/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.] */

#ifndef OPENSSL_HEADER_DES_H
#define OPENSSL_HEADER_DES_H

#include <openssl/base.h>

#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_is_weak_key checks if |key| is a weak or semi-weak key, see SP 800-67r2
// section 3.3.2
OPENSSL_EXPORT int DES_is_weak_key(const DES_cblock *key);

// DES_set_key checks that |key| is not weak and the parity before calling
// |DES_set_key_unchecked|. The key schedule is always initialized, the checks
// only affect the return value:
// 0: key is not weak and has odd parity
// -1: key is not odd
// -2: key is a weak key, the parity might also be even
OPENSSL_EXPORT int DES_set_key(const DES_cblock *key, DES_key_schedule *schedule);

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

// DES_key_sched calls |DES_set_key|.
OPENSSL_EXPORT int DES_key_sched(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.
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.
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.
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);


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

#endif  // OPENSSL_HEADER_DES_H
