Argon2-CFFI
General Information
| Field | Value |
|---|---|
| Package Name | argon2-cffi |
| Manufacturer / Vendor | Hynek Schlawack and contributors |
| Software Category | Library |
| Primary Documentation | Documentation, GitHub, PyPI |
| Programming Language(s) | Python, C (via CFFI bindings) |
| License | MIT License |
| Deployed Version(s) | >=25.1.0 |
| Most Recent Available Version | 25.1.0 |
| Last Review Date | 2026-01-27 |
Overview
argon2-cffi is a Python library that provides secure password hashing using the Argon2 algorithm. Argon2 won the Password Hashing Competition in 2015 and is specifically designed to be resistant to GPU cracking attacks and side-channel attacks through its memory-hard computation approach. The library offers a simple, production-ready API for password hashing and verification operations.
Within the medical device software, argon2-cffi is integrated exclusively into the API Gateway service to provide secure credential management for authenticated user access. It is used in two key components:
- Argon2AuthenticationService: The primary authentication service in the API Gateway that handles password hashing during user registration and password verification during login operations.
- Argon2PasswordHasher: A utility component in the user account management tooling that enforces password strength requirements (minimum 12 characters, uppercase, lowercase, digits, and special characters) before hashing, and provides rehash capability when security parameters are updated.
The library uses the Argon2id variant by default, which combines resistance to both side-channel timing attacks (from Argon2i) and GPU-based cracking (from Argon2d), making it the recommended choice for password hashing in production environments.
argon2-cffi was selected over alternatives (bcrypt, scrypt, PBKDF2) due to:
- Argon2's status as the Password Hashing Competition winner, representing the current state-of-the-art in password hashing security
- Memory-hard design that significantly increases the cost of parallel GPU-based attacks
- Configurable security parameters (time cost, memory cost, parallelism) allowing tuning for specific hardware and security requirements
- Active maintenance with regular updates and Python version support (currently 3.8 through 3.14)
- Strong community adoption with over 5.6 million weekly downloads
- MIT license permitting commercial use in medical device software
- CII Best Practices badge certification demonstrating project quality standards
Functional Requirements
The following functional capabilities of this SOUP are relied upon by the medical device software.
| Requirement ID | Description | Source / Reference |
|---|---|---|
| FR-001 | Hash plaintext passwords using the Argon2id algorithm with cryptographically secure random salt | PasswordHasher.hash() method |
| FR-002 | Verify plaintext passwords against stored Argon2id hashes | PasswordHasher.verify() method |
| FR-003 | Raise VerifyMismatchError exception when password verification fails | argon2.exceptions.VerifyMismatchError |
| FR-004 | Determine if a password hash requires rehashing due to parameter changes | PasswordHasher.check_needs_rehash() method |
| FR-005 | Generate hashes in PHC string format with embedded parameters and salt | $argon2id$v=VERSION$m=MEM,t=TIME,p=PAR$SALT$HASH |
| FR-006 | Accept both Unicode string and bytes input for password values | PasswordHasher input handling |
Performance Requirements
The following performance expectations are relevant to the medical device software.
| Requirement ID | Description | Acceptance Criteria |
|---|---|---|
| PR-001 | Password hashing shall complete within acceptable API latency bounds | Hash operation completes within overall authentication timeout |
| PR-002 | Password verification shall support concurrent login requests | Verification completes within 500ms under normal system load |
| PR-003 | Memory allocation during hashing shall not cause resource exhaustion | Memory usage bounded by configured memory_cost parameter |
Hardware Requirements
The following hardware dependencies or constraints are imposed by this SOUP component.
| Requirement ID | Description | Notes / Limitations |
|---|---|---|
| HR-001 | Sufficient system memory for Argon2 memory-hard computation | Default memory cost requires approximately 64 MiB per concurrent hash operation |
| HR-002 | Multi-core CPU recommended for optimal parallelism | Argon2 can utilize multiple CPU cores for parallel lane computation |
| HR-003 | x86-64 or ARM64 processor architecture | Pre-built wheels available for common platforms |
Software Requirements
The following software dependencies and environmental assumptions are required by this SOUP component.
| Requirement ID | Description | Dependency / Version Constraints |
|---|---|---|
| SR-001 | Python runtime environment | Python >=3.8 (device uses Python 3.12) |
| SR-002 | argon2-cffi-bindings for native Argon2 implementation | Automatically installed as dependency |
| SR-003 | CFFI (C Foreign Function Interface) for Python | Bundled with argon2-cffi-bindings |
Known Anomalies Assessment
This section evaluates publicly reported issues, defects, or security vulnerabilities associated with this SOUP component and their relevance to the medical device software.
As of 2026-01-27, no CVEs or security vulnerabilities have been reported against the argon2-cffi library. A comprehensive review of the National Vulnerability Database (NVD), Snyk vulnerability database, GitHub Security Advisories, and PyPI security reports identified no known security issues affecting this package. The library has maintained a clean security record throughout its release history. According to Snyk's security analysis, the package has been scanned for vulnerabilities and deemed safe to use, with a health score of 87/100. The project maintains a formal security policy (SECURITY.md) and has earned the CII Best Practices badge, demonstrating commitment to security best practices.
The underlying Argon2 algorithm has undergone extensive cryptographic review as part of the Password Hashing Competition and is recommended by OWASP for password storage. The algorithm's memory-hard design provides strong resistance against:
- GPU-based attacks: Memory bandwidth requirements make parallel GPU cracking economically impractical
- ASIC attacks: Custom hardware provides limited advantage due to memory access patterns
- Side-channel attacks: Argon2id variant provides data-independent memory access patterns
The device's usage pattern maintains security best practices:
- Strong password requirements: The
Argon2PasswordHasherenforces minimum password complexity (12+ characters, mixed case, digits, special characters) before hashing - Secure defaults: The library's default parameters (Argon2id, 64 MiB memory, 3 iterations, 4 parallel lanes) align with current security recommendations
- No custom parameter weakening: The device uses the library's default secure parameters without reduction
- Constant-time verification: The
verify()method uses constant-time comparison to prevent timing attacks - Automatic salt generation: Each password hash includes a cryptographically secure random salt, preventing rainbow table attacks
- Hash portability: The PHC string format allows hashes to be verified even if parameters are later updated
Risk Control Measures
The following risk control measures are implemented to mitigate potential security and operational risks associated with this SOUP component:
- Password strength validation enforces minimum complexity requirements (12+ characters, mixed case, digits, special characters) before hashing
- Authentication rate limiting prevents brute-force attacks at the API layer
- Secure password transmission over HTTPS prevents interception
- Hash storage in encrypted database prevents direct hash extraction
- Account lockout policies provide defense-in-depth against credential attacks
- Secure library defaults are used without parameter weakening
Assessment Methodology
The following methodology was used to identify and assess known anomalies:
-
Sources consulted:
- National Vulnerability Database (NVD) search for "argon2-cffi" and "argon2"
- Snyk vulnerability database and package health analysis
- GitHub Security Advisories for hynek/argon2-cffi
- PyPI security reports
- OWASP Password Storage Cheat Sheet recommendations
-
Criteria for determining applicability:
- Vulnerability must affect deployed versions (>=25.1.0)
- Vulnerability must be exploitable through the device's authentication interfaces
- Attack vector must be reachable in the deployment environment
- Existing input validation and security controls must not mitigate the vulnerability
Signature meaning
The signatures for the approval process of this document can be found in the verified commits at the repository for the QMS. As a reference, the team members who are expected to participate in this document and their roles in the approval process, as defined in Annex I Responsibility Matrix of the GP-001, are:
- Author: Team members involved
- Reviewer: JD-003 Design & Development Manager, JD-004 Quality Manager & PRRC
- Approver: JD-001 General Manager