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/*  crypto.h                                                             */
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#ifndef CRYPTO_H
#define CRYPTO_H

#include "core/crypto/hashing_context.h"
#include "core/io/resource.h"
#include "core/io/resource_loader.h"
#include "core/io/resource_saver.h"
#include "core/object/reference.h"

class CryptoKey : public Resource {
	GDCLASS(CryptoKey, Resource);

protected:
	static void _bind_methods();
	static CryptoKey *(*_create)();

public:
	static CryptoKey *create();
	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 {
	GDCLASS(X509Certificate, Resource);

protected:
	static void _bind_methods();
	static X509Certificate *(*_create)();

public:
	static X509Certificate *create();
	virtual Error load(String p_path) = 0;
	virtual Error load_from_memory(const uint8_t *p_buffer, int p_len) = 0;
	virtual Error save(String p_path) = 0;
};

class HMACContext : public Reference {
	GDCLASS(HMACContext, Reference);

protected:
	static void _bind_methods();
	static HMACContext *(*_create)();

public:
	static HMACContext *create();

	virtual Error start(HashingContext::HashType p_hash_type, PackedByteArray p_key) = 0;
	virtual Error update(PackedByteArray p_data) = 0;
	virtual PackedByteArray finish() = 0;

	HMACContext() {}
};

class Crypto : public Reference {
	GDCLASS(Crypto, Reference);

protected:
	static void _bind_methods();
	static Crypto *(*_create)();
	static void (*_load_default_certificates)(String p_path);

public:
	static Crypto *create();
	static void load_default_certificates(String p_path);

	virtual PackedByteArray generate_random_bytes(int p_bytes) = 0;
	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;

	PackedByteArray hmac_digest(HashingContext::HashType p_hash_type, PackedByteArray p_key, PackedByteArray p_msg);

	// Compares two PackedByteArrays for equality without leaking timing information in order to prevent timing attacks.
	// @see: https://paragonie.com/blog/2015/11/preventing-timing-attacks-on-string-comparison-with-double-hmac-strategy
	bool constant_time_compare(PackedByteArray p_trusted, PackedByteArray p_received);

	Crypto() {}
};

class ResourceFormatLoaderCrypto : public ResourceFormatLoader {
public:
	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = nullptr, bool p_use_sub_threads = false, float *r_progress = nullptr, bool p_no_cache = false);
	virtual void get_recognized_extensions(List<String> *p_extensions) const;
	virtual bool handles_type(const String &p_type) const;
	virtual String get_resource_type(const String &p_path) const;
};

class ResourceFormatSaverCrypto : public ResourceFormatSaver {
public:
	virtual Error save(const String &p_path, const RES &p_resource, uint32_t p_flags = 0);
	virtual void get_recognized_extensions(const RES &p_resource, List<String> *p_extensions) const;
	virtual bool recognize(const RES &p_resource) const;
};

#endif // CRYPTO_H