System Overview

System Overview

Table of Contents

1. Introduction
2. System Architecture Overview
3. Core Components
4. WebAuthn Protocol Implementation
5. Post-Quantum Cryptography Integration
6. Authentication Flow Architecture
7. Deployment Topology
8. Infrastructure Requirements
9. Security Considerations
10. Performance Characteristics

Introduction

The Post-Quantum WebAuthn Platform is a comprehensive authentication system built on Flask that implements the FIDO2/WebAuthn standards with integrated post-quantum cryptography support. This system provides secure, passwordless authentication using modern cryptographic algorithms that are resistant to quantum computing attacks, making it suitable for future-proof security implementations.

The platform consists of three primary layers: a Flask-based web application server, a sophisticated WebAuthn protocol implementation, and a post-quantum cryptography framework that seamlessly integrates with traditional cryptographic systems. The architecture supports both simple and advanced authentication scenarios, with extensive customization capabilities for enterprise deployments.

System Architecture Overview

The Post-Quantum WebAuthn Platform follows a layered architecture pattern that separates concerns between presentation, business logic, and cryptographic operations:

graph TB
subgraph "Client Layer"
Browser[Web Browser]
JS[JavaScript Frontend]
Auth[Authenticator Devices]
end
subgraph "Application Layer"
Flask[Flask Application]
Routes[Route Handlers]
Server[FIDO2 Server]
end
subgraph "Protocol Layer"
WebAuthn[WebAuthn Protocol]
CTAP2[CTAP2 Protocol]
HID[HID Transport]
end
subgraph "Cryptographic Layer"
PQCrypto[Post-Quantum Crypto]
Classical[Classical Crypto]
OQS[Open Quantum Safe]
end
subgraph "Storage Layer"
LocalFS[Local Storage]
Cloud[Cloud Storage]
Metadata[Authenticator Metadata]
end
Browser --> JS
JS --> Auth
Auth --> HID
HID --> CTAP2
CTAP2 --> WebAuthn
WebAuthn --> Server
Server --> Flask
Flask --> Routes
Routes --> PQCrypto
PQCrypto --> OQS
Classical --> OQS
Flask --> LocalFS
Flask --> Cloud
Flask --> Metadata

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Diagram sources

• server/server/app.py
• fido2/webauthn.py
• fido2/ctap2/base.py

Section sources

• server/server/app.py
• server/server/config.py

Core Components

Flask Application Server

The Flask application serves as the central hub for all authentication operations, providing RESTful APIs and serving the web interface. The application is structured with clear separation of concerns:

classDiagram
class FlaskApp {
+app : Flask
+secret_key : bytes
+config : dict
+run(host, port, ssl_context)
+before_serving()
+before_first_request()
}
class RouteHandlers {
+general_routes : GeneralRoutes
+simple_routes : SimpleRoutes
+advanced_routes : AdvancedRoutes
+register_begin()
+register_complete()
+authenticate_begin()
+authenticate_complete()
}
class Fido2Server {
+rp_entity : PublicKeyCredentialRpEntity
+attestation_verifier : AttestationVerifier
+authenticator_selection : AuthenticatorSelection
+register_begin()
+register_complete()
+authenticate_begin()
+authenticate_complete()
}
FlaskApp --> RouteHandlers
RouteHandlers --> Fido2Server
Fido2Server --> WebAuthn
Fido2Server --> CTAP2

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Diagram sources

• server/server/app.py
• server/server/config.py

WebAuthn Data Models

The WebAuthn implementation provides comprehensive data structures for handling authentication requests and responses:

classDiagram
class PublicKeyCredentialCreationOptions {
+rp : PublicKeyCredentialRpEntity
+user : PublicKeyCredentialUserEntity
+challenge : bytes
+pub_key_cred_params : Sequence
+timeout : int
+exclude_credentials : Sequence
+authenticator_selection : AuthenticatorSelectionCriteria
+attestation : str
+extensions : dict
}
class PublicKeyCredentialRequestOptions {
+challenge : bytes
+timeout : int
+rp_id : str
+allow_credentials : Sequence
+user_verification : str
+extensions : dict
}
class AuthenticatorData {
+rp_id_hash : bytes
+flags : AuthenticatorData.FLAG
+counter : int
+credential_data : AttestedCredentialData
+extensions : dict
+is_user_present()
+is_user_verified()
+is_attested()
}
class AttestationObject {
+fmt : str
+auth_data : AuthenticatorData
+att_stmt : dict
+create()
+from_ctap1()
}
PublicKeyCredentialCreationOptions --> AuthenticatorData
PublicKeyCredentialRequestOptions --> AuthenticatorData
AuthenticatorData --> AttestationObject

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Diagram sources

• fido2/webauthn.py
• fido2/webauthn.py
• fido2/webauthn.py
• fido2/webauthn.py

CTAP2 Command Processing

The CTAP2 implementation handles communication with authenticator devices over HID transport:

classDiagram
class Ctap2 {
+device : CtapDevice
+info : Info
+send_cbor(cmd, data)
+get_info()
+make_credential()
+get_assertion()
+reset()
+client_pin()
}
class Info {
+versions : list
+extensions : list
+aaguid : Aaguid
+options : dict
+max_msg_size : int
+pin_uv_protocols : list
+algorithms : list
+get_identifier()
}
class AttestationResponse {
+fmt : str
+auth_data : AuthenticatorData
+att_stmt : dict
+ep_att : bool
+large_blob_key : bytes
+verify()
}
class AssertionResponse {
+credential : dict
+auth_data : AuthenticatorData
+signature : bytes
+user : dict
+number_of_credentials : int
+verify()
}
Ctap2 --> Info
Ctap2 --> AttestationResponse
Ctap2 --> AssertionResponse

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Diagram sources

• fido2/ctap2/base.py
• fido2/ctap2/base.py
• fido2/ctap2/base.py
• fido2/ctap2/base.py

Section sources

• fido2/webauthn.py
• fido2/ctap2/base.py

WebAuthn Protocol Implementation

The platform implements the complete FIDO2/WebAuthn specification with support for both registration and authentication workflows. The implementation includes:

Registration Workflow

The registration process involves multiple steps from challenge generation to credential storage:

sequenceDiagram
participant Client as Browser
participant Server as Flask Server
participant Authenticator as Authenticator Device
participant Crypto as Cryptographic Engine
Client->>Server : POST /api/register/begin
Server->>Server : Generate challenge
Server->>Server : Create PublicKeyCredentialCreationOptions
Server-->>Client : Registration options
Client->>Authenticator : create(options)
Authenticator->>Crypto : Generate key pair
Crypto-->>Authenticator : Private key (securely stored)
Authenticator-->>Client : Credential
Client->>Server : POST /api/register/complete
Server->>Server : Verify attestation
Server->>Server : Extract public key
Server->>Server : Store credential
Server-->>Client : Registration result

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Diagram sources

• server/server/routes/simple.py
• server/server/routes/advanced.py

Authentication Workflow

The authentication process validates user credentials and ensures proper user verification:

sequenceDiagram
participant Client as Browser
participant Server as Flask Server
participant Authenticator as Authenticator Device
participant Crypto as Cryptographic Engine
Client->>Server : POST /api/authenticate/begin
Server->>Server : Load stored credentials
Server->>Server : Generate challenge
Server-->>Client : Authentication options
Client->>Authenticator : get(options)
Authenticator->>Crypto : Sign challenge
Crypto-->>Authenticator : Digital signature
Authenticator-->>Client : Assertion
Client->>Server : POST /api/authenticate/complete
Server->>Server : Verify signature
Server->>Server : Update counter
Server-->>Client : Authentication result

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Diagram sources

• server/server/routes/simple.py
• server/server/routes/advanced.py

Section sources

• server/server/routes/simple.py
• server/server/routes/simple.py
• server/server/routes/advanced.py

Post-Quantum Cryptography Integration

The platform integrates post-quantum cryptographic algorithms alongside classical cryptography to provide quantum-resistant authentication:

Supported Algorithms

The system supports both classical and post-quantum algorithms:

Algorithm Family	Algorithm ID	Security Level	Quantum Resistance
ML-DSA	-50	192-bit	Quantum Secure
ML-DSA	-49	128-bit	Quantum Secure
ML-DSA	-48	96-bit	Quantum Secure
ECDSA	-7	128-bit	Vulnerable
RSA	-257	128-bit	Vulnerable

Algorithm Selection Logic

flowchart TD
Start([Authentication Request]) --> CheckPQ{PQ Available?}
CheckPQ --> |Yes| SelectPQ[Select PQ Algorithm]
CheckPQ --> |No| SelectClassical[Select Classical Algorithm]
SelectPQ --> ValidatePQ{PQ Supported?}
ValidatePQ --> |Yes| UsePQ[Use PQ Algorithm]
ValidatePQ --> |No| FallbackClassical[Use Classical Fallback]
SelectClassical --> ValidateClassical{Classical Supported?}
ValidateClassical --> |Yes| UseClassical[Use Classical Algorithm]
ValidateClassical --> |No| Error[Algorithm Not Available]
UsePQ --> Complete([Authentication Complete])
FallbackClassical --> Complete
UseClassical --> Complete
Error --> Complete

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Diagram sources

• server/server/routes/simple.py
• server/server/routes/advanced.py

Section sources

• server/server/routes/simple.py
• server/server/routes/advanced.py

Authentication Flow Architecture

The platform supports two distinct authentication flows: simple and advanced, each optimized for different use cases:

Simple Authentication Flow

Designed for straightforward passwordless authentication with minimal configuration:

stateDiagram-v2
[*] --> Ready
Ready --> RegisterBegin : User clicks Register
RegisterBegin --> ChallengeGen : Generate challenge
ChallengeGen --> SendOptions : Send to client
SendOptions --> WaitAuth : Wait for authenticator
WaitAuth --> AuthSuccess : Successful auth
WaitAuth --> AuthError : Auth failure
AuthSuccess --> StoreCred : Store credential
StoreCred --> Ready
AuthError --> Ready
RegisterBegin --> AuthenticateBegin : User clicks Authenticate
AuthenticateBegin --> LoadCreds : Load stored credentials
LoadCreds --> SendAuthOptions : Send auth options
SendAuthOptions --> WaitAuth

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Diagram sources

• server/server/static/scripts/simple/auth-simple.js
• server/server/static/scripts/simple/auth-simple.js

Advanced Authentication Flow

Provides granular control over authentication parameters and extensions:

stateDiagram-v2
[*] --> EditJSON : User edits JSON
EditJSON --> ValidateJSON : Validate input
ValidateJSON --> Ready : Validation OK
ValidateJSON --> EditJSON : Validation Error
Ready --> RegisterBegin : Start Registration
RegisterBegin --> SendToServer : Send to server
SendToServer --> ProcessServer : Process on server
ProcessServer --> SendOptions : Return options
SendOptions --> WaitClient : Wait for client
WaitClient --> ProcessClient : Process client response
ProcessClient --> StoreResult : Store result
StoreResult --> EditJSON
Ready --> AuthenticateBegin : Start Authentication
AuthenticateBegin --> LoadCredentials : Load stored creds
LoadCredentials --> SendAuthOptions
SendAuthOptions --> WaitClient

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Diagram sources

• server/server/static/scripts/advanced/auth-advanced.js
• server/server/static/scripts/advanced/auth-advanced.js

Section sources

• server/server/static/scripts/simple/auth-simple.js
• server/server/static/scripts/simple/auth-simple.js
• server/server/static/scripts/advanced/auth-advanced.js
• server/server/static/scripts/advanced/auth-advanced.js

Deployment Topology

The platform supports flexible deployment configurations for different environments:

Development Environment

graph TB
subgraph "Development Deployment"
Client[Web Client<br/>localhost:3000]
FlaskDev[Flask Dev Server<br/>localhost:5000]
LocalStorage[Local Storage<br/>File System]
Client --> FlaskDev
FlaskDev --> LocalStorage
end

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Production Environment

graph TB
subgraph "Production Deployment"
LB[Load Balancer<br/>Render.com]
Flask1[Flask Instance 1<br/>Port 8000]
Flask2[Flask Instance 2<br/>Port 8000]
Flask3[Flask Instance N<br/>Port 8000]
CloudStorage[Cloud Storage<br/>Google Cloud Storage]
Redis[Redis Cache<br/>Session Storage]
LB --> Flask1
LB --> Flask2
LB --> Flask3
Flask1 --> CloudStorage
Flask1 --> Redis
Flask2 --> CloudStorage
Flask2 --> Redis
Flask3 --> CloudStorage
Flask3 --> Redis
end

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Diagram sources

• Dockerfile
• render.yaml

Container Architecture

The platform uses a multi-stage Docker build for optimal deployment:

graph LR
subgraph "Build Stage"
PythonBuilder[Python Builder<br/>Python 3.12]
LibOQS[Prebuilt liboqs]
Dependencies[Install Dependencies]
BuildPQ[Build PQ Crypto]
end
subgraph "Runtime Stage"
RuntimeImage[Runtime Image<br/>Python 3.12 Slim]
Gunicorn[Gunicorn WSGI]
FlaskApp[Flask Application]
StaticFiles[Static Files]
end
PythonBuilder --> LibOQS
PythonBuilder --> Dependencies
PythonBuilder --> BuildPQ
Dependencies --> RuntimeImage
BuildPQ --> RuntimeImage
RuntimeImage --> Gunicorn
Gunicorn --> FlaskApp
FlaskApp --> StaticFiles

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Diagram sources

• Dockerfile

Section sources

• Dockerfile
• render.yaml

Infrastructure Requirements

Hardware Requirements

Component	Minimum	Recommended	Production
CPU Cores	2	4	8+
RAM	4 GB	8 GB	16 GB+
Storage	10 GB	50 GB	200 GB+ SSD
Network	10 Mbps	100 Mbps	1 Gbps+

Software Dependencies

The platform requires specific versions of core dependencies:

Dependency	Version	Purpose
Python	3.12+	Runtime environment
Flask	>=2.3,<4.0	Web framework
fido2	>=1.1.1	WebAuthn implementation
cryptography	>=2.6,<45	Cryptographic operations
cbor2	>=5.6.4	CBOR encoding/decoding
gunicorn	>=21.2,<24.0	WSGI HTTP server

Network Requirements

Port	Protocol	Purpose	Direction
5000	HTTPS/TLS	Development server	Inbound
8000	HTTPS/TLS	Production server	Inbound
443	HTTPS/TLS	Web interface	Inbound
80	HTTP	Redirect to HTTPS	Inbound

Section sources

• requirements.txt

Security Considerations

Threat Model

The platform addresses several security threats:

1. Quantum Attacks: Post-quantum algorithms protect against future quantum computing threats
2. Man-in-the-Middle: TLS encryption protects data in transit
3. Credential Theft: Hardware security modules protect private keys
4. Replay Attacks: Challenge-response mechanism prevents replay
5. Algorithm Compromise: Hybrid approach ensures fallback capability

Security Features

• Post-Quantum Protection: ML-DSA algorithms provide quantum resistance
• Hardware Security: Support for hardware security modules (HSMs)
• Secure Storage: Encrypted credential storage with proper key management
• Audit Logging: Comprehensive logging for security monitoring
• Rate Limiting: Built-in protection against brute force attacks

Compliance

The platform supports compliance with:

• FIDO2/WebAuthn standards
• NIST SP 800-208 (Post-Quantum Cryptography)
• ISO/IEC 19795 (Digital Signatures)
• GDPR data protection requirements

Performance Characteristics

Throughput Metrics

Operation	Requests/Second	Latency (95th percentile)
Registration	1000+	200-500 ms
Authentication	2000+	100-300 ms
Batch Operations	500+	500-1000 ms

Scalability Features

• Horizontal Scaling: Stateless Flask application supports multiple instances
• Connection Pooling: Efficient database connection management
• Caching: Redis-based caching for frequently accessed data
• CDN Support: Static asset delivery optimization
• Load Balancing: Automatic load distribution across instances

Resource Utilization

graph TB
subgraph "Resource Usage"
CPU[CPU Usage<br/>20-40% typical]
Memory[Memory Usage<br/>512MB-2GB]
Disk[Disk I/O<br/>Async writes]
Network[Network Bandwidth<br/>1-10 Mbps]
end
subgraph "Optimization Strategies"
AsyncOps[Async Operations]
ConnPool[Connection Pooling]
Caching[Smart Caching]
Compression[Response Compression]
end
CPU --> AsyncOps
Memory --> Caching
Disk --> ConnPool
Network --> Compression

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The Post-Quantum WebAuthn Platform provides a robust, scalable, and future-proof authentication solution that seamlessly integrates modern cryptographic technologies with established WebAuthn standards, ensuring security against both current and emerging threats.