPAIR_ID, PEER_PUBKEY_ID, PEER_CERT_ID);
}

See also

wolfSSL_iotsafe_on_ex

wolfSSL_CTX_iotsafe_enable

wolfSSL_iotsafe_on_ex()

int wolfSSL_iotsafe_on_ex	(	WOLFSSL *	ssl,
		byte *	privkey_id,
		byte *	ecdh_keypair_slot,
		byte *	peer_pubkey_slot,
		byte *	peer_cert_slot,
		word16	id_size
	)

This function connects the IoT-Safe TLS callbacks to the given SSL session. This is equivalent to wolfSSL_iotsafe_on except that the IDs for the IoT-SAFE slots can be passed by reference, and the length of the ID fields can be specified via the parameter "id_size".

Parameters

ssl	pointer to the WOLFSSL object where the callbacks will be enabled
privkey_id	pointer to the id of the iot-safe applet slot containing the private key for the host
ecdh_keypair_slot	pointer to the id of the iot-safe applet slot to store the ECDH keypair
peer_pubkey_slot	pointer to the of id the iot-safe applet slot to store the other endpoint's public key for ECDH
peer_cert_slot	pointer to the id of the iot-safe applet slot to store the other endpoint's public key for verification
id_size	size of each slot ID

Returns

0 upon success

NOT_COMPILED_IN if HAVE_PK_CALLBACKS is disabled

BAD_FUNC_ARG if the ssl pointer is invalid

Example

// Define key ids for IoT-Safe (16 bit, little endian)
#define PRIVKEY_ID 0x0201
#define ECDH_KEYPAIR_ID 0x0301
#define PEER_PUBKEY_ID 0x0401
#define PEER_CERT_ID 0x0501
#define ID_SIZE (sizeof(word16))
 
word16 privkey = PRIVKEY_ID,
         ecdh_keypair = ECDH_KEYPAIR_ID,
         peer_pubkey = PEER_PUBKEY_ID,
         peer_cert = PEER_CERT_ID;
 
 
 
// Create new ssl session
WOLFSSL *ssl;
ssl = wolfSSL_new(ctx);
if (!ssl)
    return NULL;
// Enable IoT-Safe and associate key slots
ret = wolfSSL_CTX_iotsafe_enable(ctx);
if (ret == 0) {
    ret = wolfSSL_CTX_iotsafe_on_ex(ssl, &privkey, &ecdh_keypair, &peer_pubkey, &peer_cert, ID_SIZE);
}

See also

wolfSSL_iotsafe_on

wolfSSL_CTX_iotsafe_enable