Encrypted Advertising Data (EAD)

Encrypted Advertising Data (EAD) More...

Macros
#define	BT_EAD_RANDOMIZER_SIZE   5
	Randomizer size in bytes.
#define	BT_EAD_KEY_SIZE   16
	Key size in bytes.
#define	BT_EAD_IV_SIZE   8
	Initialisation Vector size in bytes.
#define	BT_EAD_MIC_SIZE   4
	MIC size in bytes.
#define	BT_EAD_ENCRYPTED_PAYLOAD_SIZE(payload_size)    ((payload_size) + BT_EAD_RANDOMIZER_SIZE + BT_EAD_MIC_SIZE)
	Get the size (in bytes) of the encrypted advertising data for a given payload size in bytes.
#define	BT_EAD_DECRYPTED_PAYLOAD_SIZE(encrypted_payload_size)    ((encrypted_payload_size) - (BT_EAD_RANDOMIZER_SIZE + BT_EAD_MIC_SIZE))
	Get the size (in bytes) of the decrypted payload for a given payload size in bytes.

Functions
int	bt_ead_encrypt (const uint8_t session_key[16], const uint8_t iv[8], const uint8_t *payload, size_t payload_size, uint8_t *encrypted_payload)
	Encrypt and authenticate the given advertising data.
int	bt_ead_decrypt (const uint8_t session_key[16], const uint8_t iv[8], const uint8_t *encrypted_payload, size_t encrypted_payload_size, uint8_t *payload)
	Decrypt and authenticate the given encrypted advertising data.

Detailed Description

Encrypted Advertising Data (EAD)

Macro Definition Documentation

BT_EAD_DECRYPTED_PAYLOAD_SIZE

#define BT_EAD_DECRYPTED_PAYLOAD_SIZE

(

encrypted_payload_size

)

((encrypted_payload_size) - (BT_EAD_RANDOMIZER_SIZE + BT_EAD_MIC_SIZE))

#include <zephyr/bluetooth/ead.h>

Get the size (in bytes) of the decrypted payload for a given payload size in bytes.

BT_EAD_ENCRYPTED_PAYLOAD_SIZE

#define BT_EAD_ENCRYPTED_PAYLOAD_SIZE

(

payload_size

)

((payload_size) + BT_EAD_RANDOMIZER_SIZE + BT_EAD_MIC_SIZE)

#include <zephyr/bluetooth/ead.h>

Get the size (in bytes) of the encrypted advertising data for a given payload size in bytes.

BT_EAD_IV_SIZE

#define BT_EAD_IV_SIZE   8

#include <zephyr/bluetooth/ead.h>

Initialisation Vector size in bytes.

BT_EAD_KEY_SIZE

#define BT_EAD_KEY_SIZE   16

#include <zephyr/bluetooth/ead.h>

Key size in bytes.

BT_EAD_MIC_SIZE

#define BT_EAD_MIC_SIZE   4

#include <zephyr/bluetooth/ead.h>

MIC size in bytes.

BT_EAD_RANDOMIZER_SIZE

#define BT_EAD_RANDOMIZER_SIZE   5

#include <zephyr/bluetooth/ead.h>

Randomizer size in bytes.

Function Documentation

bt_ead_decrypt()

int bt_ead_decrypt	(	const uint8_t	session_key[16],
		const uint8_t	iv[8],
		const uint8_t *	encrypted_payload,
		size_t	encrypted_payload_size,
		uint8_t *	payload
	)

#include <zephyr/bluetooth/ead.h>

Decrypt and authenticate the given encrypted advertising data.

Note

The term advertising structure is used to describe the advertising data with the advertising type and the length of those two.

Parameters

[in]	session_key	Key of 16 bytes used for the encryption.
[in]	iv	Initialisation Vector used to generate the nonce.
[in]	encrypted_payload	Encrypted Advertising Data received. This should only contain the advertising data from the received advertising structure, not the length nor the type.
[in]	encrypted_payload_size	Size of the received advertising data in bytes. Should be equal to the length field of the received advertising structure, minus the size of the type (1 byte).
[out]	payload	Decrypted advertising payload. Use BT_EAD_DECRYPTED_PAYLOAD_SIZE to get the right size.

Return values

0	Data have been correctly decrypted and authenticated.
-EIO	Error occurred during the decryption or the authentication.
-EINVAL	One of the argument is a NULL pointer or encrypted_payload_size is less than BT_EAD_RANDOMIZER_SIZE + BT_EAD_MIC_SIZE.

bt_ead_encrypt()

int bt_ead_encrypt	(	const uint8_t	session_key[16],
		const uint8_t	iv[8],
		const uint8_t *	payload,
		size_t	payload_size,
		uint8_t *	encrypted_payload
	)

#include <zephyr/bluetooth/ead.h>

Encrypt and authenticate the given advertising data.

The resulting data in encrypted_payload will look like that:

• Randomizer is added in the BT_EAD_RANDOMIZER_SIZE first bytes;
• Encrypted payload is added ( payload_size bytes);
• MIC is added in the last BT_EAD_MIC_SIZE bytes.

Attention

The function must be called each time the RPA is updated or the data are modified.

Note

The term advertising structure is used to describe the advertising data with the advertising type and the length of those two.

Parameters

[in]	session_key	Key of BT_EAD_KEY_SIZE bytes used for the encryption.
[in]	iv	Initialisation Vector used to generate the nonce. It must be changed each time the Session Key changes.
[in]	payload	Advertising Data to encrypt. Can be multiple advertising structures that are concatenated.
[in]	payload_size	Size of the Advertising Data to encrypt.
[out]	encrypted_payload	Encrypted Ad Data including the Randomizer and the MIC. Size must be at least BT_EAD_RANDOMIZER_SIZE + payload_size + BT_EAD_MIC_SIZE. Use BT_EAD_ENCRYPTED_PAYLOAD_SIZE to get the right size.

Return values

0	Data have been correctly encrypted and authenticated.
-EIO	Error occurred during the encryption or the authentication.
-EINVAL	One of the argument is a NULL pointer.
-ECANCELED	Error occurred during the random number generation.