fix(android): protect credentials with Android Keystore

[appergb]

User description

Fixes#817

Summary

• replace the reversible Android Base64 credential envelope with AndroidKeyStore-backed AES-256-GCM
• add a strict authenticated envelope, verified crash-safe legacy migration, rollback marker, and fixed JNI status boundary
• keep the Marketplace bearer process-memory-only on Android
• add JVM, instrumentation, Rust migration/fault-injection tests, plus x86_64 Android CI coverage

Validation

• bundle SHA-256 verified: 8d015882b6d549288f5762baac281c802913d1b1bbe7d0bff213767cc25e1238
• imported bundle HEAD verified: a1dacbafea0463c71cf17f251ed23b57a5f54135
• CI-only and test-fixture follow-ups culminate at f8296bff48d4e855a5d4718b39cef5c68c052957
• npm test passed all 24 frontend/contract tests after initializing the pinned submodule
• targeted Rust Android credential tests: 5 passed after reusing one simulated Keystore instance across the migration reload
• Android Gradle/JVM/instrumentation and emulator coverage passed in PR CI

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PR Type

Bug fix, Enhancement, Tests

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Description

• Protect Android credentials with Keystore-backed AES-256-GCM

• Add crash-safe migration scrubbing Marketplace tokens

• Implement JNI bridge and Kotlin Keystore vault classes

• Add JVM, instrumentation, and CI test coverage

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Diagram Walkthrough

flowchart LR
legacy["Base64 Envelope"] -->|read & sanitize| sanitized["Bearer-free Base64"]
sanitized -->|migrate| new_env["V2 AES-GCM Envelope"]
new_env -->|decrypt/encrypt| keystore["Android KeyStore"]
keystore -->|rollback barrier| marker["Migration Complete Marker"]
new_env -->|fail-closed| secure_remove["Secure Erase on Failure"]

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File Walkthrough

	Relevant files
Enhancement	5 files android_credentials.rs New Keystore-backed credential store module +1285/-0 credentials.rs Integrate Keystore vault with migration +237/-245 jni.rs Add JNI bridge for Keystore operations +214/-1 OpenLessCredentialVault.kt Kotlin Keystore vault facade +184/-0 OpenLessCredentialCipher.kt Pure AES-GCM packet codec +45/-0
Configuration changes	3 files mod.rs Register android_credentials module +2/-0 copy-android-scaffolding.mjs Copy test scaffolding to generated project +65/-14 ci.yml Add Android x86_64 CI and emulator tests +63/-2
Tests	3 files OpenLessCredentialCipherTest.kt JVM unit tests for AES-GCM cipher +111/-0 OpenLessCredentialVaultInstrumentedTest.kt Instrumented Keystore integration tests +89/-0 android-credential-keystore-contract.test.mjs Contract tests for Keystore implementation +248/-0

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[github-actions]

PR Reviewer Guide 🔍

(Review updated until commit 11fb522)

Here are some key observations to aid the review process:

🎫 Ticket compliance analysis 🔶 817 - Partially compliant Compliant requirements: Protect persisted Android credentials with Android Keystore-backed authenticated encryption using a non-exportable key, unique nonce per write, and atomic owner-private storage. Bind ciphertext format/version and account key as authenticated data; reject tampering and fail closed. Migrate legacy Base64 envelopes without exposing values to logs/events/frontend; delete the legacy plaintext-equivalent file only after verified migration. Define safe behavior for locked/unavailable/invalidated Keystore keys. Marketplace OAuth token remains memory-only on Android and requires re-login after restart. Add Android/JVM or instrumented tests for round-trip, tamper, key invalidation, migration, file permissions, and secret non-exposure. Non-compliant requirements: (empty) Requires further human verification: "Independently security-review the implementation before merging." This is an organizational process step, not verifiable from the code alone.

⏱️ Estimated effort to review: 4 🔵🔵🔵🔵⚪

🧪 PR contains tests

🔒 No security concerns identified

⚡ No major issues detected

[github-actions]

Persistent review updated to latest commit b34870a

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Persistent review updated to latest commit 470de3b

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Persistent review updated to latest commit aa1ddbe

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Persistent review updated to latest commit f8296bf

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Persistent review updated to latest commit c163070

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Persistent review updated to latest commit e28772a

[github-actions]

Persistent review updated to latest commit 3c186cb

[github-actions]

Persistent review updated to latest commit 1cb899e

[github-actions]

Persistent review updated to latest commit 11fb522