Hi@zzzzz
The CSEc (Cryptographic Services Engine - compressed) module in NXP's S32K1 series MCU does not support any asymmetric encryption algorithms, including RSA, ECC, Ed25519, etc.
1. There are many lightweight C libraries available online that implement Ed25519ph, Since we haven't tested this, we can't recommend it to you.
2. If performance or security requirements are high, consider connecting an external security chip that supports asymmetric encryption (such as the NXP A71CH or ATECC608A) via the SPI/I2C interface.