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securitycritical PriorityID: capacitor-7-biometric-enclave-invalidation-guardrail

Capacitor 7 Biometric Enclave Key Invalidation on Enrollment Mutation

Enforces hardware-backed cryptographic key invalidation within the Secure Enclave and Android Keystore whenever biometric enrollments change. Prevents unauthorized decryption by secondary biometrics added to an already-enrolled device by requiring explicit enclave-bound key generation with enrollment mutation guards.

Prohibited Anti-Pattern: Persisting Sensitive Tokens with Generic Biometric Prompts Without Hardware Key Invalidation

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---
description: Capacitor 7 Biometric Enclave Key Invalidation on Enrollment Mutation - Enforces hardware-backed cryptographic key invalidation within the Secure Enclave and Android Keystore whenever biometric enrollments change. Prevents unauthorized decryption by secondary biometrics added to an already-enrolled device by requiring explicit enclave-bound key generation with enrollment mutation guards.
globs: src/services/auth/**/*.{ts,tsx}, src/services/crypto/**/*.{ts,tsx}, src/services/storage/**/*.{ts,tsx}, src/plugins/**/*.{ts,tsx}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/capacitor-7-biometric-enclave-invalidation-guardrail"
---

# Capacitor 7 Biometric Enclave Key Invalidation on Enrollment Mutation

> **Severity**: CRITICAL | **Category**: security
> **Anti-Pattern Warning**: Persisting Sensitive Tokens with Generic Biometric Prompts Without Hardware Key Invalidation

## System Constraints
You are a Principal Security Architect enforcing Capacitor 7 Biometric Enclave Invalidation Guardrails. Mandate that all biometric authentication flows bind cryptographic key lifecycle directly to device biometric state, ensuring hardware-level revocation whenever Face ID, Touch ID, or Android Biometric enrollments are altered.

## Strict Guidelines
- Engineers MUST ALWAYS enforce hardware key invalidation flags on key generation (`kSecAccessControlBiometryCurrentSet` on iOS and `setUserAuthenticationParameters(0, KeyProperties.AUTH_BIOMETRIC_STRONG)` with `setInvalidatedByBiometricEnrollment(true)` on Android via native Capacitor bridge).
- Engineers MUST NOT decouple biometric prompt resolution (boolean success) from the cryptographic unwrapping of payload secrets stored in the hardware security module.
- Code MUST catch hardware key invalidation exceptions (`errSecKeyInvalidated` / `KeyPermanentlyInvalidatedException`) specifically, immediately terminating the active user session and purging local sensitive caches.
- Services MUST re-initialize cryptographic key pairs and prompt the user for primary credential re-authentication whenever a key invalidation error is caught.
- Components NEVER store sensitive access tokens or refresh tokens in unprotected SharedPreferences, Keychain without biometric ACLs, or unencrypted Capacitor Preferences.

## Bad vs Good Implementations
### Biometric Authentication with Hardware-Enforced Invalidation Handling

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: The code uses a detached biometric check where success merely returns a boolean before fetching unencrypted or non-enclave-bound data from Preferences. If an adversary adds their fingerprint to an unlocked device, this check passes and exposes the token.
```typescript
import { NativeBiometric } from 'capacitor-native-biometric';
import { Preferences } from '@capacitor/preferences';

export async function getSessionToken(): Promise<string | null> {
  // Anti-pattern: Verifies biometrics purely via software flow without hardware enclave binding.
  // If a rogue biometric fingerprint/face is added to the device, this still evaluates to true.
  const result = await NativeBiometric.verifyIdentity({
    reason: 'Authenticate to access secure data',
    title: 'Authenticate',
  });

  if (result) {
    const { value } = await Preferences.get({ key: 'auth_token' });
    return value;
  }
  return null;
}
```

#### Production Standard (Correct)
> **Standard**: Cryptographic material is securely unwrapped using Enclave keys configured to self-destruct upon enrollment changes. If a biometric modification occurs, the hardware throws an invalidation error, caught cleanly to purge compromised local state.
```typescript
import { NativeBiometric, BiometricOptions } from 'capacitor-native-biometric';
import { SecureEnclaveStorage } from '@/services/crypto/SecureEnclaveStorage';
import { AuthService } from '@/services/auth/AuthService';

export async function getHardwareProtectedSessionToken(): Promise<string> {
  const SEC_ITEM_ALIAS = 'app_session_master_key';

  try {
    // Invariant: Secret is decrypted directly via Enclave/Keystore bound to current biometric set.
    // iOS enforces kSecAccessControlBiometryCurrentSet;
    // Android enforces KeyGenParameterSpec.Builder.setInvalidatedByBiometricEnrollment(true).
    const decryptedToken = await SecureEnclaveStorage.decryptWithBiometrics({
      keyAlias: SEC_ITEM_ALIAS,
      promptMessage: 'Unlock your secure session',
      invalidateOnEnrollmentChange: true,
    });

    return decryptedToken;
  } catch (error: any) {
    if (
      error?.code === 'KEY_PERMANENTLY_INVALIDATED' ||
      error?.message?.includes('errSecKeyInvalidated')
    ) {
      // Hard invariant: Enrollment mutation detected. Evict state and force full re-auth.
      await AuthService.purgeCorruptedSessionState();
      throw new Error('Biometric enrollments changed. Hardware key revoked. Please re-login.');
    }
    throw error;
  }
}
```
Recommended MCP Servers (mcp-serverlist.com)

Equip agent with system tools to verify code for this stack.

Capacitor Mobile Security MCP
Inspects Capacitor iOS and Android native bridge configurations for insecure Keychain and Keystore flags.
Recommended Agent Skills (askills.dev)

Ready-to-use executable skill functions tailored to this stack.

Mobile Hardware Security Auditor
Validates that native Keychain and Keystore access control lists include explicit biometric enrollment invalidation flags.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Capacitor 7 Biometric Enclave Key Invalidation on Enrollment Mutation

Capacitor 7 Biometric Enclave Key Invalidation on Enrollment Mutation defines an industrial-grade behavioral standard for security engineering. Enforces hardware-backed cryptographic key invalidation within the Secure Enclave and Android Keystore whenever biometric enrollments change. Prevents unauthorized decryption by secondary biometrics added to an already-enrolled device by requiring explicit enclave-bound key generation with enrollment mutation guards. Modern software architectures require strict adherence to deterministic patterns to guarantee high availability, maintainability, and zero security vulnerabilities.

Framework Paradigm Shift & Drift MechanicsLLMs are trained on millions of open-source repositories containing outdated code, legacy idioms, and unpatched antipatterns. When coding assistants generate implementations for this stack, they default to common statistical tokens: Persisting Sensitive Tokens with Generic Biometric Prompts Without Hardware Key Invalidation Without an explicit system instruction file, developers spend hours debugging silent failures.
Failure Modes & Production Blast Radius

Hazard Analysis: What Breaks Without This Rule

The following failure modes have been cataloged from hundreds of hours of production code reviews where AI assistants produced non-compliant implementations:

Failure ModeAI Symptom (The Anti-Pattern)SeverityProduction Impact & Remedy
AI Hallucination & Deprecation DriftPersisting Sensitive Tokens with Generic Biometric Prompts Without Hardware Key InvalidationCritical
Violating this industrial standard introduces regression bugs, security risks, and unexpected runtime failures in production.
Enforce explicit behavioral system directives across all AI coding assistants in your repository.
Silent Architecture InconsistencyAI assistants produce mixed paradigms across files, creating fragmented codebase conventions.Medium
Increases cognitive load during code reviews and leads to maintenance debt across engineering teams.
Pin project conventions in .cursor/rules, CLAUDE.md, and AGENTS.md so all team agents follow identical guardrails.
Architectural Directives in Detail

Step-by-Step Production Directives

Each rule constraint below is injected into the AI agent's system prompt to establish deterministic boundaries:

1

Engineers MUST ALWAYS enforce hardware key invalidation flags on key generation (`kSecAccessControlBiometryCurrentSet` on iOS and `setUserAuthenticationParameters(0, KeyProperties.AUTH_BIOMETRIC_STRONG)` with `setInvalidatedByBiometricEnrollment(true)` on Android via native Capacitor bridge).

Engineers MUST ALWAYS enforce hardware key invalidation flags on key generation (`kSecAccessControlBiometryCurrentSet` on iOS and `setUserAuthenticationParameters(0, KeyProperties.AUTH_BIOMETRIC_STRONG)` with `setInvalidatedByBiometricEnrollment(true)` on Android via native Capacitor bridge).

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
2

Engineers MUST NOT decouple biometric prompt resolution (boolean success) from the cryptographic unwrapping of payload secrets stored in the hardware security module.

Engineers MUST NOT decouple biometric prompt resolution (boolean success) from the cryptographic unwrapping of payload secrets stored in the hardware security module.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
3

Code MUST catch hardware key invalidation exceptions (`errSecKeyInvalidated` / `KeyPermanentlyInvalidatedException`) specifically, immediately terminating the active user session and purging local sensitive caches.

Code MUST catch hardware key invalidation exceptions (`errSecKeyInvalidated` / `KeyPermanentlyInvalidatedException`) specifically, immediately terminating the active user session and purging local sensitive caches.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
4

Services MUST re-initialize cryptographic key pairs and prompt the user for primary credential re-authentication whenever a key invalidation error is caught.

Services MUST re-initialize cryptographic key pairs and prompt the user for primary credential re-authentication whenever a key invalidation error is caught.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
5

Components NEVER store sensitive access tokens or refresh tokens in unprotected SharedPreferences, Keychain without biometric ACLs, or unencrypted Capacitor Preferences.

Components NEVER store sensitive access tokens or refresh tokens in unprotected SharedPreferences, Keychain without biometric ACLs, or unencrypted Capacitor Preferences.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
Technical Questions & Answers

Frequently Asked Technical Questions

Common questions developers face when configuring AI coding assistants for this stack:

Q:Why is Capacitor 7 Biometric Enclave Key Invalidation on Enrollment Mutation critical for AI coding assistants?

Enforces hardware-backed cryptographic key invalidation within the Secure Enclave and Android Keystore whenever biometric enrollments change. Prevents unauthorized decryption by secondary biometrics added to an already-enrolled device by requiring explicit enclave-bound key generation with enrollment mutation guards. Without explicit behavioral boundaries, AI coding assistants (Cursor, Claude Code, Windsurf, Codex) rely on training data averages, which frequently produce deprecated, inefficient, or vulnerable code patterns.

Q:How does adopting this rule prevent AI hallucinations?

This rule explicitly declares what the AI must avoid (Persisting Sensitive Tokens with Generic Biometric Prompts Without Hardware Key Invalidation) and prescribes verified positive examples. Grounding the LLM with negative and positive pairs eliminates guesswork.

Q:Which AI coding environments are supported?

This specification is multi-platform compatible: Cursor (.cursor/rules/*.mdc & .cursorrules), Anthropic Claude Code (CLAUDE.md), Windsurf (.windsurfrules), Codex / Cline (AGENTS.md), and GitHub Copilot (.github/copilot-instructions.md).

Q:Can I combine this rule with other technology stacks?

Yes. Use the Interactive Stack Builder or download an Agent Pack to merge this rule with other frontend, backend, database, security, and DevOps rules without syntax collision.

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