Encryption
The Ably.Rest.Crypto object exposes the following public methods:
Methods
getDefaultParams
CipherParams Crypto.getDefaultParams(Object params)
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.<span lang=“go”>returns a CipherParams object with fields set to default values. This generates random secret key and initialization vector (iv) values.
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 example at the top) or when setting channel options with channel#setOptions.
Parameters
- params
- The cipher params that you want to specify. It must at a minimum include a
key, which should be either a binary (ArrayBufferorWordArray) or a base64-encodedString.
Returns
On success, the method returns a complete CipherParams object. Failure will raise an exception.
Example
var cipherParams = Ably.Rest.Crypto.getDefaultParams({key: <key>});
var channelOpts = { cipher: cipherParams };
var channel = rest.channels.get('oak-ate-tie', channelOpts);
CopyCopied!generateRandomKey
Crypto.generateRandomKey(Int keyLength?, callback(ErrorInfo err,
Bufferkey))
This call obtains a randomly-generated binary key of the specified key length.
Parameters
- keyLength
- Optional
Intwith the length of key to generate. For AES, this should be either 128 or 256. If unspecified, defaults to 256. - callback
- is a function of the form
function(err, key)which is called upon completion
Callback result
On successfully generating a key, the callback is called with that key as a WordArray, and err is null. On failure to create a key, err contains an ErrorInfo object describing the failure reason.
Example
Ably.Rest.Crypto.generateRandomKey(256, function(err, key) {
if(err) {
console.log("Key generation failed: " + err.toString());
} else {
var channel = rest.channels.get('oak-ate-tie', {cipher: {key: key}});
}
});
CopyCopied!Related types
ChannelOptions Object
Channel options are used for setting channel parameters and configuring encryption.
ChannelOptions, a plain JavaScript object, may optionally be specified when instancing a Channel, and this may be used to specify channel-specific options. The following attributes can be defined on the object:
Properties
- params
- Optional parameters which specify behaviour of the channel.Type:
JSON Object - cipher
- 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:
CipherParamsor an options object containing at a minimum akey
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 (
ArrayBufferorWordArray) or base64-encodedStringcontaining 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 “aes” or “AES“Type:
String - keyLength
- 256 The key length in bits of the cipher, either 128 or 256Type:
Integer - mode
- CBC The cipher modeType:
String