Agent-Skills.md

Agent Skills: Security & Credentials

Use when storing credentials securely, encrypting data, implementing passkeys, securing AI/agentic features against prompt injection, code signing, or managing certificates and provisioning profiles.

UncategorizedID: charleswiltgen/axiom/axiom-security

Repository

charleswiltgen/axiom
CharlesWiltgenLicense: MIT
1,03279

Install this agent skill to your local

pnpm dlx add-skill https://github.com/CharlesWiltgen/Axiom/tree/HEAD/axiom-codex/skills/axiom-security

Skill Files

Browse the full folder contents for axiom-security.

Download Skill

Loading file tree…

axiom-codex/skills/axiom-security/SKILL.md

Skill Metadata

Name
axiom-security
Description
Use when storing credentials securely, encrypting data, implementing passkeys, securing AI/agentic features against prompt injection, code signing, or managing certificates and provisioning profiles.

Security & Credentials

You MUST use this skill for ANY keychain, encryption, passkey, app integrity, agentic/AI feature security, file protection, or code signing work.

Quick Reference

| Symptom / Task | Reference | |----------------|-----------| | Store tokens, passwords, API keys securely | See skills/keychain.md | | Choose kSecAttrAccessible level, biometric protection | See skills/keychain.md | | SecItem function signatures, attribute constants | See skills/keychain-ref.md | | errSecDuplicateItem, errSecItemNotFound, errSecInteractionNotAllowed | See skills/keychain-diag.md | | Encrypt data, sign payloads, key management | See skills/cryptokit.md | | Hash functions, HMAC, AES-GCM, ChaChaPoly, ECDSA, EdDSA, key agreement | See skills/cryptokit-ref.md | | Passkey sign-in, WebAuthn, ASAuthorizationController | See skills/passkeys.md | | One-time code AutoFill for credential providers OS27 | See skills/passkeys.md (Delivered Verification Codes) | | App integrity verification, DCAppAttestService, fraud metric | See skills/app-attest.md | | Prompt injection, securing AI agents / agentic features, tool confirmation | See skills/agentic-security.md | | NSFileProtection levels, data protection at rest | See skills/file-protection-ref.md | | SensitiveContentAnalysis verdict must never leave the device (no analytics/moderation queue/synced cache; license §3.3.3) | See axiom-vision (skills/vision-ref.md) | | Certificate management, provisioning profiles, CI/CD signing | See skills/code-signing.md | | Certificate not found, profile mismatch, entitlement errors | See skills/code-signing-diag.md | | Certificate CLI, profile inspection, entitlement extraction | See skills/code-signing-ref.md | | Apple Pay payment certs / pass type certs / Tap to Pay entitlement | See axiom-payments suite |

Decision Tree

digraph security {
    start [label="Security task" shape=ellipse];
    what [label="What do you need?" shape=diamond];

    start -> what;
    what -> "skills/keychain.md" [label="store/retrieve\ncredentials, tokens,\nsecrets"];
    what -> "skills/keychain-ref.md" [label="SecItem API syntax,\nattribute constants,\naccess levels"];
    what -> "skills/keychain-diag.md" [label="keychain errors\n(errSec codes)"];
    what -> "skills/cryptokit.md" [label="encrypt data,\nsign payloads,\nSecure Enclave keys"];
    what -> "skills/cryptokit-ref.md" [label="CryptoKit API\n(AES, ECDSA, HPKE,\npost-quantum)"];
    what -> "skills/passkeys.md" [label="passkey sign-in,\nreplace passwords"];
    what -> "skills/app-attest.md" [label="app integrity,\nfraud prevention"];
    what -> "skills/agentic-security.md" [label="AI agent security,\nprompt injection"];
    what -> "skills/file-protection-ref.md" [label="file encryption,\nNSFileProtection"];
    what -> "skills/code-signing.md" [label="set up signing,\nprofiles, CI/CD"];
    what -> "skills/code-signing-diag.md" [label="signing errors,\nupload rejections"];
    what -> "skills/code-signing-ref.md" [label="CLI commands,\nprofile inspection"];
}
  1. Store tokens, passwords, API keys securely? → skills/keychain.md 1a. Need SecItem function signatures, attribute constants? → skills/keychain-ref.md 1b. Keychain errors (errSecDuplicateItem, errSecItemNotFound)? → skills/keychain-diag.md
  2. Encrypt data, sign payloads, manage keys? → skills/cryptokit.md 2a. Need CryptoKit API details (AES-GCM, ECDSA, HPKE, post-quantum)? → skills/cryptokit-ref.md
  3. Implement passkey sign-in, replace passwords? → skills/passkeys.md
  4. Verify app integrity, prevent fraud? → skills/app-attest.md
  5. Securing an agentic/AI feature (prompt injection, tool confirmation, lock-screen intents)? → skills/agentic-security.md
  6. File encryption at rest, NSFileProtection levels? → skills/file-protection-ref.md
  7. Set up code signing, manage certificates, CI/CD? → skills/code-signing.md 7a. Code signing error troubleshooting? → skills/code-signing-diag.md 7b. Certificate CLI commands, profile inspection? → skills/code-signing-ref.md
  8. Build/upload failures after signing? → See axiom-build
  9. App Store submission prep? → /skill axiom-shipping
  10. Privacy manifests, tracking transparency? → See axiom-integration
  11. Data persistence (SwiftData, Core Data, storage strategy)? → /skill axiom-data
  12. TLS configuration, certificate pinning for network requests? → /skill axiom-networking
  13. Want automated security scan? → security-privacy-scanner (Agent)

Conflict Resolution

security vs axiom-build: When build fails with signing errors:

  • Code signing errors (certificate, profile, entitlement) → use security
  • Environment issues (Xcode version, simulator, Derived Data) → use axiom-build
  • If unsure, check the error message: CODESIGN, ITMS-90xxx, errSec → security

security vs shipping: When preparing for App Store:

  • Privacy manifests, submission checklists, rejections → use shipping
  • Code signing for distribution, certificate management → use security

security vs axiom-data: When storing sensitive data:

  • Tokens, passwords, API keys → use security (keychain)
  • User preferences, non-sensitive settings → use axiom-data (UserDefaults/SwiftData)
  • File encryption levels for database files → use security (file-protection-ref)
  • SQLite-specific Data Protection (.db/-wal/-shm trio, widget-while-locked access) → See axiom-data (skills/grdb-app-groups.md) §4

security vs axiom-networking: When securing network communication:

  • TLS configuration, certificate pinning → use axiom-networking
  • Signing API requests, encrypting payloads → use security (CryptoKit)

Critical Patterns

Keychain (skills/keychain.md):

  • SecItem mental model: uniqueness constraints, data protection classes
  • Biometric access control (Face ID / Touch ID)
  • Keychain sharing between app and extensions
  • Background access pitfalls, Mac keychain differences
  • Migration from UserDefaults/@AppStorage for sensitive data

Keychain API (skills/keychain-ref.md):

  • SecItemAdd/CopyMatching/Update/Delete signatures
  • Item class attributes, uniqueness constraint rules
  • kSecAttrAccessible levels and when each applies
  • Access control flags, biometric integration
  • Complete error code reference

Keychain Diagnostics (skills/keychain-diag.md):

  • errSecDuplicateItem from unexpected uniqueness constraints
  • errSecItemNotFound despite item existing (query mismatch)
  • errSecInteractionNotAllowed in background contexts
  • Access group and entitlement mismatches
  • Items disappearing after app updates

CryptoKit (skills/cryptokit.md):

  • AES-GCM and ChaChaPoly authenticated encryption
  • ECDSA/EdDSA digital signatures
  • Secure Enclave hardware-backed keys
  • Key agreement (ECDH) for end-to-end encryption
  • HPKE for modern asymmetric encryption
  • Post-quantum algorithms (ML-KEM, ML-DSA)
  • CommonCrypto migration path

CryptoKit API (skills/cryptokit-ref.md):

  • Hash functions (SHA-256/384/512, SHA-3), HMAC
  • Symmetric encryption (AES-GCM, ChaChaPoly)
  • Asymmetric signing (P256, P384, P521, Curve25519, Ed25519)
  • Key agreement, key derivation (HKDF)
  • Secure Enclave key creation and usage
  • Swift Crypto cross-platform parity

Passkeys (skills/passkeys.md):

  • ASAuthorizationController registration and assertion flows
  • AutoFill-assisted requests (QuickType bar integration)
  • Automatic passkey upgrades for existing users (iOS 18+)
  • Combined credential requests (passkey + password + Sign in with Apple)
  • Associated domains configuration for WebAuthn

App Attest (skills/app-attest.md):

  • DCAppAttestService attestation and assertion flows
  • Server-side validation of attestation objects
  • macOS support + tampering signals (extensions, key access control) from the 27 cycle
  • Fraud metric as an investigation signal
  • DeviceCheck 2-bit per-device state
  • Gradual rollout strategies for large install bases
  • Handling unsupported devices gracefully

Agentic Security (skills/agentic-security.md):

  • Threat modeling agentic features (indirect prompt injection, Lethal Trifecta)
  • Deterministic vs probabilistic mitigations (redaction, spotlighting, confirmation, unlock gating)
  • Foundation Models lifecycle modifiers (.onToolCall confirmation, .historyTransform)
  • App Intents authenticationPolicy and schema risk metadata

File Protection (skills/file-protection-ref.md):

  • NSFileProtection levels (complete, completeUnlessOpen, afterFirstUnlock, none)
  • Hardware-accelerated encryption tied to device passcode
  • Background file access requirements
  • Keychain vs file protection comparison

Code Signing (skills/code-signing.md):

  • Automatic vs manual signing tradeoffs
  • Certificate and profile management across teams
  • fastlane match for team-wide certificate sharing
  • CI/CD signing setup (GitHub Actions, Xcode Cloud)
  • Distribution build preparation (App Store, TestFlight, Ad Hoc)

Code Signing Diagnostics (skills/code-signing-diag.md):

  • Certificate issues (expired, missing, wrong type, revoked)
  • Provisioning profile issues (expired, missing cert, wrong App ID)
  • Entitlement mismatches (capability in Xcode but not in profile)
  • Keychain issues in CI (locked keychain, errSecInternalComponent)
  • Archive/export failures (wrong export method, wrong cert type)

Code Signing CLI (skills/code-signing-ref.md):

  • security find-identity, security cms -D for profile inspection
  • codesign -d --entitlements for entitlement extraction
  • Certificate types, validity periods, per-account limits
  • fastlane match commands and Keychain management

Automated Scanning

Security audit → Launch security-privacy-scanner agent (scans for hardcoded credentials, insecure token storage, Privacy Manifest coverage gaps, ATS violations, missing ATT descriptions, missing export compliance, weak Keychain ACLs, and compound rejection risks; scores posture HARDENED/GAPS/VULNERABLE)

Anti-Rationalization

| Thought | Reality | |---------|---------| | "I'll store the token in UserDefaults for now" | UserDefaults is a plist file readable by any process with file access. Keychain takes 10 lines. skills/keychain.md shows the pattern. | | "My app doesn't need encryption" | If you store any user data at rest, iOS file protection is free. skills/file-protection-ref.md covers protection levels. | | "CommonCrypto works fine, no need to migrate" | CommonCrypto is C API with manual memory management and no compile-time safety. CryptoKit prevents buffer overflows and key misuse. | | "I'll just use automatic signing" | Automatic signing works until CI, team scaling, or capability changes break it. Understand manual signing before you need it. skills/code-signing.md covers both. | | "Passkeys are too new, passwords are fine" | Passkeys are phishing-resistant and supported since iOS 16. The migration path supports both simultaneously. skills/passkeys.md shows combined flows. | | "I'll regenerate all certificates to fix this" | Regenerating revokes existing certs and breaks every teammate's build. Diagnose first. skills/code-signing-diag.md has the diagnostic flow. | | "App Attest is overkill for my app" | If your app has any server-verified purchase, promotion, or competitive feature, tampered clients will exploit it. skills/app-attest.md covers gradual rollout. | | "I'll use @unchecked Sendable on my crypto wrapper" | Hiding thread-safety issues from the compiler in security code is how data corruption happens. See axiom-concurrency for safe patterns. | | "kSecAttrAccessibleAlways is fine" | Deprecated since iOS 12. Items are accessible even when device is locked and unencrypted during backup. Use kSecAttrAccessibleAfterFirstUnlock at minimum. | | "Prompt injection won't hit our little AI feature" | Any external content reaching your model (a calendar invite, a feed post) is the attack surface, and the model picks the actions. skills/agentic-security.md has the threat model and the deterministic mitigations. |

Example Invocations

User: "How do I store an auth token securely?" → Read: skills/keychain.md

User: "errSecDuplicateItem when saving to keychain" → Read: skills/keychain-diag.md

User: "What are the SecItem attribute constants?" → Read: skills/keychain-ref.md

User: "How do I encrypt user data with AES?" → Read: skills/cryptokit.md

User: "What's the CryptoKit API for ECDSA signing?" → Read: skills/cryptokit-ref.md

User: "How do I add passkey sign-in to my app?" → Read: skills/passkeys.md

User: "How do I verify my app hasn't been tampered with?" → Read: skills/app-attest.md

User: "How do I protect my app's AI agent from prompt injection?" → Read: skills/agentic-security.md

User: "Should my Siri intent work from the lock screen?" → Read: skills/agentic-security.md

User: "What NSFileProtection level should I use?" → Read: skills/file-protection-ref.md

User: "My build fails with 'No signing certificate found'" → Read: skills/code-signing-diag.md

User: "How do I set up fastlane match for CI?" → Read: skills/code-signing.md

User: "How do I inspect a provisioning profile?" → Read: skills/code-signing-ref.md

User: "Scan my code for security issues" → Invoke: security-privacy-scanner agent