---
name: "argon2id-password-hashing-strategy"
description: "Hash and verify passwords with industry standard memory-hard Argon2id algorithm."
metadata:
  author: "P-H-C"
  version: "1.0.0"
  runtime_compatibility:
    - "codex"
    - "claude-code"
    - "cursor"
    - "windsurf"
triggers:
  - "hash password with argon2id"
  - "verify password argon2"
  - "configure argon2 memory cost"
permissions:
  fs_read: true
  fs_write: "workspace"
  shell_exec: false
  net_access: false
---

# Argon2id Memory-Hard Password Hashing

Implements password hashing conforming to OWASP guidelines using Argon2id: memory cost (m), time cost (t), parallelism (p), cryptographically random salting, and constant-time password verification.

## When to Invoke
Invoke this skill whenever you need to:
- hash password with argon2id
- verify password argon2
- configure argon2 memory cost

## Execution SOP & Rules
1. Use Argon2id variant exclusively (combines resistance to side-channel and GPU cracking attacks).
2. Configure OWASP recommended minimums: memoryCost: 65536 (64MB), timeCost: 3, parallelism: 1.
3. Generate a unique cryptographically secure 16-byte salt for every hashed password.
4. Perform password comparisons using constant-time string comparisons to eliminate timing leaks.

## Verification Checklist
- Run local linting, syntax validation, and type-checks before reporting completion.
- Ensure all created or modified files adhere to workspace boundaries and avoid uncommitted secrets.
- Verify tests or build commands exit cleanly with return code 0.