Class KeyFactorySpi

java.lang.Object
java.security.KeyFactorySpi
org.bouncycastle.jcajce.provider.asymmetric.sm9.KeyFactorySpi
public class KeyFactorySpi extends KeyFactorySpi
KeyFactory for the SM9 master keys (sm9sign and sm9encrypt): the master public and private keys round-trip through their JCA X.509 / PKCS#8 encodings (the GM/T 0080-2020 key material under the GM algorithm OID; the bare GM/T 0080-2020 form is the lightweight key-parameter class's getEncoded()).

A user's identity-based key is not decodable in isolation - it additionally needs the master public key and the identity, and for an encryption key the hid and the usage (KEM / decryption or key exchange) too - so it does not decode from a plain PKCS#8 spec. Rebuild a stored user key from its encoding plus that context with an SM9SigUserPrivateKeySpec / SM9EncUserPrivateKeySpec (also handed back by getKeySpec), or derive it afresh from the master private key via the master key's generateUserKeyPair method.