API v 0.8
JavaScript

Encryption

The Ably.Realtime.Crypto object exposes the following public methods:

This call obtains a CipherParams object using the values passed in (which must be a subset of CipherParams fields that at a minimum includes a key), filling in any unspecified fields with default values, and checks that the result is a valid and self-consistent.

You will rarely need to call this yourself, since the client library will handle it for you if you specify cipher params when initializing a channel (as in the getting started example).

Parameters

params
The cipher params that you want to specify. It must at a minimum include a key, which should be either a binary () or a base64-encoded String.

Returns

On success, the method returns a complete CipherParams object. Failure will raise an exception.

Example

JavaScript
var cipherParams = Ably.Realtime.Crypto.getDefaultParams({key: <key>}); var channelOpts = { cipher: cipherParams }; var channel = realtime.channels.get('mud-ate-ago', channelOpts);
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Crypto.generateRandomKey(Int keyLength?, callback(ErrorInfo err, Buffer key))

This call obtains a randomly-generated binary key of the specified key length.

Parameters

keyLength
Optional Int with the length of key to generate. For AES, this should be either 128 or 256. If unspecified, defaults to 256128.
callback
is a function of the form function(err, key) which is called upon completion

Example

JavaScript
Ably.Realtime.Crypto.generateRandomKey(256, function(err, key) { if(err) { console.log("Key generation failed: " + err.toString()); } else { var channel = realtime.channels.get('mud-ate-ago', {cipher: {key: key}}); } });
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Channel options are used for configuring encryption.

Properties

Requests encryption for this channel when not null, and specifies encryption-related parameters (such as algorithm, chaining mode, key length and key). See an exampleType: CipherParams

A CipherParams contains configuration options for a channel cipher, including algorithm, mode, key length and key. Ably client libraries currently support AES with CBC, PKCS#7 with a default key length of 256 bits. All implementations also support AES128.

Individual client libraries may support either instancing a CipherParams directly, using Crypto.getDefaultParams(), or generating one automatically when initializing a channel, as in this example.

Properties

key
A binary () or base64-encoded String containing the secret key used for encryption and decryption
algorithm
AES The name of the algorithm in the default system provider, or the lower-cased version of it; eg β€œaes” or β€œAESβ€œType: String
keyLength
256 The key length in bits of the cipher, either 128 or 256Type: Integer
mode
CBC The cipher modeType: String