EN-304-617_v0.0.6.md

1. Identify critical data types requiring local caching (preferences, configuration, essential state) → Critical data cached locally
2. Verify browser caches critical data locally when RDPS accessible → Cached data accessible offline
3. Disconnect RDPS connectivity and verify cached data remains accessible → Browser functions with cached data
4. Test that browser continues functioning with cached data during outage → Staleness policies enforced
5. Verify cache staleness policies implemented (e.g., maximum cache age) → Users notified of stale data
6. Test that stale cached data is marked and users notified of potential outdatedness → Cache synchronizes on reconnection
7. Restore RDPS connectivity and verify cache synchronization occurs → Conflict resolution implemented
8. Test conflict resolution when local cached data differs from RDPS data → Cache size limits enforced
9. Verify cache size limits enforced to prevent excessive local storage consumption → Eviction policies functional
10. Test cache eviction policies (LRU, priority-based) when limits reached → Cache integrity maintained

**Pass Criteria**: Critical data cached AND accessible offline AND staleness detection AND synchronization on reconnection

**Fail Criteria**: No caching OR cached data inaccessible offline OR no staleness detection OR synchronization fails

**Evidence**: Cache storage verification, offline functionality testing, staleness policy documentation, synchronization logs, conflict resolution testing, cache size limit enforcement

**References**:

- HTTP Caching: https://developer.mozilla.org/en-US/docs/Web/HTTP/Caching
- Cache-Control Best Practices: https://web.dev/http-cache/
- Offline First Design: https://offlinefirst.org/
- Service Workers Caching: https://web.dev/service-workers-cache-storage/

### Assessment: RDPS-REQ-8 (Secure authentication for RDPS access)

**Reference**: RDPS-REQ-8 - Browser shall implement secure authentication for RDPS access

**Given**: A conformant browser with RDPS-1 or higher capability

**Task**: RDPS authentication prevents unauthorized access to user data, enforces multi-tenancy boundaries, and enables audit trails linking actions to identities. Weak authentication enables data breaches, privacy violations, and unauthorized modifications. Strong authentication with secure credential storage, session management, token refresh, and multi-factor support where appropriate ensures only authorized browsers access RDPS data.

**Verification**:

1. Verify browser implements secure authentication mechanism (OAuth 2.0, OIDC, or equivalent) → Secure authentication mechanism implemented
2. Test that authentication credentials stored securely (encrypted, OS keychain integration) → Credentials stored securely
3. Verify authentication tokens time-limited (expiration enforced) → Tokens time-limited with expiration
4. Test token refresh mechanism for long-lived sessions → Token refresh functional
5. Verify expired tokens handled gracefully (automatic refresh or re-authentication) → Expired token handling graceful
6. Test that authentication failures trigger clear user prompts → Authentication failures prompt user
7. Verify session binding to prevent token theft attacks → Session binding prevents theft
8. Test that authentication tokens transmitted only over encrypted channels → Tokens transmitted encrypted only
9. Verify logout functionality properly invalidates tokens → Logout invalidates tokens
10. Test multi-factor authentication support if required for sensitive data → MFA supported where required

**Pass Criteria**: Strong authentication mechanism AND secure credential storage AND token expiration AND encrypted transmission

**Fail Criteria**: Weak authentication OR plaintext credentials OR no token expiration OR unencrypted token transmission

**Evidence**: Authentication mechanism documentation, credential storage analysis, token lifecycle testing, session security verification, logout effectiveness testing

**References**:

- OAuth 2.0 RFC 6749: https://www.rfc-editor.org/rfc/rfc6749
- OpenID Connect: https://openid.net/connect/
- OWASP Authentication Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/Authentication_Cheat_Sheet.html
- Token-Based Authentication: https://auth0.com/learn/token-based-authentication-made-easy/

### Assessment: RDPS-REQ-9 (Certificate pinning for RDPS)

**Reference**: RDPS-REQ-9 - Browser shall validate server certificates and enforce certificate pinning for RDPS

**Given**: A conformant browser with RDPS-1 or higher capability

**Task**: Certificate pinning prevents man-in-the-middle attacks exploiting compromised Certificate Authorities by validating RDPS endpoints against pre-configured expected certificates or public keys. Without pinning, attackers with rogue CA certificates can intercept RDPS communications despite TLS encryption. Certificate pinning with backup pins, pin rotation procedures, and failure reporting provides defense-in-depth against sophisticated attacks targeting RDPS infrastructure.

**Verification**:

1. Review browser configuration for RDPS certificate pins (leaf cert, intermediate, or public key hashes) → Certificate pins configured
2. Test successful RDPS connection with correctly pinned certificate → Correctly pinned certificates accepted
3. Attempt connection with valid but unpinned certificate and verify rejection → Unpinned certificates rejected
4. Test that pinning failure triggers clear error without allowing connection → Pinning failures block connection
5. Verify backup pins configured to prevent operational lockout → Backup pins prevent lockout
6. Test pin rotation procedure during certificate renewal → Pin rotation procedure documented
7. Verify pinning failures reported to manufacturer for monitoring → Failures reported for monitoring
8. Test that pin validation occurs before establishing data connection → Validation occurs before data connection
9. Verify pin configuration immutable by web content or local tampering → Pin configuration tamper-resistant
10. Test graceful degradation if pinning causes connectivity issues (with user consent) → Graceful degradation with user consent

**Pass Criteria**: Certificate pinning enforced AND backup pins configured AND rotation procedure documented AND failures reported

**Fail Criteria**: No pinning OR single point of failure (no backup pins) OR no rotation procedure OR failures not reported

**Evidence**: Certificate pin configuration, pinning enforcement testing, backup pin verification, rotation procedure documentation, failure reporting logs

**References**:

- RFC 7469 Public Key Pinning: https://www.rfc-editor.org/rfc/rfc7469
- OWASP Certificate Pinning: https://owasp.org/www-community/controls/Certificate_and_Public_Key_Pinning
- Certificate Pinning Best Practices: https://noncombatant.org/2015/05/01/about-http-public-key-pinning/
- Chrome Certificate Pinning: https://www.chromium.org/Home/chromium-security/security-faq/

### Assessment: RDPS-REQ-10 (RDPS connection timeout controls)

**Reference**: RDPS-REQ-10 - Browser shall implement timeout controls for RDPS connections

**Given**: A conformant browser with RDPS-1 or higher capability

**Task**: Connection timeouts prevent browsers from hanging indefinitely on unresponsive RDPS endpoints due to network issues, server failures, or denial-of-service attacks. Without timeouts, user experience degrades as browser features become non-responsive waiting for RDPS responses. Appropriate timeout values balanced between network latency tolerance and responsiveness enable reliable RDPS operations with graceful failure handling.

**Verification**:

1. Review browser RDPS timeout configuration (connection timeout, read timeout) → Connection timeout configured appropriately
2. Test connection establishment timeout (e.g., 30 seconds for initial connection) → Read timeout enforced
3. Simulate slow server response and verify read timeout enforced (e.g., 60 seconds) → Timeouts trigger graceful errors
4. Test that timeout triggers graceful error handling (not crash or hang) → Users notified with actionable messages
5. Verify user notified of timeout with actionable message → Timeout values network-appropriate
6. Test timeout values appropriate for expected network conditions → Different timeouts for operation criticality
7. Verify different timeout values for critical vs non-critical operations → Valid slow operations not aborted
8. Test that timeouts don't prematurely abort valid slow operations → Enterprise timeout configuration available
9. Verify timeout configuration adjustable for enterprise deployments → Behavior consistent across networks
10. Test timeout behavior under various network conditions (WiFi, cellular, slow networks) → No hangs or crashes on timeout

**Pass Criteria**: Connection and read timeouts configured AND graceful error handling AND user notification AND enterprise configurability

**Fail Criteria**: No timeouts OR hangs on unresponsive servers OR no user notification OR timeouts too aggressive

**Evidence**: Timeout configuration documentation, timeout enforcement testing, error handling verification, user notification screenshots, network condition testing results

**References**:

- HTTP Timeouts: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Keep-Alive
- Network Timeout Best Practices: https://www.nginx.com/blog/performance-tuning-tips-tricks/
- Resilient System Design: https://aws.amazon.com/builders-library/timeouts-retries-and-backoff-with-jitter/

### Assessment: RDPS-REQ-11 (RDPS connectivity failure logging)

**Reference**: RDPS-REQ-11 - Browser shall log RDPS connectivity failures and errors

**Given**: A conformant browser with RDPS-1 or higher capability

**Task**: Comprehensive RDPS failure logging enables troubleshooting, performance monitoring, security incident detection, and reliability improvement. Without detailed logs, diagnosing RDPS issues becomes impossible, preventing root cause analysis and remediation. Structured logging with error details, timestamps, retry attempts, and contextual information supports operational visibility and continuous improvement.

**Verification**:

1. Simulate various RDPS failure scenarios (network timeout, DNS failure, connection refused, TLS error) → All failure types logged
2. Verify each failure type logged with appropriate severity level → Appropriate severity levels assigned
3. Confirm logs include timestamp, error type, RDPS endpoint, and failure reason → Logs include complete metadata
4. Test that retry attempts logged with attempt number and delay → Retry attempts documented
5. Verify authentication failures logged separately with rate limiting (prevent log flooding) → Authentication failures logged with rate limiting
6. Test that logs accessible to administrators for troubleshooting → Logs accessible to administrators
7. Verify user privacy protected (no sensitive data in logs) → User privacy protected
8. Test log rotation to prevent unbounded growth → Log rotation implemented
9. Verify critical failures trigger alerts or prominent log markers → Critical failures marked/alerted
10. Test log export capability for analysis tools → Export capability available

**Pass Criteria**: All failure types logged AND complete metadata AND privacy protected AND log management implemented

**Fail Criteria**: Failures not logged OR insufficient metadata OR sensitive data exposed OR unbounded log growth

**Evidence**: Log samples for various failure types, log schema documentation, privacy analysis, log rotation verification, export functionality testing

**References**:

- OWASP Logging Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/Logging_Cheat_Sheet.html
- Log Management Best Practices: https://www.sans.org/white-papers/33528/

### Assessment: RDPS-REQ-12 (Graceful functionality degradation when RDPS unavailable)

**Reference**: RDPS-REQ-12 - Browser shall gracefully degrade functionality when RDPS unavailable

**Given**: A conformant browser with RDPS-1 or higher capability

**Task**: Graceful degradation ensures browsers remain usable during RDPS outages by maintaining core functionality while clearly communicating reduced capabilities to users. Without graceful degradation, RDPS failures cause complete feature unavailability, error messages, or undefined behavior confusing users. Intelligent degradation with feature prioritization, offline alternatives, and status communication balances service continuity with user expectations during infrastructure disruptions.

**Verification**:

1. Identify browser features dependent on RDPS connectivity → Core browser functionality maintained during outage
2. Document expected degradation behavior for each RDPS-dependent feature → RDPS-dependent features degrade gracefully
3. Simulate RDPS unavailability and verify core browser functionality remains operational → Users notified clearly of reduced functionality
4. Test that RDPS-dependent features degrade gracefully (don't crash or show errors) → Offline alternatives activate automatically
5. Verify users receive clear notification of reduced functionality with explanation → Features restore automatically on reconnection
6. Test that cached/offline alternatives activate automatically when RDPS unavailable → Degradation state visible in UI
7. Verify degraded features automatically restore when RDPS connectivity returns → No data loss during degradation
8. Test that degradation state visible in browser UI (status indicator, settings) → Manual retry available for operations
9. Verify no data loss occurs during degradation period → Degradation behavior matches documentation
10. Test user ability to manually retry RDPS-dependent operations → User experience remains acceptable

**Pass Criteria**: Core functionality maintained AND graceful degradation implemented AND user notifications clear AND automatic restoration on reconnection

**Fail Criteria**: Browser crashes OR features fail with errors OR no user notification OR functionality doesn't restore

**Evidence**: Degradation behavior documentation, offline functionality testing, user notification screenshots, reconnection restoration verification, data integrity testing

**References**:

- Graceful Degradation Patterns: https://developer.mozilla.org/en-US/docs/Glossary/Graceful_degradation
- Resilient Web Design: https://resilientwebdesign.com/
- Offline First: https://offlinefirst.org/

### Assessment: RDPS-REQ-13 (Credentials protection from RDPS exposure)

**Reference**: RDPS-REQ-13 - Browser shall not expose sensitive authentication credentials to RDPS

**Given**: A conformant browser with RDPS-1 or higher capability

**Task**: Authentication credentials (passwords, tokens, keys) shall never be transmitted to or stored in RDPS to prevent credential theft, unauthorized access, and account compromise. Even with encrypted transmission, storing credentials in RDPS creates centralized breach targets and insider threat risks. The application of zero-knowledge architecture where only derived authentication proofs or encrypted credentials (with client-side keys) are shared ensures RDPS compromise cannot directly expose user credentials.

**Verification**:

1. Review RDPS data inventory and verify no passwords or plaintext credentials transmitted → No plaintext credentials in RDPS traffic
2. Capture network traffic during authentication and verify credentials not sent to RDPS → Only tokens or derived proofs transmitted
3. Test that only authentication tokens or derived proofs transmitted to RDPS → Credentials encrypted if stored remotely
4. Verify RDPS receives hashed/encrypted credentials at most (not plaintext) → Encryption keys remain client-side
5. Test that cryptographic keys for credential encryption stored client-side only → Password changes handled locally
6. Verify password changes occur locally without RDPS involvement in plaintext handling → RDPS cannot authenticate independently
7. Test that RDPS cannot authenticate users without client cooperation → Recovery mechanisms protect credentials
8. Verify credential recovery/reset mechanisms don't expose credentials to RDPS → Breach simulation confirms credential safety
9. Test that RDPS data breach simulation doesn't reveal credentials → Documentation explicit about credential handling
10. Verify security documentation explicitly states credentials never sent to RDPS → Zero-knowledge architecture implemented

**Pass Criteria**: No plaintext credentials to RDPS AND only tokens/proofs transmitted AND encryption keys client-side AND zero-knowledge architecture

**Fail Criteria**: Credentials sent to RDPS OR RDPS can authenticate users OR encryption keys on server OR plaintext storage

**Evidence**: Network traffic analysis showing no credentials, RDPS data inventory review, encryption key location verification, breach simulation results, security architecture documentation

**References**:

- Zero-Knowledge Architecture: https://en.wikipedia.org/wiki/Zero-knowledge_proof
- Credential Storage Best Practices: https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html
- Client-Side Encryption: https://www.owasp.org/index.php/Cryptographic_Storage_Cheat_Sheet

### Assessment: RDPS-REQ-14 (RDPS request rate limiting)

**Reference**: RDPS-REQ-14 - Browser shall implement rate limiting for RDPS requests

**Given**: A conformant browser with RDPS-1 or higher capability

**Task**: Rate limiting prevents browsers from overwhelming RDPS infrastructure with excessive requests due to bugs, loops, or malicious content, protecting service availability for all users. Without rate limiting, single misbehaving clients can cause denial of service, increase costs, and degrade performance for legitimate users. Client-side rate limiting with request throttling, burst allowances, and backoff on rate limit errors ensures responsible RDPS resource consumption.

**Verification**:

1. Review browser rate limiting configuration for RDPS requests → Rate limiting configured appropriately
2. Test normal operation remains within rate limits → Normal operation within limits
3. Trigger rapid RDPS requests (e.g., through script loop) and verify throttling applied → Excessive requests throttled
4. Test that rate limiting implemented per-operation type (different limits for different APIs) → Per-operation type limits enforced
5. Verify burst allowances permit short spikes without immediate throttling → Burst allowances functional
6. Test that rate limit exceeded triggers exponential backoff (not immediate retry) → Backoff on limit exceeded
7. Verify user notified when rate limits significantly impact functionality → User notification for significant impacts
8. Test that rate limits documented for developers/administrators → Rate limits documented
9. Verify enterprise deployments can adjust rate limits for their needs → Enterprise configurability available
10. Test that rate limiting doesn't prevent legitimate high-frequency operations → Legitimate operations not blocked

**Pass Criteria**: Rate limiting implemented AND per-operation limits AND burst handling AND backoff on exceeded limits

**Fail Criteria**: No rate limiting OR single global limit OR no burst handling OR immediate retry on limit

**Evidence**: Rate limiting configuration documentation, throttling test results, burst handling verification, backoff behavior analysis, enterprise configuration options

**References**:

- API Rate Limiting: https://cloud.google.com/architecture/rate-limiting-strategies-techniques
- Token Bucket Algorithm: https://en.wikipedia.org/wiki/Token_bucket
- Rate Limiting Best Practices: https://www.keycdn.com/support/rate-limiting

### Assessment: RDPS-REQ-15 (RDPS data validation before processing)

**Reference**: RDPS-REQ-15 - Browser shall validate all data received from RDPS before processing

**Given**: A conformant browser with RDPS-1 or higher capability

**Task**: Comprehensive data validation prevents compromised or malicious RDPS from injecting harmful data into browsers, causing security vulnerabilities, crashes, or unexpected behavior. Without validation, attackers who compromise RDPS can exploit browsers by sending malformed data, injection attacks, or excessive payloads. Multi-layer validation with schema enforcement, type checking, size limits, and sanitization provides defense-in-depth against RDPS compromise.

**Verification**:

1. Review RDPS data validation implementation for all data types → Schema validation enforced
2. Test that browser validates data schema matches expected format → Type checking comprehensive
3. Verify type checking enforced (strings, numbers, booleans validated correctly) → Size limits prevent overflow
4. Test size limits prevent excessive data payloads from RDPS → Content sanitization applied
5. Verify data sanitization for HTML/JavaScript content from RDPS → Malformed data rejected gracefully
6. Test that malformed JSON/data rejected with appropriate errors → Unexpected fields handled safely
7. Verify unexpected fields in RDPS responses ignored or flagged → NULL/undefined handling secure
8. Test that NULL/undefined values handled safely → Numeric range validation implemented
9. Verify numeric ranges validated (no integer overflow, invalid values) → Validation failures logged
10. Test that validation failures logged for security monitoring → Defense-in-depth validation layers

**Pass Criteria**: Schema validation enforced AND type checking comprehensive AND size limits applied AND sanitization for risky content

**Fail Criteria**: No validation OR incomplete type checking OR no size limits OR no sanitization

**Evidence**: Validation implementation review, malformed data rejection testing, injection attempt results, size limit enforcement verification, validation failure logs

**References**:

- Input Validation: https://cheatsheetseries.owasp.org/cheatsheets/Input_Validation_Cheat_Sheet.html
- JSON Schema Validation: https://json-schema.org/
- Data Sanitization: https://cheatsheetseries.owasp.org/cheatsheets/XSS_Filter_Evasion_Cheat_Sheet.html

### Assessment: RDPS-REQ-16 (Data at rest encryption in RDPS storage)

**Reference**: RDPS-REQ-16 - Browser shall encrypt sensitive data at rest in RDPS storage

**Given**: A conformant browser with RDPS-2 or higher capability

**Task**: Encryption at rest protects RDPS data from unauthorized access through physical media theft, backup compromises, or infrastructure breaches. Without encryption, attackers gaining physical or logical access to RDPS storage can read all user data directly. Strong encryption with secure key management, algorithm compliance (AES-256), and access controls ensures data confidentiality even if storage media compromised.

**Verification**:

1. Review RDPS storage architecture and encryption implementation → Sensitive data encrypted at rest
2. Verify sensitive data encrypted before writing to storage → Strong encryption algorithm used (AES-256)
3. Test that encryption uses strong algorithms (AES-256-GCM or equivalent) → Keys stored separately from data
4. Verify encryption keys stored separately from encrypted data → Secure key management system
5. Test that encryption keys managed through secure key management system → Key rotation implemented
6. Verify key rotation procedures documented and implemented → Backups also encrypted
7. Test that backups also encrypted with appropriate key management → Key access requires authentication
8. Verify access to encryption keys requires authentication and authorization → Documentation comprehensive
9. Test that encryption at rest documented in security architecture → Regulatory compliance verified
10. Verify compliance with regulatory requirements (GDPR, applicable sector regulations) → Encryption covers all sensitive data types

**Pass Criteria**: AES-256 or equivalent encryption AND separate key storage AND key management system AND backup encryption

**Fail Criteria**: No encryption OR weak algorithms OR keys with data OR no key management

**Evidence**: Encryption architecture documentation, algorithm verification, key storage analysis, key management system review, backup encryption testing, compliance attestation

**References**:

- NIST Encryption Standards: https://csrc.nist.gov/publications/detail/sp/800-175b/final
- Data at Rest Encryption: https://cloud.google.com/security/encryption-at-rest
- Key Management Best Practices: https://csrc.nist.gov/publications/detail/sp/800-57-part-1/rev-5/final

### Assessment: RDPS-REQ-17 (Mutual TLS authentication for RDPS)

**Reference**: RDPS-REQ-17 - Browser shall implement mutual TLS authentication for RDPS connections

**Given**: A conformant browser with RDPS-2 or higher capability

**Task**: Mutual TLS (mTLS) provides bidirectional authentication where both browser and RDPS server verify each other's identity through certificates, preventing unauthorized clients from accessing RDPS and unauthorized servers from impersonating RDPS. Standard TLS only authenticates the server, allowing any client to connect. mTLS with client certificates, certificate validation, and revocation checking ensures only authorized browsers access RDPS infrastructure.

**Verification**:

1. Verify browser configured with client certificate for RDPS authentication → Browser has valid client certificate
2. Test successful mTLS connection with valid client and server certificates → mTLS connection successful with both certs
3. Attempt connection without client certificate and verify RDPS rejects connection → Missing client certificate rejected
4. Test with expired client certificate and confirm connection rejected → Expired client certificates rejected
5. Verify client certificate validation enforced on RDPS side → RDPS validates client certificates
6. Test client certificate revocation checking (CRL or OCSP) → Revocation checking functional
7. Verify client certificate securely stored (encrypted, OS keychain) → Client certificate stored securely
8. Test client certificate renewal process → Renewal process documented
9. Verify server still validates client certificate chain (intermediates, root) → Full chain validation performed
10. Test that mTLS protects against man-in-the-middle even with compromised CA → Enhanced MITM protection

**Pass Criteria**: Client certificates configured AND mTLS enforced AND revocation checking AND secure certificate storage

**Fail Criteria**: No client certificates OR mTLS not enforced OR no revocation checking OR insecure storage

**Evidence**: mTLS configuration documentation, connection testing with various certificate states, revocation checking verification, certificate storage analysis, MITM attack prevention testing

**References**:

- Mutual TLS: https://www.cloudflare.com/learning/access-management/what-is-mutual-tls/
- RFC 8446 TLS 1.3: https://www.rfc-editor.org/rfc/rfc8446
- Client Certificate Authentication: https://docs.microsoft.com/en-us/azure/application-gateway/mutual-authentication-overview

### Assessment: RDPS-REQ-18 (Redundant data copies for recovery)

**Reference**: RDPS-REQ-18 - Browser shall maintain redundant copies of critical data for recovery

**Given**: A conformant browser with RDPS-2 or higher capability

**Task**: Redundant data storage protects against data loss from hardware failures, corruption, ransomware, or operational errors by maintaining multiple synchronized copies across independent storage systems. Without redundancy, single points of failure can cause permanent data loss, service disruption, and user impact. Multi-region or multi-datacenter replication with consistency guarantees, automatic failover, and integrity verification ensures data availability and durability.

**Verification**:

1. Review RDPS architecture documentation for redundancy implementation → Critical data has multiple replicas
2. Verify critical data replicated to at least 2 independent storage systems → Replicas in independent failure domains
3. Test that replicas maintained in different failure domains (servers, racks, datacenters) → Replication mechanism documented
4. Verify replication synchronization mechanism (synchronous or asynchronous) → Data consistency maintained
5. Test data consistency between replicas → Automatic failover functional
6. Simulate primary storage failure and verify automatic failover to replica → Recovery from replica successful
7. Test data recovery from replica maintains integrity → Replication lag monitored
8. Verify replication lag monitored and alerted if excessive → Corruption detection and correction
9. Test that replica corruption detected and corrected → Geo-distribution implemented if required
10. Verify geo-distribution of replicas if required for disaster recovery → Recovery tested regularly

**Pass Criteria**: Multiple independent replicas AND different failure domains AND automatic failover AND consistency maintained

**Fail Criteria**: Single copy only OR replicas in same failure domain OR no failover OR consistency not guaranteed

**Evidence**: Architecture diagrams showing redundancy, replica configuration documentation, failover testing results, consistency verification, recovery procedure testing

**References**:

- Database Replication: https://en.wikipedia.org/wiki/Replication_(computing)
- AWS Multi-Region Architecture: https://aws.amazon.com/blogs/architecture/disaster-recovery-dr-architecture-on-aws-part-i-strategies-for-recovery-in-the-cloud/
- Data Redundancy Best Practices: https://cloud.google.com/architecture/dr-scenarios-planning-guide

### Assessment: RDPS-REQ-19 (Data recovery from backups with integrity verification)

**Reference**: RDPS-REQ-19 - Browser shall support data recovery from backups with integrity verification

**Given**: A conformant browser with RDPS-2 or higher capability

**Task**: Backup recovery enables restoration from data corruption, accidental deletion, ransomware, or catastrophic failures by maintaining historical data snapshots with integrity guarantees. Without verified backups, recovery attempts may restore corrupted data, incomplete datasets, or tampered backups. Automated backup with encryption, integrity verification, recovery testing, and documented procedures ensures reliable data restoration when needed.

**Verification**:

1. Review backup strategy documentation (frequency, retention, scope) → Automated backups on schedule
2. Verify backups created automatically on defined schedule → Integrity verification implemented
3. Test backup integrity verification using checksums or cryptographic hashes → Backups encrypted at rest
4. Verify backups encrypted at rest with separate key management → All critical data backed up
5. Test backup completeness (all critical data included) → Recovery successful in simulation
6. Simulate data loss scenario and perform recovery from backup → Recovered data integrity verified
7. Verify recovered data integrity matches pre-loss state → Point-in-time recovery functional
8. Test point-in-time recovery to specific timestamp → Retention policy enforced
9. Verify backup retention policy enforced (old backups purged appropriately) → Recovery procedures documented
10. Test that recovery procedures documented and tested regularly → Regular recovery testing performed

**Pass Criteria**: Automated backups AND integrity verification AND successful recovery testing AND encryption at rest

**Fail Criteria**: Manual backups only OR no integrity verification OR recovery not tested OR unencrypted backups

**Evidence**: Backup strategy documentation, integrity verification logs, recovery test results, encryption verification, retention policy configuration

**References**:

- Backup and Recovery: https://csrc.nist.gov/publications/detail/sp/800-34/rev-1/final
- 3-2-1 Backup Rule: https://www.backblaze.com/blog/the-3-2-1-backup-strategy/
- Backup Integrity: https://www.sans.org/white-papers/36607/

### Assessment: RDPS-REQ-20 (Data retention policies with secure deletion)

**Reference**: RDPS-REQ-20 - Browser shall implement data retention policies with secure deletion

**Given**: A conformant browser with RDPS-2 or higher capability

**Task**: Data retention policies ensure compliance with regulations (GDPR right to erasure, data minimization), reduce security exposure from storing unnecessary data, and manage storage costs. Without enforced retention and secure deletion, RDPS accumulates excessive personal data, violates privacy regulations, and creates larger breach targets. Automated retention with secure multi-pass deletion, deletion verification, and audit logging ensures compliant data lifecycle management.

**Verification**:

1. Review data retention policy documentation for all RDPS data types → Retention policies documented comprehensively
2. Verify retention periods defined per data classification and regulatory requirements → Retention periods per data type defined
3. Test automated deletion after retention period expires → Automated deletion implemented
4. Verify secure deletion prevents data recovery (multi-pass overwrite or cryptographic erasure) → Secure deletion prevents recovery
5. Test that deletion requests from users processed within regulatory timeframes → User deletion requests honored timely
6. Verify deletion confirmation provided to users → Deletion confirmation provided
7. Test that deleted data removed from backups per retention policy → Backups also cleaned per policy
8. Verify deletion logged for audit and compliance purposes → Deletion audit trail maintained
9. Test that related data (indexes, caches, logs) also deleted → Related data deleted completely
10. Verify regulatory compliance (GDPR Article 17, CCPA) demonstrated → Regulatory compliance verified

**Pass Criteria**: Retention policies defined AND automated deletion AND secure erasure AND audit logging

**Fail Criteria**: No retention policies OR manual deletion only OR recoverable after deletion OR no audit trail

**Evidence**: Retention policy documentation, automated deletion verification, secure erasure testing, deletion audit logs, regulatory compliance attestation

**References**:

- GDPR Right to Erasure: https://gdpr-info.eu/art-17-gdpr/
- NIST Data Sanitization: https://csrc.nist.gov/publications/detail/sp/800-88/rev-1/final
- Secure Data Deletion: https://www.usenix.org/legacy/event/fast11/tech/full_papers/Wei.pdf

### Assessment: RDPS-REQ-21 (Per-user per-origin access controls)

**Reference**: RDPS-REQ-21 - Browser shall enforce access controls on RDPS data per-user and per-origin

**Given**: A conformant browser with RDPS-2 or higher capability

**Task**: Granular access controls prevent unauthorized data access across user boundaries and origin boundaries, enforcing multi-tenancy isolation and same-origin policy in RDPS storage. Without strict access controls, compromised users or origins can access other users' data, violating privacy and security. Role-based access control (RBAC) or attribute-based access control (ABAC) with authentication, authorization, and audit trails ensures proper data isolation.

**Verification**:

1. Review RDPS access control model (RBAC, ABAC, or equivalent) → Access control model documented
2. Test that User A cannot access User B's RDPS data → Cross-user access blocked
3. Verify origin-based isolation (origin A cannot access origin B's data) → Cross-origin access prevented
4. Test authentication required before any RDPS data access → Authentication enforced universally
5. Verify authorization checks performed for every data operation → Authorization per-operation checked
6. Test access control enforcement at database/storage layer (not just application) → Storage-layer enforcement implemented
7. Verify access control bypass attempts logged and blocked → Bypass attempts logged and blocked
8. Test that administrators have appropriate elevated access with audit logging → Administrator access audited
9. Verify principle of least privilege applied (minimal necessary access granted) → Least privilege enforced
10. Test access controls survive privilege escalation attempts → Privilege escalation prevented

**Pass Criteria**: Per-user isolation enforced AND per-origin isolation enforced AND storage-layer controls AND bypass prevention

**Fail Criteria**: Cross-user access possible OR cross-origin access allowed OR application-only controls OR no bypass detection

**Evidence**: Access control model documentation, cross-user access testing, cross-origin isolation verification, privilege escalation testing, audit logs

**References**:

- RBAC: https://csrc.nist.gov/projects/role-based-access-control
- OWASP Access Control: https://cheatsheetseries.owasp.org/cheatsheets/Authorization_Cheat_Sheet.html
- Multi-Tenancy Security: https://www.microsoft.com/en-us/research/publication/multi-tenant-databases-for-software-as-a-service/

### Assessment: RDPS-REQ-22 (RDPS access and modification auditing)

**Reference**: RDPS-REQ-22 - Browser shall audit all RDPS access and modifications

**Given**: A conformant browser with RDPS-2 or higher capability

**Task**: Comprehensive audit logging of RDPS operations enables security incident detection, forensic investigation, compliance verification, and insider threat monitoring. Without detailed audit trails, unauthorized access goes undetected, data breaches can't be traced, and compliance audits fail. Tamper-resistant audit logs with who, what, when, where details provide accountability and support security operations.

**Verification**:

1. Review audit logging implementation for RDPS operations → All read operations logged
2. Verify all data read operations logged with user, origin, timestamp, data type → Write operations logged with changes
3. Test that all write/modify operations logged with before/after values → Delete operations documented
4. Verify delete operations logged with deleted data reference → Failed attempts captured
5. Test that failed access attempts logged (authentication, authorization failures) → Administrative actions logged
6. Verify administrative operations logged with elevated privilege markers → Logs tamper-protected
7. Test audit log tamper protection (append-only, cryptographic signatures) → Retention requirements met
8. Verify audit logs retained per compliance requirements → SIEM export functional
9. Test audit log export for SIEM integration → Forensic detail sufficient
10. Verify audit logs include sufficient detail for forensic investigation → Audit log performance acceptable

**Pass Criteria**: All operations logged AND tamper protection AND retention compliance AND forensic detail sufficient

**Fail Criteria**: Operations not logged OR logs can be tampered OR insufficient retention OR missing critical details

**Evidence**: Audit log samples, tamper protection verification, retention policy documentation, SIEM integration testing, forensic analysis demonstration

**References**:

- Audit Logging: https://csrc.nist.gov/publications/detail/sp/800-92/final
- OWASP Logging Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/Logging_Cheat_Sheet.html
- Tamper-Evident Logging: https://www.usenix.org/legacy/event/sec09/tech/full_papers/waters.pdf

### Assessment: RDPS-REQ-23 (Data integrity verification using cryptographic hashes)

**Reference**: RDPS-REQ-23 - Browser shall implement data integrity verification using cryptographic hashes

**Given**: A conformant browser with RDPS-2 or higher capability

**Task**: Cryptographic integrity verification detects unauthorized modifications, corruption, or tampering of RDPS data by comparing current hash values against stored reference hashes. Without integrity verification, silent data corruption, malicious modifications, or storage system failures go undetected until data loss occurs. Continuous integrity monitoring with strong hash algorithms (SHA-256), automatic verification, and corruption alerts ensures data trustworthiness.

**Verification**:

1. Review integrity verification implementation using cryptographic hashes → Strong cryptographic hash algorithm used
2. Verify hash algorithm is cryptographically strong (SHA-256, SHA-3, or better) → Hashes computed at write time
3. Test that hashes computed at data write and stored securely → Periodic verification performed
4. Verify periodic integrity verification checks data against stored hashes → Modifications update hashes correctly
5. Test that data modifications update hash values appropriately → Mismatches detected and alerted
6. Verify hash mismatches detected and alerted → Corruption detection functional
7. Test corruption detected through integrity verification → Automated remediation implemented
8. Verify automated remediation (restore from backup) on corruption detection → Hashes stored separately from data
9. Test that hash values stored separately from data (prevent correlated corruption) → All critical data covered
10. Verify integrity verification covers all critical data types → Performance impact acceptable

**Pass Criteria**: SHA-256 or stronger hashes AND periodic verification AND mismatch detection AND automated remediation

**Fail Criteria**: Weak hash algorithms OR no verification OR mismatches not detected OR no remediation

**Evidence**: Hash algorithm documentation, integrity verification configuration, corruption detection testing, remediation procedure verification, performance analysis

**References**:

- Cryptographic Hash Functions: https://csrc.nist.gov/projects/hash-functions
- Data Integrity: https://csrc.nist.gov/glossary/term/data_integrity
- SHA-256: https://en.wikipedia.org/wiki/SHA-2

### Assessment: RDPS-REQ-24 (RDPS endpoint substitution attack protection)

**Reference**: RDPS-REQ-24 - Browser shall protect against RDPS endpoint substitution attacks

**Given**: A conformant browser with RDPS-2 or higher capability

**Task**: Endpoint substitution attacks occur when attackers redirect browser-RDPS communications to malicious servers through DNS poisoning, ARP spoofing, or configuration tampering, enabling data interception and manipulation. Without endpoint validation, browsers communicate with attacker-controlled servers believing they're legitimate RDPS. Certificate pinning, endpoint verification, domain validation, and secure configuration storage prevent endpoint substitution and ensure browsers connect only to legitimate RDPS infrastructure.

**Verification**:

1. Review RDPS endpoint configuration storage and protection mechanisms → Endpoints stored tamper-resistant
2. Verify endpoints stored in tamper-resistant configuration (encrypted, integrity-protected) → Modifications require authentication
3. Test that endpoint modifications require authentication and authorization → Certificate pinning enforced
4. Verify certificate pinning prevents connection to substituted endpoints with different certificates → DNS poisoning detected and blocked
5. Test DNS poisoning attack and verify browser detects and blocks malicious endpoint → Domain validation performed
6. Verify domain validation performed before establishing RDPS connections → Configuration changes logged
7. Test that endpoint configuration changes logged for audit → Fallback endpoints validated
8. Verify fallback endpoints also validated and pinned → MITM with substitution detected
9. Test that man-in-the-middle attacks with endpoint substitution detected → User notifications for security events
10. Verify users notified of endpoint changes or security warnings → Endpoint integrity maintained

**Pass Criteria**: Tamper-resistant endpoint storage AND certificate pinning AND domain validation AND MITM detection

**Fail Criteria**: Endpoints easily modified OR no certificate pinning OR no domain validation OR MITM undetected

**Evidence**: Endpoint configuration security analysis, certificate pinning verification, DNS poisoning test results, MITM attack prevention testing, audit logs

**References**:

- DNS Security: https://www.icann.org/resources/pages/dnssec-what-is-it-why-important-2019-03-05-en
- Certificate Pinning: https://owasp.org/www-community/controls/Certificate_and_Public_Key_Pinning
- Endpoint Security: https://cheatsheetseries.owasp.org/cheatsheets/Transport_Layer_Protection_Cheat_Sheet.html

### Assessment: RDPS-REQ-25 (Replay attack defense for RDPS communications)

**Reference**: RDPS-REQ-25 - Browser shall implement defense against replay attacks on RDPS communications

**Given**: A conformant browser with RDPS-2 or higher capability

**Task**: Replay attacks allow attackers who intercept RDPS communications to re-transmit captured requests, potentially duplicating transactions, bypassing authentication, or causing unintended operations. Without replay protection, encrypted traffic remains vulnerable to replay even when confidentiality is maintained. Nonces, timestamps, sequence numbers, and request signing with replay detection prevent attackers from reusing captured network traffic.

**Verification**:

1. Review RDPS communication protocol for replay protection mechanisms → Nonces or unique IDs in requests
2. Verify requests include nonces (numbers used once) or unique request IDs → Duplicate nonces rejected
3. Test that server rejects duplicate nonces within time window → Timestamps validated server-side
4. Verify timestamps included in requests with server-side validation → Expired requests rejected
5. Test that expired timestamps rejected (e.g., requests older than 5 minutes) → Sequence number tracking implemented
6. Verify sequence numbers tracked to detect out-of-order or duplicate requests → Replay attacks detected in testing
7. Test replay attack by capturing and retransmitting valid request → Replayed requests rejected
8. Verify replayed request detected and rejected by RDPS → Detection events logged
9. Test that replay detection logged for security monitoring → Cryptographic binding prevents tampering
10. Verify cryptographic signatures bind requests to prevent modification during replay → Replay window appropriately sized

**Pass Criteria**: Nonces or timestamps enforced AND duplicate detection AND replay attacks blocked AND security logging

**Fail Criteria**: No replay protection OR duplicates accepted OR replay attacks succeed OR no logging

**Evidence**: Protocol documentation showing replay protection, nonce/timestamp implementation review, replay attack test results, detection logging verification

**References**:

- Replay Attack Prevention: https://en.wikipedia.org/wiki/Replay_attack
- Nonce: https://en.wikipedia.org/wiki/Cryptographic_nonce
- OWASP Session Management: https://cheatsheetseries.owasp.org/cheatsheets/Session_Management_Cheat_Sheet.html

### Assessment: RDPS-REQ-26 (Data minimization principles for RDPS transmissions)

**Reference**: RDPS-REQ-26 - Browser shall enforce data minimization principles for RDPS transmissions

**Given**: A conformant browser with RDPS-2 or higher capability

**Task**: Data minimization limits RDPS data collection and transmission to only what is strictly necessary for functionality, reducing privacy risks, regulatory exposure, and breach impact. Without minimization, excessive data collection creates compliance violations (GDPR Article 5), larger attack surfaces, and user privacy concerns. Purpose limitation, necessity assessment, and data filtering ensure only required data transmitted to RDPS.

**Verification**:

1. Review RDPS data inventory and verify necessity justification for each data type → All transmitted data justified as necessary
2. Test that browser transmits only functionally required data to RDPS → No excessive data collection
3. Verify no excessive or speculative data collection occurs → PII minimized or pseudonymized
4. Test that personal identifiable information (PII) minimized or pseudonymized → Aggregation/anonymization applied
5. Verify data aggregation or anonymization applied where possible → Users can review transmitted data
6. Test that users can review what data transmitted to RDPS → Minimization documented publicly
7. Verify data minimization documented in privacy policy and data processing agreements → Unnecessary fields removed
8. Test that unused or unnecessary data fields removed from transmissions → Retention minimized
9. Verify data retention limited to minimum required period → GDPR compliance demonstrated
10. Test compliance with GDPR Article 5 data minimization principle → Regular minimization audits performed

**Pass Criteria**: Necessity justification for all data AND PII minimization AND user transparency AND GDPR compliance

**Fail Criteria**: Excessive data collected OR no justification OR PII not minimized OR GDPR non-compliance

**Evidence**: Data inventory with necessity justifications, PII minimization verification, user transparency features, GDPR compliance documentation, privacy policy review

**References**:

- GDPR Article 5 Data Minimization: https://gdpr-info.eu/art-5-gdpr/
- Data Minimization Best Practices: https://ico.org.uk/for-organisations/guide-to-data-protection/guide-to-the-general-data-protection-regulation-gdpr/principles/data-minimisation/

### Assessment: RDPS-REQ-27 (User controls for RDPS data synchronization)

**Reference**: RDPS-REQ-27 - Browser shall provide user controls for RDPS data synchronization

**Given**: A conformant browser with RDPS-2 or higher capability

**Task**: User control over RDPS synchronization respects user autonomy, enables privacy management, and supports varied connectivity scenarios where users may prefer local-only operation. Without controls, users cannot disable synchronization for privacy, bandwidth conservation, or regulatory compliance (e.g., data localization requirements). Granular synchronization controls with clear UI, immediate effect, and data deletion options empower users to manage their data lifecycle.

**Verification**:

1. Verify browser provides UI for enabling/disabling RDPS synchronization → Global synchronization toggle available
2. Test that synchronization can be disabled globally → Per-data-type controls functional
3. Verify per-data-type synchronization controls (e.g., sync preferences but not history) → Changes take effect immediately
4. Test that disabling synchronization takes effect immediately → Data deletion option provided
5. Verify existing RDPS data optionally deletable when disabling synchronization → Settings persist across restarts
6. Test that synchronization state persists across browser restarts → UI accessible and discoverable
7. Verify synchronization settings accessible and discoverable in browser UI → Status clearly indicated
8. Test that synchronization status clearly indicated to users → Re-enable requires explicit action
9. Verify re-enabling synchronization requires explicit user action → Controls well-documented
10. Test that synchronization controls documented in user documentation → User autonomy respected

**Pass Criteria**: Global and per-type controls AND immediate effect AND data deletion option AND clear UI

**Fail Criteria**: No user controls OR changes delayed OR no deletion option OR hidden UI

**Evidence**: UI screenshots showing synchronization controls, settings persistence testing, data deletion verification, user documentation review

**References**:

- User Privacy Controls: https://www.w3.org/TR/privacy-controls/
- GDPR Right to Data Portability: https://gdpr-info.eu/art-20-gdpr/
- Privacy UX Best Practices: https://www.smashingmagazine.com/2019/04/privacy-ux-better-notifications-permission-requests/

### Assessment: RDPS-REQ-28 (Secure data export from RDPS for data portability)

**Reference**: RDPS-REQ-28 - Browser shall implement secure data export from RDPS for data portability

**Given**: A conformant browser with RDPS-2 or higher capability

**Task**: Data portability enables users to export their RDPS data for backup, migration to alternative browsers, or regulatory compliance (GDPR Article 20), preventing vendor lock-in and respecting user data ownership. Without export capability, users cannot recover data, switch browsers, or exercise portability rights. Secure export with authentication, encryption, integrity verification, and standard formats empowers users while preventing unauthorized data extraction.

**Verification**:

1. Verify browser provides data export functionality for RDPS data → Export functionality available
2. Test that export requires user authentication before proceeding → Authentication required
3. Verify exported data includes all user-accessible RDPS data → All accessible data exported
4. Test export format is standard and machine-readable (JSON, XML, CSV) → Standard format used
5. Verify exported data integrity protected (checksums, signatures) → Integrity protection applied
6. Test that export encrypted during download if sensitive → Encryption during download
7. Verify export logged for audit and security monitoring → Export operations logged
8. Test export rate limiting to prevent abuse or data scraping → Rate limiting prevents abuse
9. Verify export includes metadata (timestamps, data types, sources) → Metadata included
10. Test that exported data importable to another browser (interoperability) → Cross-browser compatibility

**Pass Criteria**: Export functionality AND authentication required AND standard format AND integrity protection

**Fail Criteria**: No export capability OR no authentication OR proprietary format OR no integrity protection

**Evidence**: Export functionality demonstration, authentication verification, format documentation, integrity verification testing, interoperability testing

**References**:

- GDPR Data Portability: https://gdpr-info.eu/art-20-gdpr/
- Data Liberation: https://en.wikipedia.org/wiki/Google_Data_Liberation_Front
- JSON Format: https://www.json.org/json-en.html

### Assessment: RDPS-REQ-29 (User-configurable RDPS endpoint security settings)

**Reference**: RDPS-REQ-29 - When user-configurable RDPS endpoints provided, all associated security settings shall be configurable

**Given**: A conformant browser with RDPS-2 or higher capability supporting user-configurable endpoints

**Task**: When browsers allow users to configure custom RDPS endpoints (e.g., enterprise deployments, self-hosted infrastructure), all security settings shall be configurable to maintain security equivalent to default RDPS. Without configurable security settings, users cannot enforce certificate pinning, encryption requirements, or authentication for custom endpoints, creating security gaps. Comprehensive security configuration with validation, documentation, and testing ensures custom endpoints maintain security posture.

**Verification**:

1. Verify browser supports user-configurable RDPS endpoints → Custom endpoint configuration available
2. Test that users can configure custom endpoint URLs → Certificate pinning for custom endpoints
3. Verify certificate pinning configurable for custom endpoints → TLS requirements configurable
4. Test that TLS version requirements configurable (enforce TLS 1.3+) → Authentication methods selectable
5. Verify authentication method configurable (OAuth, mTLS, API keys) → Timeout configuration available
6. Test that connection timeout values configurable → Retry parameters adjustable
7. Verify retry and backoff parameters configurable → Encryption settings configurable
8. Test that data encryption settings configurable → Secure defaults enforced
9. Verify all security settings have secure defaults → Insecure configs warned/blocked
10. Test that insecure configurations warned or blocked → Configuration documented

**Pass Criteria**: Comprehensive security configuration AND secure defaults AND insecure config warnings AND documentation complete

**Fail Criteria**: Limited configuration OR no defaults OR insecure configs allowed OR poor documentation

**Evidence**: Configuration UI documentation, security settings verification, secure defaults testing, insecure configuration prevention testing

**References**:

- Enterprise Configuration: https://chromeenterprise.google/policies/
- Secure Configuration: https://www.cisecurity.org/cis-benchmarks/
- Configuration Management: https://csrc.nist.gov/glossary/term/configuration_management

### Assessment: RDPS-REQ-30 (RDPS service availability verification before critical operations)

**Reference**: RDPS-REQ-30 - Browser shall verify RDPS service availability before critical operations

**Given**: A conformant browser with RDPS-2 or higher capability performing critical operations dependent on remote data processing

**Task**: This assessment verifies that browsers check RDPS service availability before executing critical operations (authentication synchronization, encryption key retrieval, security policy validation) that depend on remote data processing. The assessment confirms that availability checks include timeout controls, the browser safely defers or fails operations when the service is unavailable, and users receive appropriate notifications.

**Verification**:

1. Identify all browser operations classified as critical and dependent on RDPS → Availability verification implemented for all critical operations
2. Test browser with RDPS fully available and responsive → Health check endpoints or APIs used for verification
3. Verify critical operations check service availability before execution → Timeout controls implemented (5-10 seconds)
4. Test browser with RDPS temporarily unavailable (network disconnected) → Retry logic with exponential backoff present
5. Verify browser detects unavailability before attempting critical operations → Circuit breaker pattern implemented to prevent cascade failures
6. Test browser with RDPS responding slowly (high latency) → Browser defers operations when service unavailable
7. Verify availability checks respect timeout limits (5-10 seconds typical) → Safe failure with error messaging when operation cannot be deferred
8. Test browser with RDPS returning unhealthy status codes (503, 500) → User notifications provided for deferred operations
9. Verify browser treats unhealthy responses as unavailable → Cached data used with integrity verification when applicable
10. Test that browser defers or safely fails critical operations when RDPS unavailable → Manual retry options available to users

**Pass Criteria**: Availability verification for all critical operations AND health checks implemented AND timeout controls (5-10s) AND deferred/safe failure when unavailable AND user notifications AND documentation complete

**Fail Criteria**: No availability verification OR critical operations attempted without checks OR no timeout controls OR unsafe failures OR no user notifications OR incomplete documentation

**Evidence**: Critical operations catalog, availability verification code review, health check endpoint documentation, timeout configuration, unavailability testing results, user notification examples, circuit breaker implementation

**References**:

- Health Check API Pattern: https://microservices.io/patterns/observability/health-check-api.html
- Circuit Breaker Pattern: https://martinfowler.com/bliki/CircuitBreaker.html
- Service Availability: https://sre.google/sre-book/availability-table/

### Assessment: RDPS-REQ-31 (Connection pooling with security controls for RDPS)

**Reference**: RDPS-REQ-31 - Browser shall implement connection pooling with security controls for RDPS

**Given**: A conformant browser with RDPS-2 or higher capability implementing connection pooling for remote data processing systems

**Task**: This assessment verifies that browsers implement secure connection pooling for RDPS communications with per-user per-origin isolation, connection validation before reuse, eviction policies, pool size limits, and protection against connection smuggling attacks.

**Verification**:

1. Verify browser implements connection pooling for RDPS communications → Per-user per-origin connection pools implemented
2. Test that connections are pooled per-user and per-origin (no cross-user sharing) → Authentication state maintained per connection
3. Verify each pooled connection maintains separate authentication state → No credential sharing across contexts
4. Test that credentials never leak between different security contexts → Connection validation before reuse
5. Verify browser validates connections before reuse (certificate, TLS state) → Eviction policies implemented (idle timeout, max lifetime)
6. Test connection eviction policies (idle timeout, max lifetime, max request count) → Pool size limits enforced (6-8 per origin typical)
7. Verify connection pool size limits enforced (prevent resource exhaustion) → Stale connection detection and eviction
8. Test that browser detects and evicts stale or unhealthy connections → Connection smuggling attack prevention
9. Verify protection against connection smuggling attacks → Enterprise configuration options available
10. Test that enterprise administrators can configure or disable pooling → Connection pooling documented with security considerations

**Pass Criteria**: Per-user per-origin pooling AND authentication isolation AND connection validation before reuse AND eviction policies AND pool size limits AND smuggling prevention AND enterprise controls AND documentation complete

**Fail Criteria**: Cross-user connection sharing OR credential leakage OR no connection validation OR no eviction policies OR unlimited pool size OR smuggling vulnerabilities OR no enterprise controls OR incomplete documentation

**Evidence**: Connection pooling implementation code review, per-user per-origin isolation testing, credential isolation verification, connection validation testing, eviction policy configuration, pool size limit testing, connection smuggling attack testing, enterprise configuration documentation

**References**:

- HTTP Connection Management: https://developer.mozilla.org/en-US/docs/Web/HTTP/Connection_management_in_HTTP_1.x
- Connection Pooling Security: https://owasp.org/www-community/vulnerabilities/Insecure_Transport
- Request Smuggling: https://portswigger.net/web-security/request-smuggling

### Assessment: RDPS-REQ-32 (RDPS authentication token protection from extraction and theft)

**Reference**: RDPS-REQ-32 - Browser shall protect RDPS authentication tokens from extraction and theft

**Given**: A conformant browser with RDPS-2 or higher capability storing authentication tokens for remote data processing systems

**Task**: This assessment verifies that browsers protect RDPS authentication tokens using OS-provided secure storage with hardware-backed encryption when available, implement token lifetime management and automatic rotation, prevent plaintext storage and memory extraction, and support remote token revocation by users and policy enforcement by administrators.

**Verification**:

1. Identify all RDPS authentication token types stored by browser → OS secure storage used for all token types
2. Verify tokens stored using OS secure storage mechanisms (Keychain, Credential Manager, Secret Service) → Hardware-backed encryption when available
3. Test that tokens encrypted with hardware-backed keys when available (TPM, Secure Enclave) → No plaintext token storage
4. Verify tokens never stored in plaintext on disk → Web content cannot access tokens
5. Test that tokens not accessible to web content via standard storage APIs → Memory protection implemented
6. Verify memory protection prevents token extraction via dumps or debugging → Token lifetime management present
7. Test token lifetime management (short access tokens, longer refresh tokens) → Automatic token rotation implemented
8. Verify automatic token rotation before expiration → Secure revocation on logout
9. Test secure token revocation on logout → Tokens never in URLs or HTTP headers
10. Verify token transmission uses TLS 1.3+ with certificate pinning → Remote token revocation interface available

**Pass Criteria**: OS secure storage for all tokens AND hardware-backed encryption when available AND no plaintext storage AND web content isolation AND memory protection AND token lifetime management AND automatic rotation AND secure revocation AND TLS 1.3+ transmission AND remote revocation UI AND documentation complete

**Fail Criteria**: Plaintext token storage OR web content access to tokens OR no memory protection OR no lifetime management OR no token rotation OR insecure revocation OR tokens in URLs OR no remote revocation OR incomplete documentation

**Evidence**: Token storage implementation code review, OS secure storage verification, hardware-backed encryption testing, web content isolation testing, memory protection verification, token lifetime configuration, rotation mechanism testing, revocation testing, TLS transmission verification, remote revocation UI documentation

**References**:

- OAuth 2.0 Security Best Practices: https://datatracker.ietf.org/doc/html/draft-ietf-oauth-security-topics
- Hardware-Backed Keystore: https://developer.android.com/training/articles/keystore

### Assessment: RDPS-REQ-33 (End-to-end encryption for all critical data in RDPS)

**Reference**: RDPS-REQ-33 - Browser shall implement end-to-end encryption for all critical data in RDPS (RDPS-3 requirement)

**Given**: A conformant browser with RDPS-3 capability processing critical data through remote data processing systems

**Task**: This assessment verifies that browsers implement end-to-end encryption for all critical RDPS data with client-side key generation, authenticated encryption before transmission, server-side inability to decrypt, secure key backup and recovery mechanisms, metadata protection, and user education about E2EE trade-offs.

**Verification**:

1. Identify all critical data processed through RDPS by the browser → Client-side encryption key generation implemented
2. Verify encryption keys generated locally on client device using CSPRNG → Strong KDF used for key derivation (high iteration count)
3. Test that keys derived from user credentials use strong KDF (PBKDF2, Argon2, scrypt) → Authenticated encryption for all critical data
4. Verify all critical data encrypted on client before transmission → Data remains encrypted at rest remotely
5. Test that authenticated encryption algorithms used (AES-256-GCM, ChaCha20-Poly1305) → Server cannot decrypt data (verified via architecture review)
6. Verify encrypted data remains encrypted at rest in RDPS storage → Secure key backup/recovery with E2EE guarantees
7. Test that RDPS provider cannot decrypt data (server-side decryption impossible) → Client-side key rotation capability
8. Verify key backup and recovery mechanisms maintain E2EE guarantees → Metadata protection implemented
9. Test key rotation without server involvement → User education about E2EE trade-offs
10. Verify metadata protection implemented (encrypted filenames, padding, obfuscation) → Data loss warnings for lost keys without recovery

**Pass Criteria**: Client-side key generation AND strong KDF AND authenticated encryption for all critical data AND encrypted at rest AND server cannot decrypt AND secure key backup/recovery AND key rotation AND metadata protection AND user education AND documentation complete

**Fail Criteria**: Server-side key generation OR weak KDF OR unauthenticated encryption OR plaintext at rest OR server can decrypt OR insecure key backup OR no key rotation OR metadata leakage OR no user education OR incomplete documentation

**Evidence**: E2EE implementation architecture review, key generation code review, KDF configuration, encryption algorithm verification, server-side decryption impossibility proof, key backup/recovery documentation, key rotation testing, metadata protection verification, user interface documentation

**References**:

- End-to-End Encryption: https://www.w3.org/TR/webauthn-3/#end-to-end-encryption
- Signal Protocol: https://signal.org/docs/
- Authenticated Encryption: https://csrc.nist.gov/projects/block-cipher-techniques/bcm/modes-development

### Assessment: RDPS-REQ-34 (Hardware-backed key storage for RDPS encryption keys)

**Reference**: RDPS-REQ-34 - Browser shall use hardware-backed key storage for RDPS encryption keys (RDPS-3 requirement)

**Given**: A conformant browser with RDPS-3 capability on platforms supporting hardware-backed key storage (TPM, Secure Enclave, TEE, HSM)

**Task**: This assessment verifies that browsers use hardware security modules (TPM, Secure Enclave, TrustZone, HSM) for RDPS encryption keys when available, with non-exportable device-bound keys, authentication requirements, secure hardware operations, key attestation support, software fallback warnings, and enterprise policy enforcement for hardware requirements.

**Verification**:

1. Identify platforms with hardware security modules (TPM, Secure Enclave, TrustZone, HSM) → Hardware security module detection implemented
2. Verify browser detects available hardware security features on each platform → Preferential use of hardware-backed storage
3. Test that browser preferentially uses hardware-backed storage when available → Non-exportable keys bound to device
4. Verify keys stored in hardware are non-exportable (bound to device) → Authentication required for key usage
5. Test that authentication required for hardware key usage (PIN, biometric) → Cryptographic operations in secure hardware
6. Verify cryptographic operations performed inside secure hardware → Key material never exposed to software
7. Test that key material never exposed to OS or browser process → Key attestation implemented
8. Verify key attestation provides proof of hardware-backed storage → Software fallback with security warnings
9. Test fallback to software storage shows clear security warnings → Enterprise policy enforcement for hardware requirement
10. Verify enterprise policies can require hardware-backed storage → Platform compatibility and limitations documented

**Pass Criteria**: Hardware detection on all supported platforms AND preferential hardware usage AND non-exportable keys AND authentication required AND operations in secure hardware AND key attestation AND fallback warnings AND enterprise policies AND documentation complete

**Fail Criteria**: No hardware detection OR no preferential hardware usage OR exportable keys OR no authentication OR operations in software OR no attestation OR silent fallback OR no enterprise policies OR incomplete documentation

**Evidence**: Hardware security module detection code review, key storage implementation verification, non-exportability testing, authentication requirement verification, secure hardware operation confirmation, attestation testing, fallback warning examples, enterprise policy documentation, platform compatibility matrix

**References**:

- TPM 2.0: https://trustedcomputinggroup.org/resource/tpm-library-specification/
- Apple Secure Enclave: https://support.apple.com/guide/security/secure-enclave-sec59b0b31ff/web
- Web Authentication API: https://www.w3.org/TR/webauthn-3/

### Assessment: RDPS-REQ-35 (High-availability RDPS architecture with failover)

**Reference**: RDPS-REQ-35 - Browser shall implement high-availability RDPS architecture with failover (RDPS-3 requirement)

**Given**: A conformant browser with RDPS-3 capability requiring high availability for critical remote data processing operations

**Task**: This assessment verifies that browsers implement high-availability RDPS architecture with geographically distributed endpoints, automatic failover within 30-60 seconds, load balancing, session state preservation, graceful degradation for partial failures, and documented availability targets with MTTR specifications.

**Verification**:

1. Verify browser configuration supports multiple RDPS endpoints (primary/secondary) → Multiple RDPS endpoints configured (primary/secondary/tertiary)
2. Test that endpoints geographically distributed across regions → Geographic distribution across regions
3. Verify health monitoring detects endpoint failures → Health monitoring and failure detection
4. Test automatic failover switches to backup endpoint within 30-60 seconds → Failover within acceptable timeframe (30-60s)
5. Verify failed operations retried automatically without user intervention → Automatic operation retry
6. Test load balancing distributes traffic across healthy endpoints → Load balancing across healthy endpoints
7. Verify connection fallback sequence (primary → secondary → tertiary) → Session state preservation during failover
8. Test that session state preserved during failover → Graceful handling of partial failures
9. Verify partial failures handled gracefully (degraded service vs total failure) → Failover event logging and user notification
10. Test automatic recovery to primary endpoint after restoration → Availability targets and MTTR documented

**Pass Criteria**: Multiple geographically distributed endpoints AND health monitoring AND automatic failover (30-60s) AND operation retry AND load balancing AND session preservation AND graceful degradation AND automatic recovery AND logging/notifications AND availability targets documented

**Fail Criteria**: Single endpoint OR same geographic region OR no health monitoring OR manual failover OR no retry OR no load balancing OR session loss OR catastrophic failures OR no logging OR unavailability targets undocumented

**Evidence**: RDPS endpoint configuration documentation, geographic distribution verification, health monitoring implementation, failover timing tests, retry mechanism verification, load balancing testing, session preservation testing, partial failure handling tests, recovery testing, availability metrics and MTTR documentation

**References**:

- Failover Design Patterns: https://docs.microsoft.com/en-us/azure/architecture/patterns/category/resiliency
- SLA Targets: https://sre.google/sre-book/availability-table/

### Assessment: RDPS-REQ-36 (RDPS disaster recovery procedures documentation and testing)

**Reference**: RDPS-REQ-36 - Browser shall document and test RDPS disaster recovery procedures (RDPS-3 requirement)

**Given**: A conformant browser with RDPS-3 capability requiring disaster recovery capabilities for critical remote data processing

**Task**: This assessment verifies that browsers have documented and regularly tested (annually minimum) disaster recovery procedures for RDPS with defined RTO/RPO targets, backup strategies, restoration procedures, alternative processing sites, role assignments, and validation across multiple disaster scenarios with documented improvements.

**Verification**:

1. Verify comprehensive DR procedures documented for RDPS infrastructure → Comprehensive DR documentation exists
2. Test that RTO and RPO defined for all critical RDPS components → RTO and RPO defined for critical components
3. Verify backup strategies documented (full, incremental, continuous replication) → Backup strategies documented (frequency, type, retention)
4. Test that restoration procedures provide step-by-step instructions → Step-by-step restoration procedures
5. Verify roles and responsibilities defined for disaster recovery → Roles and responsibilities clearly defined
6. Test that alternative processing sites identified and documented → Alternative processing sites identified
7. Verify backup frequency and retention periods specified → Regular DR testing performed (annual minimum, quarterly preferred)
8. Test that DR procedures tested at least annually (preferably quarterly) → Multiple disaster scenarios tested
9. Verify various disaster scenarios tested (datacenter outage, data corruption, breach) → Actual RTO/RPO measured and compared to targets
10. Test that actual RTO/RPO measured against targets during testing → Test results documented with improvements implemented

**Pass Criteria**: Comprehensive DR documentation AND defined RTO/RPO AND backup strategies AND restoration procedures AND regular testing (annual minimum) AND multiple scenarios tested AND measured RTO/RPO AND improvements documented AND user communication AND documentation complete

**Fail Criteria**: No DR documentation OR undefined RTO/RPO OR no backup strategy OR no restoration procedures OR no regular testing OR single scenario only OR unmeasured RTO/RPO OR no improvements OR no user communication OR incomplete documentation

**Evidence**: DR procedure documentation, RTO/RPO specifications, backup strategy documentation, restoration procedure manuals, DR test schedules and reports, test scenario documentation, RTO/RPO measurement results, improvement tracking, user communication materials

**References**:

- Disaster Recovery Planning: https://csrc.nist.gov/publications/detail/sp/800-34/rev-1/final
- Business Continuity: https://www.iso.org/standard/75106.html
- Backup and Recovery: https://aws.amazon.com/disaster-recovery/

### Assessment: RDPS-REQ-37 (Real-time RDPS integrity monitoring)

**Reference**: RDPS-REQ-37 - Browser shall implement real-time RDPS integrity monitoring (RDPS-3 requirement)

**Given**: A conformant browser with RDPS-3 capability requiring continuous integrity monitoring of remote data processing systems

**Task**: This assessment verifies that browsers implement real-time RDPS data integrity monitoring using cryptographic verification (HMAC, signatures, Merkle trees), immutable audit trails, automated real-time violation detection and alerting, protected monitoring infrastructure, and comprehensive coverage across all RDPS components with user/administrator notifications.

**Verification**:

1. Verify cryptographic integrity verification implemented (HMAC, signatures, Merkle trees) → Cryptographic integrity verification implemented
2. Test that integrity checks cover all critical RDPS data (user data, configs, logs) → All critical data covered by integrity monitoring
3. Verify integrity monitoring runs continuously or at high frequency (minutes to hours) → Continuous or high-frequency monitoring (minutes to hours)
4. Test that immutable audit trails prevent retroactive tampering → Immutable audit trails implemented
5. Verify integrity violations detected in real-time or near-real-time (minutes) → Real-time or near-real-time detection (within minutes)
6. Test that security alerts generated automatically upon detection → Automated security alerts generated
7. Verify incident response procedures triggered for integrity violations → Incident response integration
8. Test that integrity monitoring infrastructure protected from compromise → Monitoring infrastructure protected from compromise
9. Verify comprehensive monitoring across all RDPS components → Comprehensive coverage of all RDPS components
10. Test that users and administrators notified of integrity violations → User and administrator notifications with status dashboards