// Copyright 2005-2016 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.

#include <openssl/rsa.h>

#include <assert.h>

#include <limits.h>

#include <string.h>

#include <openssl/bn.h>

#include <openssl/digest.h>

#include <openssl/err.h>

#include <openssl/mem.h>

#include "../../internal.h"

#include "../bcm_interface.h"

#include "../service_indicator/internal.h"

#include "internal.h"

using namespace bssl;

int bssl::RSA_padding_add_PKCS1_type_1(uint8_t *to, size_t to_len,

                                       const uint8_t *from, size_t from_len) {

  // See RFC 8017, section 9.2.

  if (to_len < RSA_PKCS1_PADDING_SIZE) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_KEY_SIZE_TOO_SMALL);

    return 0;

  }

  if (from_len > to_len - RSA_PKCS1_PADDING_SIZE) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY);

    return 0;

  }

  to[0] = 0;

  to[1] = 1;

  OPENSSL_memset(to + 2, 0xff, to_len - 3 - from_len);

  to[to_len - from_len - 1] = 0;

  OPENSSL_memcpy(to + to_len - from_len, from, from_len);

  return 1;

}

int bssl::RSA_padding_check_PKCS1_type_1(uint8_t *out, size_t *out_len,

                                         size_t max_out, const uint8_t *from,

                                         size_t from_len) {

  // See RFC 8017, section 9.2. This is part of signature verification and thus

  // does not need to run in constant-time.

  if (from_len < 2) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_SMALL);

    return 0;

  }

  // Check the header.

  if (from[0] != 0 || from[1] != 1) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_BLOCK_TYPE_IS_NOT_01);

    return 0;

  }

  // Scan over padded data, looking for the 00.

  size_t pad;

  for (pad = 2 /* header */; pad < from_len; pad++) {

    if (from[pad] == 0x00) {

      break;

    }

    if (from[pad] != 0xff) {

      OPENSSL_PUT_ERROR(RSA, RSA_R_BAD_FIXED_HEADER_DECRYPT);

      return 0;

    }

  }

  if (pad == from_len) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_NULL_BEFORE_BLOCK_MISSING);

    return 0;

  }

  if (pad < 2 /* header */ + 8) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_BAD_PAD_BYTE_COUNT);

    return 0;

  }

  // Skip over the 00.

  pad++;

  if (from_len - pad > max_out) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE);

    return 0;

  }

  OPENSSL_memcpy(out, from + pad, from_len - pad);

  *out_len = from_len - pad;

  return 1;

}

int bssl::RSA_padding_add_none(uint8_t *to, size_t to_len, const uint8_t *from,

                               size_t from_len) {

  if (from_len > to_len) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);

    return 0;

  }

  if (from_len < to_len) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_SMALL);

    return 0;

  }

  OPENSSL_memcpy(to, from, from_len);

  return 1;

}

int bssl::PKCS1_MGF1(uint8_t *out, size_t len, const uint8_t *seed,

                     size_t seed_len, const EVP_MD *md) {

  int ret = 0;

  ScopedEVP_MD_CTX ctx;

  FIPS_service_indicator_lock_state();

  size_t md_len = EVP_MD_size(md);

  for (uint32_t i = 0; len > 0; i++) {

    uint8_t counter[4];

    counter[0] = (uint8_t)(i >> 24);

    counter[1] = (uint8_t)(i >> 16);

    counter[2] = (uint8_t)(i >> 8);

    counter[3] = (uint8_t)i;

    if (!EVP_DigestInit_ex(ctx.get(), md, nullptr) ||

        !EVP_DigestUpdate(ctx.get(), seed, seed_len) ||

        !EVP_DigestUpdate(ctx.get(), counter, sizeof(counter))) {

      goto err;

    }

    if (md_len <= len) {

      if (!EVP_DigestFinal_ex(ctx.get(), out, nullptr)) {

        goto err;

      }

      out += md_len;

      len -= md_len;

    } else {

      uint8_t digest[EVP_MAX_MD_SIZE];

      if (!EVP_DigestFinal_ex(ctx.get(), digest, nullptr)) {

        goto err;

      }

      OPENSSL_memcpy(out, digest, len);

      len = 0;

    }

  }

  ret = 1;

err:

  FIPS_service_indicator_unlock_state();

  return ret;

}

static const uint8_t kPSSZeroes[] = {0, 0, 0, 0, 0, 0, 0, 0};

int RSA_verify_PKCS1_PSS_mgf1(const RSA *rsa, const uint8_t *mHash,

                              const EVP_MD *Hash, const EVP_MD *mgf1Hash,

                              const uint8_t *EM, int sLen) {

  if (mgf1Hash == nullptr) {

    mgf1Hash = Hash;

  }

  int ret = 0;

  uint8_t *DB = nullptr;

  const uint8_t *H;

  ScopedEVP_MD_CTX ctx;

  unsigned MSBits;

  size_t emLen, maskedDBLen, salt_start;

  FIPS_service_indicator_lock_state();

  size_t hLen = EVP_MD_size(Hash);

  if (sLen == RSA_PSS_SALTLEN_DIGEST) {

    sLen = (int)hLen;

  } else if (sLen == RSA_PSS_SALTLEN_AUTO) {

    // Leave `sLen` negative, which will trigger the logic below to recover and

    // allow any salt length.

  } else if (sLen < 0) {

    // Other negative values are reserved.

    OPENSSL_PUT_ERROR(RSA, RSA_R_SLEN_CHECK_FAILED);

    goto err;

  }

  MSBits = (RSA_bits(rsa) - 1) & 0x7;

  emLen = RSA_size(rsa);

  if (EM[0] & (0xFF << MSBits)) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_FIRST_OCTET_INVALID);

    goto err;

  }

  if (MSBits == 0) {

    EM++;

    emLen--;

  }

  // `sLen` may be negative for the non-standard salt length recovery mode.

  if (emLen < hLen + 2 || (sLen >= 0 && emLen < hLen + (size_t)sLen + 2)) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE);

    goto err;

  }

  if (EM[emLen - 1] != 0xbc) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_LAST_OCTET_INVALID);

    goto err;

  }

  maskedDBLen = emLen - hLen - 1;

  H = EM + maskedDBLen;

  DB = reinterpret_cast<uint8_t *>(OPENSSL_malloc(maskedDBLen));

  if (!DB) {

    goto err;

  }

  if (!PKCS1_MGF1(DB, maskedDBLen, H, hLen, mgf1Hash)) {

    goto err;

  }

  for (size_t i = 0; i < maskedDBLen; i++) {

    DB[i] ^= EM[i];

  }

  if (MSBits) {

    DB[0] &= 0xFF >> (8 - MSBits);

  }

  // This step differs slightly from EMSA-PSS-VERIFY (RFC 8017) step 10 because

  // it accepts a non-standard salt recovery flow. DB should be some number of

  // zeros, a one, then the salt.

  for (salt_start = 0; DB[salt_start] == 0 && salt_start < maskedDBLen - 1;

       salt_start++) {

    ;

  }

  if (DB[salt_start] != 0x1) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_SLEN_RECOVERY_FAILED);

    goto err;

  }

  salt_start++;

  // If a salt length was specified, check it matches.

  if (sLen >= 0 && maskedDBLen - salt_start != (size_t)sLen) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_SLEN_CHECK_FAILED);

    goto err;

  }

  uint8_t H_[EVP_MAX_MD_SIZE];

  if (!EVP_DigestInit_ex(ctx.get(), Hash, nullptr) ||

      !EVP_DigestUpdate(ctx.get(), kPSSZeroes, sizeof(kPSSZeroes)) ||

      !EVP_DigestUpdate(ctx.get(), mHash, hLen) ||

      !EVP_DigestUpdate(ctx.get(), DB + salt_start, maskedDBLen - salt_start) ||

      !EVP_DigestFinal_ex(ctx.get(), H_, nullptr)) {

    goto err;

  }

  if (OPENSSL_memcmp(H_, H, hLen) != 0) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_BAD_SIGNATURE);

    goto err;

  }

  ret = 1;

err:

  OPENSSL_free(DB);

  FIPS_service_indicator_unlock_state();

  return ret;

}

int RSA_padding_add_PKCS1_PSS_mgf1(const RSA *rsa, unsigned char *EM,

                                   const unsigned char *mHash,

                                   const EVP_MD *Hash, const EVP_MD *mgf1Hash,

                                   int sLenRequested) {

  int ret = 0;

  ScopedEVP_MD_CTX ctx;

  size_t maskedDBLen, MSBits, emLen;

  size_t hLen;

  unsigned char *H, *salt = nullptr, *p;

  if (mgf1Hash == nullptr) {

    mgf1Hash = Hash;

  }

  FIPS_service_indicator_lock_state();

  hLen = EVP_MD_size(Hash);

  unsigned rsa_bits = RSA_bits(rsa);

  if (rsa_bits == 0) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_EMPTY_PUBLIC_KEY);

    goto err;

  }

  MSBits = (rsa_bits - 1) & 0x7;

  emLen = RSA_size(rsa);

  if (MSBits == 0) {

    assert(emLen >= 1);

    *EM++ = 0;

    emLen--;

  }

  if (emLen < hLen + 2) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);

    goto err;

  }

  size_t sLen;

  if (sLenRequested == RSA_PSS_SALTLEN_DIGEST) {

    sLen = hLen;

  } else if (sLenRequested == RSA_PSS_SALTLEN_AUTO) {

    // Use the maximum possible salt length.

    sLen = emLen - hLen - 2;

  } else if (sLenRequested < 0) {

    // Other negative values are reserved.

    OPENSSL_PUT_ERROR(RSA, RSA_R_SLEN_CHECK_FAILED);

    goto err;

  } else {

    sLen = (size_t)sLenRequested;

  }

  if (emLen - hLen - 2 < sLen) {

    OPENSSL_PUT_ERROR(RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);

    goto err;

  }

  if (sLen > 0) {

    salt = reinterpret_cast<uint8_t *>(OPENSSL_malloc(sLen));

    if (!salt) {

      goto err;

    }

    BCM_rand_bytes(salt, sLen);

  }

  maskedDBLen = emLen - hLen - 1;

  H = EM + maskedDBLen;

  if (!EVP_DigestInit_ex(ctx.get(), Hash, nullptr) ||

      !EVP_DigestUpdate(ctx.get(), kPSSZeroes, sizeof(kPSSZeroes)) ||

      !EVP_DigestUpdate(ctx.get(), mHash, hLen) ||

      !EVP_DigestUpdate(ctx.get(), salt, sLen) ||

      !EVP_DigestFinal_ex(ctx.get(), H, nullptr)) {

    goto err;

  }

  // Generate dbMask in place then perform XOR on it

  if (!PKCS1_MGF1(EM, maskedDBLen, H, hLen, mgf1Hash)) {

    goto err;

  }

  p = EM;

  // Initial PS XORs with all zeroes which is a NOP so just update

  // pointer. Note from a test above this value is guaranteed to

  // be non-negative.

  p += emLen - sLen - hLen - 2;

  *p++ ^= 0x1;

  if (sLen > 0) {

    for (size_t i = 0; i < sLen; i++) {

      *p++ ^= salt[i];

    }

  }

  if (MSBits) {

    EM[0] &= 0xFF >> (8 - MSBits);

  }

  // H is already in place so just set final 0xbc

  EM[emLen - 1] = 0xbc;

  ret = 1;

err:

  OPENSSL_free(salt);

  FIPS_service_indicator_unlock_state();

  return ret;

}