> ## Documentation Index
> Fetch the complete documentation index at: https://core.anylayer.org/llms.txt
> Use this file to discover all available pages before exploring further.

# ZK Privacy Guide

> Implementing privacy-preserving features with ZKScore

## Overview

ZKScore implements zero-knowledge proof technology to enable privacy-preserving reputation verification without revealing sensitive data.

## Privacy Features

### Selective Disclosure

Prove specific claims without revealing all data:

<CodeGroup>
  ```javascript JavaScript theme={null}
  // Prove score > 500 without revealing exact score
  const proof = await client.generateZKProof({
    type: 'score_threshold',
    user: 'alice.zks',
    threshold: 500
  });

  // Verify proof without seeing actual score
  const isValid = await client.verifyZKProof(proof, {
    type: 'score_threshold',
    threshold: 500
  });
  ```
</CodeGroup>

### Achievement Proofs

<CodeGroup>
  ```javascript JavaScript theme={null}
  // Prove achievement without revealing other achievements
  const achievementProof = await client.generateZKProof({
    type: 'achievement',
    user: 'alice.zks',
    achievementId: 'defi-pioneer'
  });

  // Verify achievement proof
  const hasAchievement = await client.verifyZKProof(achievementProof, {
    type: 'achievement',
    achievementId: 'defi-pioneer'
  });
  ```
</CodeGroup>

## Privacy-Preserving Access Control

### ZK Gating

<CodeGroup>
  ```javascript JavaScript theme={null}
  class ZKPrivacyGate {
    constructor(client) {
      this.client = client;
    }
    
    async checkPrivateAccess(userAddress, requirements) {
      try {
        const proofs = [];
        
        // Generate proofs for each requirement
        for (const requirement of requirements) {
          const proof = await this.client.generateZKProof({
            type: requirement.type,
            user: userAddress,
            ...requirement.params
          });
          proofs.push(proof);
        }
        
        return {
          hasAccess: true,
          proofs: proofs,
          privacyLevel: 'high'
        };
      } catch (error) {
        return {
          hasAccess: false,
          error: error.message
        };
      }
    }
    
    async verifyPrivateAccess(proofs, requirements) {
      try {
        for (let i = 0; i < proofs.length; i++) {
          const proof = proofs[i];
          const requirement = requirements[i];
          
          const isValid = await this.client.verifyZKProof(proof, requirement);
          if (!isValid) {
            return { hasAccess: false, reason: 'Invalid proof' };
          }
        }
        
        return { hasAccess: true, privacyLevel: 'high' };
      } catch (error) {
        return { hasAccess: false, error: error.message };
      }
    }
  }
  ```
</CodeGroup>

## Encrypted Attestations

### Private Attestation Creation

<CodeGroup>
  ```javascript JavaScript theme={null}
  // Create encrypted attestation
  const encryptedAttestation = await client.createEncryptedAttestation({
    recipient: 'alice.zks',
    schema: 'private_skill_verification',
    data: {
      skill: 'Advanced Solidity',
      level: 9,
      salary: 150000, // Private salary information
      company: 'Crypto Corp'
    },
    encryptionKey: 'recipient_public_key',
    expiration: Math.floor(Date.now() / 1000) + (365 * 24 * 60 * 60)
  });

  console.log('Encrypted attestation created:', encryptedAttestation.id);
  ```
</CodeGroup>

### Attestation Decryption

<CodeGroup>
  ```javascript JavaScript theme={null}
  // Decrypt attestation (only recipient can decrypt)
  const decryptedData = await client.decryptAttestation(
    encryptedAttestation.id,
    'recipient_private_key'
  );

  console.log('Decrypted data:', decryptedData);
  ```
</CodeGroup>

## Privacy Settings

### User Privacy Controls

<CodeGroup>
  ```javascript JavaScript theme={null}
  // Set privacy preferences
  await client.setPrivacySettings({
    user: 'alice.zks',
    settings: {
      scoreVisibility: 'threshold_only', // Only show if above threshold
      achievementVisibility: 'selective', // Only show specific achievements
      attestationVisibility: 'encrypted', // Encrypt sensitive attestations
      dataSharing: 'minimal' // Minimal data sharing
    }
  });

  // Get privacy settings
  const settings = await client.getPrivacySettings('alice.zks');
  console.log('Privacy settings:', settings);
  ```
</CodeGroup>

### Data Minimization

<CodeGroup>
  ```javascript JavaScript theme={null}
  // Request minimal data
  const minimalScore = await client.getScore('alice.zks', {
    privacy: 'minimal',
    reveal: 'threshold_only',
    threshold: 500
  });

  // Only reveals if score >= 500, doesn't reveal exact score
  console.log('Meets threshold:', minimalScore.meetsThreshold);
  ```
</CodeGroup>

## Advanced Privacy Features

### Homomorphic Encryption

<CodeGroup>
  ```javascript JavaScript theme={null}
  // Perform computations on encrypted data
  const encryptedScore = await client.getEncryptedScore('alice.zks');
  const encryptedThreshold = await client.encryptValue(500);

  // Check if encrypted score > encrypted threshold without decrypting
  const comparison = await client.compareEncryptedValues(
    encryptedScore,
    encryptedThreshold
  );

  console.log('Score meets threshold:', comparison.result);
  ```
</CodeGroup>

### Multi-Party Computation

<CodeGroup>
  ```javascript JavaScript theme={null}
  // Collaborative score verification
  const mpcResult = await client.multiPartyComputation({
    participants: ['alice.zks', 'bob.zks', 'charlie.zks'],
    computation: 'average_score',
    privacy: 'high'
  });

  console.log('Average score:', mpcResult.average);
  console.log('Individual scores remain private:', mpcResult.private);
  ```
</CodeGroup>

## Privacy Compliance

### GDPR Compliance

<CodeGroup>
  ```javascript JavaScript theme={null}
  // GDPR-compliant data handling
  const gdprCompliantScore = await client.getScore('alice.zks', {
    compliance: 'gdpr',
    dataRetention: 'minimal',
    consentRequired: true
  });

  // Data portability
  const exportData = await client.exportUserData('alice.zks', {
    format: 'json',
    includePrivate: false
  });
  ```
</CodeGroup>

### Data Anonymization

<CodeGroup>
  ```javascript JavaScript theme={null}
  // Anonymize user data
  const anonymizedData = await client.anonymizeData({
    user: 'alice.zks',
    level: 'high',
    preserveFunctionality: true
  });

  console.log('Anonymized data:', anonymizedData);
  ```
</CodeGroup>

## Privacy Best Practices

### Implementation Guidelines

1. **Minimal Data Collection**: Only collect necessary data
2. **Encryption**: Encrypt sensitive data at rest and in transit
3. **Access Controls**: Implement strict access controls
4. **Audit Logs**: Maintain privacy audit logs
5. **User Consent**: Obtain explicit consent for data processing

### Privacy by Design

1. **Default Privacy**: Set privacy as the default
2. **Transparency**: Be transparent about data usage
3. **User Control**: Give users control over their data
4. **Regular Audits**: Conduct regular privacy audits
5. **Compliance**: Ensure regulatory compliance

## Privacy Testing

### Privacy Verification

<CodeGroup>
  ```javascript JavaScript theme={null}
  // Test privacy features
  const privacyTest = await client.testPrivacyFeatures({
    user: 'alice.zks',
    tests: [
      'selective_disclosure',
      'encrypted_attestations',
      'data_minimization',
      'access_control'
    ]
  });

  console.log('Privacy test results:', privacyTest);
  ```
</CodeGroup>

## Related Documentation

* [Privacy Features](/advanced/privacy)
* [ZK Proofs](/advanced/zk-proofs)
* [Attesters Guide](/guides/attesters)