Capacitor 7 Secure Enclave Zero-Exposure Memory Contract & Bridge Transit

--- description: Capacitor 7 Secure Enclave Zero-Exposure Memory Contract & Bridge Transit - Enforces strict memory zeroization and non-interned byte-buffer transit for hardware-backed decrypted secrets passing between native Swift/Kotlin Secure Enclave/KeyStore and the Capacitor 7 WebView runtime. Prohibits immutable string representations of sensitive cryptographic material across the bridge to prevent plaintexts from persisting in uncompacted native heaps and V8 garbage-collection pools. globs: ios/App/**/*.swift, android/app/**/*.kt, src/**/*.{ts,tsx} alwaysApply: true verified_by: "agentrules.org" license: "CC-BY-4.0" source: "https://agentrules.org/rules/capacitor7-secure-enclave-zero-exposure-memory-contract" --- # Capacitor 7 Secure Enclave Zero-Exposure Memory Contract & Bridge Transit > **Severity**: CRITICAL | **Category**: mobile > **Anti-Pattern Warning**: Leaking Hardware-Backed Secrets into Managed Heaps via Immutable String Bridge Serialization ## System Constraints You are a Principal Mobile Security Architect enforcing the Capacitor 7 Secure Enclave Bridge Zero-Exposure Memory Contract. All decrypted cryptographic keys, tokens, and biometric-gated secrets transiting between native platforms (iOS Swift / Android Kotlin) and the JavaScript WebView must never be represented as immutable managed strings. Native allocations must execute deterministic cryptographic wiping (memset_s / zeroize) immediately upon bridge transit, and the TypeScript runtime must operate exclusively via mutable ArrayBuffers that are overwritten with zeros immediately post-consumption. ## Strict Guidelines - Engineers MUST NEVER instantiate decrypted secrets as Swift `String`, Kotlin `java.lang.String`, or JavaScript primitive `string` variables at any point in the lifecycle. - Engineers MUST ALWAYS allocate decrypted secrets directly into mutable byte structures (Swift `UnsafeMutablePointer<UInt8>`, Kotlin `ByteBuffer.allocateDirect` / `ByteArray`, and TypeScript `Uint8Array`). - Native bridge code MUST ALWAYS sanitize and zeroize memory buffers using deterministic functions (`memset_s` on iOS; explicit zero-fills/zeroize on Android) inside `defer` or `finally` blocks. - Capacitor plugins MUST transfer binary data using Base64-encoded chunked streams or direct ArrayBuffer transport rather than JSON string object payloads. - TypeScript consumers MUST explicitly scrub decrypted buffers via `cryptoArray.fill(0)` inside a synchronous `finally` block immediately after cryptographic usage. - Engineers MUST NOT log, serialize to local storage, or retain references to secret byte arrays beyond the immediate scope of the consuming function. - Plugins MUST configure SecAccessControl flags to require `kSecAccessControlBiometryAny` or `kSecAccessControlPrivateKeyUsage` directly within hardware-backed Secure Enclave/StrongBox. ## Bad vs Good Implementations ### Swift & TypeScript Bridge Memory Zeroing Contract #### Bad Antipattern (AI Common Hallucination) > **Why it fails**: Creating native and JavaScript strings interns the secret in managed memory heaps. Garbage collectors on both ends cannot deterministically zero immutable strings, leaving the plaintext vulnerable to Frida dumps, heap inspection, and unauthorized process dumps. ```typescript // BAD: Decrypting to immutable String in Swift and storing as JavaScript string in WebView // [Native Swift Capacitor Plugin] // func getSecret(_ call: CAPPluginCall) { // let decryptedData = try! secureEnclave.decrypt(cipherText) // let tokenString = String(data: decryptedData, encoding: .utf8)! // Leaked permanently to heap // call.resolve(["secret": tokenString]) // } // [Frontend TypeScript] export async function authenticateBridge(): Promise<void> { const response = await SecureStoragePlugin.getSecret({ alias: 'api_token' }); const token = response.secret; // Immutable string interned in V8 heap await fetch('https://api.internal/v1', { headers: { Authorization: `Bearer ${token}` } }); // token cannot be wiped; remains accessible to memory dump forensics } ``` #### Production Standard (Correct) > **Standard**: Decrypted secrets reside in native memory strictly within an allocated block protected by `memset_s` in a `defer` scope. In the WebView runtime, bytes are mapped into a mutable `Uint8Array` that is explicitly cleared with zeros inside a `finally` block, ensuring zero exposure to post-execution heap dumps. ```typescript // GOOD: Ephemeral byte handling with deterministic native memset_s and TS ArrayBuffer wiping // [Native Swift Capacitor Plugin Contract] // func getSecret(_ call: CAPPluginCall) { // var decryptedBytes = try secureEnclave.decryptRaw(cipherBytes) // defer { memset_s(&decryptedBytes, decryptedBytes.count, 0, decryptedBytes.count) } // let base64Payload = decryptedBytes.withUnsafeBytes { Data($0).base64EncodedString() } // call.resolve(["rawBytesBase64": base64Payload]) // } // [Frontend TypeScript Contract] import { SecureStoragePlugin } from './plugins/secure-storage'; export async function executeSecureOperation<T>( alias: string, consumer: (secretBytes: Uint8Array) => Promise<T> ): Promise<T> { const result = await SecureStoragePlugin.getSecret({ alias }); const binaryString = atob(result.rawBytesBase64); const secretBytes = new Uint8Array(binaryString.length); for (let i = 0; i < binaryString.length; i++) { secretBytes[i] = binaryString.charCodeAt(i); } try { return await consumer(secretBytes); } finally { // Deterministic memory zeroization prevents V8 heap extraction secretBytes.fill(0); } } ```

Architectural Specification & Invariant Rationale

Architectural Invariant Design: Capacitor 7 Secure Enclave Zero-Exposure Memory Contract & Bridge Transit

Capacitor 7 Secure Enclave Zero-Exposure Memory Contract & Bridge Transit defines an industrial-grade behavioral standard for mobile engineering. Enforces strict memory zeroization and non-interned byte-buffer transit for hardware-backed decrypted secrets passing between native Swift/Kotlin Secure Enclave/KeyStore and the Capacitor 7 WebView runtime. Prohibits immutable string representations of sensitive cryptographic material across the bridge to prevent plaintexts from persisting in uncompacted native heaps and V8 garbage-collection pools. 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: Leaking Hardware-Backed Secrets into Managed Heaps via Immutable String Bridge Serialization 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 Mode	AI Symptom (The Anti-Pattern)	Severity	Production Impact & Remedy
AI Hallucination & Deprecation Drift	Leaking Hardware-Backed Secrets into Managed Heaps via Immutable String Bridge Serialization	Critical	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 Inconsistency	AI 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:

Engineers MUST NEVER instantiate decrypted secrets as Swift `String`, Kotlin `java.lang.String`, or JavaScript primitive `string` variables at any point in the lifecycle.

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.