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EXT_DIAG (Extended diagnostics library). (See Section 2.3, “Licensed Features”.)

Certain UDS/KWP2000 services can be restricted to protect your ECU from having unauthorised changes or having its contents read out over the diagnostic link.

The relevant services can either be completely disallowed, or allowed only if the required seed-key security exchange has been passed successfully. (The options are detailed below.)

Even if flash reprogramming via UDS is allowed, you may wish to disable this facility if run-time circumstances are not appropriate (e.g. vehicle moving or engine running). The 'inhibit_reprogramming' inport allows you to control whether reprogramming is permitted at run time.

None.

You must implement your own security function to use seed-key security; it is not supplied by Pi Innovo, because it will be specific and confidential to you. The function must be written such that it does not depend on any statically allocated variables and does not call any functions, including functions inserted by the compiler for math utilities for example. This is to ensure that it is fully relocatable, which is required for it to run as part of the boot loader in reprogramming mode, as well as in normal application mode.

To add your function to the build, place the C file alongside the model, and then instruct RTW to include it in the build by using the Custom Code... Include list of additional:... Source files option, alongside other model configuration and build options in the Code Generation/Real-Time Workshop section (the exact menu item depends on MATLAB version).

Alternatively, you can compile your C code to make an object (.o) file and specify it in the Libraries option nearby. This is useful if you wish to be cautious with confidentiality by avoiding application-builders needing to have the C source code available.

The function name for the security algorithm and the second empty function that marks the end of it are fixed. If they are missing, a linker error will be reported. A complete example block of code is presented below, in which the "secret" algorithm is to reverse the order of the two seed bytes to form the correct key:

#include "openecu.h"


/*****************************************************************************
 *  Purpose: Called by the library when UDS/KW2000 diagnostic security access
 *           is required.
 *  Returns: Return code to send to tool on error, otherwise zero if OK.
 *  Notes:   Code is copied to nonvolatile memory and must be relocatable. It
 *           must not call any functions (including compiler arithmetic
 *           utilities).
 *****************************************************************************
 */
U8 psc_diag_security_callback
(
    const U8*  pdgf_request_message,      /* The received unpacked request message */
    U16        pdgf_request_message_len,  /* Total byte length of request message  */
    U8*        pdgf_seed_buffer,          /* Place seed here, or access it when computing correct key */
    U8*        pdgf_seed_len,             /* Specify your seed length (in bytes) here (max 8 bytes) */
    U32        pdgf_random                /* Pseudorandom number you may use to generate seed */
)
{

    if (pdgf_request_message_len < 2)
    {
        return 0x13; /* invalid length */
    }

    switch (pdgf_request_message[1])
    {
    case 0x03: /* a requestSeed value we choose to support */
        /* Set up the seed bytes, here using the provided random number */
        pdgf_seed_buffer[0] = (U8) pdgf_random & 0xff;
        pdgf_seed_buffer[1] = (U8) (pdgf_random >> 8);
        *pdgf_seed_len = 2;
        return 0;
        break;
    case 0x04: /* corresponding sendKey value */
        if ((pdgf_request_message_len == 4) &&
            (pdgf_request_message[2] == pdgf_seed_buffer[1]) &&
            (pdgf_request_message[3] == pdgf_seed_buffer[0])   )
        {
            /* security passed -- bytes reversed! */
            return 0;
        }
        else
        {
            return 0x35; /* invalid key */
        }
        break;
    default:
        return 0x12; /* unsupported parameters */
        break;
    }
}

/*****************************************************************************
 *  Purpose: Marks the end of the security function above.
 *  Returns: None.
 *  Notes:   Must be placed immediately after the security function. The
 *           platform uses this to calculate the size of the security function
 *           when relocating it to non-volatile memory for use in
 *           reprogramming mode.
 *****************************************************************************
 */
void psc_diag_security_end
(
    void
)
{
}