signerAlgorithm was derived from params.algorithm (the generated key)
instead of the signing key, causing BouncyCastle to throw when signing
RSA keys with an EC attestation key. Now reads signingKeyPair.private.algorithm.
Device ID tags (serial/imei/meid/secondImei) were blanket-rejected
instead of flowing through to software cert gen like AOSP does.
Narrowed rejection to DEVICE_UNIQUE_ATTESTATION only.