Document AES and new Crypto/CryptoKey functions.

This commit is contained in:
Fabio Alessandrelli 2020-06-18 12:39:56 +02:00
parent dcd5433b3b
commit 2e7976181b
3 changed files with 199 additions and 3 deletions

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<?xml version="1.0" encoding="UTF-8" ?>
<class name="AESContext" inherits="Reference" version="3.2">
<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="PoolByteArray">
</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="PoolByteArray">
</argument>
<argument index="2" name="iv" type="PoolByteArray" default="PoolByteArray( )">
</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="PoolByteArray">
</return>
<argument index="0" name="src" type="PoolByteArray">
</argument>
<description>
Run the desired operation for this AES context. Will return a [PoolByteArray] 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>

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@ -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="PoolByteArray">
</return>
<argument index="0" name="key" type="CryptoKey">
</argument>
<argument index="1" name="ciphertext" type="PoolByteArray">
</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="PoolByteArray">
</return>
<argument index="0" name="key" type="CryptoKey">
</argument>
<argument index="1" name="plaintext" type="PoolByteArray">
</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="PoolByteArray">
</return>
@ -68,6 +104,34 @@
[/codeblock]
</description>
</method>
<method name="sign">
<return type="PoolByteArray">
</return>
<argument index="0" name="hash_type" type="int" enum="HashingContext.HashType">
</argument>
<argument index="1" name="hash" type="PoolByteArray">
</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="PoolByteArray">
</argument>
<argument index="2" name="signature" type="PoolByteArray">
</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>

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@ -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] ("*.key" file).
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 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] (should be a "*.key" file).
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>
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>