# zero_trust_principles.yaml
zero_trust_principles:
  never_trust_always_verify:
    - verify_every_request
    - assume_breach
    - treat_every_network_as_hostile
 
  least_privilege_access:
    - just_in_time_access
    - just_enough_access
    - role_based_access_control
    - attribute_based_access_control
 
  assume_breach:
    - segment_access
    - minimize_blast_radius
    - encrypt_all_data
    - comprehensive_logging
 
pillars:
  identity:
    - strong_authentication
    - continuous_validation
    - risk_based_access
 
  devices:
    - device_health_verification
    - endpoint_protection
    - mobile_device_management
 
  networks:
    - micro_segmentation
    - encrypted_traffic
    - network_access_control
 
  applications:
    - secure_access
    - api_security
    - workload_protection
 
  data:
    - data_classification
    - encryption
    - data_loss_prevention
 
  visibility:
    - comprehensive_logging
    - analytics
    - automation

# identity_verification.py
from dataclasses import dataclass
from typing import Dict, List, Optional
from datetime import datetime, timedelta
from enum import Enum
 
class RiskLevel(Enum):
    LOW = "low"
    MEDIUM = "medium"
    HIGH = "high"
    CRITICAL = "critical"
 
class AuthenticationStrength(Enum):
    WEAK = 1
    STANDARD = 2
    STRONG = 3
    VERY_STRONG = 4
 
@dataclass
class UserContext:
    """User context for access decision."""
    user_id: str
    session_id: str
    device_id: str
    ip_address: str
    location: Dict
    user_agent: str
    authentication_method: str
    authentication_time: datetime
    authentication_strength: AuthenticationStrength
 
@dataclass
class AccessRequest:
    """Access request details."""
    resource: str
    action: str
    user_context: UserContext
    request_time: datetime
    additional_context: Dict
 
class ContinuousVerificationEngine:
    """Engine for continuous identity verification."""
 
    def __init__(self, config: Dict):
        self.config = config
        self.risk_thresholds = config.get("risk_thresholds", {
            RiskLevel.LOW: 0.3,
            RiskLevel.MEDIUM: 0.5,
            RiskLevel.HIGH: 0.7,
            RiskLevel.CRITICAL: 0.9
        })
 
    def evaluate_access(self, request: AccessRequest) -> Dict:
        """Evaluate access request with continuous verification."""
 
        # Calculate risk score
        risk_score = self._calculate_risk_score(request)
        risk_level = self._determine_risk_level(risk_score)
 
        # Determine required authentication strength
        required_strength = self._get_required_strength(request.resource, risk_level)
 
        # Check if current authentication is sufficient
        current_strength = request.user_context.authentication_strength
 
        if current_strength.value < required_strength.value:
            return {
                "decision": "step_up_required",
                "required_strength": required_strength.name,
                "current_strength": current_strength.name,
                "risk_score": risk_score,
                "risk_level": risk_level.value
            }
 
        # Check session validity
        session_valid = self._verify_session(request.user_context)
        if not session_valid:
            return {
                "decision": "reauthentication_required",
                "reason": "Session expired or invalid",
                "risk_score": risk_score
            }
 
        # Check device trust
        device_trusted = self._verify_device(request.user_context)
        if not device_trusted:
            return {
                "decision": "denied",
                "reason": "Untrusted device",
                "risk_score": risk_score
            }
 
        return {
            "decision": "allowed",
            "risk_score": risk_score,
            "risk_level": risk_level.value,
            "conditions": self._get_access_conditions(risk_level)
        }
 
    def _calculate_risk_score(self, request: AccessRequest) -> float:
        """Calculate risk score for access request."""
 
        score = 0.0
        factors = []
 
        # Time-based risk
        auth_age = (request.request_time - request.user_context.authentication_time).total_seconds()
        if auth_age > 3600:  # More than 1 hour
            score += 0.1
            factors.append("stale_authentication")
 
        # Location risk
        location_risk = self._assess_location_risk(request.user_context.location)
        score += location_risk
        if location_risk > 0.2:
            factors.append("unusual_location")
 
        # Device risk
        device_risk = self._assess_device_risk(request.user_context.device_id)
        score += device_risk
        if device_risk > 0.2:
            factors.append("untrusted_device")
 
        # Resource sensitivity
        resource_sensitivity = self._get_resource_sensitivity(request.resource)
        score += resource_sensitivity * 0.3
 
        # Behavior anomaly
        behavior_risk = self._assess_behavior_anomaly(request)
        score += behavior_risk
        if behavior_risk > 0.2:
            factors.append("anomalous_behavior")
 
        return min(score, 1.0)
 
    def _determine_risk_level(self, score: float) -> RiskLevel:
        """Determine risk level from score."""
 
        if score < self.risk_thresholds[RiskLevel.LOW]:
            return RiskLevel.LOW
        elif score < self.risk_thresholds[RiskLevel.MEDIUM]:
            return RiskLevel.MEDIUM
        elif score < self.risk_thresholds[RiskLevel.HIGH]:
            return RiskLevel.HIGH
        else:
            return RiskLevel.CRITICAL
 
    def _get_required_strength(
        self,
        resource: str,
        risk_level: RiskLevel
    ) -> AuthenticationStrength:
        """Determine required authentication strength."""
 
        # Resource-specific requirements
        sensitive_resources = self.config.get("sensitive_resources", [])
 
        if resource in sensitive_resources:
            return AuthenticationStrength.VERY_STRONG
 
        # Risk-based requirements
        strength_map = {
            RiskLevel.LOW: AuthenticationStrength.STANDARD,
            RiskLevel.MEDIUM: AuthenticationStrength.STRONG,
            RiskLevel.HIGH: AuthenticationStrength.VERY_STRONG,
            RiskLevel.CRITICAL: AuthenticationStrength.VERY_STRONG
        }
 
        return strength_map[risk_level]
 
    def _verify_session(self, context: UserContext) -> bool:
        """Verify session is still valid."""
        # Implementation: Check session store, verify not revoked
        return True
 
    def _verify_device(self, context: UserContext) -> bool:
        """Verify device trust status."""
        # Implementation: Check device inventory, verify compliance
        return True
 
    def _assess_location_risk(self, location: Dict) -> float:
        """Assess risk based on location."""
        # Implementation: Check against normal locations, known bad IPs
        return 0.0
 
    def _assess_device_risk(self, device_id: str) -> float:
        """Assess risk based on device."""
        # Implementation: Check device health, compliance
        return 0.0
 
    def _get_resource_sensitivity(self, resource: str) -> float:
        """Get sensitivity level of resource."""
        # Implementation: Look up resource classification
        return 0.3
 
    def _assess_behavior_anomaly(self, request: AccessRequest) -> float:
        """Assess behavioral anomaly."""
        # Implementation: Compare against baseline behavior
        return 0.0
 
    def _get_access_conditions(self, risk_level: RiskLevel) -> List[str]:
        """Get access conditions based on risk level."""
 
        conditions = []
 
        if risk_level in [RiskLevel.HIGH, RiskLevel.CRITICAL]:
            conditions.append("session_recording")
            conditions.append("enhanced_logging")
 
        if risk_level == RiskLevel.CRITICAL:
            conditions.append("time_limited_access")
            conditions.append("supervisor_notification")
 
        return conditions

# micro_segmentation.py
from dataclasses import dataclass
from typing import List, Dict, Optional
from enum import Enum
import ipaddress
 
class SegmentType(Enum):
    WORKLOAD = "workload"
    USER = "user"
    SERVICE = "service"
    DATA = "data"
 
@dataclass
class NetworkSegment:
    """Network segment definition."""
    segment_id: str
    name: str
    segment_type: SegmentType
    cidr_ranges: List[str]
    labels: Dict[str, str]
    trust_level: int  # 1-5
 
@dataclass
class SegmentPolicy:
    """Policy defining allowed communication."""
    policy_id: str
    name: str
    source_segment: str
    destination_segment: str
    allowed_ports: List[int]
    allowed_protocols: List[str]
    conditions: Dict
    action: str  # allow, deny, log
 
class MicroSegmentationEngine:
    """Micro-segmentation policy engine."""
 
    def __init__(self):
        self.segments: Dict[str, NetworkSegment] = {}
        self.policies: List[SegmentPolicy] = []
        self.default_policy = "deny"
 
    def create_segment(self, segment: NetworkSegment):
        """Create a new network segment."""
        self.segments[segment.segment_id] = segment
 
    def add_policy(self, policy: SegmentPolicy):
        """Add segmentation policy."""
 
        # Validate segments exist
        if policy.source_segment not in self.segments:
            raise ValueError(f"Source segment {policy.source_segment} not found")
        if policy.destination_segment not in self.segments:
            raise ValueError(f"Destination segment {policy.destination_segment} not found")
 
        self.policies.append(policy)
 
    def evaluate_traffic(
        self,
        source_ip: str,
        destination_ip: str,
        port: int,
        protocol: str
    ) -> Dict:
        """Evaluate if traffic is allowed."""
 
        # Find source and destination segments
        source_segment = self._find_segment(source_ip)
        dest_segment = self._find_segment(destination_ip)
 
        if not source_segment or not dest_segment:
            return {
                "allowed": False,
                "reason": "Unknown segment",
                "action": "deny"
            }
 
        # Find matching policy
        matching_policy = self._find_matching_policy(
            source_segment.segment_id,
            dest_segment.segment_id,
            port,
            protocol
        )
 
        if not matching_policy:
            return {
                "allowed": False,
                "reason": "No matching policy",
                "action": self.default_policy
            }
 
        if matching_policy.action == "deny":
            return {
                "allowed": False,
                "reason": f"Denied by policy {matching_policy.policy_id}",
                "action": "deny"
            }
 
        return {
            "allowed": True,
            "policy": matching_policy.policy_id,
            "action": matching_policy.action,
            "conditions": matching_policy.conditions
        }
 
    def _find_segment(self, ip: str) -> Optional[NetworkSegment]:
        """Find segment containing IP address."""
 
        ip_addr = ipaddress.ip_address(ip)
 
        for segment in self.segments.values():
            for cidr in segment.cidr_ranges:
                network = ipaddress.ip_network(cidr)
                if ip_addr in network:
                    return segment
 
        return None
 
    def _find_matching_policy(
        self,
        source_segment: str,
        dest_segment: str,
        port: int,
        protocol: str
    ) -> Optional[SegmentPolicy]:
        """Find policy matching the traffic."""
 
        for policy in self.policies:
            if policy.source_segment != source_segment:
                continue
            if policy.destination_segment != dest_segment:
                continue
            if port not in policy.allowed_ports and '*' not in policy.allowed_ports:
                continue
            if protocol not in policy.allowed_protocols and '*' not in policy.allowed_protocols:
                continue
 
            return policy
 
        return None
 
    def generate_firewall_rules(self) -> List[Dict]:
        """Generate firewall rules from policies."""
 
        rules = []
 
        for policy in self.policies:
            source_segment = self.segments[policy.source_segment]
            dest_segment = self.segments[policy.destination_segment]
 
            for source_cidr in source_segment.cidr_ranges:
                for dest_cidr in dest_segment.cidr_ranges:
                    for port in policy.allowed_ports:
                        for protocol in policy.allowed_protocols:
                            rules.append({
                                "name": f"{policy.policy_id}-{len(rules)}",
                                "source": source_cidr,
                                "destination": dest_cidr,
                                "port": port,
                                "protocol": protocol,
                                "action": policy.action,
                                "priority": self._calculate_priority(policy)
                            })
 
        return sorted(rules, key=lambda r: r["priority"])
 
    def _calculate_priority(self, policy: SegmentPolicy) -> int:
        """Calculate rule priority."""
        # More specific rules get higher priority (lower number)
        priority = 1000
 
        if policy.action == "deny":
            priority -= 100
 
        source = self.segments[policy.source_segment]
        if len(source.cidr_ranges) == 1:
            priority -= 50  # More specific source
 
        return priority

# device_trust.py
from dataclasses import dataclass
from typing import Dict, List, Optional
from datetime import datetime
from enum import Enum
 
class DeviceComplianceStatus(Enum):
    COMPLIANT = "compliant"
    NON_COMPLIANT = "non_compliant"
    UNKNOWN = "unknown"
    QUARANTINED = "quarantined"
 
@dataclass
class DeviceHealth:
    """Device health status."""
    device_id: str
    os_version: str
    os_patch_level: str
    antivirus_status: str
    antivirus_definitions_age_days: int
    encryption_enabled: bool
    firewall_enabled: bool
    secure_boot_enabled: bool
    last_scan_time: datetime
    vulnerabilities: List[Dict]
    compliance_status: DeviceComplianceStatus
 
class DeviceTrustManager:
    """Manage device trust for Zero Trust."""
 
    def __init__(self, config: Dict):
        self.config = config
        self.compliance_policies = self._load_compliance_policies()
 
    def _load_compliance_policies(self) -> Dict:
        """Load device compliance policies."""
        return {
            "os_patch_max_age_days": 30,
            "antivirus_definitions_max_age_days": 3,
            "required_encryption": True,
            "required_firewall": True,
            "max_critical_vulnerabilities": 0,
            "max_high_vulnerabilities": 2
        }
 
    def assess_device(self, device_health: DeviceHealth) -> Dict:
        """Assess device compliance and trust level."""
 
        violations = []
        trust_score = 100
 
        # Check OS patch level
        if self._is_os_outdated(device_health.os_patch_level):
            violations.append({
                "check": "os_patch_level",
                "severity": "high",
                "message": "OS patch level is outdated"
            })
            trust_score -= 20
 
        # Check antivirus
        if device_health.antivirus_status != "active":
            violations.append({
                "check": "antivirus_status",
                "severity": "critical",
                "message": "Antivirus is not active"
            })
            trust_score -= 30
 
        if device_health.antivirus_definitions_age_days > self.compliance_policies["antivirus_definitions_max_age_days"]:
            violations.append({
                "check": "antivirus_definitions",
                "severity": "medium",
                "message": "Antivirus definitions are outdated"
            })
            trust_score -= 10
 
        # Check encryption
        if self.compliance_policies["required_encryption"] and not device_health.encryption_enabled:
            violations.append({
                "check": "encryption",
                "severity": "critical",
                "message": "Disk encryption is not enabled"
            })
            trust_score -= 25
 
        # Check firewall
        if self.compliance_policies["required_firewall"] and not device_health.firewall_enabled:
            violations.append({
                "check": "firewall",
                "severity": "high",
                "message": "Firewall is not enabled"
            })
            trust_score -= 15
 
        # Check vulnerabilities
        critical_vulns = len([v for v in device_health.vulnerabilities if v.get("severity") == "critical"])
        high_vulns = len([v for v in device_health.vulnerabilities if v.get("severity") == "high"])
 
        if critical_vulns > self.compliance_policies["max_critical_vulnerabilities"]:
            violations.append({
                "check": "critical_vulnerabilities",
                "severity": "critical",
                "message": f"{critical_vulns} critical vulnerabilities found"
            })
            trust_score -= 30
 
        if high_vulns > self.compliance_policies["max_high_vulnerabilities"]:
            violations.append({
                "check": "high_vulnerabilities",
                "severity": "high",
                "message": f"{high_vulns} high vulnerabilities found"
            })
            trust_score -= 15
 
        # Determine compliance status
        compliance_status = self._determine_compliance_status(violations)
 
        return {
            "device_id": device_health.device_id,
            "compliance_status": compliance_status.value,
            "trust_score": max(0, trust_score),
            "violations": violations,
            "recommendations": self._get_recommendations(violations),
            "access_level": self._determine_access_level(trust_score)
        }
 
    def _is_os_outdated(self, patch_level: str) -> bool:
        """Check if OS patch level is outdated."""
        # Implementation: Compare against known good patch levels
        return False
 
    def _determine_compliance_status(self, violations: List[Dict]) -> DeviceComplianceStatus:
        """Determine compliance status from violations."""
 
        critical_violations = [v for v in violations if v["severity"] == "critical"]
        high_violations = [v for v in violations if v["severity"] == "high"]
 
        if critical_violations:
            return DeviceComplianceStatus.QUARANTINED
        elif high_violations:
            return DeviceComplianceStatus.NON_COMPLIANT
        elif violations:
            return DeviceComplianceStatus.NON_COMPLIANT
        else:
            return DeviceComplianceStatus.COMPLIANT
 
    def _get_recommendations(self, violations: List[Dict]) -> List[str]:
        """Get remediation recommendations."""
 
        recommendations = []
 
        for violation in violations:
            check = violation["check"]
 
            if check == "os_patch_level":
                recommendations.append("Update operating system to latest patch level")
            elif check == "antivirus_status":
                recommendations.append("Enable and activate antivirus software")
            elif check == "antivirus_definitions":
                recommendations.append("Update antivirus definitions")
            elif check == "encryption":
                recommendations.append("Enable full disk encryption")
            elif check == "firewall":
                recommendations.append("Enable system firewall")
            elif check in ["critical_vulnerabilities", "high_vulnerabilities"]:
                recommendations.append("Apply security patches to address vulnerabilities")
 
        return recommendations
 
    def _determine_access_level(self, trust_score: int) -> str:
        """Determine access level based on trust score."""
 
        if trust_score >= 80:
            return "full"
        elif trust_score >= 60:
            return "restricted"
        elif trust_score >= 40:
            return "limited"
        else:
            return "denied"

# zero_trust_logging.py
from dataclasses import dataclass
from typing import Dict, List, Optional
from datetime import datetime
from enum import Enum
import json
import hashlib
 
class AccessDecision(Enum):
    ALLOWED = "allowed"
    DENIED = "denied"
    STEP_UP_REQUIRED = "step_up_required"
    CONDITIONAL = "conditional"
 
@dataclass
class ZeroTrustLogEntry:
    """Zero Trust audit log entry."""
    log_id: str
    timestamp: datetime
    event_type: str
    user_id: str
    device_id: str
    source_ip: str
    resource: str
    action: str
    decision: AccessDecision
    risk_score: float
    authentication_method: str
    session_id: str
    conditions_applied: List[str]
    policy_matched: Optional[str]
    details: Dict
    integrity_hash: str
 
class ZeroTrustAuditLogger:
    """Comprehensive logging for Zero Trust."""
 
    def __init__(self, storage_backend):
        self.storage = storage_backend
        self.log_chain = []
 
    def log_access_decision(
        self,
        user_id: str,
        device_id: str,
        source_ip: str,
        resource: str,
        action: str,
        decision: AccessDecision,
        risk_score: float,
        authentication_method: str,
        session_id: str,
        conditions_applied: List[str] = None,
        policy_matched: str = None,
        details: Dict = None
    ) -> ZeroTrustLogEntry:
        """Log access decision."""
 
        previous_hash = self.log_chain[-1] if self.log_chain else "genesis"
 
        entry = ZeroTrustLogEntry(
            log_id=self._generate_log_id(),
            timestamp=datetime.utcnow(),
            event_type="access_decision",
            user_id=user_id,
            device_id=device_id,
            source_ip=source_ip,
            resource=resource,
            action=action,
            decision=decision,
            risk_score=risk_score,
            authentication_method=authentication_method,
            session_id=session_id,
            conditions_applied=conditions_applied or [],
            policy_matched=policy_matched,
            details=details or {},
            integrity_hash=""
        )
 
        # Calculate integrity hash
        entry.integrity_hash = self._calculate_hash(entry, previous_hash)
        self.log_chain.append(entry.integrity_hash)
 
        # Store entry
        self.storage.store(self._serialize_entry(entry))
 
        return entry
 
    def log_policy_evaluation(
        self,
        user_id: str,
        resource: str,
        policies_evaluated: List[str],
        matched_policy: Optional[str],
        evaluation_time_ms: float
    ) -> ZeroTrustLogEntry:
        """Log policy evaluation details."""
 
        entry = ZeroTrustLogEntry(
            log_id=self._generate_log_id(),
            timestamp=datetime.utcnow(),
            event_type="policy_evaluation",
            user_id=user_id,
            device_id="",
            source_ip="",
            resource=resource,
            action="evaluate",
            decision=AccessDecision.ALLOWED if matched_policy else AccessDecision.DENIED,
            risk_score=0,
            authentication_method="",
            session_id="",
            conditions_applied=[],
            policy_matched=matched_policy,
            details={
                "policies_evaluated": policies_evaluated,
                "evaluation_time_ms": evaluation_time_ms
            },
            integrity_hash=""
        )
 
        previous_hash = self.log_chain[-1] if self.log_chain else "genesis"
        entry.integrity_hash = self._calculate_hash(entry, previous_hash)
        self.log_chain.append(entry.integrity_hash)
 
        self.storage.store(self._serialize_entry(entry))
        return entry
 
    def _generate_log_id(self) -> str:
        """Generate unique log ID."""
        import uuid
        return str(uuid.uuid4())
 
    def _calculate_hash(self, entry: ZeroTrustLogEntry, previous_hash: str) -> str:
        """Calculate integrity hash."""
 
        data = {
            "log_id": entry.log_id,
            "timestamp": entry.timestamp.isoformat(),
            "event_type": entry.event_type,
            "user_id": entry.user_id,
            "decision": entry.decision.value,
            "previous_hash": previous_hash
        }
 
        serialized = json.dumps(data, sort_keys=True)
        return hashlib.sha256(serialized.encode()).hexdigest()
 
    def _serialize_entry(self, entry: ZeroTrustLogEntry) -> Dict:
        """Serialize log entry for storage."""
        return {
            "log_id": entry.log_id,
            "timestamp": entry.timestamp.isoformat(),
            "event_type": entry.event_type,
            "user_id": entry.user_id,
            "device_id": entry.device_id,
            "source_ip": entry.source_ip,
            "resource": entry.resource,
            "action": entry.action,
            "decision": entry.decision.value,
            "risk_score": entry.risk_score,
            "authentication_method": entry.authentication_method,
            "session_id": entry.session_id,
            "conditions_applied": entry.conditions_applied,
            "policy_matched": entry.policy_matched,
            "details": entry.details,
            "integrity_hash": entry.integrity_hash
        }