Data Security Overview

PubNub is serious about the security of your data. Using TLS and AES256 encryption algorithms, and with HIPAA, GDPR, SOC2 type 2, and CCPA compliance, you can be sure your data is safeguarded.

There are several ways in which PubNub helps to secure your app:

User ID / UUID

User ID is also referred to as UUID/uuid in some APIs and server responses but holds the value of the userId parameter you set during initialization.

Connection security

PubNub offers connection level security through TLS Encryption (Transport Layer Security). It's enabled by default and generally there is no reason to disable it for any production application.

Configuring TLS

TLS is enabled by default. If you need to disable it for any reason, it can be done during the PubNub object initialization.


Some PubNub SDKs, the parameter name is ssl (a legacy name for TLS) but it represents the latest connection encryption technology available. SSL v3 was deprecated due to a security exploit that was discovered and TLS was developed to replace it as the industry standard. Many will refer to TLS as SSL out of habit.

var pubnub = new PubNub({
subscribeKey: "mySubscribeKey",
publishKey: "myPublishKey",
userId: "myUniqueUserId",
ssl: false // default 'true'

TCP connection troubleshooting

If you need to capture the TCP traffic (a tcpdump to a .pcap file) to analyze and debug the network traffic, you may need to disable TLS in your development environment. This level of analysis is only necessary to troubleshoot the most difficult network connection and communication issues that are typically outside of the PubNub domain.

Message encryption

PubNub SDKs allow you to configure the encryption/decryption algorithms using pre-bundled packages for encrypting/decrypting data (cryptors) in your apps through crypto modules.


Why encrypt messages?

Crypto module

A crypto module is the part of PubNub SDKs that contains multiple cryptor implementations that enable the encryption and decryption of data within the application. It can be configured to use different encryption algorithms. By default, PubNub SDKs offer crypto modules with the following encryption/decryption capabilities:

  • Legacy encryption with 128-bit cipher key entropy (legacy module)
  • Recommended AES-CBC 256-bit (CBC block cipher mode) encryption

If you're using one of the latest PubNub SDKs, your clients can decrypt content encrypted using either of the modules, regardless of the one you use for data encryption.

If you use the legacy module and your data is encrypted with 128-bit cipher key entropy, you can still decrypt data encrypted using the recommended AES-CBC 256-bit module. This backward compatibility works both ways - if you use the recommended 256-bit module, you can decrypt data encrypted using the legacy module.

This way, you can switch to the recommended AES-CBC 256-bit encryption and still interact with historical messages or messages sent from older clients.

Legacy encryption with 128-bit cipher key entropy

You don't have to change your encryption configuration if you want to keep using the legacy encryption. If you want to use the recommended 256-bit AES-CBC encryption, you must explicitly set that in PubNub config.

If you do not explicitly select either module in your app and have cipherKey and, optionally, useRandomInitializationVector set in PubNub configuration, the client defaults to using the legacy encryption.

For information on how to configure modules, refer to the Configuration documentation of each SDK.

Keep your clients up to date

Apps not using the latest SDK version will not be able to decrypt data encrypted using the 256-bit AES-CBC cipher. Make sure to update your clients or encrypt data using the legacy module.

Upgrade to 256-bit encryption

For information on how to migrate to the recommended encryption algorithm, refer to 256-bit AES-CBC Encryption.

Encryption scope

Depending on whether you want to encrypt all messages and files or just some of them, create and register a crypto module differently.

  • To fully encrypt every message and file in all channels for a given API key, specify and register the crypto module as part of the PubNub configuration when you create the object.

  • To only encrypt some or partially encrypt messages, do not specify the crypto module as part of the PubNub configuration. Instead, create a standalone instance of a crypto module and call one of the available encrypt() or decrypt() methods.

Encrypting messages

To configure encryption for all messages and files in all channels for a given API key, you need to register a module, provide a cipherKey, and, optionally, decide whether to use a random initialization vector to encrypt (and decrypt) data.

For information on partial encryption, refer to the Partial Message Encryption section.

var pubnub = new PubNub({
// all necessary config options
cryptoModule: PubNub.CryptoModule.aesCbcCryptoModule({cipherKey: 'pubnubenigma'})

The raw message never leaves a trusted authority providing for full circle data encryption. It's encrypted at the time of publish by the PubNub SDK before it's sent and it remains encrypted as it's routed through the PubNub Network till it reaches the client that subscribes to it.

The subscribing client needs to decrypt it using the same cipher key. All data that is persisted in Message Persistence (and logging systems) is encrypted and can't be decrypted by anyone unless they hold the required cipher key.

Protect your cipher key

You shouldn't share the cipher key outside of the PubNub network.

Partial message encryption

Sometimes, only encrypting certain parts of your message makes more sense than encrypting the whole payload. If you're using Mobile Push Notifications and encrypt all messages and files, PubNub will not be able to read the mobile push keys and values that you provide in your message payload. In such cases, you need to encrypt only the sensitive data in your message payload while leaving other pieces of data as clear text.

It is best to create a separate crypto module instance and call the encrypt() or decrypt() methods on that instance.

APNs example

Let's use an example message payload to demonstrate the proper way to do precise and necessary message data encryption specific to an APNs payload.

Before encryption:

"pn_apns": {
"aps": {
"alert": "Your test results are available.",
"sound" : "bingbong.aiff"
"results": {
"test_name": "pregnancy",
"results": "positive",
"notes": "You are having twins!"

Encrypt it:

In the above message payload, the only data that really must be encrypted is the results object. Everything else can remain as plain text.

const clearText = JSON.stringify(
{"test_name":"pregnancy","results":"positive","notes":"You are having twins!"});

// create a crypto module instance
const cryptoModule = PubNub.CryptoModule.aesCbcCryptoModule({
cipherKey: "pubnubenigma"

const secureText = cryptoModule.encrypt(clearText);

You can now add the secureData variable to the payload so that PubNub and third party mobile push vendors can process the Push payload correctly.

Using a cipher key, pubnubrealtimecommunicationplatf in this example (your cipher key will be more complex, but exactly 32 chars are required for 256 AES cipher keys), to encrypt only the confidential data, the resulting message payload would be as follows.

After encryption:

"pn_apns": {
"aps": {
"alert": "Your test results are available.",
"sound" : "bingbong.aiff"
"results": "Nio2At2uvQzteLoSqznLkZQ3dlFlMzLGlUwbsMndZ7/7tllq2joJw6WcUv3XpMdEugYRnoEvsrlhEVkSnBibxaxDDWMFEDvKS+VLlA8mfmg="
Partial Message Encryption

You may need to encrypt certain data values within the APNs/FCM payload, but be sure not to encrypt any APNs/FCM keys, or any values that need to be parsed as unencrypted text by those mobile push services.

Decrypting messages

On the message receiver side, your client must also have the same module and cipher key to use the decrypt API on the encrypted parts of the message payload.

// parse the received message and pass the encrypted parts to decrypt API.
const secureText =

const clearData = pubnub.decrypt(secureText);

For more examples of decrypting messages in other languages, refer to the Configuration and/or Miscellaneous documentation of each SDK.

File encryption

Much like messages, you can also encrypt the files sent from your clients using a crypto module.

If you registered a crypto module in the configuration, you don't have to explicitly specify it in the method to encrypt or decypt the uploaded files.

Do not pass cipher key

If you do pass a cipher key in the sendFile or downloadFile methods, it overrides the crypto module configuration and the legacy encryption with 128-bit cipher key entropy is used.

Refer to Encrypting Messages for information on how to configure the crypto module.

With client-side encryption, the SDK encrypts file data before it's uploaded to the storage service. The receiving client must decrypt the data upon download using the same key before it's displayed in the end-user application.

Encrypting files

The following example shows how to encrypt a file using the crypto module registered in PubNub config.

 import fs from 'fs';

const myFile = fs.readFileSync('./cat_picture.jpg');

const result = await pubnub.sendFile({
channel: 'my_channel',
message: 'Look at this photo!',
file: { data: myFile, name: 'cat_picture.jpg', mimeType: 'application/json' }

Decrypting files

The following example shows how to decrypt a file using the crypto module registered in PubNub config.

const file = await pubnub.downloadFile({
channel: 'my_channel',
id: 'd9515cb7-48a7-41a4-9284-f4bf331bc770',
name: 'cat_picture.jpg'

For more examples of encrypting/decrypting files in other languages, refer to the Configuration and/or Files documentation of each SDK.

Custom encryption

The message and file encryption/decryption functionality is decoupled from our SDKs, which allows you to provide your implementations of the methods responsible for encrypting and decrypting message and file data.

Each PubNub SDK exposes an interface to register a list of different cryptors


An implementation of a specific cryptographic algorithm used for data encryption/decryption that adheres to a standard interface.

For decryption, any of the cryptors on the list may be applied depending on the one used when initially sending the message/file. The SDK inspects the incoming payload and decides which cryptor to use.

Implementation guidelines

The way to use custom encryption in PubNub SDKs differs across SDKs, as some of them provide file encryption and some don't. However, the general implementation flow remains the same:

  1. Implement the Crypto and StreamingCrypto interfaces (actual names vary) and provide concrete implementations for the methods they provide. Refer to the Crypto interfaces section to find out which interface you should implement.

  2. Create a new Crypto module instance with your cryptor implementation and pass it to PubNub configuration or use it standalone for partial encryption. Refer to each SDK's Crypto module documentation.

Example custom cryptor implementation

This example uses Kotlin, but the general idea is the same across all SDKs.

  1. Implement the Cryptor interface. Note that the id() method should return a ByteArray of exactly 4 bytes.
fun myCustomCryptor() = object : Cryptor {
override fun id(): ByteArray {
// Should return a ByteArray of exactly 4 bytes.
return byteArrayOf('C'.code.toByte(), 'U'.code.toByte(), 'S'.code.toByte(), 'T'.code.toByte())

override fun encrypt(data: ByteArray): EncryptedData {
// implement your crypto logic
return EncryptedData(metadata = null, data = data)

override fun decrypt(encryptedData: EncryptedData): ByteArray {
// implement your crypto logic
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  1. Use your newly created myCustomCryptor that implements the Cryptor interface to instantiate a CryptoModule:
val customCryptor = myCustomCryptor()
val cryptoModule = CryptoModule.createNewCryptoModule(defaultCryptor = customCryptor)

Interfaces to implement

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