// Copyright 1999-2016 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/pkcs8.h>

#include <assert.h>

#include <limits.h>

#include <string.h>

#include <openssl/bytestring.h>

#include <openssl/cipher.h>

#include <openssl/digest.h>

#include <openssl/err.h>

#include <openssl/mem.h>

#include <openssl/nid.h>

#include <openssl/rand.h>

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

#include "../internal.h"

#include "internal.h"

static int pkcs12_encode_password(const char *in, size_t in_len, uint8_t **out,

                                  size_t *out_len) {

  bssl::ScopedCBB cbb;

  if (!CBB_init(cbb.get(), in_len * 2)) {

    return 0;

  }

  // Convert the password to BMPString, or UCS-2. See

  // https://tools.ietf.org/html/rfc7292#appendix-B.1.

  CBS cbs;

  CBS_init(&cbs, (const uint8_t *)in, in_len);

  while (CBS_len(&cbs) != 0) {

    uint32_t c;

    if (!CBS_get_utf8(&cbs, &c) || !CBB_add_ucs2_be(cbb.get(), c)) {

      OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_INVALID_CHARACTERS);

      return 0;

    }

  }

  // Terminate the result with a UCS-2 NUL.

  if (!CBB_add_ucs2_be(cbb.get(), 0) || !CBB_finish(cbb.get(), out, out_len)) {

    return 0;

  }

  return 1;

}

int pkcs12_key_gen(const char *pass, size_t pass_len, const uint8_t *salt,

                   size_t salt_len, uint8_t id, uint32_t iterations,

                   size_t out_len, uint8_t *out, const EVP_MD *md) {

  // See https://tools.ietf.org/html/rfc7292#appendix-B. Quoted parts of the

  // specification have errata applied and other typos fixed.

  if (iterations < 1) {

    OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_BAD_ITERATION_COUNT);

    return 0;

  }

  int ret = 0;

  EVP_MD_CTX ctx;

  EVP_MD_CTX_init(&ctx);

  uint8_t *pass_raw = NULL, *I = NULL;

  size_t pass_raw_len = 0, I_len = 0;

  {

    // If |pass| is NULL, we use the empty string rather than {0, 0} as the raw

    // password.

    if (pass != NULL &&

        !pkcs12_encode_password(pass, pass_len, &pass_raw, &pass_raw_len)) {

      goto err;

    }

    // In the spec, |block_size| is called "v", but measured in bits.

    size_t block_size = EVP_MD_block_size(md);

    // 1. Construct a string, D (the "diversifier"), by concatenating v/8 copies

    // of ID.

    uint8_t D[EVP_MAX_MD_BLOCK_SIZE];

    OPENSSL_memset(D, id, block_size);

    // 2. Concatenate copies of the salt together to create a string S of length

    // v(ceiling(s/v)) bits (the final copy of the salt may be truncated to

    // create S). Note that if the salt is the empty string, then so is S.

    //

    // 3. Concatenate copies of the password together to create a string P of

    // length v(ceiling(p/v)) bits (the final copy of the password may be

    // truncated to create P).  Note that if the password is the empty string,

    // then so is P.

    //

    // 4. Set I=S||P to be the concatenation of S and P.

    if (salt_len + block_size - 1 < salt_len ||

        pass_raw_len + block_size - 1 < pass_raw_len) {

      OPENSSL_PUT_ERROR(PKCS8, ERR_R_OVERFLOW);

      goto err;

    }

    size_t S_len = block_size * ((salt_len + block_size - 1) / block_size);

    size_t P_len = block_size * ((pass_raw_len + block_size - 1) / block_size);

    I_len = S_len + P_len;

    if (I_len < S_len) {

      OPENSSL_PUT_ERROR(PKCS8, ERR_R_OVERFLOW);

      goto err;

    }

    I = reinterpret_cast<uint8_t *>(OPENSSL_malloc(I_len));

    if (I_len != 0 && I == NULL) {

      goto err;

    }

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

      I[i] = salt[i % salt_len];

    }

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

      I[i + S_len] = pass_raw[i % pass_raw_len];

    }

    while (out_len != 0) {

      // A. Set A_i=H^r(D||I). (i.e., the r-th hash of D||I,

      // H(H(H(... H(D||I))))

      uint8_t A[EVP_MAX_MD_SIZE];

      unsigned A_len;

      if (!EVP_DigestInit_ex(&ctx, md, NULL) ||

          !EVP_DigestUpdate(&ctx, D, block_size) ||

          !EVP_DigestUpdate(&ctx, I, I_len) ||

          !EVP_DigestFinal_ex(&ctx, A, &A_len)) {

        goto err;

      }

      for (uint32_t iter = 1; iter < iterations; iter++) {

        if (!EVP_DigestInit_ex(&ctx, md, NULL) ||

            !EVP_DigestUpdate(&ctx, A, A_len) ||

            !EVP_DigestFinal_ex(&ctx, A, &A_len)) {

          goto err;

        }

      }

      size_t todo = out_len < A_len ? out_len : A_len;

      OPENSSL_memcpy(out, A, todo);

      out += todo;

      out_len -= todo;

      if (out_len == 0) {

        break;

      }

      // B. Concatenate copies of A_i to create a string B of length v bits (the

      // final copy of A_i may be truncated to create B).

      uint8_t B[EVP_MAX_MD_BLOCK_SIZE];

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

        B[i] = A[i % A_len];

      }

      // C. Treating I as a concatenation I_0, I_1, ..., I_(k-1) of v-bit

      // blocks, where k=ceiling(s/v)+ceiling(p/v), modify I by setting

      // I_j=(I_j+B+1) mod 2^v for each j.

      assert(I_len % block_size == 0);

      for (size_t i = 0; i < I_len; i += block_size) {

        unsigned carry = 1;

        for (size_t j = block_size - 1; j < block_size; j--) {

          carry += I[i + j] + B[j];

          I[i + j] = (uint8_t)carry;

          carry >>= 8;

        }

      }

    }

    ret = 1;

  }

err:

  OPENSSL_free(I);

  OPENSSL_free(pass_raw);

  EVP_MD_CTX_cleanup(&ctx);

  return ret;

}

static int pkcs12_pbe_cipher_init(const struct pbe_suite *suite,

                                  EVP_CIPHER_CTX *ctx, uint32_t iterations,

                                  const char *pass, size_t pass_len,

                                  const uint8_t *salt, size_t salt_len,

                                  int is_encrypt) {

  const EVP_CIPHER *cipher = suite->cipher_func();

  const EVP_MD *md = suite->md_func();

  uint8_t key[EVP_MAX_KEY_LENGTH];

  uint8_t iv[EVP_MAX_IV_LENGTH];

  if (!pkcs12_key_gen(pass, pass_len, salt, salt_len, PKCS12_KEY_ID, iterations,

                      EVP_CIPHER_key_length(cipher), key, md) ||

      !pkcs12_key_gen(pass, pass_len, salt, salt_len, PKCS12_IV_ID, iterations,

                      EVP_CIPHER_iv_length(cipher), iv, md)) {

    OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_KEY_GEN_ERROR);

    return 0;

  }

  int ret = EVP_CipherInit_ex(ctx, cipher, NULL, key, iv, is_encrypt);

  OPENSSL_cleanse(key, EVP_MAX_KEY_LENGTH);

  OPENSSL_cleanse(iv, EVP_MAX_IV_LENGTH);

  return ret;

}

static int pkcs12_pbe_decrypt_init(const struct pbe_suite *suite,

                                   EVP_CIPHER_CTX *ctx, const char *pass,

                                   size_t pass_len, CBS *param) {

  CBS pbe_param, salt;

  uint64_t iterations;

  if (!CBS_get_asn1(param, &pbe_param, CBS_ASN1_SEQUENCE) ||

      !CBS_get_asn1(&pbe_param, &salt, CBS_ASN1_OCTETSTRING) ||

      !CBS_get_asn1_uint64(&pbe_param, &iterations) ||

      CBS_len(&pbe_param) != 0 || CBS_len(param) != 0) {

    OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_DECODE_ERROR);

    return 0;

  }

  if (!pkcs12_iterations_acceptable(iterations)) {

    OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_BAD_ITERATION_COUNT);

    return 0;

  }

  return pkcs12_pbe_cipher_init(suite, ctx, (uint32_t)iterations, pass,

                                pass_len, CBS_data(&salt), CBS_len(&salt),

                                0 /* decrypt */);

}

static const struct pbe_suite kBuiltinPBE[] = {

    {

        NID_pbe_WithSHA1And40BitRC2_CBC,

        // 1.2.840.113549.1.12.1.6

        {0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x0c, 0x01, 0x06},

        10,

        EVP_rc2_40_cbc,

        EVP_sha1,

        pkcs12_pbe_decrypt_init,

    },

    {

        NID_pbe_WithSHA1And128BitRC4,

        // 1.2.840.113549.1.12.1.1

        {0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x0c, 0x01, 0x01},

        10,

        EVP_rc4,

        EVP_sha1,

        pkcs12_pbe_decrypt_init,

    },

    {

        NID_pbe_WithSHA1And3_Key_TripleDES_CBC,

        // 1.2.840.113549.1.12.1.3

        {0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x0c, 0x01, 0x03},

        10,

        EVP_des_ede3_cbc,

        EVP_sha1,

        pkcs12_pbe_decrypt_init,

    },

    {

        NID_pbes2,

        // 1.2.840.113549.1.5.13

        {0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x05, 0x0d},

        9,

        NULL,

        NULL,

        PKCS5_pbe2_decrypt_init,

    },

};

static const struct pbe_suite *get_pkcs12_pbe_suite(int pbe_nid) {

  for (unsigned i = 0; i < OPENSSL_ARRAY_SIZE(kBuiltinPBE); i++) {

    if (kBuiltinPBE[i].pbe_nid == pbe_nid &&

        // If |cipher_func| or |md_func| are missing, this is a PBES2 scheme.

        kBuiltinPBE[i].cipher_func != NULL && kBuiltinPBE[i].md_func != NULL) {

      return &kBuiltinPBE[i];

    }

  }

  return NULL;

}

int pkcs12_pbe_encrypt_init(CBB *out, EVP_CIPHER_CTX *ctx, int alg_nid,

                            const EVP_CIPHER *alg_cipher, uint32_t iterations,

                            const char *pass, size_t pass_len,

                            const uint8_t *salt, size_t salt_len) {

  // TODO(davidben): OpenSSL has since extended |pbe_nid| to control either

  // the PBES1 scheme or the PBES2 PRF. E.g. passing |NID_hmacWithSHA256| will

  // select PBES2 with HMAC-SHA256 as the PRF. Implement this if anything uses

  // it. See 5693a30813a031d3921a016a870420e7eb93ec90 in OpenSSL.

  if (alg_nid == -1) {

    return PKCS5_pbe2_encrypt_init(out, ctx, alg_cipher, iterations, pass,

                                   pass_len, salt, salt_len);

  }

  const struct pbe_suite *suite = get_pkcs12_pbe_suite(alg_nid);

  if (suite == NULL) {

    OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_UNKNOWN_ALGORITHM);

    return 0;

  }

  // See RFC 7292, appendix C. All our supported "PBES1" schemes are the PKCS#12

  // schemes, which use a different KDF. The true PBES1 schemes in RFC 8018 use

  // PBKDF1, which use a very similar PBEParameter structure, but require the

  // salt be exactly 8 bytes.

  CBB algorithm, param;

  if (!CBB_add_asn1(out, &algorithm, CBS_ASN1_SEQUENCE) ||

      !CBB_add_asn1_element(&algorithm, CBS_ASN1_OBJECT, suite->oid,

                            suite->oid_len) ||

      !CBB_add_asn1(&algorithm, &param, CBS_ASN1_SEQUENCE) ||

      !CBB_add_asn1_octet_string(&param, salt, salt_len) ||

      !CBB_add_asn1_uint64(&param, iterations) || !CBB_flush(out)) {

    return 0;

  }

  return pkcs12_pbe_cipher_init(suite, ctx, iterations, pass, pass_len, salt,

                                salt_len, 1 /* encrypt */);

}

int pkcs8_pbe_decrypt(uint8_t **out, size_t *out_len, CBS *algorithm,

                      const char *pass, size_t pass_len, const uint8_t *in,

                      size_t in_len) {

  int ret = 0;

  uint8_t *buf = NULL;

  bssl::ScopedEVP_CIPHER_CTX ctx;

  CBS obj;

  const struct pbe_suite *suite = NULL;

  if (!CBS_get_asn1(algorithm, &obj, CBS_ASN1_OBJECT)) {

    OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_DECODE_ERROR);

    goto err;

  }

  for (unsigned i = 0; i < OPENSSL_ARRAY_SIZE(kBuiltinPBE); i++) {

    if (CBS_mem_equal(&obj, kBuiltinPBE[i].oid, kBuiltinPBE[i].oid_len)) {

      suite = &kBuiltinPBE[i];

      break;

    }

  }

  if (suite == NULL) {

    OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_UNKNOWN_ALGORITHM);

    goto err;

  }

  if (!suite->decrypt_init(suite, ctx.get(), pass, pass_len, algorithm)) {

    OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_KEYGEN_FAILURE);

    goto err;

  }

  buf = reinterpret_cast<uint8_t *>(OPENSSL_malloc(in_len));

  if (buf == NULL) {

    goto err;

  }

  if (in_len > INT_MAX) {

    OPENSSL_PUT_ERROR(PKCS8, ERR_R_OVERFLOW);

    goto err;

  }

  int n1, n2;

  if (!EVP_DecryptUpdate(ctx.get(), buf, &n1, in, (int)in_len) ||

      !EVP_DecryptFinal_ex(ctx.get(), buf + n1, &n2)) {

    goto err;

  }

  *out = buf;

  *out_len = n1 + n2;

  ret = 1;

  buf = NULL;

err:

  OPENSSL_free(buf);

  return ret;

}

EVP_PKEY *PKCS8_parse_encrypted_private_key(CBS *cbs, const char *pass,

                                            size_t pass_len) {

  // See RFC 5208, section 6.

  CBS epki, algorithm, ciphertext;

  if (!CBS_get_asn1(cbs, &epki, CBS_ASN1_SEQUENCE) ||

      !CBS_get_asn1(&epki, &algorithm, CBS_ASN1_SEQUENCE) ||

      !CBS_get_asn1(&epki, &ciphertext, CBS_ASN1_OCTETSTRING) ||

      CBS_len(&epki) != 0) {

    OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_DECODE_ERROR);

    return 0;

  }

  uint8_t *out;

  size_t out_len;

  if (!pkcs8_pbe_decrypt(&out, &out_len, &algorithm, pass, pass_len,

                         CBS_data(&ciphertext), CBS_len(&ciphertext))) {

    return 0;

  }

  CBS pki;

  CBS_init(&pki, out, out_len);

  EVP_PKEY *ret = EVP_parse_private_key(&pki);

  OPENSSL_free(out);

  return ret;

}

int PKCS8_marshal_encrypted_private_key(CBB *out, int pbe_nid,

                                        const EVP_CIPHER *cipher,

                                        const char *pass, size_t pass_len,

                                        const uint8_t *salt, size_t salt_len,

                                        int iterations, const EVP_PKEY *pkey) {

  int ret = 0;

  uint8_t *plaintext = NULL, *salt_buf = NULL;

  size_t plaintext_len = 0;

  bssl::ScopedEVP_CIPHER_CTX ctx;

  {

    // Generate a random salt if necessary.

    if (salt == NULL) {

      if (salt_len == 0) {

        salt_len = PKCS5_SALT_LEN;

      }

      salt_buf = reinterpret_cast<uint8_t *>(OPENSSL_malloc(salt_len));

      if (salt_buf == NULL || !RAND_bytes(salt_buf, salt_len)) {

        goto err;

      }

      salt = salt_buf;

    }

    if (iterations <= 0) {

      iterations = PKCS12_DEFAULT_ITER;

    }

    // Serialize the input key.

    CBB plaintext_cbb;

    if (!CBB_init(&plaintext_cbb, 128) ||

        !EVP_marshal_private_key(&plaintext_cbb, pkey) ||

        !CBB_finish(&plaintext_cbb, &plaintext, &plaintext_len)) {

      CBB_cleanup(&plaintext_cbb);

      goto err;

    }

    CBB epki;

    if (!CBB_add_asn1(out, &epki, CBS_ASN1_SEQUENCE) ||

        !pkcs12_pbe_encrypt_init(&epki, ctx.get(), pbe_nid, cipher,

                                 (uint32_t)iterations, pass, pass_len, salt,

                                 salt_len)) {

      goto err;

    }

    size_t max_out = plaintext_len + EVP_CIPHER_CTX_block_size(ctx.get());

    if (max_out < plaintext_len) {

      OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_TOO_LONG);

      goto err;

    }

    CBB ciphertext;

    uint8_t *ptr;

    int n1, n2;

    if (!CBB_add_asn1(&epki, &ciphertext, CBS_ASN1_OCTETSTRING) ||

        !CBB_reserve(&ciphertext, &ptr, max_out) ||

        !EVP_CipherUpdate(ctx.get(), ptr, &n1, plaintext, plaintext_len) ||

        !EVP_CipherFinal_ex(ctx.get(), ptr + n1, &n2) ||

        !CBB_did_write(&ciphertext, n1 + n2) || !CBB_flush(out)) {

      goto err;

    }

    ret = 1;

  }

err:

  OPENSSL_free(plaintext);

  OPENSSL_free(salt_buf);

  return ret;

}