SFTP Management

SFTP Management Module: Comprehensive Technical Documentation

For The Satoshi Terminal

---

Table of Contents

1. Abstract

2. Architectural Overview

   • Secure Communication Protocol Stack

   • Asynchronous Data Flow Design

   • Subsystem Modularity

3. Connection Configuration

   • Advanced Authentication Mechanisms

   • Network Topology Considerations

   • SSH Session Layer Protocol Specifications

4. File Transfer Lifecycle

   • Session Negotiation and Key Exchange

   • Cryptographic Data Handling

   • Integrity Verification via MAC Algorithms

5. Advanced Automation and Scheduling

   • CRON-Compatible Recurrence Framework

   • Dependency-Driven Workflow Triggers

   • Multi-Dimensional Task Parallelization

6. Operational Diagnostics

   • Deep Packet Inspection for SFTP Layers

   • Network Latency Profiling and Optimization

   • Transfer Queue Contention Resolution

7. Security Framework

   • NIST-Compliant Key Rotation Policies

   • Elliptic Curve Cryptography Implementation

   • Hardening Against MITM and Replay Attacks

8. Integration Interfaces

   • RESTful API Endpoint Enumeration

   • Event-Driven Webhook Architecture

   • RPC-based Transfer Orchestration

9. Performance Tuning

   • Bandwidth Throttling and Prioritization

   • Dynamic Buffer Size Allocation

   • Multi-Threaded File Block Processing

10. Compliance and Auditability

    • PCI DSS Data Flow Mapping

    • SOX-Compliant Logging Infrastructure

    • ISO/IEC 27001 Alignment Metrics

11. Troubleshooting and Support Escalation

    • Low-Level Error Code Analysis

    • Configuration Anomaly Detection Algorithms

    • Tiered Support Procedures

12. Glossary of Technical Terms

13. Appendices

    • Supported Cipher Suites

    • RFC References

---

1. Abstract

The SFTP Management Module of The Satoshi Terminal represents an apex implementation of secure file transfer systems, utilizing SSH-2 (RFC 4251) as a foundational framework. Its architecture integrates cryptographic rigor with operational flexibility, ensuring robust, low-latency, and scalable data exchange mechanisms. This documentation elucidates every facet of its operation, optimized for technically advanced users and system architects.

---

2. Architectural Overview

2.1 Secure Communication Protocol Stack

• The module operates atop the SSH Transport Layer Protocol (RFC 4253), leveraging:

  • Diffie-Hellman Key Exchange (DHKE): Secures the pre-authentication handshake.

  • AES-GCM Encryption: Ensures high-speed, low-overhead payload encryption.

  • HMAC-SHA2: Protects data integrity through keyed hash algorithms.

2.2 Asynchronous Data Flow Design

• The system employs event-driven I/O mechanisms (e.g., epoll/kqueue):

  • Non-blocking Sockets: Minimize thread contention.

  • Transfer Pipelining: Parallelizes file segmentation for optimized throughput.

2.3 Subsystem Modularity

• Connection Manager: Stateless design for rapid reinitialization during disruptions.

• Scheduler Kernel: CRON-enhanced internal timing engine.

• Audit Layer: Immutable append-only logging for regulatory compliance.

---

3. Connection Configuration

3.1 Advanced Authentication Mechanisms

• Public Key Authentication (RFC 4252):

  • RSA (2048-bit minimum) and ECDSA support.

  • Configurable certificate-based trust anchors.

• Host-Based Authentication:

  • Leverages the client's machine identity via FQDN mapping.

• Password-Based Authentication: Secured with bcrypt hashing and challenge-response protocols.

3.2 Network Topology Considerations

• NAT Traversal: Automatic handling of network address translations.

• IPv6 Compatibility: Dual-stack configurations for hybrid environments.

• TLS Layer Integration: Optional encapsulation for added transport security.

3.3 SSH Session Layer Protocol Specifications

• Adaptive compression via zlib reduces payload overhead.

• Key re-exchange triggers every 1 GB or 60 minutes (configurable).

---

4. File Transfer Lifecycle

4.1 Session Negotiation and Key Exchange

1. Client Init Message (SSH_MSG_KEXINIT): Initiates cryptographic parameters.

2. Server Response: Selects compatible cipher suite.

3. Session Confirmation: Establishes bidirectional encryption.

4.2 Cryptographic Data Handling

• Uses AES-256-GCM for payloads with inline MAC verification.

• All keys derived via HKDF (HMAC-based Key Derivation Function).

4.3 Integrity Verification via MAC Algorithms

• SHA2-256 ensures tamper-evident data blocks.

• Configurable retries for hash mismatches.

---

5. Advanced Automation and Scheduling

5.1 CRON-Compatible Recurrence Framework

• Enables granular scheduling with UNIX CRON syntax.

• Supports "at least once" delivery guarantees for critical transfers.

5.2 Dependency-Driven Workflow Triggers

• Triggers include:

  • File system events (inotify/FSChange hooks).

  • RESTful API callbacks.

  • Log-based triggers for dynamic workflow reconfiguration.

5.3 Multi-Dimensional Task Parallelization

• Uses weighted round-robin algorithms to allocate resources across tasks.

• Isolates I/O threads to reduce CPU-bound contention.

---

6. Operational Diagnostics

6.1 Deep Packet Inspection for SFTP Layers

• Analyzes SSH_MSG_CHANNEL_DATA packets for performance bottlenecks.

• Identifies protocol anomalies (e.g., undefined opcode requests).

6.2 Network Latency Profiling and Optimization

• Measures RTT (Round-Trip Time) per connection.

• Dynamically adjusts TCP window size based on observed throughput.

6.3 Transfer Queue Contention Resolution

• Implements priority inversion mitigation.

• Supports dynamic queue reordering based on SLA parameters.

---

7. Security Framework

7.1 NIST-Compliant Key Rotation Policies

• Automates private key lifecycle with configurable rotation intervals.

• Supports "grace period" key overlap for seamless transitions.

7.2 Elliptic Curve Cryptography Implementation

• ECDH over P-256 (prime256v1) ensures high-security with minimal CPU impact.

7.3 Hardening Against MITM and Replay Attacks

• Session replay prevented via nonce-based sequence numbering.

• Mitigates downgrade attacks with enforced cipher suite pinning.

---

8. Integration Interfaces

8.1 RESTful API Endpoint Enumeration

• POST /api/v1/sftp/upload: Initiates secure file uploads.

• GET /api/v1/sftp/status: Fetches real-time connection diagnostics.

• DELETE /api/v1/sftp/session: Terminates live sessions forcefully.

8.2 Event-Driven Webhook Architecture

• Pushes updates for:

  • Transfer completion events.

  • Authentication anomalies.

  • SLA breach notifications.

8.3 RPC-Based Transfer Orchestration

• Uses gRPC for high-throughput, low-latency task management.

---

9. Performance Tuning

9.1 Bandwidth Throttling and Prioritization

• Rate limiting enforced via token bucket algorithms.

• QoS tagging for prioritizing critical transfers.

9.2 Dynamic Buffer Size Allocation

• Adaptive resizing based on:

  • Current congestion levels.

  • Packet loss statistics.

9.3 Multi-Threaded File Block Processing

• Implements scatter/gather I/O to maximize disk and network concurrency.

---

10. Compliance and Auditability

10.1 PCI DSS Data Flow Mapping

• Provides comprehensive transfer flowcharts.

• Verifies encryption at all stages of the pipeline.

10.2 SOX-Compliant Logging Infrastructure

• Timestamped logs with cryptographic integrity checks.

• Audit trails for user actions and automated processes.

10.3 ISO/IEC 27001 Alignment Metrics

• Automated checks for compliance with Annex A.10 (Cryptography).

---

11. Troubleshooting and Support Escalation

11.1 Low-Level Error Code Analysis

• Error codes (e.g., SSH_DISCONNECT_HOST_NOT_ALLOWED) mapped to resolution guides.

11.2 Configuration Anomaly Detection Algorithms

• Detects misconfigurations in:

  • Key formats.

  • Network policies.

11.3 Tiered Support Procedures

• Tier 1: Initial diagnosis using built-in tools.

• Tier 2: Escalation to backend specialists.

• Tier 3: Collaboration with external server administrators.

---

12. Glossary of Technical Terms

---

13. Appendices

Supported Cipher Suites

• AES-256-GCM

• ChaCha20-Poly1305

• AES-128-CTR

RFC References

• RFC 4251 (SSH Protocol Architecture)

• RFC 4253 (SSH Transport Layer Protocol)

---