Chapter 05: Privacy and Ethics

// Example: Privacy-Preserving Mental Health AI System
import { PrivacyEngine } from '@wia/mental-002';

class PrivacyProtectedMentalHealthSystem {
  constructor() {
    this.privacyEngine = new PrivacyEngine({
      complianceStandards: ['HIPAA', 'GDPR', 'CCPA'],
      encryptionStandard: 'AES-256-GCM',
      keyManagement: 'HSM', // Hardware Security Module
      auditLogging: 'comprehensive',
      dataMinimization: true
    });

    this.encryptionKeys = this.initializeKeyManagement();
    this.accessControl = this.initializeAccessControl();
  }

  async storePatientData(data, userId) {
    // Data classification
    const classified = await this.privacyEngine.classifyData(data);

    // Pseudonymization - replace identifying information
    const pseudonymized = await this.privacyEngine.pseudonymize(data, {
      userId,
      preserveUtility: true, // Maintain data usefulness for AI
      reversible: true // Allow re-identification when authorized
    });

    // Encryption at rest
    const encrypted = await this.privacyEngine.encrypt(pseudonymized, {
      algorithm: 'AES-256-GCM',
      keyId: this.encryptionKeys.dataKey,
      additionalAuthData: { userId, timestamp: new Date() }
    });

    // Store with access controls
    await this.storeWithAccessControl(encrypted, {
      userId,
      dataClassification: classified.level,
      accessPolicy: this.defineAccessPolicy(classified),
      retentionPeriod: this.calculateRetentionPeriod(classified)
    });

    // Audit log
    await this.logDataAccess({
      action: 'store',
      userId,
      dataType: classified.type,
      timestamp: new Date(),
      authorized: true
    });

    return {
      stored: true,
      dataId: pseudonymized.id,
      classification: classified.level
    };
  }

  async retrievePatientData(dataId, requestingUser, purpose) {
    // Authorization check
    const authorized = await this.accessControl.checkAuthorization({
      requestingUser,
      dataId,
      purpose,
      requiredPermissions: ['read_patient_data']
    });

    if (!authorized.granted) {
      await this.logDataAccess({
        action: 'retrieve_denied',
        requestingUser,
        dataId,
        reason: authorized.denialReason,
        timestamp: new Date()
      });
      throw new Error('Access denied: ' + authorized.denialReason);
    }

    // Retrieve encrypted data
    const encrypted = await this.retrieveEncryptedData(dataId);

    // Decrypt
    const decrypted = await this.privacyEngine.decrypt(encrypted, {
      keyId: this.encryptionKeys.dataKey,
      verifyIntegrity: true
    });

    // Re-identify if authorized (otherwise return pseudonymized)
    const data = authorized.allowReIdentification ?
      await this.privacyEngine.reIdentify(decrypted, authorized.userId) :
      decrypted;

    // Audit log
    await this.logDataAccess({
      action: 'retrieve',
      requestingUser,
      dataId,
      purpose,
      timestamp: new Date(),
      authorized: true
    });

    // Apply purpose limitation - redact data not needed for stated purpose
    return this.applyPurposeLimitation(data, purpose);
  }

  async processWithDifferentialPrivacy(dataset, analysisType) {
    // Apply differential privacy for aggregate analysis
    const dpEngine = this.privacyEngine.differentialPrivacy({
      epsilon: 1.0, // Privacy budget
      delta: 1e-5,
      sensitivity: this.calculateSensitivity(analysisType)
    });

    // Add calibrated noise to protect individual privacy
    const noisyResult = await dpEngine.analyze(dataset, analysisType);

    return {
      result: noisyResult,
      privacyGuarantee: {
        epsilon: 1.0,
        delta: 1e-5,
        interpretation: 'Individual records cannot be distinguished'
      }
    };
  }

  defineAccessPolicy(classification) {
    // Role-based access control policies
    const policies = {
      'highly-sensitive': {
        allowedRoles: ['treating-clinician', 'patient-self'],
        requiresMFA: true,
        requiresJustification: true,
        auditLevel: 'comprehensive',
        dataRetention: '7-years' // HIPAA minimum
      },
      'sensitive': {
        allowedRoles: ['treating-clinician', 'care-team', 'patient-self'],
        requiresMFA: true,
        requiresJustification: false,
        auditLevel: 'standard',
        dataRetention: '7-years'
      },
      'general': {
        allowedRoles: ['all-authorized'],
        requiresMFA: false,
        requiresJustification: false,
        auditLevel: 'basic',
        dataRetention: '3-years'
      }
    };

    return policies[classification.level] || policies['highly-sensitive'];
  }

  async anonymizeForResearch(dataset, researchPurpose) {
    // K-anonymity: Ensure each record is indistinguishable from k-1 others
    const kAnonymized = await this.privacyEngine.applyKAnonymity(dataset, {
      k: 5,
      quasiIdentifiers: ['age', 'gender', 'zipCode'],
      generalizationHierarchies: this.loadGeneralizationHierarchies()
    });

    // L-diversity: Ensure diversity in sensitive attributes
    const lDiverse = await this.privacyEngine.applyLDiversity(kAnonymized, {
      l: 3,
      sensitiveAttributes: ['diagnosis', 'medications']
    });

    // Remove direct identifiers
    const anonymized = this.removeDirectIdentifiers(lDiverse);

    // Document privacy methods for research ethics board
    await this.documentPrivacyMethods({
      researchPurpose,
      privacyTechniques: ['k-anonymity', 'l-diversity', 'de-identification'],
      remainingRisks: 'Low risk of re-identification',
      timestamp: new Date()
    });

    return anonymized;
  }
}