Used to create an HMAC for a message using a key.
The HMACContext class is useful for advanced HMAC use cases, such as streaming the message as it supports creating the message over time rather than providing it all at once. [codeblock] extends Node var ctx = HMACContext.new()

func _ready(): var key = "supersecret".to_utf8() var err = ctx.start(HashingContext.HASH_SHA256, key) assert(err == OK) var msg1 = "this is ".to_utf8() var msg2 = "super duper secret".to_utf8() err = ctx.update(msg1) assert(err == OK) err = ctx.update(msg2) assert(err == OK) var hmac = ctx.finish() print(hmac.hex_encode()) [/codeblock] And in C# we can use the following. [codeblock] using Godot; using System; using System.Diagnostics;

public class CryptoNode : Node { private HMACContext ctx = new HMACContext(); public override void _Ready() { PoolByteArray key = String("supersecret").to_utf8(); Error err = ctx.Start(HashingContext.HASH_SHA256, key); GD.Assert(err == OK); PoolByteArray msg1 = String("this is ").to_utf8(); PoolByteArray msg2 = String("super duper secret").to_utf8(); err = ctx.Update(msg1); GD.Assert(err == OK); err = ctx.Update(msg2); GD.Assert(err == OK); PoolByteArray hmac = ctx.Finish(); GD.Print(hmac.HexEncode()); } } [/codeblock] [b]Note:[/b] Not available in HTML5 exports.
Returns the resulting HMAC. If the HMAC failed, an empty [PoolByteArray] is returned.
Initializes the HMACContext. This method cannot be called again on the same HMACContext until [method finish] has been called.
Updates the message to be HMACed. This can be called multiple times before [method finish] is called to append [code]data[/code] to the message, but cannot be called until [method start] has been called.