curl/lib/curl_ntlm_core.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ***************************************************************************/

#include "curl_setup.h"

#if defined(USE_NTLM)

/*
 * NTLM details:
 *
 * https://davenport.sourceforge.io/ntlm.html
 * https://www.innovation.ch/java/ntlm.html
 */

#if !defined(USE_WINDOWS_SSPI) || defined(USE_WIN32_CRYPTO)

#ifdef USE_OPENSSL

#  ifdef USE_OPENSSL
#    include <openssl/des.h>
#    ifndef OPENSSL_NO_MD4
#      include <openssl/md4.h>
#    endif
#    include <openssl/md5.h>
#    include <openssl/ssl.h>
#    include <openssl/rand.h>
#  else
#    include <des.h>
#    ifndef OPENSSL_NO_MD4
#      include <md4.h>
#    endif
#    include <md5.h>
#    include <ssl.h>
#    include <rand.h>
#  endif
#  if (OPENSSL_VERSION_NUMBER < 0x00907001L)
#    define DES_key_schedule des_key_schedule
#    define DES_cblock des_cblock
#    define DES_set_odd_parity des_set_odd_parity
#    define DES_set_key des_set_key
#    define DES_ecb_encrypt des_ecb_encrypt
#    define DESKEY(x) x
#    define DESKEYARG(x) x
#  else
#    define DESKEYARG(x) *x
#    define DESKEY(x) &x
#  endif

#elif defined(USE_GNUTLS_NETTLE)

#  include <nettle/des.h>
#  include <nettle/md4.h>

#elif defined(USE_GNUTLS)

#  include <gcrypt.h>
#  define MD5_DIGEST_LENGTH 16
#  define MD4_DIGEST_LENGTH 16

#elif defined(USE_MBEDTLS)

#  include <mbedtls/des.h>
#  include <mbedtls/md4.h>
#  if !defined(MBEDTLS_MD4_C)
#    include "curl_md4.h"
#  endif

#elif defined(USE_NSS)

#  include <nss.h>
#  include <pk11pub.h>
#  include <hasht.h>
#  include "curl_md4.h"
#  define MD5_DIGEST_LENGTH MD5_LENGTH

#elif defined(USE_DARWINSSL)

#  include <CommonCrypto/CommonCryptor.h>
#  include <CommonCrypto/CommonDigest.h>

#elif defined(USE_OS400CRYPTO)
#  include "cipher.mih"  /* mih/cipher */
#  include "curl_md4.h"
#elif defined(USE_WIN32_CRYPTO)
#  include <wincrypt.h>
#else
#  error "Can't compile NTLM support without a crypto library."
#endif

#include "urldata.h"
#include "non-ascii.h"
#include "strcase.h"
#include "curl_ntlm_core.h"
#include "curl_md5.h"
#include "curl_hmac.h"
#include "warnless.h"
#include "curl_endian.h"
#include "curl_des.h"
/* The last 3 #include files should be in this order */
#include "curl_printf.h"
#include "curl_memory.h"
#include "memdebug.h"

#define NTLM_HMAC_MD5_LEN     (16)
#define NTLMv2_BLOB_SIGNATURE "\x01\x01\x00\x00"
#define NTLMv2_BLOB_LEN       (44 -16 + ntlm->target_info_len + 4)

/*
* Turns a 56-bit key into being 64-bit wide.
*/
static void extend_key_56_to_64(const unsigned char *key_56, char *key)
{
  key[0] = key_56[0];
  key[1] = (unsigned char)(((key_56[0] << 7) & 0xFF) | (key_56[1] >> 1));
  key[2] = (unsigned char)(((key_56[1] << 6) & 0xFF) | (key_56[2] >> 2));
  key[3] = (unsigned char)(((key_56[2] << 5) & 0xFF) | (key_56[3] >> 3));
  key[4] = (unsigned char)(((key_56[3] << 4) & 0xFF) | (key_56[4] >> 4));
  key[5] = (unsigned char)(((key_56[4] << 3) & 0xFF) | (key_56[5] >> 5));
  key[6] = (unsigned char)(((key_56[5] << 2) & 0xFF) | (key_56[6] >> 6));
  key[7] = (unsigned char) ((key_56[6] << 1) & 0xFF);
}

#ifdef USE_OPENSSL
/*
 * Turns a 56 bit key into the 64 bit, odd parity key and sets the key.  The
 * key schedule ks is also set.
 */
static void setup_des_key(const unsigned char *key_56,
                          DES_key_schedule DESKEYARG(ks))
{
  DES_cblock key;

  /* Expand the 56-bit key to 64-bits */
  extend_key_56_to_64(key_56, (char *) &key);

  /* Set the key parity to odd */
  DES_set_odd_parity(&key);

  /* Set the key */
  DES_set_key(&key, ks);
}

#elif defined(USE_GNUTLS_NETTLE)

static void setup_des_key(const unsigned char *key_56,
                          struct des_ctx *des)
{
  char key[8];

  /* Expand the 56-bit key to 64-bits */
  extend_key_56_to_64(key_56, key);

  /* Set the key parity to odd */
  Curl_des_set_odd_parity((unsigned char *) key, sizeof(key));

  /* Set the key */
  des_set_key(des, (const uint8_t *) key);
}

#elif defined(USE_GNUTLS)

/*
 * Turns a 56 bit key into the 64 bit, odd parity key and sets the key.
 */
static void setup_des_key(const unsigned char *key_56,
                          gcry_cipher_hd_t *des)
{
  char key[8];

  /* Expand the 56-bit key to 64-bits */
  extend_key_56_to_64(key_56, key);

  /* Set the key parity to odd */
  Curl_des_set_odd_parity((unsigned char *) key, sizeof(key));

  /* Set the key */
  gcry_cipher_setkey(*des, key, sizeof(key));
}

#elif defined(USE_MBEDTLS)

static bool encrypt_des(const unsigned char *in, unsigned char *out,
                        const unsigned char *key_56)
{
  mbedtls_des_context ctx;
  char key[8];

  /* Expand the 56-bit key to 64-bits */
  extend_key_56_to_64(key_56, key);

  /* Set the key parity to odd */
  mbedtls_des_key_set_parity((unsigned char *) key);

  /* Perform the encryption */
  mbedtls_des_init(&ctx);
  mbedtls_des_setkey_enc(&ctx, (unsigned char *) key);
  return mbedtls_des_crypt_ecb(&ctx, in, out) == 0;
}

#elif defined(USE_NSS)

/*
 * Expands a 56 bit key KEY_56 to 64 bit and encrypts 64 bit of data, using
 * the expanded key.  The caller is responsible for giving 64 bit of valid
 * data is IN and (at least) 64 bit large buffer as OUT.
 */
static bool encrypt_des(const unsigned char *in, unsigned char *out,
                        const unsigned char *key_56)
{
  const CK_MECHANISM_TYPE mech = CKM_DES_ECB; /* DES cipher in ECB mode */
  PK11SlotInfo *slot = NULL;
  char key[8];                                /* expanded 64 bit key */
  SECItem key_item;
  PK11SymKey *symkey = NULL;
  SECItem *param = NULL;
  PK11Context *ctx = NULL;
  int out_len;                                /* not used, required by NSS */
  bool rv = FALSE;

  /* use internal slot for DES encryption (requires NSS to be initialized) */
  slot = PK11_GetInternalKeySlot();
  if(!slot)
    return FALSE;

  /* Expand the 56-bit key to 64-bits */
  extend_key_56_to_64(key_56, key);

  /* Set the key parity to odd */
  Curl_des_set_odd_parity((unsigned char *) key, sizeof(key));

  /* Import the key */
  key_item.data = (unsigned char *)key;
  key_item.len = sizeof(key);
  symkey = PK11_ImportSymKey(slot, mech, PK11_OriginUnwrap, CKA_ENCRYPT,
                             &key_item, NULL);
  if(!symkey)
    goto fail;

  /* Create the DES encryption context */
  param = PK11_ParamFromIV(mech, /* no IV in ECB mode */ NULL);
  if(!param)
    goto fail;
  ctx = PK11_CreateContextBySymKey(mech, CKA_ENCRYPT, symkey, param);
  if(!ctx)
    goto fail;

  /* Perform the encryption */
  if(SECSuccess == PK11_CipherOp(ctx, out, &out_len, /* outbuflen */ 8,
                                 (unsigned char *)in, /* inbuflen */ 8)
      && SECSuccess == PK11_Finalize(ctx))
    rv = /* all OK */ TRUE;

fail:
  /* cleanup */
  if(ctx)
    PK11_DestroyContext(ctx, PR_TRUE);
  if(symkey)
    PK11_FreeSymKey(symkey);
  if(param)
    SECITEM_FreeItem(param, PR_TRUE);
  PK11_FreeSlot(slot);
  return rv;
}

#elif defined(USE_DARWINSSL)

static bool encrypt_des(const unsigned char *in, unsigned char *out,
                        const unsigned char *key_56)
{
  char key[8];
  size_t out_len;
  CCCryptorStatus err;

  /* Expand the 56-bit key to 64-bits */
  extend_key_56_to_64(key_56, key);

  /* Set the key parity to odd */
  Curl_des_set_odd_parity((unsigned char *) key, sizeof(key));

  /* Perform the encryption */
  err = CCCrypt(kCCEncrypt, kCCAlgorithmDES, kCCOptionECBMode, key,
                kCCKeySizeDES, NULL, in, 8 /* inbuflen */, out,
                8 /* outbuflen */, &out_len);

  return err == kCCSuccess;
}

#elif defined(USE_OS400CRYPTO)

static bool encrypt_des(const unsigned char *in, unsigned char *out,
                        const unsigned char *key_56)
{
  char key[8];
  _CIPHER_Control_T ctl;

  /* Setup the cipher control structure */
  ctl.Func_ID = ENCRYPT_ONLY;
  ctl.Data_Len = sizeof(key);

  /* Expand the 56-bit key to 64-bits */
  extend_key_56_to_64(key_56, ctl.Crypto_Key);

  /* Set the key parity to odd */
  Curl_des_set_odd_parity((unsigned char *) ctl.Crypto_Key, ctl.Data_Len);

  /* Perform the encryption */
  _CIPHER((_SPCPTR *) &out, &ctl, (_SPCPTR *) &in);

  return TRUE;
}

#elif defined(USE_WIN32_CRYPTO)

static bool encrypt_des(const unsigned char *in, unsigned char *out,
                        const unsigned char *key_56)
{
  HCRYPTPROV hprov;
  HCRYPTKEY hkey;
  struct {
    BLOBHEADER hdr;
    unsigned int len;
    char key[8];
  } blob;
  DWORD len = 8;

  /* Acquire the crypto provider */
  if(!CryptAcquireContext(&hprov, NULL, NULL, PROV_RSA_FULL,
                          CRYPT_VERIFYCONTEXT))
    return FALSE;

  /* Setup the key blob structure */
  memset(&blob, 0, sizeof(blob));
  blob.hdr.bType = PLAINTEXTKEYBLOB;
  blob.hdr.bVersion = 2;
  blob.hdr.aiKeyAlg = CALG_DES;
  blob.len = sizeof(blob.key);

  /* Expand the 56-bit key to 64-bits */
  extend_key_56_to_64(key_56, blob.key);

  /* Set the key parity to odd */
  Curl_des_set_odd_parity((unsigned char *) blob.key, sizeof(blob.key));

  /* Import the key */
  if(!CryptImportKey(hprov, (BYTE *) &blob, sizeof(blob), 0, 0, &hkey)) {
    CryptReleaseContext(hprov, 0);

    return FALSE;
  }

  memcpy(out, in, 8);

  /* Perform the encryption */
  CryptEncrypt(hkey, 0, FALSE, 0, out, &len, len);

  CryptDestroyKey(hkey);
  CryptReleaseContext(hprov, 0);

  return TRUE;
}

#endif /* defined(USE_WIN32_CRYPTO) */

 /*
  * takes a 21 byte array and treats it as 3 56-bit DES keys. The
  * 8 byte plaintext is encrypted with each key and the resulting 24
  * bytes are stored in the results array.
  */
void Curl_ntlm_core_lm_resp(const unsigned char *keys,
                            const unsigned char *plaintext,
                            unsigned char *results)
{
#ifdef USE_OPENSSL
  DES_key_schedule ks;

  setup_des_key(keys, DESKEY(ks));
  DES_ecb_encrypt((DES_cblock*) plaintext, (DES_cblock*) results,
                  DESKEY(ks), DES_ENCRYPT);

  setup_des_key(keys + 7, DESKEY(ks));
  DES_ecb_encrypt((DES_cblock*) plaintext, (DES_cblock*) (results + 8),
                  DESKEY(ks), DES_ENCRYPT);

  setup_des_key(keys + 14, DESKEY(ks));
  DES_ecb_encrypt((DES_cblock*) plaintext, (DES_cblock*) (results + 16),
                  DESKEY(ks), DES_ENCRYPT);
#elif defined(USE_GNUTLS_NETTLE)
  struct des_ctx des;
  setup_des_key(keys, &des);
  des_encrypt(&des, 8, results, plaintext);
  setup_des_key(keys + 7, &des);
  des_encrypt(&des, 8, results + 8, plaintext);
  setup_des_key(keys + 14, &des);
  des_encrypt(&des, 8, results + 16, plaintext);
#elif defined(USE_GNUTLS)
  gcry_cipher_hd_t des;

  gcry_cipher_open(&des, GCRY_CIPHER_DES, GCRY_CIPHER_MODE_ECB, 0);
  setup_des_key(keys, &des);
  gcry_cipher_encrypt(des, results, 8, plaintext, 8);
  gcry_cipher_close(des);

  gcry_cipher_open(&des, GCRY_CIPHER_DES, GCRY_CIPHER_MODE_ECB, 0);
  setup_des_key(keys + 7, &des);
  gcry_cipher_encrypt(des, results + 8, 8, plaintext, 8);
  gcry_cipher_close(des);

  gcry_cipher_open(&des, GCRY_CIPHER_DES, GCRY_CIPHER_MODE_ECB, 0);
  setup_des_key(keys + 14, &des);
  gcry_cipher_encrypt(des, results + 16, 8, plaintext, 8);
  gcry_cipher_close(des);
#elif defined(USE_MBEDTLS) || defined(USE_NSS) || defined(USE_DARWINSSL) \
  || defined(USE_OS400CRYPTO) || defined(USE_WIN32_CRYPTO)
  encrypt_des(plaintext, results, keys);
  encrypt_des(plaintext, results + 8, keys + 7);
  encrypt_des(plaintext, results + 16, keys + 14);
#endif
}

/*
 * Set up lanmanager hashed password
 */
CURLcode Curl_ntlm_core_mk_lm_hash(struct Curl_easy *data,
                                   const char *password,
                                   unsigned char *lmbuffer /* 21 bytes */)
{
  CURLcode result;
  unsigned char pw[14];
  static const unsigned char magic[] = {
    0x4B, 0x47, 0x53, 0x21, 0x40, 0x23, 0x24, 0x25 /* i.e. KGS!@#$% */
  };
  size_t len = CURLMIN(strlen(password), 14);

  Curl_strntoupper((char *)pw, password, len);
  memset(&pw[len], 0, 14 - len);

  /*
   * The LanManager hashed password needs to be created using the
   * password in the network encoding not the host encoding.
   */
  result = Curl_convert_to_network(data, (char *)pw, 14);
  if(result)
    return result;

  {
    /* Create LanManager hashed password. */

#ifdef USE_OPENSSL
    DES_key_schedule ks;

    setup_des_key(pw, DESKEY(ks));
    DES_ecb_encrypt((DES_cblock *)magic, (DES_cblock *)lmbuffer,
                    DESKEY(ks), DES_ENCRYPT);

    setup_des_key(pw + 7, DESKEY(ks));
    DES_ecb_encrypt((DES_cblock *)magic, (DES_cblock *)(lmbuffer + 8),
                    DESKEY(ks), DES_ENCRYPT);
#elif defined(USE_GNUTLS_NETTLE)
    struct des_ctx des;
    setup_des_key(pw, &des);
    des_encrypt(&des, 8, lmbuffer, magic);
    setup_des_key(pw + 7, &des);
    des_encrypt(&des, 8, lmbuffer + 8, magic);
#elif defined(USE_GNUTLS)
    gcry_cipher_hd_t des;

    gcry_cipher_open(&des, GCRY_CIPHER_DES, GCRY_CIPHER_MODE_ECB, 0);
    setup_des_key(pw, &des);
    gcry_cipher_encrypt(des, lmbuffer, 8, magic, 8);
    gcry_cipher_close(des);

    gcry_cipher_open(&des, GCRY_CIPHER_DES, GCRY_CIPHER_MODE_ECB, 0);
    setup_des_key(pw + 7, &des);
    gcry_cipher_encrypt(des, lmbuffer + 8, 8, magic, 8);
    gcry_cipher_close(des);
#elif defined(USE_MBEDTLS) || defined(USE_NSS) || defined(USE_DARWINSSL) \
  || defined(USE_OS400CRYPTO) || defined(USE_WIN32_CRYPTO)
    encrypt_des(magic, lmbuffer, pw);
    encrypt_des(magic, lmbuffer + 8, pw + 7);
#endif

    memset(lmbuffer + 16, 0, 21 - 16);
  }

  return CURLE_OK;
}

#ifdef USE_NTRESPONSES
static void ascii_to_unicode_le(unsigned char *dest, const char *src,
                                size_t srclen)
{
  size_t i;
  for(i = 0; i < srclen; i++) {
    dest[2 * i] = (unsigned char)src[i];
    dest[2 * i + 1] = '\0';
  }
}

#if defined(USE_NTLM_V2) && !defined(USE_WINDOWS_SSPI)

static void ascii_uppercase_to_unicode_le(unsigned char *dest,
                                          const char *src, size_t srclen)
{
  size_t i;
  for(i = 0; i < srclen; i++) {
    dest[2 * i] = (unsigned char)(Curl_raw_toupper(src[i]));
    dest[2 * i + 1] = '\0';
  }
}

#endif /* USE_NTLM_V2 && !USE_WINDOWS_SSPI */

/*
 * Set up nt hashed passwords
 * @unittest: 1600
 */
CURLcode Curl_ntlm_core_mk_nt_hash(struct Curl_easy *data,
                                   const char *password,
                                   unsigned char *ntbuffer /* 21 bytes */)
{
  size_t len = strlen(password);
  unsigned char *pw = malloc(len * 2);
  CURLcode result;
  if(!pw)
    return CURLE_OUT_OF_MEMORY;

  ascii_to_unicode_le(pw, password, len);

  /*
   * The NT hashed password needs to be created using the password in the
   * network encoding not the host encoding.
   */
  result = Curl_convert_to_network(data, (char *)pw, len * 2);
  if(result)
    return result;

  {
    /* Create NT hashed password. */
#ifdef USE_OPENSSL
    MD4_CTX MD4pw;
    MD4_Init(&MD4pw);
    MD4_Update(&MD4pw, pw, 2 * len);
    MD4_Final(ntbuffer, &MD4pw);
#elif defined(USE_GNUTLS_NETTLE)
    struct md4_ctx MD4pw;
    md4_init(&MD4pw);
    md4_update(&MD4pw, (unsigned int)(2 * len), pw);
    md4_digest(&MD4pw, MD4_DIGEST_SIZE, ntbuffer);
#elif defined(USE_GNUTLS)
    gcry_md_hd_t MD4pw;
    gcry_md_open(&MD4pw, GCRY_MD_MD4, 0);
    gcry_md_write(MD4pw, pw, 2 * len);
    memcpy(ntbuffer, gcry_md_read(MD4pw, 0), MD4_DIGEST_LENGTH);
    gcry_md_close(MD4pw);
#elif defined(USE_NSS) || defined(USE_OS400CRYPTO) || \
    (defined(USE_MBEDTLS) && !defined(MBEDTLS_MD4_C))
    Curl_md4it(ntbuffer, pw, 2 * len);
#elif defined(USE_MBEDTLS)
    mbedtls_md4(pw, 2 * len, ntbuffer);
#elif defined(USE_DARWINSSL)
    (void)CC_MD4(pw, (CC_LONG)(2 * len), ntbuffer);
#elif defined(USE_WIN32_CRYPTO)
    HCRYPTPROV hprov;
    if(CryptAcquireContext(&hprov, NULL, NULL, PROV_RSA_FULL,
                           CRYPT_VERIFYCONTEXT)) {
      HCRYPTHASH hhash;
      if(CryptCreateHash(hprov, CALG_MD4, 0, 0, &hhash)) {
        DWORD length = 16;
        CryptHashData(hhash, pw, (unsigned int)len * 2, 0);
        CryptGetHashParam(hhash, HP_HASHVAL, ntbuffer, &length, 0);
        CryptDestroyHash(hhash);
      }
      CryptReleaseContext(hprov, 0);
    }
#endif

    memset(ntbuffer + 16, 0, 21 - 16);
  }

  free(pw);

  return CURLE_OK;
}

#if defined(USE_NTLM_V2) && !defined(USE_WINDOWS_SSPI)

/* This returns the HMAC MD5 digest */
CURLcode Curl_hmac_md5(const unsigned char *key, unsigned int keylen,
                       const unsigned char *data, unsigned int datalen,
                       unsigned char *output)
{
  HMAC_context *ctxt = Curl_HMAC_init(Curl_HMAC_MD5, key, keylen);

  if(!ctxt)
    return CURLE_OUT_OF_MEMORY;

  /* Update the digest with the given challenge */
  Curl_HMAC_update(ctxt, data, datalen);

  /* Finalise the digest */
  Curl_HMAC_final(ctxt, output);

  return CURLE_OK;
}

/* This creates the NTLMv2 hash by using NTLM hash as the key and Unicode
 * (uppercase UserName + Domain) as the data
 */
CURLcode Curl_ntlm_core_mk_ntlmv2_hash(const char *user, size_t userlen,
                                       const char *domain, size_t domlen,
                                       unsigned char *ntlmhash,
                                       unsigned char *ntlmv2hash)
{
  /* Unicode representation */
  size_t identity_len = (userlen + domlen) * 2;
  unsigned char *identity = malloc(identity_len);
  CURLcode result = CURLE_OK;

  if(!identity)
    return CURLE_OUT_OF_MEMORY;

  ascii_uppercase_to_unicode_le(identity, user, userlen);
  ascii_to_unicode_le(identity + (userlen << 1), domain, domlen);

  result = Curl_hmac_md5(ntlmhash, 16, identity, curlx_uztoui(identity_len),
                         ntlmv2hash);

  free(identity);

  return result;
}

/*
 * Curl_ntlm_core_mk_ntlmv2_resp()
 *
 * This creates the NTLMv2 response as set in the ntlm type-3 message.
 *
 * Parameters:
 *
 * ntlmv2hash       [in] - The ntlmv2 hash (16 bytes)
 * challenge_client [in] - The client nonce (8 bytes)
 * ntlm             [in] - The ntlm data struct being used to read TargetInfo
                           and Server challenge received in the type-2 message
 * ntresp          [out] - The address where a pointer to newly allocated
 *                         memory holding the NTLMv2 response.
 * ntresp_len      [out] - The length of the output message.
 *
 * Returns CURLE_OK on success.
 */
CURLcode Curl_ntlm_core_mk_ntlmv2_resp(unsigned char *ntlmv2hash,
                                       unsigned char *challenge_client,
                                       struct ntlmdata *ntlm,
                                       unsigned char **ntresp,
                                       unsigned int *ntresp_len)
{
/* NTLMv2 response structure :
------------------------------------------------------------------------------
0     HMAC MD5         16 bytes
------BLOB--------------------------------------------------------------------
16    Signature        0x01010000
20    Reserved         long (0x00000000)
24    Timestamp        LE, 64-bit signed value representing the number of
                       tenths of a microsecond since January 1, 1601.
32    Client Nonce     8 bytes
40    Unknown          4 bytes
44    Target Info      N bytes (from the type-2 message)
44+N  Unknown          4 bytes
------------------------------------------------------------------------------
*/

  unsigned int len = 0;
  unsigned char *ptr = NULL;
  unsigned char hmac_output[NTLM_HMAC_MD5_LEN];
  curl_off_t tw;

  CURLcode result = CURLE_OK;

#if CURL_SIZEOF_CURL_OFF_T < 8
#error "this section needs 64bit support to work"
#endif

  /* Calculate the timestamp */
#ifdef DEBUGBUILD
  char *force_timestamp = getenv("CURL_FORCETIME");
  if(force_timestamp)
    tw = CURL_OFF_T_C(11644473600) * 10000000;
  else
#endif
    tw = ((curl_off_t)time(NULL) + CURL_OFF_T_C(11644473600)) * 10000000;

  /* Calculate the response len */
  len = NTLM_HMAC_MD5_LEN + NTLMv2_BLOB_LEN;

  /* Allocate the response */
  ptr = malloc(len);
  if(!ptr)
    return CURLE_OUT_OF_MEMORY;

  memset(ptr, 0, len);

  /* Create the BLOB structure */
  snprintf((char *)ptr + NTLM_HMAC_MD5_LEN, NTLMv2_BLOB_LEN,
           "%c%c%c%c"   /* NTLMv2_BLOB_SIGNATURE */
           "%c%c%c%c",  /* Reserved = 0 */
           NTLMv2_BLOB_SIGNATURE[0], NTLMv2_BLOB_SIGNATURE[1],
           NTLMv2_BLOB_SIGNATURE[2], NTLMv2_BLOB_SIGNATURE[3],
           0, 0, 0, 0);

  Curl_write64_le(tw, ptr + 24);
  memcpy(ptr + 32, challenge_client, 8);
  memcpy(ptr + 44, ntlm->target_info, ntlm->target_info_len);

  /* Concatenate the Type 2 challenge with the BLOB and do HMAC MD5 */
  memcpy(ptr + 8, &ntlm->nonce[0], 8);
  result = Curl_hmac_md5(ntlmv2hash, NTLM_HMAC_MD5_LEN, ptr + 8,
                         NTLMv2_BLOB_LEN + 8, hmac_output);
  if(result) {
    free(ptr);
    return result;
  }

  /* Concatenate the HMAC MD5 output  with the BLOB */
  memcpy(ptr, hmac_output, NTLM_HMAC_MD5_LEN);

  /* Return the response */
  *ntresp = ptr;
  *ntresp_len = len;

  return result;
}

/*
 * Curl_ntlm_core_mk_lmv2_resp()
 *
 * This creates the LMv2 response as used in the ntlm type-3 message.
 *
 * Parameters:
 *
 * ntlmv2hash        [in] - The ntlmv2 hash (16 bytes)
 * challenge_client  [in] - The client nonce (8 bytes)
 * challenge_client  [in] - The server challenge (8 bytes)
 * lmresp           [out] - The LMv2 response (24 bytes)
 *
 * Returns CURLE_OK on success.
 */
CURLcode  Curl_ntlm_core_mk_lmv2_resp(unsigned char *ntlmv2hash,
                                      unsigned char *challenge_client,
                                      unsigned char *challenge_server,
                                      unsigned char *lmresp)
{
  unsigned char data[16];
  unsigned char hmac_output[16];
  CURLcode result = CURLE_OK;

  memcpy(&data[0], challenge_server, 8);
  memcpy(&data[8], challenge_client, 8);

  result = Curl_hmac_md5(ntlmv2hash, 16, &data[0], 16, hmac_output);
  if(result)
    return result;

  /* Concatenate the HMAC MD5 output  with the client nonce */
  memcpy(lmresp, hmac_output, 16);
  memcpy(lmresp+16, challenge_client, 8);

  return result;
}

#endif /* USE_NTLM_V2 && !USE_WINDOWS_SSPI */

#endif /* USE_NTRESPONSES */

#endif /* !USE_WINDOWS_SSPI || USE_WIN32_CRYPTO */

#endif /* USE_NTLM */