Some manufacturers may enable CCP seed/key security for certain CCP operations, particularly in software which is released to production. Configuring this in the application is discussed in Section 5.1.21, “CCP seed/key security (pcp_CCPSecurity)”.

CCP seed/key security requires that a Win32 DLL is built containing a function which will generate a key value from a seed value supplied by the ECU. The name and function prototype are specified in the ASAP1A and ASAP2 standards to be

BOOL SEEDKEYAPI ASAP1A_CCP_ComputeKeyFromSeed(BYTE           *Seed,
                                              unsigned short  SizeSeed,
                                              BYTE           *Key,
                                              unsigned short  MaxSizeKey,
                                              unsigned short *SizeKey);
// Seed: Pointer to seed data
// SizeSeed:Size of seed data (length of ‚Seed‘)
// Key: Pointer, where DLL should insert the calculated key data.
// MaxSizeKey: Maximum size of ‚Key‘.
// SizeKey: Should be set from DLL corresponding to the number of data
// inserted to ‚Key‘ (at most ‚MaxSizeKey‘)
// Result: The value FALSE (= 0) indicates that the key could not be
// calculated from seed data (e.g. ‚MaxSizeKey‘ is too small).
// TRUE (!= 0) indicates success of key calculation.

Vision allows differently-named functions to be used, which may be convenient in cases such as supplying a single DLL containing multiple different seed/key algorithms for different strategies). Note though that this may make seed/key DLLs for Vision incompatibile with other calibrations tools which require a single function per DLL with a fixed name per the ASAP standard.