/* 

   Unix SMB/CIFS implementation.

   code to encrypt/decrypt data using the user session key

   Copyright (C) Andrew Tridgell 2004

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <http://www.gnu.org/licenses/>.

*/

#include "includes.h"

#include "libcli/auth/libcli_auth.h"

/*

  encrypt or decrypt a blob of data using the user session key

  as used in lsa_SetSecret

  before calling, the out blob must be initialised to be the same size

  as the in blob

*/

int sess_crypt_blob(DATA_BLOB *out, const DATA_BLOB *in, const DATA_BLOB *session_key,

        enum samba_gnutls_direction encrypt)

{

  int i, k, rc;

  if (in->length % 8 != 0) {

    return GNUTLS_E_INVALID_REQUEST;

  }

  if (session_key->length < 7) {

    return GNUTLS_E_INVALID_REQUEST;

  }

  for (i=0,k=0;

       i<in->length;

       i += 8, k += 7) {

    uint8_t bin[8], bout[8], key[7];

    memcpy(bin,  &in->data[i], 8);

    if (k + 7 > session_key->length) {

      k = (session_key->length - k);

    }

    memcpy(key, &session_key->data[k], 7);

    rc = des_crypt56_gnutls(bout, bin, key, encrypt);

    if (rc != 0) {

      ZERO_ARRAY(bin);

      ZERO_ARRAY(bout);

      ZERO_ARRAY(key);

      return rc;

    }

    memcpy(&out->data[i], bout, 8);

    ZERO_ARRAY(bin);

    ZERO_ARRAY(bout);

    ZERO_ARRAY(key);

  }

  return 0;

}

/*

  a convenient wrapper around sess_crypt_blob() for strings, using the LSA convention

  note that we round the length to a multiple of 8. This seems to be needed for 

  compatibility with windows

  caller should free using data_blob_free()

*/

DATA_BLOB sess_encrypt_string(const char *str, const DATA_BLOB *session_key)

{

  DATA_BLOB ret, src;

  int slen = strlen(str);

  int dlen = (slen+7) & ~7;

  int rc;

  src = data_blob(NULL, 8+dlen);

  if (!src.data) {

    return data_blob(NULL, 0);

  }

  ret = data_blob(NULL, 8+dlen);

  if (!ret.data) {

    data_blob_free(&src);

    return data_blob(NULL, 0);

  }

  SIVAL(src.data, 0, slen);

  SIVAL(src.data, 4, 1);

  memset(src.data+8, 0,   dlen);

  memcpy(src.data+8, str, slen);

  rc = sess_crypt_blob(&ret, &src, session_key, SAMBA_GNUTLS_ENCRYPT);

  data_blob_free(&src);

  if (rc != 0) {

    data_blob_free(&ret);

    return data_blob(NULL, 0);

  }

  return ret;

}

/*

  a convenient wrapper around sess_crypt_blob() for strings, using the LSA convention

  caller should free the returned string

*/

char *sess_decrypt_string(TALLOC_CTX *mem_ctx, 

        DATA_BLOB *blob, const DATA_BLOB *session_key)

{

  DATA_BLOB out;

  int rc, slen;

  char *ret;

  if (blob->length < 8) {

    return NULL;

  }

  out = data_blob_talloc_s(mem_ctx, NULL, blob->length);

  if (!out.data) {

    return NULL;

  }

  rc = sess_crypt_blob(&out, blob, session_key, SAMBA_GNUTLS_DECRYPT);

  if (rc != 0) {

    data_blob_free(&out);

    return NULL;

  }

  if (IVAL(out.data, 4) != 1) {

    DEBUG(0,("Unexpected revision number %d in session encrypted string\n",

       IVAL(out.data, 4)));

    data_blob_free(&out);

    return NULL;

  }

  slen = IVAL(out.data, 0);

  if (slen > blob->length - 8) {

    DEBUG(0,("Invalid crypt length %d\n", slen));

    data_blob_free(&out);

    return NULL;

  }

  ret = talloc_strndup(mem_ctx, (const char *)(out.data+8), slen);

  data_blob_free(&out);

  DEBUG(0,("decrypted string '%s' of length %d\n", ret, slen));

  return ret;

}

/*

  a convenient wrapper around sess_crypt_blob() for DATA_BLOBs, using the LSA convention

  note that we round the length to a multiple of 8. This seems to be needed for 

  compatibility with windows

  caller should free using data_blob_free()

*/

DATA_BLOB sess_encrypt_blob(TALLOC_CTX *mem_ctx, DATA_BLOB *blob_in, const DATA_BLOB *session_key)

{

  DATA_BLOB ret, src;

  int dlen = (blob_in->length+7) & ~7;

  int rc;

  src = data_blob_talloc_s(mem_ctx, NULL, 8 + dlen);

  if (!src.data) {

    return data_blob(NULL, 0);

  }

  ret = data_blob_talloc_s(mem_ctx, NULL, 8 + dlen);

  if (!ret.data) {

    data_blob_free(&src);

    return data_blob(NULL, 0);

  }

  SIVAL(src.data, 0, blob_in->length);

  SIVAL(src.data, 4, 1);

  memset(src.data+8, 0, dlen);

  memcpy(src.data+8, blob_in->data, blob_in->length);

  rc = sess_crypt_blob(&ret, &src, session_key, SAMBA_GNUTLS_ENCRYPT);

  data_blob_free(&src);

  if (rc != 0) {

    data_blob_free(&ret);

    return data_blob(NULL, 0);

  }

  return ret;

}

/*

  Decrypt a DATA_BLOB using the LSA convention

*/

NTSTATUS sess_decrypt_blob(TALLOC_CTX *mem_ctx, const DATA_BLOB *blob, const DATA_BLOB *session_key, 

         DATA_BLOB *ret)

{

  DATA_BLOB out;

  int rc, slen;

  if (blob->length < 8) {

    DEBUG(0, ("Unexpected length %d in session encrypted secret (BLOB)\n",

        (int)blob->length));

    return NT_STATUS_INVALID_PARAMETER;

  }

  out = data_blob_talloc_s(mem_ctx, NULL, blob->length);

  if (!out.data) {

    return NT_STATUS_NO_MEMORY;

  }

  rc = sess_crypt_blob(&out, blob, session_key, SAMBA_GNUTLS_DECRYPT);

  if (rc != 0) {

    data_blob_free(&out);

    return gnutls_error_to_ntstatus(rc, NT_STATUS_ACCESS_DISABLED_BY_POLICY_OTHER);

  }

  if (IVAL(out.data, 4) != 1) {

    DEBUG(2,("Unexpected revision number %d in session encrypted secret (BLOB)\n",

       IVAL(out.data, 4)));

    return NT_STATUS_UNKNOWN_REVISION;

  }

  slen = IVAL(out.data, 0);

  if (slen > blob->length - 8) {

    DEBUG(0,("Invalid crypt length %d in session encrypted secret (BLOB)\n", slen));

    return NT_STATUS_WRONG_PASSWORD;

  }

  *ret = data_blob_talloc_s(mem_ctx, out.data + 8, slen);

  if (slen && !ret->data) {

    return NT_STATUS_NO_MEMORY;

  }

  data_blob_free(&out);

  return NT_STATUS_OK;

}