> For the complete documentation index, see [llms.txt](https://zoom.gitbook.io/zoom/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://zoom.gitbook.io/zoom/contents.md).

# Contents

### **1. Introduction**

\
*1.1 Outline* \
*1.1.1 E2E Encryption for Zoom Meetings*

### 2. Background and Security Goals 

\
*2.1 Limitations*

### 3. User Identity and Key Management 

\
*3.1 Non-Cryptographic Identity at Zoom* 

*3.2 Cryptographic User Identity* 

*3.3 Displaying Identity* 

*3.3.1 Identifying Accounts* 

*3.3.2 Identifying Users* 

*3.4 Multi-Device Support* 

*3.4.1 Per-User Keys* 

*3.4.2 Backup Keys* 

*3.4.3 Escrow Keys* 

*3.4.1 Lockdown Mode* 

*3.5 Consistent Identities With Sighchains* 

*3.5.1 Sighchains* 

*3.5.2 Overview of Sighchain Types* 

*3.5.3 User Sighchains* 

*3.5.4 Email Sighchains* 

*3.5.5 Account Sighchains* 

*3.5.6 ADN Sighchains* 

*3.5.7 Membership Sighchains* 

*3.6 Sighchain Fingerprints* 

*3.7 Client Key Management* 

*3.7.1 Storing Secret Keys on Device* 

*3.7.2 Device Management Interface* 

*3.8 Account Escrow* 

*3.8.1 Escrow Administrators and the EA Sighchain* 

*3.8.2 Users’ Escrow Device Management* 

*3.8.3 EA Permissions* 

*3.8.4 User Recovery* 

*3.8.5 Legal Discovery* 

*3.9 Highlighting Untrusted Devices with Contact Sync* 

*3.10 Compromise Prevention for Device Provisioning* 

*3.11 Security Properties* 

*3.11.1 MitM Between a User’s Devices* 

*3.11.2 MitM Between Different Users* 

*3.11.3 Integrity* 

*3.11.4 Security Limitations* 

*3.11.5 Privacy Limitations*

### 4. Transparency Tree 

*4.1 Zoom Transparency Tree* 

*4.2 Integration Details* 

*4.2.1 ZTT Auditing* 

*4.2.2 Provisioning* 

*4.2.3 Self-Audit and Refresh* 

*4.2.4 Validating User Identity* 

*4.2.5 Contact List Updates* 

*4.3 Security Properties*

*5 Identity Provider Attestations* 

*5.1 Associating Accounts with Identity Providers* 

*5.2 IDP Attestations 5.3 Updating Snapshots* 

*5.4 Validating IDP Attestations* 

*5.5 Zoom Identity Snapshots* 

*5.6 Security Properties*

### *6. Encryption for Zoom Mail Service* 

*6.1 Encrypted Email Protocol* 

*6.2 Emails to Users without Devices* 

*6.3 Emails to and from External Users* 

*6.4 Mailing Lists 6.5 Calendar Email Integration* 

*6.6 Encrypting Non-Email Data* 

*6.7 Security Properties* 

*6.7.1 Spam Detection and Contact Monitoring*

### 7. Encryption for Zoom Meetings 

*7.1 Zoom Meetings* 

*7.2 Enhanced Encryption* 

*7.3 End-to-End Encryption*

*7.3.1 Security Goals* 

*7.4 System Components* 

*7.5 Cryptographic Algorithms* 

*7.5.1 Signing* 

*7.5.2 Authenticated Public-Key Encryption* 

*7.6 Join/Leave Protocol flow*

*7.6.1 Server Key Certificate Chains* 

*7.6.2 Participant Key Generation*

*7.6.3 Leader Join* 

*7.6.4 Participant Join (Leader)* 

*7.6.5 Participant Join (Non-Leader)* 

*7.6.6 Key Rotation* 

*7.6.7 Leader Participant List* 

*7.6.8 Liveness* 

*7.6.9 Locked Meetings* 

*7.6.10 Meeting Teardown*

*7.7 Meeting Leader Security Code* 

*7.8 E2E Encryption for Breakout Rooms* 

*7.9 Abuse Management and Reporting* 

*7.10 IDP Attestations for E2EE Meetings* 

*7.11 E2EE Meetings with Cryptographic Identity* 

*7.12 Security Properties for E2EE Meetings* 

*7.12.1 Areas to Improve*

### 8. Encryption for Zoom Phone 

*8.1 E2EE Zoom Phone Calls* 

*8.1.1 Join/Leave Protocol*

*8.1.2 Phone Security Code* 

*8.2 Advanced Encryption for Voicemail* 

*8.2.1 Security Properties*

### A. Release Schedule

B Understanding Multiple Devices 

B.1 A Claim about Device Equivalence Classes

### C. Cake-AES 

C.1 Encryption 

C.2 Decryption 

C.3 Random-Access Decryption