/*
 * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the OpenSSL license (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <openssl/cipher.h>
#include <openssl/nid.h>

#include "../fipsmodule/cipher/internal.h"
#include "../internal.h"


#define c2l(c, l)                         \
  do {                                    \
    (l) = ((uint32_t)(*((c)++)));         \
    (l) |= ((uint32_t)(*((c)++))) << 8L;  \
    (l) |= ((uint32_t)(*((c)++))) << 16L; \
    (l) |= ((uint32_t)(*((c)++))) << 24L; \
  } while (0)

#define c2ln(c, l1, l2, n)                     \
  do {                                         \
    (c) += (n);                                \
    (l1) = (l2) = 0;                           \
    switch (n) {                               \
      case 8:                                  \
        (l2) = ((uint32_t)(*(--(c)))) << 24L;  \
        [[fallthrough]];                       \
      case 7:                                  \
        (l2) |= ((uint32_t)(*(--(c)))) << 16L; \
        [[fallthrough]];                       \
      case 6:                                  \
        (l2) |= ((uint32_t)(*(--(c)))) << 8L;  \
        [[fallthrough]];                       \
      case 5:                                  \
        (l2) |= ((uint32_t)(*(--(c))));        \
        [[fallthrough]];                       \
      case 4:                                  \
        (l1) = ((uint32_t)(*(--(c)))) << 24L;  \
        [[fallthrough]];                       \
      case 3:                                  \
        (l1) |= ((uint32_t)(*(--(c)))) << 16L; \
        [[fallthrough]];                       \
      case 2:                                  \
        (l1) |= ((uint32_t)(*(--(c)))) << 8L;  \
        [[fallthrough]];                       \
      case 1:                                  \
        (l1) |= ((uint32_t)(*(--(c))));        \
    }                                          \
  } while (0)

#define l2c(l, c)                              \
  do {                                         \
    *((c)++) = (uint8_t)(((l)) & 0xff);        \
    *((c)++) = (uint8_t)(((l) >> 8L) & 0xff);  \
    *((c)++) = (uint8_t)(((l) >> 16L) & 0xff); \
    *((c)++) = (uint8_t)(((l) >> 24L) & 0xff); \
  } while (0)

#define l2cn(l1, l2, c, n)                          \
  do {                                              \
    (c) += (n);                                     \
    switch (n) {                                    \
      case 8:                                       \
        *(--(c)) = (uint8_t)(((l2) >> 24L) & 0xff); \
        [[fallthrough]];                            \
      case 7:                                       \
        *(--(c)) = (uint8_t)(((l2) >> 16L) & 0xff); \
        [[fallthrough]];                            \
      case 6:                                       \
        *(--(c)) = (uint8_t)(((l2) >> 8L) & 0xff);  \
        [[fallthrough]];                            \
      case 5:                                       \
        *(--(c)) = (uint8_t)(((l2)) & 0xff);        \
        [[fallthrough]];                            \
      case 4:                                       \
        *(--(c)) = (uint8_t)(((l1) >> 24L) & 0xff); \
        [[fallthrough]];                            \
      case 3:                                       \
        *(--(c)) = (uint8_t)(((l1) >> 16L) & 0xff); \
        [[fallthrough]];                            \
      case 2:                                       \
        *(--(c)) = (uint8_t)(((l1) >> 8L) & 0xff);  \
        [[fallthrough]];                            \
      case 1:                                       \
        *(--(c)) = (uint8_t)(((l1)) & 0xff);        \
    }                                               \
  } while (0)

typedef struct rc2_key_st {
  uint16_t data[64];
} RC2_KEY;

static void RC2_encrypt(uint32_t *d, RC2_KEY *key) {
  int i, n;
  uint16_t *p0, *p1;
  uint16_t x0, x1, x2, x3, t;
  uint32_t l;

  l = d[0];
  x0 = (uint16_t)l & 0xffff;
  x1 = (uint16_t)(l >> 16L);
  l = d[1];
  x2 = (uint16_t)l & 0xffff;
  x3 = (uint16_t)(l >> 16L);

  n = 3;
  i = 5;

  p0 = p1 = &key->data[0];
  for (;;) {
    t = (x0 + (x1 & ~x3) + (x2 & x3) + *(p0++)) & 0xffff;
    x0 = (t << 1) | (t >> 15);
    t = (x1 + (x2 & ~x0) + (x3 & x0) + *(p0++)) & 0xffff;
    x1 = (t << 2) | (t >> 14);
    t = (x2 + (x3 & ~x1) + (x0 & x1) + *(p0++)) & 0xffff;
    x2 = (t << 3) | (t >> 13);
    t = (x3 + (x0 & ~x2) + (x1 & x2) + *(p0++)) & 0xffff;
    x3 = (t << 5) | (t >> 11);

    if (--i == 0) {
      if (--n == 0) {
        break;
      }
      i = (n == 2) ? 6 : 5;

      x0 += p1[x3 & 0x3f];
      x1 += p1[x0 & 0x3f];
      x2 += p1[x1 & 0x3f];
      x3 += p1[x2 & 0x3f];
    }
  }

  d[0] = (uint32_t)(x0 & 0xffff) | ((uint32_t)(x1 & 0xffff) << 16L);
  d[1] = (uint32_t)(x2 & 0xffff) | ((uint32_t)(x3 & 0xffff) << 16L);
}

static void RC2_decrypt(uint32_t *d, RC2_KEY *key) {
  int i, n;
  uint16_t *p0, *p1;
  uint16_t x0, x1, x2, x3, t;
  uint32_t l;

  l = d[0];
  x0 = (uint16_t)l & 0xffff;
  x1 = (uint16_t)(l >> 16L);
  l = d[1];
  x2 = (uint16_t)l & 0xffff;
  x3 = (uint16_t)(l >> 16L);

  n = 3;
  i = 5;

  p0 = &key->data[63];
  p1 = &key->data[0];
  for (;;) {
    t = ((x3 << 11) | (x3 >> 5)) & 0xffff;
    x3 = (t - (x0 & ~x2) - (x1 & x2) - *(p0--)) & 0xffff;
    t = ((x2 << 13) | (x2 >> 3)) & 0xffff;
    x2 = (t - (x3 & ~x1) - (x0 & x1) - *(p0--)) & 0xffff;
    t = ((x1 << 14) | (x1 >> 2)) & 0xffff;
    x1 = (t - (x2 & ~x0) - (x3 & x0) - *(p0--)) & 0xffff;
    t = ((x0 << 15) | (x0 >> 1)) & 0xffff;
    x0 = (t - (x1 & ~x3) - (x2 & x3) - *(p0--)) & 0xffff;

    if (--i == 0) {
      if (--n == 0) {
        break;
      }
      i = (n == 2) ? 6 : 5;

      x3 = (x3 - p1[x2 & 0x3f]) & 0xffff;
      x2 = (x2 - p1[x1 & 0x3f]) & 0xffff;
      x1 = (x1 - p1[x0 & 0x3f]) & 0xffff;
      x0 = (x0 - p1[x3 & 0x3f]) & 0xffff;
    }
  }

  d[0] = (uint32_t)(x0 & 0xffff) | ((uint32_t)(x1 & 0xffff) << 16L);
  d[1] = (uint32_t)(x2 & 0xffff) | ((uint32_t)(x3 & 0xffff) << 16L);
}

static void RC2_cbc_encrypt(const uint8_t *in, uint8_t *out, size_t length,
                            RC2_KEY *ks, uint8_t *iv, int encrypt) {
  uint32_t tin0, tin1;
  uint32_t tout0, tout1, xor0, xor1;
  long l = length;
  uint32_t tin[2];

  if (encrypt) {
    c2l(iv, tout0);
    c2l(iv, tout1);
    iv -= 8;
    for (l -= 8; l >= 0; l -= 8) {
      c2l(in, tin0);
      c2l(in, tin1);
      tin0 ^= tout0;
      tin1 ^= tout1;
      tin[0] = tin0;
      tin[1] = tin1;
      RC2_encrypt(tin, ks);
      tout0 = tin[0];
      l2c(tout0, out);
      tout1 = tin[1];
      l2c(tout1, out);
    }
    if (l != -8) {
      c2ln(in, tin0, tin1, l + 8);
      tin0 ^= tout0;
      tin1 ^= tout1;
      tin[0] = tin0;
      tin[1] = tin1;
      RC2_encrypt(tin, ks);
      tout0 = tin[0];
      l2c(tout0, out);
      tout1 = tin[1];
      l2c(tout1, out);
    }
    l2c(tout0, iv);
    l2c(tout1, iv);
  } else {
    c2l(iv, xor0);
    c2l(iv, xor1);
    iv -= 8;
    for (l -= 8; l >= 0; l -= 8) {
      c2l(in, tin0);
      tin[0] = tin0;
      c2l(in, tin1);
      tin[1] = tin1;
      RC2_decrypt(tin, ks);
      tout0 = tin[0] ^ xor0;
      tout1 = tin[1] ^ xor1;
      l2c(tout0, out);
      l2c(tout1, out);
      xor0 = tin0;
      xor1 = tin1;
    }
    if (l != -8) {
      c2l(in, tin0);
      tin[0] = tin0;
      c2l(in, tin1);
      tin[1] = tin1;
      RC2_decrypt(tin, ks);
      tout0 = tin[0] ^ xor0;
      tout1 = tin[1] ^ xor1;
      l2cn(tout0, tout1, out, l + 8);
      xor0 = tin0;
      xor1 = tin1;
    }
    l2c(xor0, iv);
    l2c(xor1, iv);
  }
  tin[0] = tin[1] = 0;
}

static const uint8_t key_table[256] = {
    0xd9, 0x78, 0xf9, 0xc4, 0x19, 0xdd, 0xb5, 0xed, 0x28, 0xe9, 0xfd, 0x79,
    0x4a, 0xa0, 0xd8, 0x9d, 0xc6, 0x7e, 0x37, 0x83, 0x2b, 0x76, 0x53, 0x8e,
    0x62, 0x4c, 0x64, 0x88, 0x44, 0x8b, 0xfb, 0xa2, 0x17, 0x9a, 0x59, 0xf5,
    0x87, 0xb3, 0x4f, 0x13, 0x61, 0x45, 0x6d, 0x8d, 0x09, 0x81, 0x7d, 0x32,
    0xbd, 0x8f, 0x40, 0xeb, 0x86, 0xb7, 0x7b, 0x0b, 0xf0, 0x95, 0x21, 0x22,
    0x5c, 0x6b, 0x4e, 0x82, 0x54, 0xd6, 0x65, 0x93, 0xce, 0x60, 0xb2, 0x1c,
    0x73, 0x56, 0xc0, 0x14, 0xa7, 0x8c, 0xf1, 0xdc, 0x12, 0x75, 0xca, 0x1f,
    0x3b, 0xbe, 0xe4, 0xd1, 0x42, 0x3d, 0xd4, 0x30, 0xa3, 0x3c, 0xb6, 0x26,
    0x6f, 0xbf, 0x0e, 0xda, 0x46, 0x69, 0x07, 0x57, 0x27, 0xf2, 0x1d, 0x9b,
    0xbc, 0x94, 0x43, 0x03, 0xf8, 0x11, 0xc7, 0xf6, 0x90, 0xef, 0x3e, 0xe7,
    0x06, 0xc3, 0xd5, 0x2f, 0xc8, 0x66, 0x1e, 0xd7, 0x08, 0xe8, 0xea, 0xde,
    0x80, 0x52, 0xee, 0xf7, 0x84, 0xaa, 0x72, 0xac, 0x35, 0x4d, 0x6a, 0x2a,
    0x96, 0x1a, 0xd2, 0x71, 0x5a, 0x15, 0x49, 0x74, 0x4b, 0x9f, 0xd0, 0x5e,
    0x04, 0x18, 0xa4, 0xec, 0xc2, 0xe0, 0x41, 0x6e, 0x0f, 0x51, 0xcb, 0xcc,
    0x24, 0x91, 0xaf, 0x50, 0xa1, 0xf4, 0x70, 0x39, 0x99, 0x7c, 0x3a, 0x85,
    0x23, 0xb8, 0xb4, 0x7a, 0xfc, 0x02, 0x36, 0x5b, 0x25, 0x55, 0x97, 0x31,
    0x2d, 0x5d, 0xfa, 0x98, 0xe3, 0x8a, 0x92, 0xae, 0x05, 0xdf, 0x29, 0x10,
    0x67, 0x6c, 0xba, 0xc9, 0xd3, 0x00, 0xe6, 0xcf, 0xe1, 0x9e, 0xa8, 0x2c,
    0x63, 0x16, 0x01, 0x3f, 0x58, 0xe2, 0x89, 0xa9, 0x0d, 0x38, 0x34, 0x1b,
    0xab, 0x33, 0xff, 0xb0, 0xbb, 0x48, 0x0c, 0x5f, 0xb9, 0xb1, 0xcd, 0x2e,
    0xc5, 0xf3, 0xdb, 0x47, 0xe5, 0xa5, 0x9c, 0x77, 0x0a, 0xa6, 0x20, 0x68,
    0xfe, 0x7f, 0xc1, 0xad,
};

static void RC2_set_key(RC2_KEY *key, int len, const uint8_t *data, int bits) {
  int i, j;
  uint8_t *k;
  uint16_t *ki;
  unsigned int c, d;

  k = (uint8_t *)&key->data[0];
  *k = 0;  // for if there is a zero length key

  if (len > 128) {
    len = 128;
  }
  if (bits <= 0) {
    bits = 1024;
  }
  if (bits > 1024) {
    bits = 1024;
  }

  for (i = 0; i < len; i++) {
    k[i] = data[i];
  }

  // expand table
  d = k[len - 1];
  j = 0;
  for (i = len; i < 128; i++, j++) {
    d = key_table[(k[j] + d) & 0xff];
    k[i] = d;
  }

  // hmm.... key reduction to 'bits' bits

  j = (bits + 7) >> 3;
  i = 128 - j;
  c = (0xff >> (-bits & 0x07));

  d = key_table[k[i] & c];
  k[i] = d;
  while (i--) {
    d = key_table[k[i + j] ^ d];
    k[i] = d;
  }

  // copy from bytes into uint16_t's
  ki = &(key->data[63]);
  for (i = 127; i >= 0; i -= 2) {
    *(ki--) = ((k[i] << 8) | k[i - 1]) & 0xffff;
  }
}

typedef struct {
  int key_bits;  // effective key bits
  RC2_KEY ks;    // key schedule
} EVP_RC2_KEY;

static int rc2_init_key(EVP_CIPHER_CTX *ctx, const uint8_t *key,
                        const uint8_t *iv, int enc) {
  EVP_RC2_KEY *rc2_key = (EVP_RC2_KEY *)ctx->cipher_data;
  RC2_set_key(&rc2_key->ks, EVP_CIPHER_CTX_key_length(ctx), key,
              rc2_key->key_bits);
  return 1;
}

static int rc2_cbc_cipher(EVP_CIPHER_CTX *ctx, uint8_t *out, const uint8_t *in,
                          size_t inl) {
  EVP_RC2_KEY *key = (EVP_RC2_KEY *)ctx->cipher_data;
  static const size_t kChunkSize = 0x10000;

  while (inl >= kChunkSize) {
    RC2_cbc_encrypt(in, out, kChunkSize, &key->ks, ctx->iv, ctx->encrypt);
    inl -= kChunkSize;
    in += kChunkSize;
    out += kChunkSize;
  }
  if (inl) {
    RC2_cbc_encrypt(in, out, inl, &key->ks, ctx->iv, ctx->encrypt);
  }
  return 1;
}

static int rc2_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr) {
  EVP_RC2_KEY *key = (EVP_RC2_KEY *)ctx->cipher_data;

  switch (type) {
    case EVP_CTRL_INIT:
      key->key_bits = EVP_CIPHER_CTX_key_length(ctx) * 8;
      return 1;
    case EVP_CTRL_SET_RC2_KEY_BITS:
      // Should be overridden by later call to |EVP_CTRL_INIT|, but
      // people call it, so it may as well work.
      key->key_bits = arg;
      return 1;

    default:
      return -1;
  }
}

static const EVP_CIPHER rc2_40_cbc = {
    /*nid=*/NID_rc2_40_cbc,
    /*block_size=*/8,
    /*key_len=*/5 /* 40 bit */,
    /*iv_len=*/8,
    /*ctx_size=*/sizeof(EVP_RC2_KEY),
    /*flags=*/EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH | EVP_CIPH_CTRL_INIT,
    /*init=*/rc2_init_key,
    /*cipher=*/rc2_cbc_cipher,
    /*cleanup=*/nullptr,
    /*ctrl=*/rc2_ctrl,
};

const EVP_CIPHER *EVP_rc2_40_cbc(void) { return &rc2_40_cbc; }

static const EVP_CIPHER rc2_cbc = {
    /*nid=*/NID_rc2_cbc,
    /*block_size=*/8,
    /*key_len=*/16 /* 128 bit */,
    /*iv_len=*/8,
    /*ctx_size=*/sizeof(EVP_RC2_KEY),
    /*flags=*/EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH | EVP_CIPH_CTRL_INIT,
    /*init=*/rc2_init_key,
    /*cipher=*/rc2_cbc_cipher,
    /*cleanup=*/nullptr,
    /*ctrl=*/rc2_ctrl,
};

const EVP_CIPHER *EVP_rc2_cbc(void) { return &rc2_cbc; }