Merge pull request #39755 from Faless/crypto/encryption_pr_4.0

Crypto enhancements, AESContext, RSA public key, signature, verification.

core/crypto/aes_context.cpp

@@ -0,0 +1,116 @@
+/*************************************************************************/
+/*  aes_context.cpp                                                      */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "core/crypto/aes_context.h"
+
+Error AESContext::start(Mode p_mode, PackedByteArray p_key, PackedByteArray p_iv) {
+	ERR_FAIL_COND_V_MSG(mode != MODE_MAX, ERR_ALREADY_IN_USE, "AESContext already started. Call 'finish' before starting a new one.");
+	ERR_FAIL_COND_V_MSG(p_mode < 0 || p_mode >= MODE_MAX, ERR_INVALID_PARAMETER, "Invalid mode requested.");
+	// Key check.
+	int key_bits = p_key.size() << 3;
+	ERR_FAIL_COND_V_MSG(key_bits != 128 && key_bits != 256, ERR_INVALID_PARAMETER, "AES key must be either 16 or 32 bytes");
+	// Initialization vector.
+	if (p_mode == MODE_CBC_ENCRYPT || p_mode == MODE_CBC_DECRYPT) {
+		ERR_FAIL_COND_V_MSG(p_iv.size() != 16, ERR_INVALID_PARAMETER, "The initialization vector (IV) must be exactly 16 bytes.");
+		iv.resize(0);
+		iv.append_array(p_iv);
+	}
+	// Encryption/decryption key.
+	if (p_mode == MODE_CBC_ENCRYPT || p_mode == MODE_ECB_ENCRYPT) {
+		ctx.set_encode_key(p_key.ptr(), key_bits);
+	} else {
+		ctx.set_decode_key(p_key.ptr(), key_bits);
+	}
+	mode = p_mode;
+	return OK;
+}
+
+PackedByteArray AESContext::update(PackedByteArray p_src) {
+	ERR_FAIL_COND_V_MSG(mode < 0 || mode >= MODE_MAX, PackedByteArray(), "AESContext not started. Call 'start' before calling 'update'.");
+	int len = p_src.size();
+	ERR_FAIL_COND_V_MSG(len % 16, PackedByteArray(), "The number of bytes to be encrypted must be multiple of 16. Add padding if needed");
+	PackedByteArray out;
+	out.resize(len);
+	const uint8_t *src_ptr = p_src.ptr();
+	uint8_t *out_ptr = out.ptrw();
+	switch (mode) {
+		case MODE_ECB_ENCRYPT: {
+			for (int i = 0; i < len; i += 16) {
+				Error err = ctx.encrypt_ecb(src_ptr + i, out_ptr + i);
+				ERR_FAIL_COND_V(err != OK, PackedByteArray());
+			}
+		} break;
+		case MODE_ECB_DECRYPT: {
+			for (int i = 0; i < len; i += 16) {
+				Error err = ctx.decrypt_ecb(src_ptr + i, out_ptr + i);
+				ERR_FAIL_COND_V(err != OK, PackedByteArray());
+			}
+		} break;
+		case MODE_CBC_ENCRYPT: {
+			Error err = ctx.encrypt_cbc(len, iv.ptrw(), p_src.ptr(), out.ptrw());
+			ERR_FAIL_COND_V(err != OK, PackedByteArray());
+		} break;
+		case MODE_CBC_DECRYPT: {
+			Error err = ctx.decrypt_cbc(len, iv.ptrw(), p_src.ptr(), out.ptrw());
+			ERR_FAIL_COND_V(err != OK, PackedByteArray());
+		} break;
+		default:
+			ERR_FAIL_V_MSG(PackedByteArray(), "Bug!");
+	}
+	return out;
+}
+
+PackedByteArray AESContext::get_iv_state() {
+	ERR_FAIL_COND_V_MSG(mode != MODE_CBC_ENCRYPT && mode != MODE_CBC_DECRYPT, PackedByteArray(), "Calling 'get_iv_state' only makes sense when the context is started in CBC mode.");
+	PackedByteArray out;
+	out.append_array(iv);
+	return out;
+}
+
+void AESContext::finish() {
+	mode = MODE_MAX;
+	iv.resize(0);
+}
+
+void AESContext::_bind_methods() {
+	ClassDB::bind_method(D_METHOD("start", "mode", "key", "iv"), &AESContext::start, DEFVAL(PackedByteArray()));
+	ClassDB::bind_method(D_METHOD("update", "src"), &AESContext::update);
+	ClassDB::bind_method(D_METHOD("get_iv_state"), &AESContext::get_iv_state);
+	ClassDB::bind_method(D_METHOD("finish"), &AESContext::finish);
+	BIND_ENUM_CONSTANT(MODE_ECB_ENCRYPT);
+	BIND_ENUM_CONSTANT(MODE_ECB_DECRYPT);
+	BIND_ENUM_CONSTANT(MODE_CBC_ENCRYPT);
+	BIND_ENUM_CONSTANT(MODE_CBC_DECRYPT);
+	BIND_ENUM_CONSTANT(MODE_MAX);
+}
+
+AESContext::AESContext() {
+	mode = MODE_MAX;
+}

core/crypto/aes_context.h

@@ -0,0 +1,68 @@
+/*************************************************************************/
+/*  aes_context.h                                                        */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef AES_CONTEXT_H
+#define AES_CONTEXT_H
+
+#include "core/crypto/crypto_core.h"
+#include "core/reference.h"
+
+class AESContext : public Reference {
+	GDCLASS(AESContext, Reference);
+
+public:
+	enum Mode {
+		MODE_ECB_ENCRYPT,
+		MODE_ECB_DECRYPT,
+		MODE_CBC_ENCRYPT,
+		MODE_CBC_DECRYPT,
+		MODE_MAX
+	};
+
+private:
+	Mode mode;
+	CryptoCore::AESContext ctx;
+	PackedByteArray iv;
+
+protected:
+	static void _bind_methods();
+
+public:
+	Error start(Mode p_mode, PackedByteArray p_key, PackedByteArray p_iv = PackedByteArray());
+	PackedByteArray update(PackedByteArray p_src);
+	PackedByteArray get_iv_state();
+	void finish();
+
+	AESContext();
+};
+
+VARIANT_ENUM_CAST(AESContext::Mode);
+
+#endif // AES_CONTEXT_H

core/crypto/crypto.cpp

@@ -45,8 +45,11 @@ CryptoKey *CryptoKey::create() {
 }
 
 void CryptoKey::_bind_methods() {
-	ClassDB::bind_method(D_METHOD("save", "path"), &CryptoKey::save);
-	ClassDB::bind_method(D_METHOD("load", "path"), &CryptoKey::load);
+	ClassDB::bind_method(D_METHOD("save", "path", "public_only"), &CryptoKey::save, DEFVAL(false));
+	ClassDB::bind_method(D_METHOD("load", "path", "public_only"), &CryptoKey::load, DEFVAL(false));
+	ClassDB::bind_method(D_METHOD("is_public_only"), &CryptoKey::is_public_only);
+	ClassDB::bind_method(D_METHOD("save_to_string", "public_only"), &CryptoKey::save_to_string, DEFVAL(false));
+	ClassDB::bind_method(D_METHOD("load_from_string", "string_key", "public_only"), &CryptoKey::load_from_string, DEFVAL(false));
 }
 
 X509Certificate *(*X509Certificate::_create)() = nullptr;
@@ -83,6 +86,10 @@ void Crypto::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("generate_random_bytes", "size"), &Crypto::generate_random_bytes);
 	ClassDB::bind_method(D_METHOD("generate_rsa", "size"), &Crypto::generate_rsa);
 	ClassDB::bind_method(D_METHOD("generate_self_signed_certificate", "key", "issuer_name", "not_before", "not_after"), &Crypto::generate_self_signed_certificate, DEFVAL("CN=myserver,O=myorganisation,C=IT"), DEFVAL("20140101000000"), DEFVAL("20340101000000"));
+	ClassDB::bind_method(D_METHOD("sign", "hash_type", "hash", "key"), &Crypto::sign);
+	ClassDB::bind_method(D_METHOD("verify", "hash_type", "hash", "signature", "key"), &Crypto::verify);
+	ClassDB::bind_method(D_METHOD("encrypt", "key", "plaintext"), &Crypto::encrypt);
+	ClassDB::bind_method(D_METHOD("decrypt", "key", "ciphertext"), &Crypto::decrypt);
 }
 
 /// Resource loader/saver
@@ -98,9 +105,14 @@ RES ResourceFormatLoaderCrypto::load(const String &p_path, const String &p_origi
 	} else if (el == "key") {
 		CryptoKey *key = CryptoKey::create();
 		if (key) {
-			key->load(p_path);
+			key->load(p_path, false);
 		}
 		return key;
+	} else if (el == "pub") {
+		CryptoKey *key = CryptoKey::create();
+		if (key)
+			key->load(p_path, true);
+		return key;
 	}
 	return nullptr;
 }
@@ -108,6 +120,7 @@ RES ResourceFormatLoaderCrypto::load(const String &p_path, const String &p_origi
 void ResourceFormatLoaderCrypto::get_recognized_extensions(List<String> *p_extensions) const {
 	p_extensions->push_back("crt");
 	p_extensions->push_back("key");
+	p_extensions->push_back("pub");
 }
 
 bool ResourceFormatLoaderCrypto::handles_type(const String &p_type) const {
@@ -118,7 +131,7 @@ String ResourceFormatLoaderCrypto::get_resource_type(const String &p_path) const
 	String el = p_path.get_extension().to_lower();
 	if (el == "crt") {
 		return "X509Certificate";
-	} else if (el == "key") {
+	} else if (el == "key" || el == "pub") {
 		return "CryptoKey";
 	}
 	return "";
@@ -131,7 +144,8 @@ Error ResourceFormatSaverCrypto::save(const String &p_path, const RES &p_resourc
 	if (cert.is_valid()) {
 		err = cert->save(p_path);
 	} else if (key.is_valid()) {
-		err = key->save(p_path);
+		String el = p_path.get_extension().to_lower();
+		err = key->save(p_path, el == "pub");
 	} else {
 		ERR_FAIL_V(ERR_INVALID_PARAMETER);
 	}
@@ -146,7 +160,10 @@ void ResourceFormatSaverCrypto::get_recognized_extensions(const RES &p_resource,
 		p_extensions->push_back("crt");
 	}
 	if (key) {
-		p_extensions->push_back("key");
+		if (!key->is_public_only()) {
+			p_extensions->push_back("key");
+		}
+		p_extensions->push_back("pub");
 	}
 }
 

core/crypto/crypto.h

@@ -31,6 +31,7 @@
 #ifndef CRYPTO_H
 #define CRYPTO_H
 
+#include "core/crypto/hashing_context.h"
 #include "core/io/resource_loader.h"
 #include "core/io/resource_saver.h"
 #include "core/reference.h"
@@ -45,8 +46,11 @@ protected:
 
 public:
 	static CryptoKey *create();
-	virtual Error load(String p_path) = 0;
-	virtual Error save(String p_path) = 0;
+	virtual Error load(String p_path, bool p_public_only = false) = 0;
+	virtual Error save(String p_path, bool p_public_only = false) = 0;
+	virtual String save_to_string(bool p_public_only = false) = 0;
+	virtual Error load_from_string(String p_string_key, bool p_public_only = false) = 0;
+	virtual bool is_public_only() const = 0;
 };
 
 class X509Certificate : public Resource {
@@ -79,6 +83,11 @@ public:
 	virtual Ref<CryptoKey> generate_rsa(int p_bytes) = 0;
 	virtual Ref<X509Certificate> generate_self_signed_certificate(Ref<CryptoKey> p_key, String p_issuer_name, String p_not_before, String p_not_after) = 0;
 
+	virtual Vector<uint8_t> sign(HashingContext::HashType p_hash_type, Vector<uint8_t> p_hash, Ref<CryptoKey> p_key) = 0;
+	virtual bool verify(HashingContext::HashType p_hash_type, Vector<uint8_t> p_hash, Vector<uint8_t> p_signature, Ref<CryptoKey> p_key) = 0;
+	virtual Vector<uint8_t> encrypt(Ref<CryptoKey> p_key, Vector<uint8_t> p_plaintext) = 0;
+	virtual Vector<uint8_t> decrypt(Ref<CryptoKey> p_key, Vector<uint8_t> p_ciphertext) = 0;
+
 	Crypto() {}
 };
 

core/crypto/crypto_core.cpp

@@ -145,6 +145,16 @@ Error CryptoCore::AESContext::decrypt_ecb(const uint8_t p_src[16], uint8_t r_dst
 	return ret ? FAILED : OK;
 }
 
+Error CryptoCore::AESContext::encrypt_cbc(size_t p_length, uint8_t r_iv[16], const uint8_t *p_src, uint8_t *r_dst) {
+	int ret = mbedtls_aes_crypt_cbc((mbedtls_aes_context *)ctx, MBEDTLS_AES_ENCRYPT, p_length, r_iv, p_src, r_dst);
+	return ret ? FAILED : OK;
+}
+
+Error CryptoCore::AESContext::decrypt_cbc(size_t p_length, uint8_t r_iv[16], const uint8_t *p_src, uint8_t *r_dst) {
+	int ret = mbedtls_aes_crypt_cbc((mbedtls_aes_context *)ctx, MBEDTLS_AES_DECRYPT, p_length, r_iv, p_src, r_dst);
+	return ret ? FAILED : OK;
+}
+
 // CryptoCore
 String CryptoCore::b64_encode_str(const uint8_t *p_src, int p_src_len) {
 	int b64len = p_src_len / 3 * 4 + 4 + 1;

core/crypto/crypto_core.h

@@ -86,6 +86,8 @@ public:
 		Error set_decode_key(const uint8_t *p_key, size_t p_bits);
 		Error encrypt_ecb(const uint8_t p_src[16], uint8_t r_dst[16]);
 		Error decrypt_ecb(const uint8_t p_src[16], uint8_t r_dst[16]);
+		Error encrypt_cbc(size_t p_length, uint8_t r_iv[16], const uint8_t *p_src, uint8_t *r_dst);
+		Error decrypt_cbc(size_t p_length, uint8_t r_iv[16], const uint8_t *p_src, uint8_t *r_dst);
 	};
 
 	static String b64_encode_str(const uint8_t *p_src, int p_src_len);

core/register_core_types.cpp

@@ -34,6 +34,7 @@
 #include "core/class_db.h"
 #include "core/compressed_translation.h"
 #include "core/core_string_names.h"
+#include "core/crypto/aes_context.h"
 #include "core/crypto/crypto.h"
 #include "core/crypto/hashing_context.h"
 #include "core/engine.h"
@@ -165,6 +166,7 @@ void register_core_types() {
 
 	// Crypto
 	ClassDB::register_class<HashingContext>();
+	ClassDB::register_class<AESContext>();
 	ClassDB::register_custom_instance_class<X509Certificate>();
 	ClassDB::register_custom_instance_class<CryptoKey>();
 	ClassDB::register_custom_instance_class<Crypto>();

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>

modules/mbedtls/crypto_mbedtls.cpp

@@ -50,7 +50,7 @@ CryptoKey *CryptoKeyMbedTLS::create() {
 	return memnew(CryptoKeyMbedTLS);
 }
 
-Error CryptoKeyMbedTLS::load(String p_path) {
+Error CryptoKeyMbedTLS::load(String p_path, bool p_public_only) {
 	ERR_FAIL_COND_V_MSG(locks, ERR_ALREADY_IN_USE, "Key is in use");
 
 	PackedByteArray out;
@@ -59,42 +59,81 @@ Error CryptoKeyMbedTLS::load(String p_path) {
 
 	int flen = f->get_len();
 	out.resize(flen + 1);
-	{
-		uint8_t *w = out.ptrw();
-		f->get_buffer(w, flen);
-		w[flen] = 0; //end f string
-	}
+	f->get_buffer(out.ptrw(), flen);
+	out.write[flen] = 0; // string terminator
 	memdelete(f);
 
-	int ret = mbedtls_pk_parse_key(&pkey, out.ptr(), out.size(), nullptr, 0);
+	int ret = 0;
+	if (p_public_only) {
+		ret = mbedtls_pk_parse_public_key(&pkey, out.ptr(), out.size());
+	} else {
+		ret = mbedtls_pk_parse_key(&pkey, out.ptr(), out.size(), nullptr, 0);
+	}
 	// We MUST zeroize the memory for safety!
 	mbedtls_platform_zeroize(out.ptrw(), out.size());
-	ERR_FAIL_COND_V_MSG(ret, FAILED, "Error parsing private key '" + itos(ret) + "'.");
+	ERR_FAIL_COND_V_MSG(ret, FAILED, "Error parsing key '" + itos(ret) + "'.");
 
+	public_only = p_public_only;
 	return OK;
 }
 
-Error CryptoKeyMbedTLS::save(String p_path) {
+Error CryptoKeyMbedTLS::save(String p_path, bool p_public_only) {
 	FileAccess *f = FileAccess::open(p_path, FileAccess::WRITE);
 	ERR_FAIL_COND_V_MSG(!f, ERR_INVALID_PARAMETER, "Cannot save CryptoKeyMbedTLS file '" + p_path + "'.");
 
 	unsigned char w[16000];
 	memset(w, 0, sizeof(w));
 
-	int ret = mbedtls_pk_write_key_pem(&pkey, w, sizeof(w));
+	int ret = 0;
+	if (p_public_only) {
+		ret = mbedtls_pk_write_pubkey_pem(&pkey, w, sizeof(w));
+	} else {
+		ret = mbedtls_pk_write_key_pem(&pkey, w, sizeof(w));
+	}
 	if (ret != 0) {
 		memdelete(f);
-		memset(w, 0, sizeof(w)); // Zeroize anything we might have written.
+		mbedtls_platform_zeroize(w, sizeof(w)); // Zeroize anything we might have written.
 		ERR_FAIL_V_MSG(FAILED, "Error writing key '" + itos(ret) + "'.");
 	}
 
 	size_t len = strlen((char *)w);
 	f->store_buffer(w, len);
 	memdelete(f);
-	memset(w, 0, sizeof(w)); // Zeroize temporary buffer.
+	mbedtls_platform_zeroize(w, sizeof(w)); // Zeroize temporary buffer.
 	return OK;
 }
 
+Error CryptoKeyMbedTLS::load_from_string(String p_string_key, bool p_public_only) {
+	int ret = 0;
+	if (p_public_only) {
+		ret = mbedtls_pk_parse_public_key(&pkey, (unsigned char *)p_string_key.utf8().get_data(), p_string_key.utf8().size());
+	} else {
+		ret = mbedtls_pk_parse_key(&pkey, (unsigned char *)p_string_key.utf8().get_data(), p_string_key.utf8().size(), nullptr, 0);
+	}
+	ERR_FAIL_COND_V_MSG(ret, FAILED, "Error parsing key '" + itos(ret) + "'.");
+
+	public_only = p_public_only;
+	return OK;
+}
+
+String CryptoKeyMbedTLS::save_to_string(bool p_public_only) {
+	unsigned char w[16000];
+	memset(w, 0, sizeof(w));
+
+	int ret = 0;
+	if (p_public_only) {
+		ret = mbedtls_pk_write_pubkey_pem(&pkey, w, sizeof(w));
+	} else {
+		ret = mbedtls_pk_write_key_pem(&pkey, w, sizeof(w));
+	}
+	if (ret != 0) {
+		mbedtls_platform_zeroize(w, sizeof(w));
+		ERR_FAIL_V_MSG("", "Error saving key '" + itos(ret) + "'.");
+	}
+	String s = String::utf8((char *)w);
+	return s;
+}
+
 X509Certificate *X509CertificateMbedTLS::create() {
 	return memnew(X509CertificateMbedTLS);
 }
@@ -108,11 +147,8 @@ Error X509CertificateMbedTLS::load(String p_path) {
 
 	int flen = f->get_len();
 	out.resize(flen + 1);
-	{
-		uint8_t *w = out.ptrw();
-		f->get_buffer(w, flen);
-		w[flen] = 0; //end f string
-	}
+	f->get_buffer(out.ptrw(), flen);
+	out.write[flen] = 0; // string terminator
 	memdelete(f);
 
 	int ret = mbedtls_x509_crt_parse(&cert, out.ptr(), out.size());
@@ -211,9 +247,8 @@ void CryptoMbedTLS::load_default_certificates(String p_path) {
 		// Use builtin certs only if user did not override it in project settings.
 		PackedByteArray out;
 		out.resize(_certs_uncompressed_size + 1);
-		uint8_t *w = out.ptrw();
-		Compression::decompress(w, _certs_uncompressed_size, _certs_compressed, _certs_compressed_size, Compression::MODE_DEFLATE);
-		w[_certs_uncompressed_size] = 0; // Make sure it ends with string terminator
+		Compression::decompress(out.ptrw(), _certs_uncompressed_size, _certs_compressed, _certs_compressed_size, Compression::MODE_DEFLATE);
+		out.write[_certs_uncompressed_size] = 0; // Make sure it ends with string terminator
 #ifdef DEBUG_ENABLED
 		print_verbose("Loaded builtin certs");
 #endif
@@ -228,6 +263,7 @@ Ref<CryptoKey> CryptoMbedTLS::generate_rsa(int p_bytes) {
 	int ret = mbedtls_pk_setup(&(out->pkey), mbedtls_pk_info_from_type(MBEDTLS_PK_RSA));
 	ERR_FAIL_COND_V(ret != 0, nullptr);
 	ret = mbedtls_rsa_gen_key(mbedtls_pk_rsa(out->pkey), mbedtls_ctr_drbg_random, &ctr_drbg, p_bytes, 65537);
+	out->public_only = false;
 	ERR_FAIL_COND_V(ret != 0, nullptr);
 	return out;
 }
@@ -281,3 +317,75 @@ PackedByteArray CryptoMbedTLS::generate_random_bytes(int p_bytes) {
 	mbedtls_ctr_drbg_random(&ctr_drbg, out.ptrw(), p_bytes);
 	return out;
 }
+
+mbedtls_md_type_t CryptoMbedTLS::_md_type_from_hashtype(HashingContext::HashType p_hash_type, int &r_size) {
+	switch (p_hash_type) {
+		case HashingContext::HASH_MD5:
+			r_size = 16;
+			return MBEDTLS_MD_MD5;
+		case HashingContext::HASH_SHA1:
+			r_size = 20;
+			return MBEDTLS_MD_SHA1;
+		case HashingContext::HASH_SHA256:
+			r_size = 32;
+			return MBEDTLS_MD_SHA256;
+		default:
+			r_size = 0;
+			ERR_FAIL_V_MSG(MBEDTLS_MD_NONE, "Invalid hash type.");
+	}
+}
+
+Vector<uint8_t> CryptoMbedTLS::sign(HashingContext::HashType p_hash_type, Vector<uint8_t> p_hash, Ref<CryptoKey> p_key) {
+	int size;
+	mbedtls_md_type_t type = _md_type_from_hashtype(p_hash_type, size);
+	ERR_FAIL_COND_V_MSG(type == MBEDTLS_MD_NONE, Vector<uint8_t>(), "Invalid hash type.");
+	ERR_FAIL_COND_V_MSG(p_hash.size() != size, Vector<uint8_t>(), "Invalid hash provided. Size must be " + itos(size));
+	Ref<CryptoKeyMbedTLS> key = static_cast<Ref<CryptoKeyMbedTLS>>(p_key);
+	ERR_FAIL_COND_V_MSG(!key.is_valid(), Vector<uint8_t>(), "Invalid key provided.");
+	ERR_FAIL_COND_V_MSG(key->is_public_only(), Vector<uint8_t>(), "Invalid key provided. Cannot sign with public_only keys.");
+	size_t sig_size = 0;
+	unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
+	Vector<uint8_t> out;
+	int ret = mbedtls_pk_sign(&(key->pkey), type, p_hash.ptr(), size, buf, &sig_size, mbedtls_ctr_drbg_random, &ctr_drbg);
+	ERR_FAIL_COND_V_MSG(ret, out, "Error while signing: " + itos(ret));
+	out.resize(sig_size);
+	copymem(out.ptrw(), buf, sig_size);
+	return out;
+}
+
+bool CryptoMbedTLS::verify(HashingContext::HashType p_hash_type, Vector<uint8_t> p_hash, Vector<uint8_t> p_signature, Ref<CryptoKey> p_key) {
+	int size;
+	mbedtls_md_type_t type = _md_type_from_hashtype(p_hash_type, size);
+	ERR_FAIL_COND_V_MSG(type == MBEDTLS_MD_NONE, false, "Invalid hash type.");
+	ERR_FAIL_COND_V_MSG(p_hash.size() != size, false, "Invalid hash provided. Size must be " + itos(size));
+	Ref<CryptoKeyMbedTLS> key = static_cast<Ref<CryptoKeyMbedTLS>>(p_key);
+	ERR_FAIL_COND_V_MSG(!key.is_valid(), false, "Invalid key provided.");
+	return mbedtls_pk_verify(&(key->pkey), type, p_hash.ptr(), size, p_signature.ptr(), p_signature.size()) == 0;
+}
+
+Vector<uint8_t> CryptoMbedTLS::encrypt(Ref<CryptoKey> p_key, Vector<uint8_t> p_plaintext) {
+	Ref<CryptoKeyMbedTLS> key = static_cast<Ref<CryptoKeyMbedTLS>>(p_key);
+	ERR_FAIL_COND_V_MSG(!key.is_valid(), Vector<uint8_t>(), "Invalid key provided.");
+	uint8_t buf[1024];
+	size_t size;
+	Vector<uint8_t> out;
+	int ret = mbedtls_pk_encrypt(&(key->pkey), p_plaintext.ptr(), p_plaintext.size(), buf, &size, sizeof(buf), mbedtls_ctr_drbg_random, &ctr_drbg);
+	ERR_FAIL_COND_V_MSG(ret, out, "Error while encrypting: " + itos(ret));
+	out.resize(size);
+	copymem(out.ptrw(), buf, size);
+	return out;
+}
+
+Vector<uint8_t> CryptoMbedTLS::decrypt(Ref<CryptoKey> p_key, Vector<uint8_t> p_ciphertext) {
+	Ref<CryptoKeyMbedTLS> key = static_cast<Ref<CryptoKeyMbedTLS>>(p_key);
+	ERR_FAIL_COND_V_MSG(!key.is_valid(), Vector<uint8_t>(), "Invalid key provided.");
+	ERR_FAIL_COND_V_MSG(key->is_public_only(), Vector<uint8_t>(), "Invalid key provided. Cannot decrypt using a public_only key.");
+	uint8_t buf[2048];
+	size_t size;
+	Vector<uint8_t> out;
+	int ret = mbedtls_pk_decrypt(&(key->pkey), p_ciphertext.ptr(), p_ciphertext.size(), buf, &size, sizeof(buf), mbedtls_ctr_drbg_random, &ctr_drbg);
+	ERR_FAIL_COND_V_MSG(ret, out, "Error while decrypting: " + itos(ret));
+	out.resize(size);
+	copymem(out.ptrw(), buf, size);
+	return out;
+}

modules/mbedtls/crypto_mbedtls.h

@@ -43,15 +43,19 @@ class SSLContextMbedTLS;
 class CryptoKeyMbedTLS : public CryptoKey {
 private:
 	mbedtls_pk_context pkey;
-	int locks;
+	int locks = 0;
+	bool public_only = true;
 
 public:
 	static CryptoKey *create();
 	static void make_default() { CryptoKey::_create = create; }
 	static void finalize() { CryptoKey::_create = nullptr; }
 
-	virtual Error load(String p_path);
-	virtual Error save(String p_path);
+	virtual Error load(String p_path, bool p_public_only);
+	virtual Error save(String p_path, bool p_public_only);
+	virtual String save_to_string(bool p_public_only);
+	virtual Error load_from_string(String p_string_key, bool p_public_only);
+	virtual bool is_public_only() const { return public_only; };
 
 	CryptoKeyMbedTLS() {
 		mbedtls_pk_init(&pkey);
@@ -102,6 +106,7 @@ private:
 	mbedtls_entropy_context entropy;
 	mbedtls_ctr_drbg_context ctr_drbg;
 	static X509CertificateMbedTLS *default_certs;
+	mbedtls_md_type_t _md_type_from_hashtype(HashingContext::HashType p_hash_type, int &r_size);
 
 public:
 	static Crypto *create();
@@ -113,6 +118,10 @@ public:
 	virtual PackedByteArray generate_random_bytes(int p_bytes);
 	virtual Ref<CryptoKey> generate_rsa(int p_bytes);
 	virtual Ref<X509Certificate> generate_self_signed_certificate(Ref<CryptoKey> p_key, String p_issuer_name, String p_not_before, String p_not_after);
+	virtual Vector<uint8_t> sign(HashingContext::HashType p_hash_type, Vector<uint8_t> p_hash, Ref<CryptoKey> p_key);
+	virtual bool verify(HashingContext::HashType p_hash_type, Vector<uint8_t> p_hash, Vector<uint8_t> p_signature, Ref<CryptoKey> p_key);
+	virtual Vector<uint8_t> encrypt(Ref<CryptoKey> p_key, Vector<uint8_t> p_plaintext);
+	virtual Vector<uint8_t> decrypt(Ref<CryptoKey> p_key, Vector<uint8_t> p_ciphertext);
 
 	CryptoMbedTLS();
 	~CryptoMbedTLS();