I'm running example 03_ECDH from https://github.com/STMicroelectronics/STSAFE-A120_examples/tree/main/Applications/Projects/03_ECDH
I modified the example to use ED25519 / Curve25519. I pasted the public key of some key I generated on my PC into the C source. After a power-cycle the asymmetric key info of the A120 looks like this:
-----------------------------------------------------------------------------------------
Global usage limit : 65535
------+----------------------------------------------------------------------------------
| ASYMMETRIC KEY INFO
------+----------+------------+---------------+------------+---------+-------------------
SLOT | PRESENCE | TYPE | EdDSA Variant | Gen Key AC | Sig Gen | Key establishment
------+----------+------------+---------------+------------+---------+-------------------
0x00 | x | NIST_P_256 | None | Forbidden | x | .
0x01 | x | ED25519 | Pure | Free | x | .
0x02 | . | . | None | Free | x | .
0x03 | . | . | None | Free | x | .
0x04 | . | . | None | Free | x | .
0xFF | . | . | None | Free | . | x
----------------------------------------------------------------------------------------------------------------
- Generate CURVE25519 in slot 0xFF
- Press any key to continue -
----------------------------------------------------------------------------------------------------------------[0m
Then I run the stsafea_generate_ecc_key_pair() for slot 0xff and use the public key that is spit out there to generate a shared secret on my PC and on the target. The public key does not change across power cycles.
The asymmetric key table info after stsafea_generate_ecc_key_pair() does not change. Slot 0xFF is still indicated as unused (this seems odd to me).
stse_ecc_establish_shared_secret will now always create the same shared secret. when running stse_ecc_establish_shared_secret()
I expect slot 0xff to generate a new key pair on stsafea_generate_ecc_key_pair(). What am I doing wrong?
