Bind the non-exportable AES-256-GCM keys that seal the SQLCipher cache
passphrase to the hardware StrongBox secure element when the device has
one. Applied in the single shared place, AesGcmKeystoreCipher, so it
covers both the master (KeystoreCrypto) and auth-bound (DatabaseKeyCipher)
keys.
Devices without StrongBox throw StrongBoxUnavailableException at
KeyGenerator.generateKey(); a new generate-with-fallback path catches it
and regenerates a TEE-backed key so key creation still succeeds
everywhere. Guarded on API 28+ (minSdk is 29). Framing, seal/unseal, and
the missing-key policies are unchanged; the passphrase is still never
plaintext at rest and never logged.
Adds a JVM regression test for the StrongBox->TEE fallback via the
existing test seams (existingKey / a new generateKey seam).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
JMR-devandClaude Opus 4.8
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