IntroductionIn this tutorial, we will help you add end-to-end encryption to your product to secure your messages and user data that you deliver using Twilio Programmable Chat.How does end-to-end encryption work with Twilio?End-to-end encryption consists of securing data between two users or endpoints using a private & public key for each user or endpoint:Twilio SDK on the Client side allows users to send and receive messages, join groups and communicate with Twilio backend in other ways, while Virgil handles encryption of users' messages and data.Virgil e3kit SDK on the Client side allows you to generate a public and a private key for your user.The public key is published to Virgil Cards Service, part of the Virgil Cloud PKI. When your users want to send a message, the Virgil SDK uses the recipient's public key to encrypt the message data in a way that only the recipient's corresponding private key can decrypt it.The private key is kept on the end-user's device, enabling the user and only the user to decrypt any messages or data that other users sent to them. It's similar to the relationship between a public mailing address and a private mailbox. You look up someone's address to send them a letter, but only they can unlock their mailbox to open and read the letter.The address book (Virgil's Cards Service), mailing address (public key) and mailbox key (private key) are related to each other, but can't be traced to each other in any way that would compromise the security of the system. End-to-end encryption also locks the letter (message data), and only the recipient has the key to unlock it.This setup enables users to encrypt a message on their phone or computer, send it over the Internet with the help of Twilio to a recipient without any chance of another party reading it in transit or on the server, and have it be decrypted only by the recipient on their phone or computer. This all works seamlessly for the end-users and it only takes a few lines of code to implement using e3kit SDK.Key Features of Virgil Security's e3kitCreates public and private keys for users, and stores public keys in Virgil's Cloud PKI.Seamlessly enables your users to log in from multiple devices across iOS/Android/web browsers and use the same private key to decrypt messages/data.Encrypts and decrypts text and blobs of your choice on the client-side. Encrypted data is not readable on the server side to anyone, including hackers, third-party developers and internal team members.The SDK signs and verifies data as part of the encrypt and decrypt functions. This confirms that data is actually coming from the user who encrypted it and that it hasn't been tampered with in transit or storage.Supports private key recovery via secret questions and answers.Natively integrates with existing authentication systems, including username and password and passwordless authentication.Does your project need to be GDPR or HIPAA compliant?For GDPR compliance, just follow these guides as-is. Learn more about GDPR compliance here.For HIPAA compliance, you might need to build in message redaction functionality. Consult specific platform resources on our blog here.