// Copyright (C) 2004-2021 Artifex Software, Inc.
//
// This file is part of MuPDF.
//
// MuPDF is free software: you can redistribute it and/or modify it under the
// terms of the GNU Affero General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option)
// any later version.
//
// MuPDF is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
// details.
//
// You should have received a copy of the GNU Affero General Public License
// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>
//
// Alternative licensing terms are available from the licensor.
// For commercial licensing, see <https://www.artifex.com/> or contact
// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,
// CA 94129, USA, for further information.

#ifndef MUPDF_PDF_CRYPT_H
#define MUPDF_PDF_CRYPT_H

#include "mupdf/pdf/document.h"
#include "mupdf/pdf/object.h"

enum
{
	PDF_ENCRYPT_KEEP,
	PDF_ENCRYPT_NONE,
	PDF_ENCRYPT_RC4_40,
	PDF_ENCRYPT_RC4_128,
	PDF_ENCRYPT_AES_128,
	PDF_ENCRYPT_AES_256,
	PDF_ENCRYPT_UNKNOWN
};

/*
	Create crypt object for decrypting strings and streams
	given the Encryption and ID objects.
*/
pdf_crypt *pdf_new_crypt(fz_context *ctx, pdf_obj *enc, pdf_obj *id);
pdf_crypt *pdf_new_encrypt(fz_context *ctx, const char *opwd_utf8, const char *upwd_utf8, pdf_obj *id, int permissions, int algorithm);
void pdf_drop_crypt(fz_context *ctx, pdf_crypt *crypt);

void pdf_crypt_obj(fz_context *ctx, pdf_crypt *crypt, pdf_obj *obj, int num, int gen);
fz_stream *pdf_open_crypt(fz_context *ctx, fz_stream *chain, pdf_crypt *crypt, int num, int gen);
fz_stream *pdf_open_crypt_with_filter(fz_context *ctx, fz_stream *chain, pdf_crypt *crypt, pdf_obj *name, int num, int gen);

int pdf_crypt_version(fz_context *ctx, pdf_crypt *crypt);
int pdf_crypt_revision(fz_context *ctx, pdf_crypt *crypt);
const char *pdf_crypt_method(fz_context *ctx, pdf_crypt *crypt);
const char *pdf_crypt_string_method(fz_context *ctx, pdf_crypt *crypt);
const char *pdf_crypt_stream_method(fz_context *ctx, pdf_crypt *crypt);
int pdf_crypt_length(fz_context *ctx, pdf_crypt *crypt);
int pdf_crypt_permissions(fz_context *ctx, pdf_crypt *crypt);
int pdf_crypt_encrypt_metadata(fz_context *ctx, pdf_crypt *crypt);
unsigned char *pdf_crypt_owner_password(fz_context *ctx, pdf_crypt *crypt);
unsigned char *pdf_crypt_user_password(fz_context *ctx, pdf_crypt *crypt);
unsigned char *pdf_crypt_owner_encryption(fz_context *ctx, pdf_crypt *crypt);
unsigned char *pdf_crypt_user_encryption(fz_context *ctx, pdf_crypt *crypt);
unsigned char *pdf_crypt_permissions_encryption(fz_context *ctx, pdf_crypt *crypt);
unsigned char *pdf_crypt_key(fz_context *ctx, pdf_crypt *crypt);

void pdf_print_crypt(fz_context *ctx, fz_output *out, pdf_crypt *crypt);

void pdf_write_digest(fz_context *ctx, fz_output *out, pdf_obj *byte_range, pdf_obj *field, size_t digest_offset, size_t digest_length, pdf_pkcs7_signer *signer);

/*
	User access permissions from PDF reference.
*/
enum
{
	PDF_PERM_PRINT = 1 << 2,
	PDF_PERM_MODIFY = 1 << 3,
	PDF_PERM_COPY = 1 << 4,
	PDF_PERM_ANNOTATE = 1 << 5,
	PDF_PERM_FORM = 1 << 8,
	PDF_PERM_ACCESSIBILITY = 1 << 9, /* deprecated in pdf 2.0 (this permission is always granted) */
	PDF_PERM_ASSEMBLE = 1 << 10,
	PDF_PERM_PRINT_HQ = 1 << 11,
};

int pdf_document_permissions(fz_context *ctx, pdf_document *doc);

int pdf_signature_byte_range(fz_context *ctx, pdf_document *doc, pdf_obj *signature, fz_range *byte_range);

/*
	retrieve an fz_stream to read the bytes hashed for the signature
*/
fz_stream *pdf_signature_hash_bytes(fz_context *ctx, pdf_document *doc, pdf_obj *signature);

int pdf_signature_incremental_change_since_signing(fz_context *ctx, pdf_document *doc, pdf_obj *signature);

/*
	Retrieve the contents of a signature as a counted allocated
	block that must be freed by the caller.
*/
size_t pdf_signature_contents(fz_context *ctx, pdf_document *doc, pdf_obj *signature, char **contents);

void pdf_encrypt_data(fz_context *ctx, pdf_crypt *crypt, int num, int gen, void (*fmt_str_out)(fz_context *, void *, const unsigned char *, size_t), void *arg, const unsigned char *s, size_t n);

size_t pdf_encrypted_len(fz_context *ctx, pdf_crypt *crypt, int num, int gen, size_t len);

#endif