Document AES and new Crypto/CryptoKey functions.

doc/classes/AESContext.xml

@@ -0,0 +1,99 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<class name="AESContext" inherits="Reference" version="4.0">
+	<brief_description>
+		Interface to low level AES encryption features.
+	</brief_description>
+	<description>
+		This class provides access to AES encryption/decryption of raw data. Both AES-ECB and AES-CBC mode are supported.
+		[codeblock]
+		extends Node
+
+		var aes = AESContext.new()
+
+		func _ready():
+		    var key = "My secret key!!!" # Key must be either 16 or 32 bytes.
+		    var data = "My secret text!!" # Data size must be multiple of 16 bytes, apply padding if needed.
+		    # Encrypt ECB
+		    aes.start(AESContext.MODE_ECB_ENCRYPT, key.to_utf8())
+		    var encrypted = aes.update(data.to_utf8())
+		    aes.finish()
+		    # Decrypt ECB
+		    aes.start(AESContext.MODE_ECB_DECRYPT, key.to_utf8())
+		    var decrypted = aes.update(encrypted)
+		    aes.finish()
+		    # Check ECB
+		    assert(decrypted == data.to_utf8())
+
+		    var iv = "My secret iv!!!!" # IV must be of exactly 16 bytes.
+		    # Encrypt CBC
+		    aes.start(AESContext.MODE_CBC_ENCRYPT, key.to_utf8(), iv.to_utf8())
+		    encrypted = aes.update(data.to_utf8())
+		    aes.finish()
+		    # Decrypt CBC
+		    aes.start(AESContext.MODE_CBC_DECRYPT, key.to_utf8(), iv.to_utf8())
+		    decrypted = aes.update(encrypted)
+		    aes.finish()
+		    # Check CBC
+		    assert(decrypted == data.to_utf8())
+		[/codeblock]
+	</description>
+	<tutorials>
+	</tutorials>
+	<methods>
+		<method name="finish">
+			<return type="void">
+			</return>
+			<description>
+				Close this AES context so it can be started again. See [method start].
+			</description>
+		</method>
+		<method name="get_iv_state">
+			<return type="PackedByteArray">
+			</return>
+			<description>
+				Get the current IV state for this context (IV gets updated when calling [method update]). You normally don't need this funciton.
+				Note: This function only makes sense when the context is started with [constant MODE_CBC_ENCRYPT] or [constant MODE_CBC_DECRYPT].
+			</description>
+		</method>
+		<method name="start">
+			<return type="int" enum="Error">
+			</return>
+			<argument index="0" name="mode" type="int" enum="AESContext.Mode">
+			</argument>
+			<argument index="1" name="key" type="PackedByteArray">
+			</argument>
+			<argument index="2" name="iv" type="PackedByteArray" default="PackedByteArray(  )">
+			</argument>
+			<description>
+				Start the AES context in the given [code]mode[/code]. A [code]key[/code] of either 16 or 32 bytes must always be provided, while an [code]iv[/code] (initialization vector) of exactly 16 bytes, is only needed when [code]mode[/code] is either [constant MODE_CBC_ENCRYPT] or [constant MODE_CBC_DECRYPT].
+			</description>
+		</method>
+		<method name="update">
+			<return type="PackedByteArray">
+			</return>
+			<argument index="0" name="src" type="PackedByteArray">
+			</argument>
+			<description>
+				Run the desired operation for this AES context. Will return a [PackedByteArray] containing the result of encrypting (or decrypting) the given [code]src[/code]. See [method start] for mode of operation.
+				Note: The size of [code]src[/code] must be a multiple of 16. Apply some padding if needed.
+			</description>
+		</method>
+	</methods>
+	<constants>
+		<constant name="MODE_ECB_ENCRYPT" value="0" enum="Mode">
+			AES electronic codebook encryption mode.
+		</constant>
+		<constant name="MODE_ECB_DECRYPT" value="1" enum="Mode">
+			AES electronic codebook decryption mode.
+		</constant>
+		<constant name="MODE_CBC_ENCRYPT" value="2" enum="Mode">
+			AES cipher blocker chaining encryption mode.
+		</constant>
+		<constant name="MODE_CBC_DECRYPT" value="3" enum="Mode">
+			AES cipher blocker chaining decryption mode.
+		</constant>
+		<constant name="MODE_MAX" value="4" enum="Mode">
+			Maximum value for the mode enum.
+		</constant>
+	</constants>
+</class>

doc/classes/Crypto.xml

@@ -5,7 +5,7 @@
 	</brief_description>
 	<description>
 		The Crypto class allows you to access some more advanced cryptographic functionalities in Godot.
-		For now, this includes generating cryptographically secure random bytes, and RSA keys and self-signed X509 certificates generation. More functionalities are planned for future releases.
+		For now, this includes generating cryptographically secure random bytes, RSA keys and self-signed X509 certificates generation, asymmetric key encryption/decryption, and signing/verification.
 		[codeblock]
 		extends Node
 
@@ -21,12 +21,48 @@
 		    # Save key and certificate in the user folder.
 		    key.save("user://generated.key")
 		    cert.save("user://generated.crt")
+		    # Encryption
+		    var data = "Some data"
+		    var encrypted = crypto.encrypt(key, data.to_utf8())
+		    # Decryption
+		    var decrypted = crypto.decrypt(key, encrypted)
+		    # Signing
+		    var signature = crypto.sign(HashingContext.HASH_SHA256, data.sha256_buffer(), key)
+		    # Verifying
+		    var verified = crypto.verify(HashingContext.HASH_SHA256, data.sha256_buffer(), signature, key)
+		    # Checks
+		    assert(verified)
+		    assert(data.to_utf8() == decrypted)
 		[/codeblock]
 		[b]Note:[/b] Not available in HTML5 exports.
 	</description>
 	<tutorials>
 	</tutorials>
 	<methods>
+		<method name="decrypt">
+			<return type="PackedByteArray">
+			</return>
+			<argument index="0" name="key" type="CryptoKey">
+			</argument>
+			<argument index="1" name="ciphertext" type="PackedByteArray">
+			</argument>
+			<description>
+				Decrypt the given [code]ciphertext[/code] with the provided private [code]key[/code].
+				[b]Note[/b]: The maximum size of accepted ciphertext is limited by the key size.
+			</description>
+		</method>
+		<method name="encrypt">
+			<return type="PackedByteArray">
+			</return>
+			<argument index="0" name="key" type="CryptoKey">
+			</argument>
+			<argument index="1" name="plaintext" type="PackedByteArray">
+			</argument>
+			<description>
+				Encrypt the given [code]plaintext[/code] with the provided public [code]key[/code].
+				[b]Note[/b]: The maximum size of accepted plaintext is limited by the key size.
+			</description>
+		</method>
 		<method name="generate_random_bytes">
 			<return type="PackedByteArray">
 			</return>
@@ -68,6 +104,34 @@
 				[/codeblock]
 			</description>
 		</method>
+		<method name="sign">
+			<return type="PackedByteArray">
+			</return>
+			<argument index="0" name="hash_type" type="int" enum="HashingContext.HashType">
+			</argument>
+			<argument index="1" name="hash" type="PackedByteArray">
+			</argument>
+			<argument index="2" name="key" type="CryptoKey">
+			</argument>
+			<description>
+				Sign a given [code]hash[/code] of type [code]hash_type[/code] with the provided private [code]key[/code].
+			</description>
+		</method>
+		<method name="verify">
+			<return type="bool">
+			</return>
+			<argument index="0" name="hash_type" type="int" enum="HashingContext.HashType">
+			</argument>
+			<argument index="1" name="hash" type="PackedByteArray">
+			</argument>
+			<argument index="2" name="signature" type="PackedByteArray">
+			</argument>
+			<argument index="3" name="key" type="CryptoKey">
+			</argument>
+			<description>
+				Verify that a given [code]signature[/code] for [code]hash[/code] of type [code]hash_type[/code] against the provided public [code]key[/code].
+			</description>
+		</method>
 	</methods>
 	<constants>
 	</constants>

doc/classes/CryptoKey.xml

@@ -11,13 +11,34 @@
 	<tutorials>
 	</tutorials>
 	<methods>
+		<method name="is_public_only" qualifiers="const">
+			<return type="bool">
+			</return>
+			<description>
+				Return [code]true[/code] if this CryptoKey only has the public part, and not the private one.
+			</description>
+		</method>
 		<method name="load">
 			<return type="int" enum="Error">
 			</return>
 			<argument index="0" name="path" type="String">
 			</argument>
+			<argument index="1" name="public_only" type="bool" default="false">
+			</argument>
+			<description>
+				Loads a key from [code]path[/code]. If [code]public_only[/code] is [code]true[/code], only the public key will be loaded.
+				[b]Note[/b]: [code]path[/code] should should be a "*.pub" file if [code]public_only[/code] is [code]true[/code], a "*.key" file otherwise.
+			</description>
+		</method>
+		<method name="load_from_string">
+			<return type="int" enum="Error">
+			</return>
+			<argument index="0" name="string_key" type="String">
+			</argument>
+			<argument index="1" name="public_only" type="bool" default="false">
+			</argument>
 			<description>
-				Loads a key from [code]path[/code] ("*.key" file).
+				Loads a key from the given [code]string[/code]. If [code]public_only[/code] is [code]true[/code], only the public key will be loaded.
 			</description>
 		</method>
 		<method name="save">
@@ -25,8 +46,20 @@
 			</return>
 			<argument index="0" name="path" type="String">
 			</argument>
+			<argument index="1" name="public_only" type="bool" default="false">
+			</argument>
+			<description>
+				Saves a key to the given [code]path[/code]. If [code]public_only[/code] is [code]true[/code], only the public key will be saved.
+				[b]Note[/b]: [code]path[/code] should should be a "*.pub" file if [code]public_only[/code] is [code]true[/code], a "*.key" file otherwise.
+			</description>
+		</method>
+		<method name="save_to_string">
+			<return type="String">
+			</return>
+			<argument index="0" name="public_only" type="bool" default="false">
+			</argument>
 			<description>
-				Saves a key to the given [code]path[/code] (should be a "*.key" file).
+				Returns a string containing the key in PEM format. If [code]public_only[/code] is [code]true[/code], only the public key will be included.
 			</description>
 		</method>
 	</methods>