Add AESContext.

GDScript interface to CryptoCore::AESContext.
Also add CBC mode in CryptoCore::AESContext and expose it.

4 files changed, 196 insertions, 0 deletions

diff --git a/core/crypto/aes_context.cpp b/core/crypto/aes_context.cpp
new file mode 100644
index 0000000000..8ef1f4f1d4
--- /dev/null
+++ b/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;
+}
diff --git a/core/crypto/aes_context.h b/core/crypto/aes_context.h
new file mode 100644
index 0000000000..006ecee2ad
--- /dev/null
+++ b/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
diff --git a/core/crypto/crypto_core.cpp b/core/crypto/crypto_core.cpp
index ec25ee0d38..b0dc47e655 100644
--- a/core/crypto/crypto_core.cpp
+++ b/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;
diff --git a/core/crypto/crypto_core.h b/core/crypto/crypto_core.h
index 36d8ace723..82df9c23a8 100644
--- a/core/crypto/crypto_core.h
+++ b/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);