godot/doc/classes/HMACContext.xml

<?xml version="1.0" encoding="UTF-8" ?>
<class name="HMACContext" inherits="Reference" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
	<brief_description>
		Used to create an HMAC for a message using a key.
	</brief_description>
	<description>
		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.
	</description>
	<tutorials>
	</tutorials>
	<methods>
		<method name="finish">
			<return type="PoolByteArray" />
			<description>
				Returns the resulting HMAC. If the HMAC failed, an empty [PoolByteArray] is returned.
			</description>
		</method>
		<method name="start">
			<return type="int" enum="Error" />
			<argument index="0" name="hash_type" type="int" enum="HashingContext.HashType" />
			<argument index="1" name="key" type="PoolByteArray" />
			<description>
				Initializes the HMACContext. This method cannot be called again on the same HMACContext until [method finish] has been called.
			</description>
		</method>
		<method name="update">
			<return type="int" enum="Error" />
			<argument index="0" name="data" type="PoolByteArray" />
			<description>
				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.
			</description>
		</method>
	</methods>
	<constants>
	</constants>
</class>