/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
 * This file is part of the LibreOffice project.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * This file incorporates work covered by the following license notice:
 *
 *   Licensed to the Apache Software Foundation (ASF) under one or more
 *   contributor license agreements. See the NOTICE file distributed
 *   with this work for additional information regarding copyright
 *   ownership. The ASF licenses this file to you 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 http://www.apache.org/licenses/LICENSE-2.0 .
 */

#include <stdlib.h>
#include <string.h>

#include <sal/types.h>
#include <rtl/alloc.h>
#include <rtl/cipher.h>
#include <algorithm>

#if defined LIBO_CIPHER_OPENSSL_BACKEND
#include <o3tl/safeint.hxx>
#include <cassert>
#include <cstring>
#include <limits>
#include <openssl/evp.h>
#endif

#if !defined LIBO_CIPHER_OPENSSL_BACKEND
#define RTL_CIPHER_NTOHL(c, l) \
    ((l)  = (static_cast<sal_uInt32>(*((c)++))) << 24, \
     (l) |= (static_cast<sal_uInt32>(*((c)++))) << 16, \
     (l) |= (static_cast<sal_uInt32>(*((c)++))) <<  8, \
     (l) |= (static_cast<sal_uInt32>(*((c)++))))

#define RTL_CIPHER_HTONL(l, c) \
    (*((c)++) = static_cast<sal_uInt8>(((l) >> 24) & 0xff), \
     *((c)++) = static_cast<sal_uInt8>(((l) >> 16) & 0xff), \
     *((c)++) = static_cast<sal_uInt8>(((l) >>  8) & 0xff), \
     *((c)++) = static_cast<sal_uInt8>(((l)       ) & 0xff))

#define RTL_CIPHER_NTOHL64(c, xl, xr, n) \
{ \
    (xl) = (xr) = 0; \
    (c) += (n);  \
    switch ((n)) \
    { \
        case 8: (xr)  = (static_cast<sal_uInt32>(*(--(c)))); \
            [[fallthrough]]; \
        case 7: (xr) |= (static_cast<sal_uInt32>(*(--(c)))) <<  8; \
            [[fallthrough]]; \
        case 6: (xr) |= (static_cast<sal_uInt32>(*(--(c)))) << 16; \
            [[fallthrough]]; \
        case 5: (xr) |= (static_cast<sal_uInt32>(*(--(c)))) << 24; \
            [[fallthrough]]; \
        case 4: (xl)  = (static_cast<sal_uInt32>(*(--(c)))); \
            [[fallthrough]]; \
        case 3: (xl) |= (static_cast<sal_uInt32>(*(--(c)))) <<  8; \
            [[fallthrough]]; \
        case 2: (xl) |= (static_cast<sal_uInt32>(*(--(c)))) << 16; \
            [[fallthrough]]; \
        case 1: (xl) |= (static_cast<sal_uInt32>(*(--(c)))) << 24; \
    } \
}

#define RTL_CIPHER_HTONL64(xl, xr, c, n) \
{ \
    (c) += (n);  \
    switch ((n)) \
    { \
        case 8: *(--(c)) = static_cast<sal_uInt8>(((xr)       ) & 0xff); \
            [[fallthrough]]; \
        case 7: *(--(c)) = static_cast<sal_uInt8>(((xr) >>  8) & 0xff); \
            [[fallthrough]]; \
        case 6: *(--(c)) = static_cast<sal_uInt8>(((xr) >> 16) & 0xff); \
            [[fallthrough]]; \
        case 5: *(--(c)) = static_cast<sal_uInt8>(((xr) >> 24) & 0xff); \
            [[fallthrough]]; \
        case 4: *(--(c)) = static_cast<sal_uInt8>(((xl)       ) & 0xff); \
            [[fallthrough]]; \
        case 3: *(--(c)) = static_cast<sal_uInt8>(((xl) >>  8) & 0xff); \
            [[fallthrough]]; \
        case 2: *(--(c)) = static_cast<sal_uInt8>(((xl) >> 16) & 0xff); \
            [[fallthrough]]; \
        case 1: *(--(c)) = static_cast<sal_uInt8>(((xl) >> 24) & 0xff); \
    } \
}
#endif

typedef rtlCipherError(cipher_init_t) (
    rtlCipher          Cipher,
    rtlCipherDirection Direction,
    const sal_uInt8 *pKeyData, sal_Size nKeyLen,
    const sal_uInt8 *pArgData, sal_Size nArgLen);

typedef rtlCipherError(cipher_update_t) (
    rtlCipher   Cipher,
    const void *pData,   sal_Size nDatLen,
    sal_uInt8  *pBuffer, sal_Size nBufLen);

typedef void (cipher_delete_t) (rtlCipher Cipher);

namespace {

struct Cipher_Impl
{
    rtlCipherAlgorithm  m_algorithm;
    rtlCipherDirection  m_direction;
    rtlCipherMode       m_mode;

    cipher_init_t      *m_init;
    cipher_update_t    *m_encode;
    cipher_update_t    *m_decode;
    cipher_delete_t    *m_delete;
};

}

rtlCipher SAL_CALL rtl_cipher_create(
    rtlCipherAlgorithm Algorithm,
    rtlCipherMode      Mode) noexcept
{
    rtlCipher Cipher = nullptr;
    switch (Algorithm)
    {
        case rtl_Cipher_AlgorithmBF:
            Cipher = rtl_cipher_createBF (Mode);
            break;

        case rtl_Cipher_AlgorithmARCFOUR:
            Cipher = rtl_cipher_createARCFOUR (Mode);
            break;

        default: /* rtl_Cipher_AlgorithmInvalid */
            break;
    }
    return Cipher;
}

rtlCipherError SAL_CALL rtl_cipher_init(
    rtlCipher          Cipher,
    rtlCipherDirection Direction,
    const sal_uInt8 *pKeyData, sal_Size nKeyLen,
    const sal_uInt8 *pArgData, sal_Size nArgLen) noexcept
{
    Cipher_Impl *pImpl = static_cast<Cipher_Impl*>(Cipher);
    if (!pImpl)
        return rtl_Cipher_E_Argument;

    if (!pImpl->m_init)
        return rtl_Cipher_E_Unknown;

    return (pImpl->m_init)(
        Cipher, Direction, pKeyData, nKeyLen, pArgData, nArgLen);
}

rtlCipherError SAL_CALL rtl_cipher_encode(
    rtlCipher   Cipher,
    const void *pData,   sal_Size nDatLen,
    sal_uInt8  *pBuffer, sal_Size nBufLen) noexcept
{
    Cipher_Impl *pImpl = static_cast<Cipher_Impl*>(Cipher);
    if (!pImpl)
        return rtl_Cipher_E_Argument;

    if (!pImpl->m_encode)
        return rtl_Cipher_E_Unknown;

    return (pImpl->m_encode)(Cipher, pData, nDatLen, pBuffer, nBufLen);
}

rtlCipherError SAL_CALL rtl_cipher_decode(
    rtlCipher   Cipher,
    const void *pData,   sal_Size nDatLen,
    sal_uInt8  *pBuffer, sal_Size nBufLen) noexcept
{
    Cipher_Impl *pImpl = static_cast<Cipher_Impl*>(Cipher);
    if (!pImpl)
        return rtl_Cipher_E_Argument;

    if (!pImpl->m_decode)
        return rtl_Cipher_E_Unknown;

    return (pImpl->m_decode)(Cipher, pData, nDatLen, pBuffer, nBufLen);
}

void SAL_CALL rtl_cipher_destroy(rtlCipher Cipher) noexcept
{
    Cipher_Impl *pImpl = static_cast<Cipher_Impl*>(Cipher);
    if (pImpl && pImpl->m_delete)
        pImpl->m_delete(Cipher);
}

namespace {

#if !defined LIBO_CIPHER_OPENSSL_BACKEND
#define CIPHER_ROUNDS_BF 16

struct CipherKeyBF
{
    sal_uInt32 m_S[4][256];
    sal_uInt32 m_P[CIPHER_ROUNDS_BF + 2];
};
#endif

struct CipherContextBF
{
#if defined LIBO_CIPHER_OPENSSL_BACKEND
    EVP_CIPHER_CTX * m_context;
#else
    CipherKeyBF    m_key;
    union
    {
        sal_uInt32 m_long[2];
        sal_uInt8  m_byte[8];
    } m_iv;
    sal_uInt32     m_offset;
#endif
};

struct CipherBF_Impl
{
    Cipher_Impl     m_cipher;
    CipherContextBF m_context;
};

}

#if !defined LIBO_CIPHER_OPENSSL_BACKEND
static rtlCipherError BF_init(
    CipherContextBF *ctx,
    rtlCipherMode    eMode,
    const sal_uInt8 *pKeyData, sal_Size nKeyLen,
    const sal_uInt8 *pArgData, sal_Size nArgLen);
#endif

static rtlCipherError BF_update(
    CipherContextBF    *ctx,
    rtlCipherMode       eMode,
    rtlCipherDirection  eDirection,
    const sal_uInt8    *pData,   sal_Size nDatLen,
    sal_uInt8          *pBuffer, sal_Size nBufLen);

#if !defined LIBO_CIPHER_OPENSSL_BACKEND
static void BF_updateECB(
    CipherContextBF    *ctx,
    rtlCipherDirection  direction,
    const sal_uInt8    *pData,
    sal_uInt8          *pBuffer,
    sal_Size            nLength);

static void BF_updateCBC(
    CipherContextBF    *ctx,
    rtlCipherDirection  direction,
    const sal_uInt8    *pData,
    sal_uInt8          *pBuffer,
    sal_Size          nLength);

static void BF_updateCFB(
    CipherContextBF    *ctx,
    rtlCipherDirection  direction,
    const sal_uInt8    *pData,
    sal_uInt8          *pBuffer);

static void BF_encode(CipherKeyBF *key, sal_uInt32 *xl, sal_uInt32 *xr);

static void BF_decode(CipherKeyBF *key, sal_uInt32 *xl, sal_uInt32 *xr);

static sal_uInt32 BF(CipherKeyBF *key, sal_uInt32 x);

const CipherKeyBF BF_key =
{
    /* S */
    {
        /* S[0] */
        {
            /* 0 */
            0xD1310BA6L, 0x98DFB5ACL, 0x2FFD72DBL, 0xD01ADFB7L,
            0xB8E1AFEDL, 0x6A267E96L, 0xBA7C9045L, 0xF12C7F99L,
            0x24A19947L, 0xB3916CF7L, 0x0801F2E2L, 0x858EFC16L,
            0x636920D8L, 0x71574E69L, 0xA458FEA3L, 0xF4933D7EL,

            /* 1 */
            0x0D95748FL, 0x728EB658L, 0x718BCD58L, 0x82154AEEL,
            0x7B54A41DL, 0xC25A59B5L, 0x9C30D539L, 0x2AF26013L,
            0xC5D1B023L, 0x286085F0L, 0xCA417918L, 0xB8DB38EFL,
            0x8E79DCB0L, 0x603A180EL, 0x6C9E0E8BL, 0xB01E8A3EL,

            /* 2 */
            0xD71577C1L, 0xBD314B27L, 0x78AF2FDAL, 0x55605C60L,
            0xE65525F3L, 0xAA55AB94L, 0x57489862L, 0x63E81440L,
            0x55CA396AL, 0x2AAB10B6L, 0xB4CC5C34L, 0x1141E8CEL,
            0xA15486AFL, 0x7C72E993L, 0xB3EE1411L, 0x636FBC2AL,

            /* 3 */
            0x2BA9C55DL, 0x741831F6L, 0xCE5C3E16L, 0x9B87931EL,
            0xAFD6BA33L, 0x6C24CF5CL, 0x7A325381L, 0x28958677L,
            0x3B8F4898L, 0x6B4BB9AFL, 0xC4BFE81BL, 0x66282193L,
            0x61D809CCL, 0xFB21A991L, 0x487CAC60L, 0x5DEC8032L,

            /* 4 */
            0xEF845D5DL, 0xE98575B1L, 0xDC262302L, 0xEB651B88L,
            0x23893E81L, 0xD396ACC5L, 0x0F6D6FF3L, 0x83F44239L,
            0x2E0B4482L, 0xA4842004L, 0x69C8F04AL, 0x9E1F9B5EL,
            0x21C66842L, 0xF6E96C9AL, 0x670C9C61L, 0xABD388F0L,

            /* 5 */
            0x6A51A0D2L, 0xD8542F68L, 0x960FA728L, 0xAB5133A3L,
            0x6EEF0B6CL, 0x137A3BE4L, 0xBA3BF050L, 0x7EFB2A98L,
            0xA1F1651DL, 0x39AF0176L, 0x66CA593EL, 0x82430E88L,
            0x8CEE8619L, 0x456F9FB4L, 0x7D84A5C3L, 0x3B8B5EBEL,

            /* 6 */
            0xE06F75D8L, 0x85C12073L, 0x401A449FL, 0x56C16AA6L,
            0x4ED3AA62L, 0x363F7706L, 0x1BFEDF72L, 0x429B023DL,
            0x37D0D724L, 0xD00A1248L, 0xDB0FEAD3L, 0x49F1C09BL,
            0x075372C9L, 0x80991B7BL, 0x25D479D8L, 0xF6E8DEF7L,

            /* 7 */
            0xE3FE501AL, 0xB6794C3BL, 0x976CE0BDL, 0x04C006BAL,
            0xC1A94FB6L, 0x409F60C4L, 0x5E5C9EC2L, 0x196A2463L,
            0x68FB6FAFL, 0x3E6C53B5L, 0x1339B2EBL, 0x3B52EC6FL,
            0x6DFC511FL, 0x9B30952CL, 0xCC814544L, 0xAF5EBD09L,

            /* 8 */
            0xBEE3D004L, 0xDE334AFDL, 0x660F2807L, 0x192E4BB3L,
            0xC0CBA857L, 0x45C8740FL, 0xD20B5F39L, 0xB9D3FBDBL,
            0x5579C0BDL, 0x1A60320AL, 0xD6A100C6L, 0x402C7279L,
            0x679F25FEL, 0xFB1FA3CCL, 0x8EA5E9F8L, 0xDB3222F8L,

            /* 9 */
            0x3C7516DFL, 0xFD616B15L, 0x2F501EC8L, 0xAD0552ABL,
            0x323DB5FAL, 0xFD238760L, 0x53317B48L, 0x3E00DF82L,
            0x9E5C57BBL, 0xCA6F8CA0L, 0x1A87562EL, 0xDF1769DBL,
            0xD542A8F6L, 0x287EFFC3L, 0xAC6732C6L, 0x8C4F5573L,

            /* A */
            0x695B27B0L, 0xBBCA58C8L, 0xE1FFA35DL, 0xB8F011A0L,
            0x10FA3D98L, 0xFD2183B8L, 0x4AFCB56CL, 0x2DD1D35BL,
            0x9A53E479L, 0xB6F84565L, 0xD28E49BCL, 0x4BFB9790L,
            0xE1DDF2DAL, 0xA4CB7E33L, 0x62FB1341L, 0xCEE4C6E8L,

            /* B */
            0xEF20CADAL, 0x36774C01L, 0xD07E9EFEL, 0x2BF11FB4L,
            0x95DBDA4DL, 0xAE909198L, 0xEAAD8E71L, 0x6B93D5A0L,
            0xD08ED1D0L, 0xAFC725E0L, 0x8E3C5B2FL, 0x8E7594B7L,
            0x8FF6E2FBL, 0xF2122B64L, 0x8888B812L, 0x900DF01CL,

            /* C */
            0x4FAD5EA0L, 0x688FC31CL, 0xD1CFF191L, 0xB3A8C1ADL,
            0x2F2F2218L, 0xBE0E1777L, 0xEA752DFEL, 0x8B021FA1L,
            0xE5A0CC0FL, 0xB56F74E8L, 0x18ACF3D6L, 0xCE89E299L,
            0xB4A84FE0L, 0xFD13E0B7L, 0x7CC43B81L, 0xD2ADA8D9L,

            /* D */
            0x165FA266L, 0x80957705L, 0x93CC7314L, 0x211A1477L,
            0xE6AD2065L, 0x77B5FA86L, 0xC75442F5L, 0xFB9D35CFL,
            0xEBCDAF0CL, 0x7B3E89A0L, 0xD6411BD3L, 0xAE1E7E49L,
            0x00250E2DL, 0x2071B35EL, 0x226800BBL, 0x57B8E0AFL,

            /* E */
            0x2464369BL, 0xF009B91EL, 0x5563911DL, 0x59DFA6AAL,
            0x78C14389L, 0xD95A537FL, 0x207D5BA2L, 0x02E5B9C5L,
            0x83260376L, 0x6295CFA9L, 0x11C81968L, 0x4E734A41L,
            0xB3472DCAL, 0x7B14A94AL, 0x1B510052L, 0x9A532915L,

            /* F */
            0xD60F573FL, 0xBC9BC6E4L, 0x2B60A476L, 0x81E67400L,
            0x08BA6FB5L, 0x571BE91FL, 0xF296EC6BL, 0x2A0DD915L,
            0xB6636521L, 0xE7B9F9B6L, 0xFF34052EL, 0xC5855664L,
            0x53B02D5DL, 0xA99F8FA1L, 0x08BA4799L, 0x6E85076AL
        },

        /* S[1] */
        {
            0x4B7A70E9L, 0xB5B32944L, 0xDB75092EL, 0xC4192623L,
            0xAD6EA6B0L, 0x49A7DF7DL, 0x9CEE60B8L, 0x8FEDB266L,
            0xECAA8C71L, 0x699A17FFL, 0x5664526CL, 0xC2B19EE1L,
            0x193602A5L, 0x75094C29L, 0xA0591340L, 0xE4183A3EL,

            0x3F54989AL, 0x5B429D65L, 0x6B8FE4D6L, 0x99F73FD6L,
            0xA1D29C07L, 0xEFE830F5L, 0x4D2D38E6L, 0xF0255DC1L,
            0x4CDD2086L, 0x8470EB26L, 0x6382E9C6L, 0x021ECC5EL,
            0x09686B3FL, 0x3EBAEFC9L, 0x3C971814L, 0x6B6A70A1L,

            0x687F3584L, 0x52A0E286L, 0xB79C5305L, 0xAA500737L,
            0x3E07841CL, 0x7FDEAE5CL, 0x8E7D44ECL, 0x5716F2B8L,
            0xB03ADA37L, 0xF0500C0DL, 0xF01C1F04L, 0x0200B3FFL,
            0xAE0CF51AL, 0x3CB574B2L, 0x25837A58L, 0xDC0921BDL,

            0xD19113F9L, 0x7CA92FF6L, 0x94324773L, 0x22F54701L,
            0x3AE5E581L, 0x37C2DADCL, 0xC8B57634L, 0x9AF3DDA7L,
            0xA9446146L, 0x0FD0030EL, 0xECC8C73EL, 0xA4751E41L,
            0xE238CD99L, 0x3BEA0E2FL, 0x3280BBA1L, 0x183EB331L,

            0x4E548B38L, 0x4F6DB908L, 0x6F420D03L, 0xF60A04BFL,
            0x2CB81290L, 0x24977C79L, 0x5679B072L, 0xBCAF89AFL,
            0xDE9A771FL, 0xD9930810L, 0xB38BAE12L, 0xDCCF3F2EL,
            0x5512721FL, 0x2E6B7124L, 0x501ADDE6L, 0x9F84CD87L,

            0x7A584718L, 0x7408DA17L, 0xBC9F9ABCL, 0xE94B7D8CL,
            0xEC7AEC3AL, 0xDB851DFAL, 0x63094366L, 0xC464C3D2L,
            0xEF1C1847L, 0x3215D908L, 0xDD433B37L, 0x24C2BA16L,
            0x12A14D43L, 0x2A65C451L, 0x50940002L, 0x133AE4DDL,

            0x71DFF89EL, 0x10314E55L, 0x81AC77D6L, 0x5F11199BL,
            0x043556F1L, 0xD7A3C76BL, 0x3C11183BL, 0x5924A509L,
            0xF28FE6EDL, 0x97F1FBFAL, 0x9EBABF2CL, 0x1E153C6EL,
            0x86E34570L, 0xEAE96FB1L, 0x860E5E0AL, 0x5A3E2AB3L,

            0x771FE71CL, 0x4E3D06FAL, 0x2965DCB9L, 0x99E71D0FL,
            0x803E89D6L, 0x5266C825L, 0x2E4CC978L, 0x9C10B36AL,
            0xC6150EBAL, 0x94E2EA78L, 0xA5FC3C53L, 0x1E0A2DF4L,
            0xF2F74EA7L, 0x361D2B3DL, 0x1939260FL, 0x19C27960L,

            0x5223A708L, 0xF71312B6L, 0xEBADFE6EL, 0xEAC31F66L,
            0xE3BC4595L, 0xA67BC883L, 0xB17F37D1L, 0x018CFF28L,
            0xC332DDEFL, 0xBE6C5AA5L, 0x65582185L, 0x68AB9802L,
            0xEECEA50FL, 0xDB2F953BL, 0x2AEF7DADL, 0x5B6E2F84L,

            0x1521B628L, 0x29076170L, 0xECDD4775L, 0x619F1510L,
            0x13CCA830L, 0xEB61BD96L, 0x0334FE1EL, 0xAA0363CFL,
            0xB5735C90L, 0x4C70A239L, 0xD59E9E0BL, 0xCBAADE14L,
            0xEECC86BCL, 0x60622CA7L, 0x9CAB5CABL, 0xB2F3846EL,

            0x648B1EAFL, 0x19BDF0CAL, 0xA02369B9L, 0x655ABB50L,
            0x40685A32L, 0x3C2AB4B3L, 0x319EE9D5L, 0xC021B8F7L,
            0x9B540B19L, 0x875FA099L, 0x95F7997EL, 0x623D7DA8L,
            0xF837889AL, 0x97E32D77L, 0x11ED935FL, 0x16681281L,

            0x0E358829L, 0xC7E61FD6L, 0x96DEDFA1L, 0x7858BA99L,
            0x57F584A5L, 0x1B227263L, 0x9B83C3FFL, 0x1AC24696L,
            0xCDB30AEBL, 0x532E3054L, 0x8FD948E4L, 0x6DBC3128L,
            0x58EBF2EFL, 0x34C6FFEAL, 0xFE28ED61L, 0xEE7C3C73L,

            0x5D4A14D9L, 0xE864B7E3L, 0x42105D14L, 0x203E13E0L,
            0x45EEE2B6L, 0xA3AAABEAL, 0xDB6C4F15L, 0xFACB4FD0L,
            0xC742F442L, 0xEF6ABBB5L, 0x654F3B1DL, 0x41CD2105L,
            0xD81E799EL, 0x86854DC7L, 0xE44B476AL, 0x3D816250L,

            0xCF62A1F2L, 0x5B8D2646L, 0xFC8883A0L, 0xC1C7B6A3L,
            0x7F1524C3L, 0x69CB7492L, 0x47848A0BL, 0x5692B285L,
            0x095BBF00L, 0xAD19489DL, 0x1462B174L, 0x23820E00L,
            0x58428D2AL, 0x0C55F5EAL, 0x1DADF43EL, 0x233F7061L,

            0x3372F092L, 0x8D937E41L, 0xD65FECF1L, 0x6C223BDBL,
            0x7CDE3759L, 0xCBEE7460L, 0x4085F2A7L, 0xCE77326EL,
            0xA6078084L, 0x19F8509EL, 0xE8EFD855L, 0x61D99735L,
            0xA969A7AAL, 0xC50C06C2L, 0x5A04ABFCL, 0x800BCADCL,

            0x9E447A2EL, 0xC3453484L, 0xFDD56705L, 0x0E1E9EC9L,
            0xDB73DBD3L, 0x105588CDL, 0x675FDA79L, 0xE3674340L,
            0xC5C43465L, 0x713E38D8L, 0x3D28F89EL, 0xF16DFF20L,
            0x153E21E7L, 0x8FB03D4AL, 0xE6E39F2BL, 0xDB83ADF7L
        },

        /* S[2] */
        {
            0xE93D5A68L, 0x948140F7L, 0xF64C261CL, 0x94692934L,
            0x411520F7L, 0x7602D4F7L, 0xBCF46B2EL, 0xD4A20068L,
            0xD4082471L, 0x3320F46AL, 0x43B7D4B7L, 0x500061AFL,
            0x1E39F62EL, 0x97244546L, 0x14214F74L, 0xBF8B8840L,

            0x4D95FC1DL, 0x96B591AFL, 0x70F4DDD3L, 0x66A02F45L,
            0xBFBC09ECL, 0x03BD9785L, 0x7FAC6DD0L, 0x31CB8504L,
            0x96EB27B3L, 0x55FD3941L, 0xDA2547E6L, 0xABCA0A9AL,
            0x28507825L, 0x530429F4L, 0x0A2C86DAL, 0xE9B66DFBL,

            0x68DC1462L, 0xD7486900L, 0x680EC0A4L, 0x27A18DEEL,
            0x4F3FFEA2L, 0xE887AD8CL, 0xB58CE006L, 0x7AF4D6B6L,
            0xAACE1E7CL, 0xD3375FECL, 0xCE78A399L, 0x406B2A42L,
            0x20FE9E35L, 0xD9F385B9L, 0xEE39D7ABL, 0x3B124E8BL,

            0x1DC9FAF7L, 0x4B6D1856L, 0x26A36631L, 0xEAE397B2L,
            0x3A6EFA74L, 0xDD5B4332L, 0x6841E7F7L, 0xCA7820FBL,
            0xFB0AF54EL, 0xD8FEB397L, 0x454056ACL, 0xBA489527L,
            0x55533A3AL, 0x20838D87L, 0xFE6BA9B7L, 0xD096954BL,

            0x55A867BCL, 0xA1159A58L, 0xCCA92963L, 0x99E1DB33L,
            0xA62A4A56L, 0x3F3125F9L, 0x5EF47E1CL, 0x9029317CL,
            0xFDF8E802L, 0x04272F70L, 0x80BB155CL, 0x05282CE3L,
            0x95C11548L, 0xE4C66D22L, 0x48C1133FL, 0xC70F86DCL,

            0x07F9C9EEL, 0x41041F0FL, 0x404779A4L, 0x5D886E17L,
            0x325F51EBL, 0xD59BC0D1L, 0xF2BCC18FL, 0x41113564L,
            0x257B7834L, 0x602A9C60L, 0xDFF8E8A3L, 0x1F636C1BL,
            0x0E12B4C2L, 0x02E1329EL, 0xAF664FD1L, 0xCAD18115L,

            0x6B2395E0L, 0x333E92E1L, 0x3B240B62L, 0xEEBEB922L,
            0x85B2A20EL, 0xE6BA0D99L, 0xDE720C8CL, 0x2DA2F728L,
            0xD0127845L, 0x95B794FDL, 0x647D0862L, 0xE7CCF5F0L,
            0x5449A36FL, 0x877D48FAL, 0xC39DFD27L, 0xF33E8D1EL,

            0x0A476341L, 0x992EFF74L, 0x3A6F6EABL, 0xF4F8FD37L,
            0xA812DC60L, 0xA1EBDDF8L, 0x991BE14CL, 0xDB6E6B0DL,
            0xC67B5510L, 0x6D672C37L, 0x2765D43BL, 0xDCD0E804L,
            0xF1290DC7L, 0xCC00FFA3L, 0xB5390F92L, 0x690FED0BL,

            0x667B9FFBL, 0xCEDB7D9CL, 0xA091CF0BL, 0xD9155EA3L,
            0xBB132F88L, 0x515BAD24L, 0x7B9479BFL, 0x763BD6EBL,
            0x37392EB3L, 0xCC115979L, 0x8026E297L, 0xF42E312DL,
            0x6842ADA7L, 0xC66A2B3BL, 0x12754CCCL, 0x782EF11CL,

            0x6A124237L, 0xB79251E7L, 0x06A1BBE6L, 0x4BFB6350L,
            0x1A6B1018L, 0x11CAEDFAL, 0x3D25BDD8L, 0xE2E1C3C9L,
            0x44421659L, 0x0A121386L, 0xD90CEC6EL, 0xD5ABEA2AL,
            0x64AF674EL, 0xDA86A85FL, 0xBEBFE988L, 0x64E4C3FEL,

            0x9DBC8057L, 0xF0F7C086L, 0x60787BF8L, 0x6003604DL,
            0xD1FD8346L, 0xF6381FB0L, 0x7745AE04L, 0xD736FCCCL,
            0x83426B33L, 0xF01EAB71L, 0xB0804187L, 0x3C005E5FL,
            0x77A057BEL, 0xBDE8AE24L, 0x55464299L, 0xBF582E61L,

            0x4E58F48FL, 0xF2DDFDA2L, 0xF474EF38L, 0x8789BDC2L,
            0x5366F9C3L, 0xC8B38E74L, 0xB475F255L, 0x46FCD9B9L,
            0x7AEB2661L, 0x8B1DDF84L, 0x846A0E79L, 0x915F95E2L,
            0x466E598EL, 0x20B45770L, 0x8CD55591L, 0xC902DE4CL,

            0xB90BACE1L, 0xBB8205D0L, 0x11A86248L, 0x7574A99EL,
            0xB77F19B6L, 0xE0A9DC09L, 0x662D09A1L, 0xC4324633L,
            0xE85A1F02L, 0x09F0BE8CL, 0x4A99A025L, 0x1D6EFE10L,
            0x1AB93D1DL, 0x0BA5A4DFL, 0xA186F20FL, 0x2868F169L,

            0xDCB7DA83L, 0x573906FEL, 0xA1E2CE9BL, 0x4FCD7F52L,
            0x50115E01L, 0xA70683FAL, 0xA002B5C4L, 0x0DE6D027L,
            0x9AF88C27L, 0x773F8641L, 0xC3604C06L, 0x61A806B5L,
            0xF0177A28L, 0xC0F586E0L, 0x006058AAL, 0x30DC7D62L,

            0x11E69ED7L, 0x2338EA63L, 0x53C2DD94L, 0xC2C21634L,
            0xBBCBEE56L, 0x90BCB6DEL, 0xEBFC7DA1L, 0xCE591D76L,
            0x6F05E409L, 0x4B7C0188L, 0x39720A3DL, 0x7C927C24L,
            0x86E3725FL, 0x724D9DB9L, 0x1AC15BB4L, 0xD39EB8FCL,

            0xED545578L, 0x08FCA5B5L, 0xD83D7CD3L, 0x4DAD0FC4L,
            0x1E50EF5EL, 0xB161E6F8L, 0xA28514D9L, 0x6C51133CL,
            0x6FD5C7E7L, 0x56E14EC4L, 0x362ABFCEL, 0xDDC6C837L,
            0xD79A3234L, 0x92638212L, 0x670EFA8EL, 0x406000E0L
        },

        /* S[3] */
        {
            0x3A39CE37L, 0xD3FAF5CFL, 0xABC27737L, 0x5AC52D1BL,
            0x5CB0679EL, 0x4FA33742L, 0xD3822740L, 0x99BC9BBEL,
            0xD5118E9DL, 0xBF0F7315L, 0xD62D1C7EL, 0xC700C47BL,
            0xB78C1B6BL, 0x21A19045L, 0xB26EB1BEL, 0x6A366EB4L,

            0x5748AB2FL, 0xBC946E79L, 0xC6A376D2L, 0x6549C2C8L,
            0x530FF8EEL, 0x468DDE7DL, 0xD5730A1DL, 0x4CD04DC6L,
            0x2939BBDBL, 0xA9BA4650L, 0xAC9526E8L, 0xBE5EE304L,
            0xA1FAD5F0L, 0x6A2D519AL, 0x63EF8CE2L, 0x9A86EE22L,

            0xC089C2B8L, 0x43242EF6L, 0xA51E03AAL, 0x9CF2D0A4L,
            0x83C061BAL, 0x9BE96A4DL, 0x8FE51550L, 0xBA645BD6L,
            0x2826A2F9L, 0xA73A3AE1L, 0x4BA99586L, 0xEF5562E9L,
            0xC72FEFD3L, 0xF752F7DAL, 0x3F046F69L, 0x77FA0A59L,

            0x80E4A915L, 0x87B08601L, 0x9B09E6ADL, 0x3B3EE593L,
            0xE990FD5AL, 0x9E34D797L, 0x2CF0B7D9L, 0x022B8B51L,
            0x96D5AC3AL, 0x017DA67DL, 0xD1CF3ED6L, 0x7C7D2D28L,
            0x1F9F25CFL, 0xADF2B89BL, 0x5AD6B472L, 0x5A88F54CL,

            0xE029AC71L, 0xE019A5E6L, 0x47B0ACFDL, 0xED93FA9BL,
            0xE8D3C48DL, 0x283B57CCL, 0xF8D56629L, 0x79132E28L,
            0x785F0191L, 0xED756055L, 0xF7960E44L, 0xE3D35E8CL,
            0x15056DD4L, 0x88F46DBAL, 0x03A16125L, 0x0564F0BDL,

            0xC3EB9E15L, 0x3C9057A2L, 0x97271AECL, 0xA93A072AL,
            0x1B3F6D9BL, 0x1E6321F5L, 0xF59C66FBL, 0x26DCF319L,
            0x7533D928L, 0xB155FDF5L, 0x03563482L, 0x8ABA3CBBL,
            0x28517711L, 0xC20AD9F8L, 0xABCC5167L, 0xCCAD925FL,

            0x4DE81751L, 0x3830DC8EL, 0x379D5862L, 0x9320F991L,
            0xEA7A90C2L, 0xFB3E7BCEL, 0x5121CE64L, 0x774FBE32L,
            0xA8B6E37EL, 0xC3293D46L, 0x48DE5369L, 0x6413E680L,
            0xA2AE0810L, 0xDD6DB224L, 0x69852DFDL, 0x09072166L,

            0xB39A460AL, 0x6445C0DDL, 0x586CDECFL, 0x1C20C8AEL,
            0x5BBEF7DDL, 0x1B588D40L, 0xCCD2017FL, 0x6BB4E3BBL,
            0xDDA26A7EL, 0x3A59FF45L, 0x3E350A44L, 0xBCB4CDD5L,
            0x72EACEA8L, 0xFA6484BBL, 0x8D6612AEL, 0xBF3C6F47L,

            0xD29BE463L, 0x542F5D9EL, 0xAEC2771BL, 0xF64E6370L,
            0x740E0D8DL, 0xE75B1357L, 0xF8721671L, 0xAF537D5DL,
            0x4040CB08L, 0x4EB4E2CCL, 0x34D2466AL, 0x0115AF84L,
            0xE1B00428L, 0x95983A1DL, 0x06B89FB4L, 0xCE6EA048L,

            0x6F3F3B82L, 0x3520AB82L, 0x011A1D4BL, 0x277227F8L,
            0x611560B1L, 0xE7933FDCL, 0xBB3A792BL, 0x344525BDL,
            0xA08839E1L, 0x51CE794BL, 0x2F32C9B7L, 0xA01FBAC9L,
            0xE01CC87EL, 0xBCC7D1F6L, 0xCF0111C3L, 0xA1E8AAC7L,

            0x1A908749L, 0xD44FBD9AL, 0xD0DADECBL, 0xD50ADA38L,
            0x0339C32AL, 0xC6913667L, 0x8DF9317CL, 0xE0B12B4FL,
            0xF79E59B7L, 0x43F5BB3AL, 0xF2D519FFL, 0x27D9459CL,
            0xBF97222CL, 0x15E6FC2AL, 0x0F91FC71L, 0x9B941525L,

            0xFAE59361L, 0xCEB69CEBL, 0xC2A86459L, 0x12BAA8D1L,
            0xB6C1075EL, 0xE3056A0CL, 0x10D25065L, 0xCB03A442L,
            0xE0EC6E0EL, 0x1698DB3BL, 0x4C98A0BEL, 0x3278E964L,
            0x9F1F9532L, 0xE0D392DFL, 0xD3A0342BL, 0x8971F21EL,

            0x1B0A7441L, 0x4BA3348CL, 0xC5BE7120L, 0xC37632D8L,
            0xDF359F8DL, 0x9B992F2EL, 0xE60B6F47L, 0x0FE3F11DL,
            0xE54CDA54L, 0x1EDAD891L, 0xCE6279CFL, 0xCD3E7E6FL,
            0x1618B166L, 0xFD2C1D05L, 0x848FD2C5L, 0xF6FB2299L,

            0xF523F357L, 0xA6327623L, 0x93A83531L, 0x56CCCD02L,
            0xACF08162L, 0x5A75EBB5L, 0x6E163697L, 0x88D273CCL,
            0xDE966292L, 0x81B949D0L, 0x4C50901BL, 0x71C65614L,
            0xE6C6C7BDL, 0x327A140AL, 0x45E1D006L, 0xC3F27B9AL,

            0xC9AA53FDL, 0x62A80F00L, 0xBB25BFE2L, 0x35BDD2F6L,
            0x71126905L, 0xB2040222L, 0xB6CBCF7CL, 0xCD769C2BL,
            0x53113EC0L, 0x1640E3D3L, 0x38ABBD60L, 0x2547ADF0L,
            0xBA38209CL, 0xF746CE76L, 0x77AFA1C5L, 0x20756060L,

            0x85CBFE4EL, 0x8AE88DD8L, 0x7AAAF9B0L, 0x4CF9AA7EL,
            0x1948C25CL, 0x02FB8A8CL, 0x01C36AE4L, 0xD6EBE1F9L,
            0x90D4F869L, 0xA65CDEA0L, 0x3F09252DL, 0xC208E69FL,
            0xB74E6132L, 0xCE77E25BL, 0x578FDFE3L, 0x3AC372E6L
        }
    },

    /* P */
    {
        0x243F6A88L, 0x85A308D3L, 0x13198A2EL, 0x03707344L,
        0xA4093822L, 0x299F31D0L, 0x082EFA98L, 0xEC4E6C89L,
        0x452821E6L, 0x38D01377L, 0xBE5466CFL, 0x34E90C6CL,
        0xC0AC29B7L, 0xC97C50DDL, 0x3F84D5B5L, 0xB5470917L,
        0x9216D5D9L, 0x8979FB1BL
    }
};
#endif

#if !defined LIBO_CIPHER_OPENSSL_BACKEND
static rtlCipherError BF_init(
    CipherContextBF *ctx,
    rtlCipherMode    eMode,
    const sal_uInt8 *pKeyData, sal_Size nKeyLen,
    const sal_uInt8 *pArgData, sal_Size nArgLen)
{
    CipherKeyBF *key;
    sal_uInt32   D, DL, DR;
    sal_uInt16   i, j, k;

    key = &(ctx->m_key);

    memcpy(key, &BF_key, sizeof (CipherKeyBF));
    memset(&(ctx->m_iv), 0, sizeof(ctx->m_iv));
    ctx->m_offset = 0;

    for (i = 0, k = 0; i < CIPHER_ROUNDS_BF + 2; ++i)
    {
        D = 0;
        for (j = 0; j < 4; ++j)
        {
            D = ((D << 8) | pKeyData[k]);
            k++;
            if (k >= nKeyLen)
                k = 0;
        }
        key->m_P[i] ^= D;
    }

    rtl_secureZeroMemory(&DL, sizeof(DL));
    rtl_secureZeroMemory(&DR, sizeof(DR));

    for (i = 0; i < CIPHER_ROUNDS_BF + 2; i += 2)
    {
        BF_encode(key, &DL, &DR);
        key->m_P[i    ] = DL;
        key->m_P[i + 1] = DR;
    }

    for (i = 0; i < 4; ++i)
    {
        for (k = 0; k < 256; k += 2)
        {
            BF_encode(key, &DL, &DR);
            key->m_S[i][k    ] = DL;
            key->m_S[i][k + 1] = DR;
        }
    }

    if (pArgData && nArgLen)
    {
        nArgLen = std::min<sal_Size>(nArgLen, 8);
        if (eMode == rtl_Cipher_ModeStream)
        {
            memcpy(ctx->m_iv.m_byte, pArgData, nArgLen);
        }
        else
        {
            RTL_CIPHER_NTOHL64 (pArgData, DL, DR, nArgLen);
            ctx->m_iv.m_long[0] = DL;
            ctx->m_iv.m_long[1] = DR;
        }
    }

    return rtl_Cipher_E_None;
}
#endif

static rtlCipherError BF_update(
    CipherContextBF    *ctx,
    rtlCipherMode       eMode,
    rtlCipherDirection  eDirection,
    const sal_uInt8    *pData,   sal_Size nDatLen,
    sal_uInt8          *pBuffer, sal_Size nBufLen)
{
    /* Check arguments. */
    if (!pData || !pBuffer)
        return rtl_Cipher_E_Argument;

    if ((nDatLen <= 0) || (nDatLen > nBufLen))
        return rtl_Cipher_E_BufferSize;

    /* Update. */
#if defined LIBO_CIPHER_OPENSSL_BACKEND
    assert(eMode == rtl_Cipher_ModeStream);
    (void) eMode;
    (void) eDirection;
    while (nDatLen > o3tl::make_unsigned(std::numeric_limits<int>::max())) {
        int outl;
        if (EVP_CipherUpdate(ctx->m_context, pBuffer, &outl, pData, std::numeric_limits<int>::max())
            == 0)
        {
            return rtl_Cipher_E_Unknown;
        }
        assert(outl == std::numeric_limits<int>::max());
        pData += std::numeric_limits<int>::max();
        nDatLen -= std::numeric_limits<int>::max();
        pBuffer += std::numeric_limits<int>::max();
    }
    int outl;
    if (EVP_CipherUpdate(ctx->m_context, pBuffer, &outl, pData, static_cast<int>(nDatLen)) == 0)
    {
        return rtl_Cipher_E_Unknown;
    }
    assert(outl == static_cast<int>(nDatLen));
    // A final call to EVP_CipherFinal_ex is intentionally missing; it wouldn't fit the rtl/cipher.h
    // interface, and is hopefully not needed, as each individual Blowfish CFB update step doesn't
    // hold back any data that would need to be finally flushed.
#else
    if (eMode == rtl_Cipher_ModeECB)
    {
        /* Block mode. */
        while (nDatLen > 8)
        {
            BF_updateECB(ctx, eDirection, pData, pBuffer, 8);
            nDatLen -= 8;
            pData   += 8;
            pBuffer += 8;
        }
        BF_updateECB(ctx, eDirection, pData, pBuffer, nDatLen);
    }
    else if (eMode == rtl_Cipher_ModeCBC)
    {
        /* Block mode. */
        while (nDatLen > 8)
        {
            BF_updateCBC (ctx, eDirection, pData, pBuffer, 8);
            nDatLen -= 8;
            pData   += 8;
            pBuffer += 8;
        }
        BF_updateCBC (ctx, eDirection, pData, pBuffer, nDatLen);
    }
    else
    {
        /* Stream mode. */
        while (nDatLen > 0)
        {
            BF_updateCFB (ctx, eDirection, pData, pBuffer);
            nDatLen -= 1;
            pData   += 1;
            pBuffer += 1;
        }
    }
#endif
    return rtl_Cipher_E_None;
}

#if !defined LIBO_CIPHER_OPENSSL_BACKEND
static void BF_updateECB(
    CipherContextBF    *ctx,
    rtlCipherDirection  direction,
    const sal_uInt8    *pData,
    sal_uInt8          *pBuffer,
    sal_Size            nLength)
{
    CipherKeyBF *key;
    sal_uInt32   DL, DR;

    key = &(ctx->m_key);
    if (direction == rtl_Cipher_DirectionEncode)
    {
        RTL_CIPHER_NTOHL64(pData, DL, DR, nLength);

        BF_encode(key, &DL, &DR);

        RTL_CIPHER_HTONL(DL, pBuffer);
        RTL_CIPHER_HTONL(DR, pBuffer);
    }
    else
    {
        RTL_CIPHER_NTOHL(pData, DL);
        RTL_CIPHER_NTOHL(pData, DR);

        BF_decode(key, &DL, &DR);

        RTL_CIPHER_HTONL64(DL, DR, pBuffer, nLength);
    }
    rtl_secureZeroMemory(&DL, sizeof(DL));
    rtl_secureZeroMemory(&DR, sizeof(DR));
}

static void BF_updateCBC(
    CipherContextBF    *ctx,
    rtlCipherDirection  direction,
    const sal_uInt8    *pData,
    sal_uInt8          *pBuffer,
    sal_Size            nLength)
{
    CipherKeyBF *key;
    sal_uInt32   DL, DR;

    key = &(ctx->m_key);
    if (direction == rtl_Cipher_DirectionEncode)
    {
        RTL_CIPHER_NTOHL64(pData, DL, DR, nLength);

        DL ^= ctx->m_iv.m_long[0];
        DR ^= ctx->m_iv.m_long[1];

        BF_encode(key, &DL, &DR);

        ctx->m_iv.m_long[0] = DL;
        ctx->m_iv.m_long[1] = DR;

        RTL_CIPHER_HTONL(DL, pBuffer);
        RTL_CIPHER_HTONL(DR, pBuffer);
    }
    else
    {
        sal_uInt32 IVL, IVR;

        RTL_CIPHER_NTOHL(pData, DL);
        RTL_CIPHER_NTOHL(pData, DR);

        IVL = DL;
        IVR = DR;

        BF_decode(key, &DL, &DR);

        DL ^= ctx->m_iv.m_long[0];
        DR ^= ctx->m_iv.m_long[1];

        ctx->m_iv.m_long[0] = IVL;
        ctx->m_iv.m_long[1] = IVR;

        RTL_CIPHER_HTONL64(DL, DR, pBuffer, nLength);
    }
    rtl_secureZeroMemory(&DL, sizeof(DL));
    rtl_secureZeroMemory(&DR, sizeof(DR));
}

static void BF_updateCFB(
    CipherContextBF    *ctx,
    rtlCipherDirection  direction,
    const sal_uInt8    *pData,
    sal_uInt8          *pBuffer)
{
    sal_uInt8  *iv;
    sal_uInt32  k;

    iv = ctx->m_iv.m_byte;
    k  = ctx->m_offset;

    if (k == 0)
    {
        sal_uInt32 IVL, IVR;

        RTL_CIPHER_NTOHL64(iv, IVL, IVR, 8);
        BF_encode(&(ctx->m_key), &IVL, &IVR);
        RTL_CIPHER_HTONL64(IVL, IVR, iv, 8);

        rtl_secureZeroMemory(&IVL, sizeof(IVL));
        rtl_secureZeroMemory(&IVR, sizeof(IVR));
    }

    if (direction == rtl_Cipher_DirectionEncode)
    {
        iv[k] ^= *pData;
        *pBuffer = iv[k];
    }
    else
    {
        sal_uInt8 c = iv[k];
        iv[k] = *pData;
        *pBuffer = *pData ^ c;
    }

    ctx->m_offset = ((k + 1) & 0x07);
    iv = nullptr;
}

static void BF_encode(
    CipherKeyBF *key, sal_uInt32 *xl, sal_uInt32 *xr)
{
    sal_uInt32  t, XL, XR;
    sal_uInt16  i;

    XL = *xl;
    XR = *xr;

    for (i = 0; i < CIPHER_ROUNDS_BF; ++i)
    {
        XL ^= key->m_P[i];
        XR ^= BF (key, XL);

        t  = XL;
        XL = XR;
        XR = t;
    }

    t  = XL;
    XL = XR;
    XR = t;

    XR ^= key->m_P[CIPHER_ROUNDS_BF    ];
    XL ^= key->m_P[CIPHER_ROUNDS_BF + 1];

    *xl = XL;
    *xr = XR;

}

static void BF_decode(
    CipherKeyBF *key, sal_uInt32 *xl, sal_uInt32 *xr)
{
    sal_uInt32  t, XL, XR;
    sal_uInt16  i;

    XL = *xl;
    XR = *xr;

    for (i = CIPHER_ROUNDS_BF + 1; i > 1; --i)
    {
        XL ^= key->m_P[i];
        XR ^= BF (key, XL);

        t  = XL;
        XL = XR;
        XR = t;
    }

    t  = XL;
    XL = XR;
    XR = t;

    XR ^= key->m_P[1];
    XL ^= key->m_P[0];

    *xl = XL;
    *xr = XR;

}

static sal_uInt32 BF(CipherKeyBF *key, sal_uInt32 x)
{
    sal_uInt16 a, b, c, d;
    sal_uInt32 y;

    d = static_cast<sal_uInt16>(x & 0x00ff);
    x >>= 8;
    c = static_cast<sal_uInt16>(x & 0x00ff);
    x >>= 8;
    b = static_cast<sal_uInt16>(x & 0x00ff);
    x >>= 8;
    a = static_cast<sal_uInt16>(x & 0x00ff);

    y  = key->m_S[0][a];
    y += key->m_S[1][b];
    y ^= key->m_S[2][c];
    y += key->m_S[3][d];

    return y;
}
#endif

/**
    rtl_cipherBF (Blowfish) implementation.

    Reference: Bruce Schneier: Applied Cryptography, 2nd edition, ch. 14.3
*/
rtlCipher SAL_CALL rtl_cipher_createBF(rtlCipherMode Mode) noexcept
{
    CipherBF_Impl *pImpl = nullptr;

    if (Mode == rtl_Cipher_ModeInvalid)
        return nullptr;
#if defined LIBO_CIPHER_OPENSSL_BACKEND
    if (Mode != rtl_Cipher_ModeStream) {
        // Cannot easily support ModeECB and ModeCBC, and they aren't used in the LO code at least:
        return nullptr;
    }
#endif

    pImpl = static_cast<CipherBF_Impl*>(rtl_allocateZeroMemory(sizeof (CipherBF_Impl)));
    if (pImpl)
    {
        pImpl->m_cipher.m_algorithm = rtl_Cipher_AlgorithmBF;
        pImpl->m_cipher.m_direction = rtl_Cipher_DirectionInvalid;
        pImpl->m_cipher.m_mode      = Mode;

        pImpl->m_cipher.m_init      = rtl_cipher_initBF;
        pImpl->m_cipher.m_encode    = rtl_cipher_encodeBF;
        pImpl->m_cipher.m_decode    = rtl_cipher_decodeBF;
        pImpl->m_cipher.m_delete    = rtl_cipher_destroyBF;
    }
    return static_cast<rtlCipher>(pImpl);
}

rtlCipherError SAL_CALL rtl_cipher_initBF(
    rtlCipher          Cipher,
    rtlCipherDirection Direction,
    const sal_uInt8 *pKeyData, sal_Size nKeyLen,
    const sal_uInt8 *pArgData, sal_Size nArgLen) noexcept
{
    CipherBF_Impl *pImpl = static_cast<CipherBF_Impl*>(Cipher);

    if (!pImpl || !pKeyData)
        return rtl_Cipher_E_Argument;

    if (pImpl->m_cipher.m_algorithm != rtl_Cipher_AlgorithmBF)
        return rtl_Cipher_E_Algorithm;

    if (Direction != rtl_Cipher_DirectionInvalid)
        pImpl->m_cipher.m_direction = Direction;
    else
        return rtl_Cipher_E_Direction;

#if defined LIBO_CIPHER_OPENSSL_BACKEND
    if (pImpl->m_cipher.m_direction == rtl_Cipher_DirectionBoth) {
        // Cannot easily support DirectionBoth, and it isn't used in the LO code at least:
        return rtl_Cipher_E_Direction;
    }
    if (nKeyLen > o3tl::make_unsigned(std::numeric_limits<int>::max())) {
        return rtl_Cipher_E_BufferSize;
    }
    if (pImpl->m_context.m_context != nullptr) {
        EVP_CIPHER_CTX_free(pImpl->m_context.m_context);
    }
    pImpl->m_context.m_context = EVP_CIPHER_CTX_new();
    if (pImpl->m_context.m_context == nullptr) {
        return rtl_Cipher_E_Memory;
    }
    unsigned char iv[8];
    auto const n = std::min(nArgLen, sal_Size(8));
    std::memcpy(iv, pArgData, n);
    std::memset(iv + n, 0, 8 - n);
    if (EVP_CipherInit_ex(
            pImpl->m_context.m_context, EVP_bf_cfb(), nullptr, nullptr, iv,
            pImpl->m_cipher.m_direction == rtl_Cipher_DirectionDecode ? 0 : 1)
        == 0)
    {
        return rtl_Cipher_E_Unknown;
    }
    if (EVP_CIPHER_CTX_set_key_length(pImpl->m_context.m_context, static_cast<int>(nKeyLen)) == 0) {
        return rtl_Cipher_E_Unknown;
    }
    if (EVP_CipherInit_ex(pImpl->m_context.m_context, nullptr, nullptr, pKeyData, nullptr, -1) == 0)
    {
        return rtl_Cipher_E_Unknown;
    }
    return rtl_Cipher_E_None;
#else
    return BF_init(
        &(pImpl->m_context), pImpl->m_cipher.m_mode,
        pKeyData, nKeyLen, pArgData, nArgLen);
#endif
}

rtlCipherError SAL_CALL rtl_cipher_encodeBF(
    rtlCipher   Cipher,
    const void *pData,   sal_Size nDatLen,
    sal_uInt8  *pBuffer, sal_Size nBufLen) noexcept
{
    CipherBF_Impl *pImpl = static_cast<CipherBF_Impl*>(Cipher);
    if (!pImpl)
        return rtl_Cipher_E_Argument;

    if (pImpl->m_cipher.m_algorithm != rtl_Cipher_AlgorithmBF)
        return rtl_Cipher_E_Algorithm;

    if (pImpl->m_cipher.m_direction == rtl_Cipher_DirectionInvalid)
        return rtl_Cipher_E_Direction;

    if (pImpl->m_cipher.m_direction == rtl_Cipher_DirectionDecode)
        return rtl_Cipher_E_Direction;

    return BF_update(
        &(pImpl->m_context), pImpl->m_cipher.m_mode,
        rtl_Cipher_DirectionEncode,
        static_cast<const sal_uInt8*>(pData), nDatLen, pBuffer, nBufLen);
}

rtlCipherError SAL_CALL rtl_cipher_decodeBF(
    rtlCipher   Cipher,
    const void *pData,   sal_Size nDatLen,
    sal_uInt8  *pBuffer, sal_Size nBufLen) noexcept
{
    CipherBF_Impl *pImpl = static_cast<CipherBF_Impl*>(Cipher);
    if (!pImpl)
        return rtl_Cipher_E_Argument;

    if (pImpl->m_cipher.m_algorithm != rtl_Cipher_AlgorithmBF)
        return rtl_Cipher_E_Algorithm;

    if (pImpl->m_cipher.m_direction == rtl_Cipher_DirectionInvalid)
        return rtl_Cipher_E_Direction;

    if (pImpl->m_cipher.m_direction == rtl_Cipher_DirectionEncode)
        return rtl_Cipher_E_Direction;

    return BF_update(
        &(pImpl->m_context), pImpl->m_cipher.m_mode,
        rtl_Cipher_DirectionDecode,
        static_cast<const sal_uInt8*>(pData), nDatLen, pBuffer, nBufLen);
}

void SAL_CALL rtl_cipher_destroyBF(rtlCipher Cipher) noexcept
{
    CipherBF_Impl *pImpl = static_cast<CipherBF_Impl*>(Cipher);
    if (!pImpl)
        return;

    if (pImpl->m_cipher.m_algorithm == rtl_Cipher_AlgorithmBF)
    {
#if defined LIBO_CIPHER_OPENSSL_BACKEND
        if (pImpl->m_context.m_context != nullptr) {
            EVP_CIPHER_CTX_free(pImpl->m_context.m_context);
        }
#endif
        rtl_freeZeroMemory(pImpl, sizeof(CipherBF_Impl));
    }
    else
        free(pImpl);
}

#if !defined LIBO_CIPHER_OPENSSL_BACKEND
#define CIPHER_CBLOCK_ARCFOUR 256
#endif

namespace {

struct ContextARCFOUR_Impl
{
#if defined LIBO_CIPHER_OPENSSL_BACKEND
    EVP_CIPHER_CTX * m_context;
#else
    unsigned int m_S[CIPHER_CBLOCK_ARCFOUR];
    unsigned int m_X, m_Y;
#endif
};

struct CipherARCFOUR_Impl
{
    Cipher_Impl         m_cipher;
    ContextARCFOUR_Impl m_context;
};

}

static rtlCipherError rtl_cipherARCFOUR_update_Impl(
    ContextARCFOUR_Impl *ctx,
    const sal_uInt8     *pData,   sal_Size nDatLen,
    sal_uInt8           *pBuffer, sal_Size nBufLen);

static rtlCipherError rtl_cipherARCFOUR_init_Impl(
    ContextARCFOUR_Impl *ctx,
    const sal_uInt8     *pKeyData, sal_Size nKeyLen)
{
#if defined LIBO_CIPHER_OPENSSL_BACKEND
    if (nKeyLen > o3tl::make_unsigned(std::numeric_limits<int>::max())) {
        return rtl_Cipher_E_BufferSize;
    }
    if (ctx->m_context != nullptr) {
        EVP_CIPHER_CTX_free(ctx->m_context);
    }
    ctx->m_context = EVP_CIPHER_CTX_new();
    if (ctx->m_context == nullptr) {
        return rtl_Cipher_E_Memory;
    }
    if (EVP_CipherInit_ex(ctx->m_context, EVP_rc4(), nullptr, nullptr, nullptr, 0) == 0) {
            // RC4 en- and decryption is identical, so we can use 0=decrypt regardless of direction,
            // and thus also support rtl_Cipher_DirectionBoth
        return rtl_Cipher_E_Unknown;
    }
    if (EVP_CIPHER_CTX_set_key_length(ctx->m_context, static_cast<int>(nKeyLen)) == 0) {
        return rtl_Cipher_E_Unknown;
    }
    if (EVP_CipherInit_ex(ctx->m_context, nullptr, nullptr, pKeyData, nullptr, -1) == 0) {
        return rtl_Cipher_E_Unknown;
    }
#else
    unsigned int  K[CIPHER_CBLOCK_ARCFOUR];
    unsigned int *L, *S;
    unsigned int  x, y;
    sal_Size      n, k;

    S = &(ctx->m_S[0]);

    /* Initialize S linearly. */
    for (x = 0; x < CIPHER_CBLOCK_ARCFOUR; x++)
        S[x] = x;

    /* Initialize K with key, repeat key as necessary. */
    for (L = K, n = CIPHER_CBLOCK_ARCFOUR; n > nKeyLen; n -= nKeyLen)
    {
        for (k = 0; k < nKeyLen; k++)
        {
            L[k] = pKeyData[k];
        }

        L += nKeyLen;
    }

    for (k = 0; k < n; k++)
    {
        L[k] = pKeyData[k];
    }

    /* Initialize S with K. */
    for (x = 0, y = 0; x < CIPHER_CBLOCK_ARCFOUR; x++)
    {
        y = (y + S[x] + K[x]) % CIPHER_CBLOCK_ARCFOUR;
        /* swap S[x] and S[y] */
        unsigned int t = S[x];
        S[x] = S[y];
        S[y] = t;
    }

    /* Initialize counters X and Y. */
    ctx->m_X = 0;
    ctx->m_Y = 0;
#endif

    return rtl_Cipher_E_None;
}

static rtlCipherError rtl_cipherARCFOUR_update_Impl(
    ContextARCFOUR_Impl *ctx,
    const sal_uInt8     *pData,   sal_Size nDatLen,
    sal_uInt8           *pBuffer, sal_Size nBufLen)
{
    /* Check arguments. */
    if (!pData || !pBuffer)
        return rtl_Cipher_E_Argument;

    if ((0 >= nDatLen) || (nDatLen > nBufLen))
        return rtl_Cipher_E_BufferSize;

#if defined LIBO_CIPHER_OPENSSL_BACKEND
    while (nDatLen > o3tl::make_unsigned(std::numeric_limits<int>::max())) {
        int outl;
        if (EVP_CipherUpdate(ctx->m_context, pBuffer, &outl, pData, std::numeric_limits<int>::max())
            == 0)
        {
            return rtl_Cipher_E_Unknown;
        }
        assert(outl == std::numeric_limits<int>::max());
        pData += std::numeric_limits<int>::max();
        nDatLen -= std::numeric_limits<int>::max();
        pBuffer += std::numeric_limits<int>::max();
    }
    int outl;
    if (EVP_CipherUpdate(ctx->m_context, pBuffer, &outl, pData, static_cast<int>(nDatLen)) == 0) {
        return rtl_Cipher_E_Unknown;
    }
    assert(outl == static_cast<int>(nDatLen));
    // A final call to EVP_CipherFinal_ex is intentionally missing; it wouldn't fit the rtl/cipher.h
    // interface, and is hopefully not needed, as each individual RC4 update step doesn't hold back
    // any data that would need to be finally flushed.
#else
    unsigned int *S;
    sal_Size k;

    /* Update. */
    S = &(ctx->m_S[0]);
    for (k = 0; k < nDatLen; k++)
    {
        /* Update counters X and Y. */
        unsigned int x = ctx->m_X;
        unsigned int y = ctx->m_Y;
        x = (x + 1   ) % CIPHER_CBLOCK_ARCFOUR;
        y = (y + S[x]) % CIPHER_CBLOCK_ARCFOUR;
        ctx->m_X = x;
        ctx->m_Y = y;

        /* Swap S[x] and S[y]. */
        unsigned int t = S[x];
        S[x] = S[y];
        S[y] = t;

        /* Evaluate next key byte S[t]. */
        t = (S[x] + S[y]) % CIPHER_CBLOCK_ARCFOUR;
        pBuffer[k] = pData[k] ^ static_cast<sal_uInt8>(S[t] & 0xff);
    }
#endif

    return rtl_Cipher_E_None;
}

/**
   rtl_cipher_ARCFOUR (RC4) implementation.

  Reference: Bruce Schneier: Applied Cryptography, 2nd edition, ch. 17.1
*/
rtlCipher SAL_CALL rtl_cipher_createARCFOUR(rtlCipherMode Mode) noexcept
{
    CipherARCFOUR_Impl *pImpl = nullptr;

    if (Mode != rtl_Cipher_ModeStream)
        return nullptr;

    pImpl = static_cast<CipherARCFOUR_Impl*>(rtl_allocateZeroMemory(sizeof(CipherARCFOUR_Impl)));
    if (pImpl)
    {
        pImpl->m_cipher.m_algorithm = rtl_Cipher_AlgorithmARCFOUR;
        pImpl->m_cipher.m_direction = rtl_Cipher_DirectionInvalid;
        pImpl->m_cipher.m_mode      = rtl_Cipher_ModeStream;

        pImpl->m_cipher.m_init      = rtl_cipher_initARCFOUR;
        pImpl->m_cipher.m_encode    = rtl_cipher_encodeARCFOUR;
        pImpl->m_cipher.m_decode    = rtl_cipher_decodeARCFOUR;
        pImpl->m_cipher.m_delete    = rtl_cipher_destroyARCFOUR;
    }

    return static_cast<rtlCipher>(pImpl);
}

rtlCipherError SAL_CALL rtl_cipher_initARCFOUR(
    rtlCipher          Cipher,
    rtlCipherDirection Direction,
    const sal_uInt8 *pKeyData, sal_Size nKeyLen,
    SAL_UNUSED_PARAMETER const sal_uInt8 *, SAL_UNUSED_PARAMETER sal_Size) noexcept
{
    CipherARCFOUR_Impl *pImpl = static_cast<CipherARCFOUR_Impl*>(Cipher);

    if (!pImpl || !pKeyData)
        return rtl_Cipher_E_Argument;

    if (pImpl->m_cipher.m_algorithm != rtl_Cipher_AlgorithmARCFOUR)
        return rtl_Cipher_E_Algorithm;

    if (Direction != rtl_Cipher_DirectionInvalid)
        pImpl->m_cipher.m_direction = Direction;
    else
        return rtl_Cipher_E_Direction;

    return rtl_cipherARCFOUR_init_Impl(&(pImpl->m_context), pKeyData, nKeyLen);
}

rtlCipherError SAL_CALL rtl_cipher_encodeARCFOUR(
    rtlCipher   Cipher,
    const void *pData,   sal_Size nDatLen,
    sal_uInt8  *pBuffer, sal_Size nBufLen) noexcept
{
    CipherARCFOUR_Impl *pImpl = static_cast<CipherARCFOUR_Impl*>(Cipher);
    if (!pImpl)
        return rtl_Cipher_E_Argument;

    if (pImpl->m_cipher.m_algorithm != rtl_Cipher_AlgorithmARCFOUR)
        return rtl_Cipher_E_Algorithm;

    if (pImpl->m_cipher.m_direction == rtl_Cipher_DirectionInvalid)
        return rtl_Cipher_E_Direction;

    return rtl_cipherARCFOUR_update_Impl(
        &(pImpl->m_context),
        static_cast<const sal_uInt8*>(pData), nDatLen, pBuffer, nBufLen);
}

rtlCipherError SAL_CALL rtl_cipher_decodeARCFOUR(
    rtlCipher   Cipher,
    const void *pData,   sal_Size nDatLen,
    sal_uInt8  *pBuffer, sal_Size nBufLen) noexcept
{
    CipherARCFOUR_Impl *pImpl = static_cast<CipherARCFOUR_Impl*>(Cipher);
    if (!pImpl)
        return rtl_Cipher_E_Argument;

    if (pImpl->m_cipher.m_algorithm != rtl_Cipher_AlgorithmARCFOUR)
        return rtl_Cipher_E_Algorithm;

    if (pImpl->m_cipher.m_direction == rtl_Cipher_DirectionInvalid)
        return rtl_Cipher_E_Direction;

    return rtl_cipherARCFOUR_update_Impl(
        &(pImpl->m_context),
        static_cast<const sal_uInt8*>(pData), nDatLen, pBuffer, nBufLen);
}

void SAL_CALL rtl_cipher_destroyARCFOUR(rtlCipher Cipher) noexcept
{
    CipherARCFOUR_Impl *pImpl = static_cast<CipherARCFOUR_Impl*>(Cipher);
    if (!pImpl)
        return;

    if (pImpl->m_cipher.m_algorithm == rtl_Cipher_AlgorithmARCFOUR)
    {
#if defined LIBO_CIPHER_OPENSSL_BACKEND
        if (pImpl->m_context.m_context != nullptr) {
            EVP_CIPHER_CTX_free(pImpl->m_context.m_context);
        }
#endif
        rtl_freeZeroMemory(pImpl, sizeof(CipherARCFOUR_Impl));
    }
    else
        free(pImpl);
}

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