crypto/pkcs8/p5_pbev2.cc

// 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 <limits.h>
#include <string.h>

#include <openssl/bytestring.h>
#include <openssl/cipher.h>
#include <openssl/err.h>
#include <openssl/mem.h>
#include <openssl/nid.h>
#include <openssl/rand.h>

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


// 1.2.840.113549.1.5.12
static const uint8_t kPBKDF2[] = {0x2a, 0x86, 0x48, 0x86, 0xf7,
                                  0x0d, 0x01, 0x05, 0x0c};

// 1.2.840.113549.1.5.13
static const uint8_t kPBES2[] = {0x2a, 0x86, 0x48, 0x86, 0xf7,
                                 0x0d, 0x01, 0x05, 0x0d};

// 1.2.840.113549.2.7
static const uint8_t kHMACWithSHA1[] = {0x2a, 0x86, 0x48, 0x86,
                                        0xf7, 0x0d, 0x02, 0x07};

// 1.2.840.113549.2.9
static const uint8_t kHMACWithSHA256[] = {0x2a, 0x86, 0x48, 0x86,
                                          0xf7, 0x0d, 0x02, 0x09};

static const struct {
  uint8_t oid[9];
  uint8_t oid_len;
  int nid;
  const EVP_CIPHER *(*cipher_func)(void);
} kCipherOIDs[] = {
    // 1.2.840.113549.3.2
    {{0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x03, 0x02},
     8,
     NID_rc2_cbc,
     &EVP_rc2_cbc},
    // 1.2.840.113549.3.7
    {{0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x03, 0x07},
     8,
     NID_des_ede3_cbc,
     &EVP_des_ede3_cbc},
    // 2.16.840.1.101.3.4.1.2
    {{0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x01, 0x02},
     9,
     NID_aes_128_cbc,
     &EVP_aes_128_cbc},
    // 2.16.840.1.101.3.4.1.22
    {{0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x01, 0x16},
     9,
     NID_aes_192_cbc,
     &EVP_aes_192_cbc},
    // 2.16.840.1.101.3.4.1.42
    {{0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x01, 0x2a},
     9,
     NID_aes_256_cbc,
     &EVP_aes_256_cbc},
};

static const EVP_CIPHER *cbs_to_cipher(const CBS *cbs) {
  for (const auto &cipher : kCipherOIDs) {
    if (CBS_mem_equal(cbs, cipher.oid, cipher.oid_len)) {
      return cipher.cipher_func();
    }
  }

  return nullptr;
}

static int add_cipher_oid(CBB *out, int nid) {
  for (const auto &cipher : kCipherOIDs) {
    if (cipher.nid == nid) {
      return CBB_add_asn1_element(out, CBS_ASN1_OBJECT, cipher.oid,
                                  cipher.oid_len);
    }
  }

  OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_UNSUPPORTED_CIPHER);
  return 0;
}

const EVP_CIPHER *pkcs5_pbe2_nid_to_cipher(int nid) {
  for (const auto &cipher : kCipherOIDs) {
    if (cipher.nid == nid) {
      return cipher.cipher_func();
    }
  }
  return nullptr;
}

static int pkcs5_pbe2_cipher_init(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher,
                                  const EVP_MD *pbkdf2_md, uint32_t iterations,
                                  const char *pass, size_t pass_len,
                                  const uint8_t *salt, size_t salt_len,
                                  const uint8_t *iv, size_t iv_len, int enc) {
  if (iv_len != EVP_CIPHER_iv_length(cipher)) {
    OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_ERROR_SETTING_CIPHER_PARAMS);
    return 0;
  }

  uint8_t key[EVP_MAX_KEY_LENGTH];
  int ret = PKCS5_PBKDF2_HMAC(pass, pass_len, salt, salt_len, iterations,
                              pbkdf2_md, EVP_CIPHER_key_length(cipher), key) &&
            EVP_CipherInit_ex(ctx, cipher, NULL /* engine */, key, iv, enc);
  OPENSSL_cleanse(key, EVP_MAX_KEY_LENGTH);
  return ret;
}

int PKCS5_pbe2_encrypt_init(CBB *out, EVP_CIPHER_CTX *ctx,
                            const EVP_CIPHER *cipher, uint32_t iterations,
                            const char *pass, size_t pass_len,
                            const uint8_t *salt, size_t salt_len) {
  int cipher_nid = EVP_CIPHER_nid(cipher);
  if (cipher_nid == NID_undef) {
    OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_CIPHER_HAS_NO_OBJECT_IDENTIFIER);
    return 0;
  }

  // Generate a random IV.
  uint8_t iv[EVP_MAX_IV_LENGTH];
  if (!RAND_bytes(iv, EVP_CIPHER_iv_length(cipher))) {
    return 0;
  }

  // See RFC 2898, appendix A.
  CBB algorithm, param, kdf, kdf_param, cipher_cbb;
  if (!CBB_add_asn1(out, &algorithm, CBS_ASN1_SEQUENCE) ||
      !CBB_add_asn1_element(&algorithm, CBS_ASN1_OBJECT, kPBES2,
                            sizeof(kPBES2)) ||
      !CBB_add_asn1(&algorithm, &param, CBS_ASN1_SEQUENCE) ||
      !CBB_add_asn1(&param, &kdf, CBS_ASN1_SEQUENCE) ||
      !CBB_add_asn1_element(&kdf, CBS_ASN1_OBJECT, kPBKDF2, sizeof(kPBKDF2)) ||
      !CBB_add_asn1(&kdf, &kdf_param, CBS_ASN1_SEQUENCE) ||
      !CBB_add_asn1_octet_string(&kdf_param, salt, salt_len) ||
      !CBB_add_asn1_uint64(&kdf_param, iterations) ||
      // Specify a key length for RC2.
      (cipher_nid == NID_rc2_cbc &&
       !CBB_add_asn1_uint64(&kdf_param, EVP_CIPHER_key_length(cipher))) ||
      // Omit the PRF. We use the default hmacWithSHA1.
      // TODO(crbug.com/396434682): Improve this defaults.
      !CBB_add_asn1(&param, &cipher_cbb, CBS_ASN1_SEQUENCE) ||
      !add_cipher_oid(&cipher_cbb, cipher_nid) ||
      // RFC 2898 says RC2-CBC and RC5-CBC-Pad use a SEQUENCE with version and
      // IV, but OpenSSL always uses an OCTET STRING IV, so we do the same.
      !CBB_add_asn1_octet_string(&cipher_cbb, iv,
                                 EVP_CIPHER_iv_length(cipher)) ||
      !CBB_flush(out)) {
    return 0;
  }

  return pkcs5_pbe2_cipher_init(ctx, cipher, EVP_sha1(), iterations, pass,
                                pass_len, salt, salt_len, iv,
                                EVP_CIPHER_iv_length(cipher), 1 /* encrypt */);
}

int PKCS5_pbe2_decrypt_init(const struct pbe_suite *suite, EVP_CIPHER_CTX *ctx,
                            const char *pass, size_t pass_len, CBS *param) {
  CBS pbe_param, kdf, kdf_obj, enc_scheme, enc_obj;
  if (!CBS_get_asn1(param, &pbe_param, CBS_ASN1_SEQUENCE) ||
      CBS_len(param) != 0 ||
      !CBS_get_asn1(&pbe_param, &kdf, CBS_ASN1_SEQUENCE) ||
      !CBS_get_asn1(&pbe_param, &enc_scheme, CBS_ASN1_SEQUENCE) ||
      CBS_len(&pbe_param) != 0 ||
      !CBS_get_asn1(&kdf, &kdf_obj, CBS_ASN1_OBJECT) ||
      !CBS_get_asn1(&enc_scheme, &enc_obj, CBS_ASN1_OBJECT)) {
    OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_DECODE_ERROR);
    return 0;
  }

  // Only PBKDF2 is supported.
  if (!CBS_mem_equal(&kdf_obj, kPBKDF2, sizeof(kPBKDF2))) {
    OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_UNSUPPORTED_KEY_DERIVATION_FUNCTION);
    return 0;
  }

  // See if we recognise the encryption algorithm.
  const EVP_CIPHER *cipher = cbs_to_cipher(&enc_obj);
  if (cipher == NULL) {
    OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_UNSUPPORTED_CIPHER);
    return 0;
  }

  // Parse the KDF parameters. See RFC 8018, appendix A.2.
  CBS pbkdf2_params, salt;
  uint64_t iterations;
  if (!CBS_get_asn1(&kdf, &pbkdf2_params, CBS_ASN1_SEQUENCE) ||
      CBS_len(&kdf) != 0 ||
      !CBS_get_asn1(&pbkdf2_params, &salt, CBS_ASN1_OCTETSTRING) ||
      !CBS_get_asn1_uint64(&pbkdf2_params, &iterations)) {
    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;
  }

  // The optional keyLength parameter, if present, must match the key length of
  // the cipher.
  if (CBS_peek_asn1_tag(&pbkdf2_params, CBS_ASN1_INTEGER)) {
    uint64_t key_len;
    if (!CBS_get_asn1_uint64(&pbkdf2_params, &key_len)) {
      OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_DECODE_ERROR);
      return 0;
    }

    if (key_len != EVP_CIPHER_key_length(cipher)) {
      OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_UNSUPPORTED_KEYLENGTH);
      return 0;
    }
  }

  const EVP_MD *md = EVP_sha1();
  if (CBS_len(&pbkdf2_params) != 0) {
    CBS alg_id, prf;
    if (!CBS_get_asn1(&pbkdf2_params, &alg_id, CBS_ASN1_SEQUENCE) ||
        !CBS_get_asn1(&alg_id, &prf, CBS_ASN1_OBJECT) ||
        CBS_len(&pbkdf2_params) != 0) {
      OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_DECODE_ERROR);
      return 0;
    }

    if (CBS_mem_equal(&prf, kHMACWithSHA1, sizeof(kHMACWithSHA1))) {
      // hmacWithSHA1 is the DEFAULT, so DER requires it be omitted, but we
      // match OpenSSL in tolerating it being present.
      md = EVP_sha1();
    } else if (CBS_mem_equal(&prf, kHMACWithSHA256, sizeof(kHMACWithSHA256))) {
      md = EVP_sha256();
    } else {
      OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_UNSUPPORTED_PRF);
      return 0;
    }

    // All supported PRFs use a NULL parameter.
    CBS null;
    if (!CBS_get_asn1(&alg_id, &null, CBS_ASN1_NULL) ||
        CBS_len(&null) != 0 ||
        CBS_len(&alg_id) != 0) {
      OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_DECODE_ERROR);
      return 0;
    }
  }

  // Parse the encryption scheme parameters. Note OpenSSL does not match the
  // specification. Per RFC 2898, this should depend on the encryption scheme.
  // In particular, RC2-CBC uses a SEQUENCE with version and IV. We align with
  // OpenSSL.
  CBS iv;
  if (!CBS_get_asn1(&enc_scheme, &iv, CBS_ASN1_OCTETSTRING) ||
      CBS_len(&enc_scheme) != 0) {
    OPENSSL_PUT_ERROR(PKCS8, PKCS8_R_UNSUPPORTED_PRF);
    return 0;
  }

  return pkcs5_pbe2_cipher_init(ctx, cipher, md, (uint32_t)iterations, pass,
                                pass_len, CBS_data(&salt), CBS_len(&salt),
                                CBS_data(&iv), CBS_len(&iv), 0 /* decrypt */);
}