Editing Design/Stakeholder Requirements (StRS) (section)

= 4. Critical Quality Characteristics =

<span id="safety"></span>
== 4.1 Safety ==

<span id="system-safety"></span>
=== System Safety ===

* SAF-1: The system MUST protect users from deanonymization attacks.
* SAF-2: The system MUST prevent data loss and corruption.
* SAF-3: The system MUST maintain operational safety under stress.

<span id="data-safety"></span>
=== Data Safety ===

* SAF-4: The system MUST ensure data integrity and consistency.
* SAF-5: The system MUST prevent unauthorized data modification.
* SAF-6: The system MUST maintain secure backups where needed.

<span id="operational-safety"></span>
=== Operational Safety ===

* SAF-7: The system MUST fail safely under error conditions.
* SAF-8: The system MUST prevent cascading failures.
* SAF-9: The system MUST maintain safety during updates.

<span id="security-10"></span>
== 4.2 Security ==

<span id="network-security"></span>
=== Network Security ===

* SEC-1: The system MUST resist sophisticated traffic analysis attacks.
* SEC-2: The system MUST prevent Sybil & Eclipse attacks.
* SEC-3: The system MUST protect against denial of service.
* SEC-4: The system MUST implement secure routing protocols with path diversity.
* SEC-5: The system MUST support anonymous network routing capabilities.

<span id="data-security"></span>
=== Data Security ===

* SEC-6: The system MUST encrypt all (senstive) data.
* SEC-7: The system MUST implement secure (and distributed) key management.
* SEC-8: The system MUST prevent unauthorized access through zero-knowledge proofs.
* SEC-9: The system MUST support secure backup and recovery mechanisms.
* SEC-10: The system MUST implement perfect forward secrecy.

<span id="operational-security"></span>
=== Operational Security ===

* SEC-11: The system MUST detect and prevent attacks.
* SEC-12: The system MUST maintain security during partial network compromise.
* SEC-13: The system MUST support secure recovery procedures with minimal trust.
* SEC-14: The system MUST implement deterministic reproducible builds for verification.
* SEC-15: The system MUST be security audited.

<span id="privacy-3"></span>
== 4.3 Privacy ==

<span id="data-privacy"></span>
=== Data Privacy ===

* PRV-1: The system MUST minimize data collection and retention.
* PRV-2: The system MUST enable anonymous operations.
* PRV-3: The system MUST prevent correlation attacks.

<span id="communication-privacy"></span>
=== Communication Privacy ===

* PRV-4: The system MUST hide communication patterns.
* PRV-5: The system MUST protect metadata.
* PRV-6: The system MUST enable private group communication.

<span id="user-privacy"></span>
=== User Privacy ===

* PRV-7: The system MUST support pseudonymous identities.
* PRV-8: The system MUST enable selective disclosure.
* PRV-9: The system MUST prevent profile building.

<span id="usability-4"></span>
== 4.4 Usability ==

<span id="accessibility-2"></span>
=== Accessibility ===

* USB-1: The system MUST be usable by individuals with varying technical expertise.
* USB-2: The system MUST provide clear error messages and recovery options.
* USB-3: The system MUST support multiple languages and locales.

<span id="learnability"></span>
=== Learnability ===

* USB-4: The system MUST provide intuitive interfaces for common operations.
* USB-5: The system MUST include comprehensive user documentation.
* USB-6: The system MUST offer progressive complexity disclosure.

<span id="error-prevention"></span>
=== Error Prevention ===

* USB-7: The system MUST prevent common user errors.
* USB-8: The system MUST provide clear confirmation for critical actions.
* USB-9: The system MUST enable recovery from mistakes.

<span id="reliability-6"></span>
== 4.5 Reliability ==

<span id="system-reliability"></span>
=== System Reliability ===

* REL-1: The system MUST maintain service availability under adverse conditions.
* REL-2: The system MUST recover automatically from failures.
* REL-3: The system MUST preserve data integrity during disruptions.

<span id="network-reliability"></span>
=== Network Reliability ===

* REL-4: The system MUST handle network partitions gracefully.
* REL-5: The system MUST maintain service during node churn.
* REL-6: The system MUST provide reliable message delivery.

<span id="component-reliability"></span>
=== Component Reliability ===

* REL-7: The system MUST isolate component failures.
* REL-8: The system MUST support redundant operations.
* REL-9: The system MUST enable component replacement without disruption.

<span id="resilience"></span>
== 4.6 Resilience ==

<span id="adaptability"></span>
=== Adaptability ===

* RES-1: The system MUST adapt to changing network conditions.
* RES-2: The system MUST evolve with technological advances.
* RES-3: The system MUST support protocol upgrades.

<span id="survivability"></span>
=== Survivability ===

* RES-4: The system MUST survive targeted attacks.
* RES-5: The system MUST maintain core functions under stress.
* RES-6: The system MUST preserve critical data during failures.

<span id="recovery"></span>
=== Recovery ===

* RES-7: The system MUST restore service after disruptions.
* RES-8: The system MUST rebuild network connections automatically.
* RES-9: The system MUST recover from partial system failures.

<span id="other-quality-characteristics"></span>
== 4.7 Other Quality Characteristics ==

<span id="maintainability-5"></span>
=== Maintainability ===

* QC-1: The system MUST support modular updates and upgrades.
* QC-2: The system MUST enable component isolation for maintenance.
* QC-3: The system MUST provide diagnostic capabilities.

<span id="portability"></span>
=== Portability ===

*QC-4: The system MUST run on multiple platforms and devices.
* QC-5: The system MUST adapt to different runtime environments.
* QC-6: The system MUST support cross-platform deployment.

<span id="interoperability-4"></span>
=== Interoperability ===

*QC-7: The system MUST integrate with existing systems where needed.
* QC-8: The system MUST support standard protocols and formats.
* QC-9: The system MUST enable cross-system communication.

<span id="constraints-7"></span>