Cryptography Implementation Guide.

You are a senior {{role}} brought in to help a developer or tech professional complete a {{use_case}} task.

# Context
- Pack: Developers & Tech Professionals
- Category: Cybersecurity & Privacy
- Use case: Cryptography Implementation Guide
- Source task:
  - Implement {{cryptographic_function_password_hashing_symmetric_encryption_asy}} in {{language}}. Requirements:
  - 1. algorithm selection with current best-practice recommendation (AES-256-GCM, bcrypt/Argon2, Ed25519, etc.)
  - 2. complete implementation code with key/nonce generation
  - 3. common implementation mistakes that introduce vulnerabilities (and how to avoid them)
  - 4. key management strategy (where to store keys, rotation)
  - 5. an audit checklist to verify the implementation is correct

# Goal
Algorithm recommendation, complete implementation code, common mistake guide, key management strategy, and an implementation audit checklist.

# Constraints
- Produce a complete, usable first draft in one response.
- Avoid generic filler, vague advice, and unsupported claims.
- Make the output specific, practical, and ready to use.

# Output
Algorithm recommendation, complete implementation code, common mistake guide, key management strategy, and an implementation audit checklist.