// Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef OPENSSL_HEADER_DES_H
#define OPENSSL_HEADER_DES_H

#include <openssl/base.h>   // IWYU pragma: export

#if defined(__cplusplus)
extern "C" {
#endif


// DES.
//
// This module is deprecated and retained for legacy reasons only. It is slow
// and may leak key material with timing or cache side channels. Moreover,
// single-keyed DES is broken and can be brute-forced in under a day.
//
// Use a modern cipher, such as AES-GCM or ChaCha20-Poly1305, instead.


typedef struct DES_cblock_st {
  uint8_t bytes[8];
} DES_cblock;

typedef struct DES_ks {
  uint32_t subkeys[16][2];
} DES_key_schedule;


#define DES_KEY_SZ (sizeof(DES_cblock))
#define DES_SCHEDULE_SZ (sizeof(DES_key_schedule))

#define DES_ENCRYPT 1
#define DES_DECRYPT 0

#define DES_CBC_MODE 0
#define DES_PCBC_MODE 1

// DES_set_key performs a key schedule and initialises `schedule` with `key`.
OPENSSL_EXPORT void DES_set_key(const DES_cblock *key,
                                DES_key_schedule *schedule);

// DES_set_odd_parity sets the parity bits (the least-significant bits in each
// byte) of `key` given the other bits in each byte.
OPENSSL_EXPORT void DES_set_odd_parity(DES_cblock *key);

// DES_ecb_encrypt encrypts (or decrypts, if `is_encrypt` is `DES_DECRYPT`) a
// single DES block (8 bytes) from `in` to `out`, using the key configured in
// `schedule`.
OPENSSL_EXPORT void DES_ecb_encrypt(const DES_cblock *in, DES_cblock *out,
                                    const DES_key_schedule *schedule,
                                    int is_encrypt);

// DES_ncbc_encrypt encrypts (or decrypts, if `enc` is `DES_DECRYPT`) `len`
// bytes from `in` to `out` with DES in CBC mode. `len` must be a multiple of 8.
// The IV is taken from `ivec`. When the function completes, the IV for the next
// block is written to `ivec`.
OPENSSL_EXPORT void DES_ncbc_encrypt(const uint8_t *in, uint8_t *out,
                                     size_t len,
                                     const DES_key_schedule *schedule,
                                     DES_cblock *ivec, int enc);

// DES_ecb3_encrypt encrypts (or decrypts, if `enc` is `DES_DECRYPT`) a single
// block (8 bytes) of data from `input` to `output` using 3DES.
OPENSSL_EXPORT void DES_ecb3_encrypt(const DES_cblock *input,
                                     DES_cblock *output,
                                     const DES_key_schedule *ks1,
                                     const DES_key_schedule *ks2,
                                     const DES_key_schedule *ks3,
                                     int enc);

// DES_ede3_cbc_encrypt encrypts (or decrypts, if `enc` is `DES_DECRYPT`) `len`
// bytes from `in` to `out` with 3DES in CBC mode. 3DES uses three keys, thus
// the function takes three different `DES_key_schedule`s. `len` must be a
// multiple of 8. The IV is taken from `ivec`. When the function completes, the
// IV for the next block is written to `ivec`.
OPENSSL_EXPORT void DES_ede3_cbc_encrypt(const uint8_t *in, uint8_t *out,
                                         size_t len,
                                         const DES_key_schedule *ks1,
                                         const DES_key_schedule *ks2,
                                         const DES_key_schedule *ks3,
                                         DES_cblock *ivec, int enc);

// DES_ede2_cbc_encrypt encrypts (or decrypts, if `enc` is `DES_DECRYPT`) `len`
// bytes from `in` to `out` with 3DES in CBC mode. With this keying option, the
// first and third 3DES keys are identical. Thus, this function takes only two
// different `DES_key_schedule`s. `len` must be a multiple of 8. The IV is taken
// from `ivec`. When the function completes, the IV for the next block is
// written to `ivec`.
OPENSSL_EXPORT void DES_ede2_cbc_encrypt(const uint8_t *in, uint8_t *out,
                                         size_t len,
                                         const DES_key_schedule *ks1,
                                         const DES_key_schedule *ks2,
                                         DES_cblock *ivec, int enc);


// Deprecated functions.

// DES_set_key_unchecked calls `DES_set_key`.
OPENSSL_EXPORT void DES_set_key_unchecked(const DES_cblock *key,
                                          DES_key_schedule *schedule);

OPENSSL_EXPORT void DES_ede3_cfb64_encrypt(const uint8_t *in, uint8_t *out,
                                           long length, DES_key_schedule *ks1,
                                           DES_key_schedule *ks2,
                                           DES_key_schedule *ks3,
                                           DES_cblock *ivec, int *num, int enc);

OPENSSL_EXPORT void DES_ede3_cfb_encrypt(const uint8_t *in, uint8_t *out,
                                         int numbits, long length,
                                         DES_key_schedule *ks1,
                                         DES_key_schedule *ks2,
                                         DES_key_schedule *ks3,
                                         DES_cblock *ivec, int enc);


#if defined(__cplusplus)
}  // extern C
#endif

#endif  // OPENSSL_HEADER_DES_H