SNIP_CLASSIC_CSM_SECTION_8_3_8_5_Key_Generation_Interface

8.3.8.5 Key Generation Interface The key generation interface is used to generate a key into the key element CRYPTO_ KE_KEYGENERATE_KEY according to the algorithm defined in the key element CRYPTO_KE_KEYGENERATE_ALGORITHM. The key will be generated from the random value that is located in the key element CRYPTO_KE_KEYGENERATE_SEED. The random value can be generated, for example, with the function Csm_RandomGenerate and must be stored in CRYPTO_KE_KEYGENERATE_SEED before the key generation is triggered. It is important to check the quality of the randomness and its entropy of the seed, which depends on the used hardware, and software of a stack. The randomness has a major impact on the quality of the generated key material. The key element with the id=CRYPTO_KE_KEYGENERATE_ALGORITHM contains a type from Crypto_AlgorithmFamilyType, e.g. CRYPTO_ALGOFAM_AES, CRYPTO_ALGOFAM_RSA or CRYPTO_ALGOFAM_ED25519, that allows to generate an adequate key. As a counter example, the algorithm family type CRYPTO_ALGOFAM_SHA2_256 is not adequate because it provides no hint what key shall be generated. For the key element CRYPTO_KE_KEYGENERATE_KEY the key element configuration item CryptoKeyElement/CryptoKeyElementFormat indicates the format of the generated key. [SWS_Csm_01051] Definition of API function Csm_RandomSeed ⌈ Service Name Csm_RandomSeed Syntax Std_ReturnType Csm_RandomSeed ( uint32 keyId, const uint8* seedPtr, uint32 seedLength ) Service ID [hex] 0x69 Sync/Async Synchronous Reentrancy Reentrant but not for same keyId keyId Holds the identifier of the key for which a new seed shall be generated. seedPtr Holds a pointer to the memory location which contains the data to feed the seed. Parameters (in) seedLength Contains the length of the seed in bytes. Parameters (inout) None Parameters (out) None Return value Std_ReturnType E_OK: Request successful E_NOT_OK: Request failed CRYPTO_E_BUSY: Request failed, Crypto Driver Object is busy CRYPTO_E_KEY_NOT_VALID: Request failed, the key’s state is "invalid" CRYPTO_E_KEY_EMPTY: Request failed because of uninitialized source key element Description Feeds the key element CRYPTO_KE_RANDOM_SEED with a random seed. Available via Csm.h ⌋ [SWS_Csm_01052] Upstream requirements: SRS_CryptoStack_00019 ⌈If no errors are detected by Csm, the service Csm_RandomSeed shall call CryIf_ RandomSeed.⌋ [SWS_Csm_00955] Definition of API function Csm_KeyGenerate Upstream requirements: SRS_CryptoStack_00026, SRS_CryptoStack_00027 ⌈ Service Name Csm_KeyGenerate Syntax Std_ReturnType Csm_KeyGenerate ( uint32 keyId ) Service ID [hex] 0x6a Sync/Async Synchronous Reentrancy Reentrant but not for same keyId Parameters (in) keyId Holds the identifier of the key for which a new material shall be generated. Parameters (inout) None Parameters (out) None Return value Std_ReturnType E_OK: Request successful E_NOT_OK: Request failed CRYPTO_E_BUSY: Request failed, Crypto Driver Object is busy CRYPTO_E_KEY_NOT_VALID: Request failed, the key’s state is "invalid" CRYPTO_E_KEY_EMPTY: Request failed because of uninitialized source key element Description Generates new key material and store it in the key identified by keyId. Available via Csm.h ⌋ [SWS_Csm_01005] ⌈If no errors are detected by Csm, the service Csm_KeyGenerate shall call CryIf_KeyGenerate.⌋